Animal models are valuable for the study of complex behaviours and physiology such as the control of appetite because genetic, pharmacological and surgical approaches allow the investigation of underlying mechanisms. However, the majority of such studies are carried out in just two species, laboratory mice and rats. These conventional laboratory species have been intensely selected for high growth rate and fecundity, and have a high metabolic rate and short lifespan. These aspects limit their translational relevance for human appetite control. This review will consider the value of studies carried out in a seasonal species, the Siberian hamster, which shows natural photoperiod-regulated annual cycles in appetite, growth and fattening. Such studies reveal that this long-term control is not simply an adjustment of the known hypothalamic neuronal systems that control hunger and satiety in the short term. Long-term cyclicity is probably driven by hypothalamic tanycytes, glial cells that line the ventricular walls of the hypothalamus. These unique cells sense nutrients and metabolic hormones, integrate seasonal signals and effect plasticity of surrounding neural circuits through their function as a stem cell niche in the adult. Studies of glial cell function in the hypothalamus offer new potential for identifying central targets for appetite and body weight control amenable to dietary or pharmacological manipulation.

Androgen deprivation therapy (ADT) is used widely as part of a combined modality for the treatment of prostate cancer. However, ADT has also been associated with the development of cardiometabolic complications that can increase mortality from cardiovascular events. There is emerging evidence to suggest that ADT-related cardiometabolic risk can be mitigated by diet and lifestyle modification. While the clinical focus for a nutritional approach for achieving this effect is unclear, it may depend upon the timely assessment and targeting of dietary changes to the specific risk phenotype of the patient. The present review aims to address the metabolic origins of ADT-related cardiometabolic risk, existing evidence for the effects of dietary intervention in modifying this risk, and the priorities for future dietary strategies.

The highveld mole-rat Cryptomys hottentotus pretoriae exhibits an extreme reproductive division of labour. Reproduction in this seasonally breeding social mole-rat is restricted to a breeding pair. The non-reproductive females seem to be physiologically suppressed from reproducing, whereas the non-reproductive males are restricted from sexual activity through incest avoidance. Circulating basal concentrations of luteinizing hormone (LH) between reproductive and non-reproductive females were not significantly different, yet the response to an exogenous gonadotrophin-releasing hormone (GnRH) challenge was significantly lower in non-reproductive females when compared to reproductive females. The mean basal LH concentration in non-reproductive females was not significantly different in and out of the breeding season. However, the magnitude of the LH response in non-reproductive females out of the breeding season was greater than in the breeding season. The ovaries of reproductive females showed little change with respect to season. However, reproductive females had enhanced follicular activity in comparison to their non-reproductive counterparts. This suggests that non-reproductive females are under stricter control from the reproductive female when she is pregnant. The tropical African mole-rats exhibit a continuum of socially induced infertility with differing social species inhabiting regions of varying degrees of aridity. In this spectrum, a predominantly behavioural repression is found amongst non-reproductive females in social mesic-adapted species, whereas a strictly physiological suppression is operative amongst non-reproductive females in arid-adapted social species. Here we show that the mesic-adapted highveld mole-rat does not fit this trend in that the non-reproductive females seem to be physiologically suppressed. We discuss this in light of the seasonality of breeding and the ecological constraints that may operate during times of drought.