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Chronic administration of hydrolysed pine nut oil to mice improves insulin sensitivity and glucose tolerance and increases energy expenditure via a free fatty acid receptor 4-dependent mechanism

Published online by Cambridge University Press:  16 May 2024

Edward Taynton Wargent
Affiliation:
Institute of Translational Medicine, Clore Laboratory, University of Buckingham, Buckingham, MK18 1EG, UK
Małgorzata A. Kępczyńska
Affiliation:
Institute of Translational Medicine, Clore Laboratory, University of Buckingham, Buckingham, MK18 1EG, UK
Mads H. Kaspersen
Affiliation:
Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense, Denmark
Elisabeth Rexen Ulven
Affiliation:
Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark
Jonathan R. S. Arch
Affiliation:
Institute of Translational Medicine, Clore Laboratory, University of Buckingham, Buckingham, MK18 1EG, UK
Trond Ulven
Affiliation:
Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense, Denmark Department of Drug Design and Pharmacology, University of Copenhagen, 2100 Copenhagen, Denmark
Claire Joanne Stocker*
Affiliation:
Aston Medical School, Aston University, Birmingham, B4 7ET, UK
*
*Corresponding author: Claire Joanne Stocker, email [email protected]
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Abstract

A healthy diet is at the forefront of measures to prevent type 2 diabetes. Certain vegetable and fish oils, such as pine nut oil (PNO), have been demonstrated to ameliorate the adverse metabolic effects of a high-fat diet. The present study investigates the involvement of the free fatty acid receptors 1 (FFAR1) and 4 (FFAR4) in the chronic activity of hydrolysed PNO (hPNO) on high-fat diet-induced obesity and insulin resistance. Male C57BL/6J wild-type, FFAR1 knockout (-/-) and FFAR4-/- mice were placed on 60 % high-fat diet for 3 months. Mice were then dosed hPNO for 24 d, during which time body composition, energy intake and expenditure, glucose tolerance and fasting plasma insulin, leptin and adiponectin were measured. hPNO improved glucose tolerance and decreased plasma insulin in the wild-type and FFAR1-/- mice, but not the FFAR4-/- mice. hPNO also decreased high-fat diet-induced body weight gain and fat mass, whilst increasing energy expenditure and plasma adiponectin. None of these effects on energy balance were statistically significant in FFAR4-/- mice, but it was not shown that they were significantly less than in wild-type mice. In conclusion, chronic hPNO supplementation reduces the metabolically detrimental effects of high-fat diet on obesity and insulin resistance in a manner that is dependent on the presence of FFAR4.

Type
Research Article
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of The Nutrition Society

In 2017, there were 462 million people with type 2 diabetes (T2D), corresponding to 6·3 % of the global population, and this is estimated to increase to over 7 % by 2030(Reference Khan, Hashim and King1). Whilst genetic factors are strongly involved in susceptibility to this disease(Reference Prasad and Groop2), a healthy diet and regular physical activity are important in preventing the disease(3). The same is true of obesity(3), which is a major cause of T2D.

Some dietary oils, such as marine fish oils(Reference Wu, Micha and Imamura4,Reference Yanai, Hamasaki and Katsuyama5) and olive oil-based diets(Reference Pérez-Martínez, García-Ríos and Delgado-Lista6), have been associated with protection against metabolic disorders(Reference Forouhi, Krauss and Taubes7). NEFA are known to exert biological effects by acting as precursors of various oxidised messenger molecules and by acting directly on both intracellular and cell surface receptors. Their established biological activities suggest that NEFA may be the active ingredients responsible for dietary health benefits(Reference Ulven and Christiansen8).

The free fatty acid receptors FFAR1 (GPR40) and FFAR4 (GPR120) are G protein-coupled 7-transmembrane receptors that are activated by medium- to long-chain NEFA and have been proposed as therapeutic targets for the treatment of T2D and obesity(Reference Watterson, Hudson and Ulven9,Reference Kimura, Ichimura and Ohue-Kitano10) . FFAR1 is highly expressed in pancreatic β-cells and enhances glucose-stimulated insulin secretion in response to various medium- and long-chain NEFA(Reference Itoh, Kawamata and Harada11Reference Del Guerra, Bugliani and D’Aleo13). The receptor has been clinically validated as a target for the treatment of T2D by a phase 2 and 3 clinical study that investigated the synthetic agonist TAK-875(Reference Burant, Viswanathan and Marcinak14). FFAR1 expression in enteroendocrine cells has been associated with the release of glucose- and the appetite-regulating hormones glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide and cholecystokinin(Reference Edfalk, Steneberg and Edlund15Reference Luo, Swaminath and Brown17).

FFAR4 is expressed in intestinal enteroendocrine cells, where activation is reported to increase secretion of GLP-1, although this is controversial(Reference Secor, Fligor and Tsikis18), and to inhibit secretion of the orexigenic hormone ghrelin(Reference Hirasawa, Tsumaya and Awaji19Reference Paulsen, Larsen and Hansen22). FFAR4 is also expressed in the pancreas, adipose tissue, macrophages and the brain and has been associated with the protection of islets, improvement of insulin sensitivity and the mediation of anti-inflammatory and appetite-lowering effects(Reference Oh, Talukdar and Bae23Reference Dragano, Solon and Ramalho28).

Pine nut oil (PNO) supplementation has been found to alleviate the obesity caused by a high-fat diet in rats(Reference Bhandari and Agnihotr29). When delivered to the small intestine by delayed-release capsules, hydrolysed PNO (hPNO) enhances insulin sensitivity and acutely improves glucose tolerance in humans(Reference Sørensen, Kaspersen and Ekberg30,Reference Sørensen, Korfitzen and Kaspersen31) . Delayed-release PNO and pinolenic acid also reduce appetite, possibly by augmenting GLP-1 release and attenuating ghrelin secretion in the late postprandial state(Reference Baker, Miles and Calder32,Reference Pasman, Heimerikx and Rubingh33) . In addition, PNO and pinolenic acid increase plasma levels of the appetite-suppressing gut hormones GLP-1 and cholecystokinin in obese, post-menopausal women(Reference Baker, Miles and Calder32,Reference Pasman, Heimerikx and Rubingh33) .

Pinolenic acid, a major component (about 20 %) of PNO, acutely improves glucose tolerance via agonism of both free fatty acid receptors FFAR1 and FFAR4(Reference Christiansen, Watterson and Stocker34). A lack of FFAR4 in mice or dysfunctional FFAR4 in humans has been linked to an increased risk of obesity(Reference Ichimura, Hirasawa and Poulain-Godefroy35), whilst chronic dosing of a non-acidic sulphonamide FFAR4 agonist to high-fat diet-induced obese mice resulted in a mild improvement in obesity and a substantial improvement in insulin sensitivity(Reference Azevedo, Watterson and Wargent36).

To investigate the involvement of these receptors in the activity of PNO and pinolenic acid, the present study examined the effect of chronically administered hPNO on high-fat diet-induced obesity and insulin resistance in wild-type and FFAR1 and FFAR4 knockout mice.

Materials and methods

All procedures were conducted in accordance with the UK Government Animals (Scientific Procedures) Act 1986 and approved by the University of Buckingham Ethical Review Board (Bu16004). Male wild-type mice were obtained from Charles Rivers. Mice were received at 5 weeks of age. FFAR1-/- and FFAR4-/- mice on a C57BL/6J background (Taconic Biosciences) were maintained in-house and were crossed to the Bl6 background over more than eight generations.

The mice were housed in cages of three such that there were seven cages for each genotype and treatment, except that there were only enough mice for two cages of control FFAR4-/- mice (see online Supplementary Table 1 for number of animals per group). These numbers did not change throughout the dosing period. Mice were housed at 22°C with lights on at 08.00 h, lights off at 20.00 h and fed on standard laboratory chow (Beekay Feed; B&K Universal Ltd) until 6 weeks of age and then transferred to a high-fat diet (60 % by metabolisable energy; D12492, Research Diets) for 3 months. The diets conform with AIN93 regarding vitamin, mineral and protein content.

Mice were then dosed 250 mg/kg hPNO or vehicle (10 % dimethyl sulfoxide (DMSO), 10 % Cremophor®, 80 % mannitol solution (5 % mannitolaq) by oral gavage twice a day (1 h after lights on, and 1 h before lights out for 25 d). hPNO was produced by the treatment of PNO (The Siberian Pines Company) with aqueous NaOH as described previously(Reference Sørensen, Korfitzen and Kaspersen31). The fatty acid composition of hPNO was 20·2 % pinolenic acid, 46·7 % linoleic acid, 23·0 % oleic acid, 4·1 % palmitic acid, 2·3 % stearic acid, 1·1 % eicosenoic acid, 1·0 % eicosatrienoic acid, 0·6 % eicosadienoic acid and 0·5 % α-linolenic acid, as determined by methyl ester formation and analysis by GC(Reference Christiansen, Watterson and Stocker34). 250 mg hPNO was initially dissolved in 1 ml DMSO, followed by 1 ml Cremophor®, and finally 8 ml of 5 % mannitolaq. The hPNO solution or vehicle was made fresh before each dose and used within 30 min. The dose volume was 10 ml/kg. Body weight was measured on days 0 (before the first dose), 7, 14, 21 and 24 (day of termination).

Day 0 body weights were not significantly different between genotypes and treatment groups (online Supplementary Table 1). Energy expenditure was measured on day 7 by open-circuit indirect calorimetry with mice in their home cages(Reference Arch, Hislop and Wang37Reference Wargent, Ahmad and Lu39). An oral glucose tolerance test was performed on day 21. After fasting for 5 h, mice were dosed with glucose (3 g/kg, body weight PO by gavage). Blood samples were collected from the tail at –30, 0, +30, +60, +120 and +180 min, relative to glucose dosing. Blood glucose was measured using a glucose oxidase reagent kit (Gluc-PAP, GL2623; Randox). Plasma insulin was measured by ELISA (Ultra-Sensitive Mouse Insulin ELISA kit, catalog no. 90080; Crystal Chem). Body fat and lean content were measured on day 23 using a Minispec LF90II Nuclear Magnetic Resonance (Bruker Corporation). Mice were culled by concussion followed by cervical dislocation 5 h after the morning dose on day 24, and a terminal blood sample was collected for plasma leptin (catalog no. 90030; Chrystal Chem) and adiponectin (catalog no. MRP300; R&D Systems) ELISA measurements.

Body fat and lean content were measured at termination using a Minispec LF90II Nuclear Magnetic Resonance (Bruker Corporation).

Only differences between hPNO- and vehicle-treated mice were tested for significance to avoid the complications of interpreting multiple comparisons(Reference West and Dupras40). The statistical significance of any differences between vehicle-treated animals and drug-treated animals was determined using Prism 10·0 (GraphPad Software Inc.) by two-way ANOVA (genotype; treatment with hPNO) followed by Sidak’s post-tests. Statistical significance is shown as: *P < 0·05, **P < 0·01; ***P < 0·001; ****P < 0·0001.

Results

Energy balance

Two-way ANOVA followed by Sidak’s multiple comparison test showed that hPNO significantly reduced body weight change in wild-type (P < 0·05) and FFAR1-/- (P < 0·05) mice, but not FFAR4-/- mice over the 24 d dosing regimen (Fig. 1). However, energy intake was not affected by hPNO in any of the genotypes (Fig. 2). Likewise, hPNO significantly reduced fat mass in wild-type (P < 0·05) and FFAR1-/- (P < 0·01) mice but not FFAR4 knockout mice, whereas no difference in lean mass was observed between the groups (Fig. 3). hPNO also caused a significant increase in energy expenditure in the wild-type (P < 0·05) and FFAR1-/- (P < 0·05) mice but did not have a significant effect on FFAR4 knockout mice (Fig. 4).

Fig. 1. Body weight change of wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet during 24 d of treatment with 250 mg/kg hPNO bid. Two-way ANOVA followed by Sidak’s multiple comparison test showed no statistically significant effect of hPNO or genotype, or interaction between treatment and genotype. Results are means of 21 values (19 for FFAR4-/- control dose) ± sem. ★ P < 0·05 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; PNO, pine nut oil; hPNO, hydrolysed PNO.

Fig. 2. Cumulative energy intake of wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet during 24 d of treatment with 250 mg/kg hPNO bid. Two-way ANOVA followed by Sidak’s multiple comparison test showed no significant effect of hPNO. Results are means of 7 values ± sem. FFAR, free fatty acid receptor; hPNO, hydrolysed pine nut oil.

Fig. 3. Body composition ((a) lean mass and (b) fat mass) in wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet after 23 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4 knockout control dose) ± sem. ★ P < 0·05, ★★ P < 0·01 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; hPNO, hydrolysed pine nut oil.

Fig. 4. Total 24-h energy expenditure on day 7. Results are means of 7 values ± sem. ★ P < 0·05 for differences between mice given vehicle and PNO. PNO, pine nut oil.

Consistent with the effect on body fat content, hPNO significantly reduced plasma leptin levels in wild-type (P < 0·05) and FFAR1 knockout (P < 0·001) mice, though not in FFAR4-/- mice (Fig. 5(a)). In addition, hPNO significantly increased plasma adiponectin in wild-type (P < 0·01) and FFAR1 knockout (P < 0·05), but not FFAR4 knockout mice (Fig. 5(b)). Also, in concordance with the whole-body fat measurement, hPNO significantly decreased interscapular fat pad mass in wild-type (P < 0·05) and FFAR1-/- (P < 0·001) mice but did not have a significant effect on FFAR4-/- mice (Fig. 6). However, neither the epididymal nor the inguinal fat pad masses were significantly affected.

Fig. 5. Plasma leptin (a) and adiponectin (b) in wild-type, FFAR1 knockout and FFAR4 knockout mice on high-fat diet after 24 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4-/- control dose) ± sem. ★ P < 0·05, ★★ P < 0·01, ★★★ P < 0·001 for differences between mice given vehicle and PNO. PNO, pine nut oil; hPNO, hydrolysed PNO.

Fig. 6. Epididymal (a)–(c), inguinal (d)–(f) and interscapular (g)–(i) fat pad weights in wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet after 24 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4-/- control dose) ± sem. ★ P < 0·05, ★★ P < 0·01, ★★★ P < 0·001 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; PNO, pine nut oil; hPNO, hydrolysed PNO.

Glucose homoeostasis

hPNO improved glucose tolerance overall in wild-type (P < 0·05, Fig. 7(a)) and FFAR1-/- (P < 0·01, Fig. 7(b)) mice and specifically at 30 and 60 minutes post-glucose load. hPNO did not affect glucose tolerance in FFAR4-/- mice either overall or at any time point (Fig. 7(c)). Fasting plasma insulin was significantly lowered by hPNO in wild-type (P < 0·01) and FFAR1-/- (P < 0·05) mice (Fig. 7(d) and (e)). There was no significant effect of hPNO in FFAR4-/- mice (P = 0·24, Fig. 7(f)).

Fig. 7. Change in blood glucose levels during an oral glucose tolerance test in wild-type (a), FFAR1-/- (b) and FFAR4-/- (c) mice on high-fat diet after 21 d of treatment with 250 mg/kg hPNO bid. Fasting plasma insulin levels (after 5 h fast) in wild-type (D), FFAR1-/- (E) and FFAR4-/- (f) mice on high-fat diet after 21 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4-/- control dose) ± sem. ★ P < 0·05, ★★ P < 0·01 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; PNO, pine nut oil; hPNO, hydrolysed PNO.

Discussion

Several studies, primarily in rodents and cells, suggest that PNO and pinolenic acid reduce appetite and have potential benefits in human health(Reference Baker, Miles and Calder32,Reference Pasman, Heimerikx and Rubingh33) . Recent clinical studies support this suggestion in finding that hPNO (3 or 6 g) acutely promotes GLP-1 release and reduces appetite in humans(Reference Sørensen, Kaspersen and Ekberg30,Reference Sørensen, Korfitzen and Kaspersen31) , although no effect on glucose tolerance or insulin sensitivity was found in these studies. Pinolenic acid, a major component (about 20 %) of PNO, is a dual agonist of the free fatty acid receptors FFAR1 and FFAR4 that improves glucose tolerance acutely(Reference Christiansen, Hansen and Urban41). FFAR1 activation improves glucose tolerance by increasing insulin secretion by the pancreatic β-cells(Reference Nolan, Madiraju and Delghingaro-Augusto42). FFAR4 signalling occurs through the Gαq/11 and Gαi/o pathways and the non-canonical β-arrestin pathway(Reference Im43,Reference Hilgendorf, Johnson and Mezger44) , with the activation of Gαq/11 found to increase the translocation of glucose transporter type-4 to cell membranes in adipocytes and increase glucose uptake, whereas β-arrestin 2 mediates anti-inflammatory effects(Reference Oh, Talukdar and Bae23). A lack of FFAR4 in mice or dysfunctional FFAR4 in humans has been linked to an increased risk of obesity(Reference Ichimura, Hirasawa and Poulain-Godefroy35). To investigate the involvement of these receptors in the activity of pinolenic acid and PNO, this study examined the activity of hPNO on high-fat diet-induced obesity and insulin resistance in wild-type, FFAR1-/- and FFAR4-/- mice.

The daily dose of hPNO used in the present study was 250 mg/kg orally twice daily. This is equivalent to a total dose of 2·8 g daily in a human weighing 70 kg if doses are comparable on a body surface area(Reference Nair and Jacob45). This study shows that daily dosing with hPNO for 21 d (without the acute dose prior to the glucose tolerance test) improved insulin resistance and glucose tolerance in a high-fat diet-induced model of obesity and diabetes. hPNO has a high energy content, but the present study shows that the beneficial effects on insulin sensitivity, glucose tolerance and energy expenditure are obtained with dose levels that do not add significantly to overall energy intake or adiposity.

The effect of hPNO on glucose tolerance and insulin sensitivity was dependent on the presence of the FFAR4 receptor. This is consistent with previous publications which show that whilst chronic FFAR4 activation improves glucose tolerance by enhancing insulin sensitivity(Reference Azevedo, Watterson and Wargent36,Reference Satapati, Qian and Wu46) , FFAR1 activation instead improves glucose tolerance by enhancing glucose-induced insulin secretion(Reference Christiansen, Watterson and Stocker34,Reference Hamid, Vissing and Holst47) . FFAR1 activation retains insulin secretagogue activity even after chronic high-fat feeding(Reference Kebede, Alquier and Latour48) or chronic dosing with a specific FFAR1 agonist(Reference Christiansen, Hansen and Urban41), so FFAR1-mediated effects cannot be excluded in the present study. However, hPNO was not given immediately prior to glucose tolerance tests or plasma insulin measurements, and the effects of hPNO on glucose tolerance and insulin sensitivity were the same in FFAR1-/- and wild-type mice. Moreover, others have shown that the combined deletion of FFAR1 and FFAR4 minimally impacts glucose homoeostasis in mice compared with the deletion of FFAR4 alone(Reference Croze, Guillaume and Ethier49).

In this study, administration of hPNO for 24 d reduced body weight gain, whole-body fat content and interscapular fat pad mass of mice on a high-fat diet via FFAR4 without affecting energy intake. Energy expenditure was also increased by hPNO in wild-type but not FFAR4-/- mice, suggesting that FFAR4 plays a major role. Other receptors may contribute to the effects of PNO on insulin sensitivity and glucose tolerance, but the present study suggests that FFAR4 plays a major role.

Adiponectin increases energy expenditure(Reference Vasseur, Leprêtre and Lacquemant50) and, as the effect of hPNO on plasma adiponectin was similar to that on energy expenditure in this study, increased adiponectin levels may have been the causative factor. However, it has been shown that n-3 PUFA can increase circulating adiponectin in mice independently of FFAR4, although these effects were not shown to be directly associated with an effect on energy expenditure(Reference Pærregaard, Agerholm and Serup51). In contrast, the main effect of hPNO in this study was found to depend on FFAR4.

Conclusions

In conclusion, hPNO is effective in reducing high-fat diet-induced obesity, insulin resistance and glucose intolerance. These effects are dependent on the presence of FFAR4. PNO or pinolenic acid could have a place in a dietary or nutraceutical approach directed at impeding the development of T2D.

Acknowledgements

None.

This study was supported by the Innovation Fund Denmark (grant no. 0603-00452B).

E. T. W. was responsible for data curation (lead), formal analysis (lead), investigation (lead), methodology (lead) and writing the original draft (lead). M. A. K. was responsible for formal analysis (supporting), investigation (supporting) and writing review and editing (supporting). M. H. K. was responsible for methodology (supporting) and resources (supporting). E. R. U. was responsible for methodology (supporting), resources (supporting) and writing review and editing (equal). J. R. S. A. was responsible for resources (supporting), writing the original draft (supporting) and writing review and editing (equal). T. U. was responsible for conceptualisation (equal), funding acquisition (lead), project administration (equal) and writing review and editing (equal). C. J. S. was responsible for data curation (supporting), funding acquisition (supporting), methodology (supporting), project administration (equal), resources (equal), supervision (lead), validation (equal), visualisation (equal) and writing review and editing (equal).

The authors declare none.

Supplementary material

For supplementary material/s referred to in this article, please visit https://doi.org/10.1017/S0007114524000965

References

Khan, MAB, Hashim, MJ, King, JK, et al. (2020) Epidemiology of type 2 diabetes – global burden of disease and forecasted trends. J Epidemiol Glob Health 10, 107111.10.2991/jegh.k.191028.001CrossRefGoogle ScholarPubMed
Prasad, RB & Groop, L (2015) Genetics of type 2 diabetes-pitfalls and possibilities. Genes (Basel) 6, 87123.10.3390/genes6010087CrossRefGoogle ScholarPubMed
World Health Organisation (2021) Diabetes. https://www.who.int/news-room/fact-sheets/detail/diabetes (accessed August 2023).Google Scholar
Wu, JH, Micha, R, Imamura, F, et al. (2012) n-3 fatty acids and incident type 2 diabetes: a systematic review and meta-analysis. Br J Nutr 107, S214S227.10.1017/S0007114512001602CrossRefGoogle ScholarPubMed
Yanai, H, Hamasaki, H, Katsuyama, H, et al. (2015) Effects of intake of fish or fish oils on the development of diabetes. J Clin Med Res 7, 812.10.14740/jocmr1964wCrossRefGoogle ScholarPubMed
Pérez-Martínez, P, García-Ríos, A, Delgado-Lista, J, et al. (2011) Mediterranean diet rich in olive oil and obesity, metabolic syndrome and diabetes mellitus. Curr Pharm 17, 769777.10.2174/138161211795428948CrossRefGoogle Scholar
Forouhi, NG, Krauss, RM, Taubes, G, et al. (2018) Dietary fat and cardiometabolic health: evidence, controversies, and consensus for guidance. BMJ 361, k2139.10.1136/bmj.k2139CrossRefGoogle ScholarPubMed
Ulven, T & Christiansen, E (2015) Dietary fatty acids and their potential for controlling metabolic diseases through activation of FFA4/GPR120. Annu Rev Nutr 35, 239263.10.1146/annurev-nutr-071714-034410CrossRefGoogle ScholarPubMed
Watterson, KR, Hudson, BD, Ulven, T, et al. (2014) Treatment of type 2 diabetes by free fatty acid receptor agonists. Front Endocrinol (Lausanne) 5, 137.10.3389/fendo.2014.00137CrossRefGoogle ScholarPubMed
Kimura, I, Ichimura, A, Ohue-Kitano, R, et al. (2020) Free fatty acid receptors in health and disease. Physiol Rev 100, 171210.10.1152/physrev.00041.2018CrossRefGoogle ScholarPubMed
Itoh, Y, Kawamata, Y, Harada, M, et al. (2003) Free fatty acids regulate insulin secretion from pancreatic b cells through GPR40. Nature 422, 173176.10.1038/nature01478CrossRefGoogle Scholar
Briscoe, CP, Peat, AJ, McKeown, SC, et al. (2006) Pharmacological regulation of insulin secretion in MIN6 cells through the fatty acid receptor GPR40: identification of agonist and antagonist small molecules. Br J Pharmacol 148, 619628.10.1038/sj.bjp.0706770CrossRefGoogle ScholarPubMed
Del Guerra, S, Bugliani, M, D’Aleo, V, et al. (2010) G-protein coupled receptor 40 (GPR40) expression and its regulation in human pancreatic islets: the role of type 2 diabetes and fatty acids. Nutr Metab Cardiovasc Dis 20, 2225.10.1016/j.numecd.2009.02.008CrossRefGoogle ScholarPubMed
Burant, CF, Viswanathan, P, Marcinak, J, et al. (2012) TAK-875 v. placebo or glimepiride in type 2 diabetes mellitus: a phase 2, randomised, double-blind, placebo-controlled trial. Lancet 379, 14031411.10.1016/S0140-6736(11)61879-5CrossRefGoogle ScholarPubMed
Edfalk, S, Steneberg, P & Edlund, H (2008) Gpr40 is expressed in enteroendocrine cells and mediates free fatty acid stimulation of incretin secretion. Diabetes 57, 22802287.10.2337/db08-0307CrossRefGoogle ScholarPubMed
Liou, AP, Lu, X, Sei, Y, et al. (2011) The G-protein-coupled receptor GPR40 directly mediates long-chain fatty acid induced secretion of cholecystokinin. Gastroenterology 140, 903912.10.1053/j.gastro.2010.10.012CrossRefGoogle ScholarPubMed
Luo, J, Swaminath, G, Brown, SP, et al. (2012) A potent class of GPR40 full agonists engages the enteroinsular axis to promote glucose control in rodents. PLOS ONE 7, e46300.10.1371/journal.pone.0046300CrossRefGoogle ScholarPubMed
Secor, JD, Fligor, SC, Tsikis, ST, et al. (2021) Free fatty acid receptors as mediators and therapeutic targets in liver disease. Front Physiol 12, 656441b.10.3389/fphys.2021.656441CrossRefGoogle ScholarPubMed
Hirasawa, A, Tsumaya, K, Awaji, T, et al. (2005) Free fatty acids regulate gut incretin glucagon-like peptide-1 secretion through GPR120. Nat Med 11, 9094.10.1038/nm1168CrossRefGoogle ScholarPubMed
Engelstoft, MS, Park, WM, Sakata, I, et al. (2013) Seven transmembrane G protein-coupled receptor repertoire of gastric ghrelin cells. Mol Metab 2, 376392.10.1016/j.molmet.2013.08.006CrossRefGoogle ScholarPubMed
Gong, Z, Yoshimura, M, Aizawa, S, et al. (2014) G protein coupled receptor 120 signalling regulates ghrelin secretion in vivo and in vitro . Am J Physiol Endocrinol Metab 306, E28E35.10.1152/ajpendo.00306.2013CrossRefGoogle ScholarPubMed
Paulsen, SJ, Larsen, LK, Hansen, G, et al. (2014) Expression of the fatty acid receptor GPR120 in the gut of diet induced-obese rats and its role in GLP-1 secretion. PLOS ONE 9, e88227.10.1371/journal.pone.0088227CrossRefGoogle ScholarPubMed
Oh, DY, Talukdar, S, Bae, EJ, et al. (2010) GPR120 is an n-3 fatty acid receptor mediating potent anti-inflammatory and insulin-sensitizing effects. Cell 142, 687698.10.1016/j.cell.2010.07.041CrossRefGoogle ScholarPubMed
Cintra, DE, Ropelle, ER, Moraes, JC, et al. (2012) Unsaturated fatty acids revert diet-induced hypothalamic inflammation in obesity. PLOS ONE 7, e30571.10.1371/journal.pone.0030571CrossRefGoogle ScholarPubMed
Li, X, Yu, Y & Funk, CD (2013) Cyclooxygenase-2 induction in macrophages is modulated by docosahexaenoic acid via interactions with free fatty acid receptor 4 (FFA4). FASEB J 27, 49874997.10.1096/fj.13-235333CrossRefGoogle ScholarPubMed
Stone, VM, Dhayal, S, Brocklehurst, KJ, et al. (2014) GPR120(FFAR4) is preferentially expressed in pancreatic delta cells and regulates somatostatin secretion from murine islets of Langerhans. Diabetologia 57, 11821191.10.1007/s00125-014-3213-0CrossRefGoogle Scholar
Wellhauser, L & Belsham, DD (2014) Activation of the n-3 fatty acid receptor GPR120 mediates anti-inflammatory actions in immortalized hypothalamic neurons. J Neuroinflammation 11, 60.10.1186/1742-2094-11-60CrossRefGoogle ScholarPubMed
Dragano, NRV, Solon, C, Ramalho, AF, et al. (2017) Polyunsaturated fatty acid receptors, GPR40 and GPR120, are expressed in the hypothalamus and control energy homeostasis and inflammation. J Neuroinflammation 14, 91.10.1186/s12974-017-0869-7CrossRefGoogle ScholarPubMed
Bhandari, C & Agnihotr, N (2022) Pine nut oil supplementation alleviates the obesogenic effects in high-fat diet induced obese rats: a comparative study between epididymal and retroperitoneal adipose tissue. Nutr Res 106, 85100.10.1016/j.nutres.2022.07.003CrossRefGoogle ScholarPubMed
Sørensen, KV, Kaspersen, MH, Ekberg, JH, et al. (2021) Effects of delayed-release olive oil and hydrolyzed pine nut oil on glucose tolerance, incretin secretion and appetite in humans. Nutrients 13, 3407.10.3390/nu13103407CrossRefGoogle ScholarPubMed
Sørensen, KV, Korfitzen, SS, Kaspersen, MH, et al. (2021) Acute effects of delayed-release hydrolyzed pine nut oil on glucose tolerance, incretins, ghrelin and appetite in healthy humans. Clin Nutr 40, 21692179.10.1016/j.clnu.2020.09.043CrossRefGoogle ScholarPubMed
Baker, EJ, Miles, EA & Calder, PC (2021) A review of the functional effects of pine nut oil, pinolenic acid and its derivative eicosatrienoic acid and their potential health benefits. Prog Lipid Res 82, 101097.10.1016/j.plipres.2021.101097CrossRefGoogle ScholarPubMed
Pasman, WJ, Heimerikx, J, Rubingh, CM, et al. (2008) The effect of Korean pine nut oil on   in vitro CCK release, on appetite sensations and on gut hormones in post-menopausal overweight women. Lipids Health Dis 7, 10.10.1186/1476-511X-7-10CrossRefGoogle ScholarPubMed
Christiansen, E, Watterson, KR, Stocker, CJ, et al. (2015) Activity of dietary fatty acids on FFA1 and FFA4 and characterisation of pinolenic acid as a dual FFA1/FFA4 agonist with potential effect against metabolic diseases. Br J Nutr 113, 16771688.10.1017/S000711451500118XCrossRefGoogle ScholarPubMed
Ichimura, A, Hirasawa, A, Poulain-Godefroy, O, et al. (2012) Dysfunction of lipid sensor GPR120 leads to obesity in both mouse and human. Nature 483, 350354.10.1038/nature10798CrossRefGoogle ScholarPubMed
Azevedo, CM, Watterson, KR, Wargent, ET, et al. (2016) Non-acidic free fatty acid receptor 4 agonists with antidiabetic activity. J Med Chem 59, 88688878.10.1021/acs.jmedchem.6b00685CrossRefGoogle ScholarPubMed
Arch, JRS, Hislop, D, Wang, SJY, et al. (2006) Some mathematical and technical issues in the measurement and interpretation of open-circuit indirect calorimetry in small animals. Int J Obes 30, 13221331.10.1038/sj.ijo.0803280CrossRefGoogle ScholarPubMed
Stocker, CJ, Wargent, E, O’Dowd, J, et al. (2007) Prevention of diet-induced obesity and impaired glucose tolerance in rats following administration of leptin to their mothers. Am J Physiol Regul Integr Comp Physiol 292, R1810R1818.10.1152/ajpregu.00676.2006CrossRefGoogle ScholarPubMed
Wargent, ET, Ahmad, SJS, Lu, QR, et al. (2021) Leanness and low plasma leptin in GPR17 knockout mice are dependent on strain and associated with increased energy intake that is not suppressed by exogenous leptin. Front Endocrinol 12, 698115.10.3389/fendo.2021.698115CrossRefGoogle Scholar
West, CP & Dupras, DM (2013) 5 ways statistics can fool you- tips for practicing clinicians. Vaccine 31, 15501552.10.1016/j.vaccine.2012.11.086CrossRefGoogle ScholarPubMed
Christiansen, E, Hansen, SV, Urban, C, et al. (2013) Discovery of TUG-770: a highly potent free fatty acid receptor 1 (FFA1/GPR40) agonist for treatment of type 2 diabetes. ACS Med Chem Lett 4, 441445.10.1021/ml4000673CrossRefGoogle ScholarPubMed
Nolan, CJ, Madiraju, MSR, Delghingaro-Augusto, V, et al. (2006) Fatty acid signaling in the β-cell and insulin secretion. Diabetes 55, S16S23.10.2337/db06-S003CrossRefGoogle ScholarPubMed
Im, DS (2018) FFA4 (GPR120) as a fatty acid sensor involved in appetite control, insulin sensitivity and inflammation regulation. Mol Aspects Med 64, 92108.10.1016/j.mam.2017.09.001CrossRefGoogle ScholarPubMed
Hilgendorf, KI, Johnson, CT, Mezger, A, et al. (2019) n-3 fatty acids activate ciliary FFAR4 to control adipogenesis. Cell 179, 12891305.10.1016/j.cell.2019.11.005CrossRefGoogle ScholarPubMed
Nair, AB & Jacob, S (2016) A simple practice guide for dose conversion between animals and human. J Basic Clin Pharm 7, 2731.10.4103/0976-0105.177703CrossRefGoogle ScholarPubMed
Satapati, S, Qian, Y, Wu, MS, et al. (2017) GPR120 suppresses adipose tissue lipolysis and synergizes with GPR40 in antidiabetic efficacy. J Lipid Res 58, 15611578.10.1194/jlr.M075044CrossRefGoogle ScholarPubMed
Hamid, YH, Vissing, H, Holst, B, et al. (2005) Studies of relationships between variation of the human G protein-coupled receptor 40 Gene and Type 2 diabetes and insulin release. Diabet Med 22, 7480.10.1111/j.1464-5491.2005.01505.xCrossRefGoogle Scholar
Kebede, M, Alquier, T, Latour, MG, et al. (2008) The fatty acid receptor GPR40 plays a role in insulin secretion in vivo after high-fat feeding. Diabetes 57, 24322437.10.2337/db08-0553CrossRefGoogle Scholar
Croze, ML, Guillaume, A, Ethier, M, et al. (2021) Combined deletion of free fatty-acid receptors 1 and 4 minimally impacts glucose homeostasis in mice. Endocrinology 162, bqab002.10.1210/endocr/bqab002CrossRefGoogle Scholar
Vasseur, F, Leprêtre, F, Lacquemant, C, et al. (2003) The genetics of adiponectin. Curr Diabetes Rep 3, 151158.10.1007/s11892-003-0039-4CrossRefGoogle ScholarPubMed
Pærregaard, SI, Agerholm, M, Serup, AK, et al. (2016) FFAR4 (GPR120) signaling is not required for anti-inflammatory and insulin-sensitizing effects of n-3 fatty acids. Mediators Inflamm 2016, 1536047.10.1155/2016/1536047CrossRefGoogle ScholarPubMed
Figure 0

Fig. 1. Body weight change of wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet during 24 d of treatment with 250 mg/kg hPNO bid. Two-way ANOVA followed by Sidak’s multiple comparison test showed no statistically significant effect of hPNO or genotype, or interaction between treatment and genotype. Results are means of 21 values (19 for FFAR4-/- control dose) ±sem. ★ P < 0·05 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; PNO, pine nut oil; hPNO, hydrolysed PNO.

Figure 1

Fig. 2. Cumulative energy intake of wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet during 24 d of treatment with 250 mg/kg hPNO bid. Two-way ANOVA followed by Sidak’s multiple comparison test showed no significant effect of hPNO. Results are means of 7 values ± sem. FFAR, free fatty acid receptor; hPNO, hydrolysed pine nut oil.

Figure 2

Fig. 3. Body composition ((a) lean mass and (b) fat mass) in wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet after 23 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4 knockout control dose) ± sem. ★ P < 0·05, ★★ P < 0·01 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; hPNO, hydrolysed pine nut oil.

Figure 3

Fig. 4. Total 24-h energy expenditure on day 7. Results are means of 7 values ± sem. ★ P < 0·05 for differences between mice given vehicle and PNO. PNO, pine nut oil.

Figure 4

Fig. 5. Plasma leptin (a) and adiponectin (b) in wild-type, FFAR1 knockout and FFAR4 knockout mice on high-fat diet after 24 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4-/- control dose) ± sem. ★ P < 0·05, ★★ P < 0·01, ★★★ P < 0·001 for differences between mice given vehicle and PNO. PNO, pine nut oil; hPNO, hydrolysed PNO.

Figure 5

Fig. 6. Epididymal (a)–(c), inguinal (d)–(f) and interscapular (g)–(i) fat pad weights in wild-type, FFAR1-/- and FFAR4-/- mice on high-fat diet after 24 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4-/- control dose) ± sem. ★ P < 0·05, ★★ P < 0·01, ★★★ P < 0·001 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; PNO, pine nut oil; hPNO, hydrolysed PNO.

Figure 6

Fig. 7. Change in blood glucose levels during an oral glucose tolerance test in wild-type (a), FFAR1-/- (b) and FFAR4-/- (c) mice on high-fat diet after 21 d of treatment with 250 mg/kg hPNO bid. Fasting plasma insulin levels (after 5 h fast) in wild-type (D), FFAR1-/- (E) and FFAR4-/- (f) mice on high-fat diet after 21 d of treatment with 250 mg/kg hPNO bid. Results are means of 21 values (19 for FFAR4-/- control dose) ± sem. ★ P < 0·05, ★★ P < 0·01 for differences between mice given vehicle and PNO. FFAR, free fatty acid receptor; PNO, pine nut oil; hPNO, hydrolysed PNO.

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