Recent studies have demonstrated that metabotropic glutamate receptor 5 (mGluR5) antagonists decrease alcohol self-administration and suggest that the anti-craving medication, acamprosate, may also act to decrease mGluR5 function. To address the role of mGluR5 in behavioural actions of ethanol and acamprosate, we compared mutant mice with deletion of the mGluR5 gene and mice treated with a mGluR5 antagonist (MPEP) or acamprosate. Lack of mGluR5 or administration of MPEP reduced the severity of alcohol-induced withdrawal (AW), increased the sedative effect of alcohol (duration of loss of righting reflex; LORR), and increased basal motor activity. The motor stimulation produced by ethanol was blocked by deletion of mGluR5, but not by injection of MPEP. Both acamprosate and MPEP increased ethanol-induced LORR and reduced AW. Importantly, the protective effects of both MPEP and acamprosate on AW were found when the drugs were injected before, but not after, injection of ethanol. This indicates that the drugs prevented development of dependence rather than merely producing an anticonvulsant action. No effects of acamprosate or MPEP on ethanol-induced LORR and AW were found in mGluR5 knockout mice, demonstrating that mGluR5 is required for these actions. mGluR5 null mutant mice showed decreased alcohol consumption in some, but not all, tests. These data show the importance of mGluR5 for several actions of alcohol and support the hypothesis that some effects of acamprosate require mGluR5 signalling.

Transgenic and knockout mouse models are extensively used to study the mechanisms of tumour formation. The availability of mouse models to study metastatic spread of tumours is although quite limited. S100A4(mts1), that belongs to the S100 family of Ca-binding proteins, has been shown to function as a metastasis-promoting protein. We generated strains of mice with modified expression of S100A4 in order to understand the mechanism by which S100A4 protein stimulates metastatic spread of the tumour cells. Transgenic mice over-expressing the S100A4 gene in the mammary gland were crossed with GRS/A mice, characterized by a high incidence of spontaneous non-metastatic mammary tumours. The resulting hybrid mice developed metastatic tumours. Transgenic mice with ubiquitous expression of S100A4 developed vascular tumours, hemangiomas and contained enhanced levels of the S100A4 protein in the blood. Based on these observations we demonstrated that extracellular S100A4 functions as an angiogenic factor. Study of tumour development in the S100A4 – deficient mouse model demonstrated key role of extracellular S100A4 in stimulation of tumour development and metastasis formation.

In the vertebrate retina, vision is initiated and maintained by the photolysis and regeneration, respectively, of light-sensitive pigments in the disk membranes of the photoreceptor outer segments. This cyclical process depends on an exchange of retinoids between the photoreceptors and the retinal pigment epithelium (RPE). There is a great deal of indirect evidence that the transport of retinoids between these cellular compartments is mediated by the interphotoreceptor retinoid-binding protein (IRBP), a large glycoprotein synthesized in the photoreceptors and extruded into the interphotoreceptor matrix (IPM) that fills the subretinal space. Nevertheless, a number of in vitro experiments have demonstrated that an intermembranous transfer of retinoids can occur through an aqueous medium independent of any retinoid-binding protein. This led to the suggestion that IRBP may play the more passive role of an extracellular buffer, serving to prevent the degradation and potentially cytotoxic effects of free retinoids when large amounts are released into the IPM. We have studied the structural and functional properties of transgenic mice in which homologous recombination was used to delete the IRBP gene. Light- and electron-microscopic examination of the retinas of “knockout” (IRBP−/−) mice revealed a significant loss of photoreceptor nuclei, and profound changes in the structure and organization of the receptor outer segments. Consistent with these observations, electroretinographic recordings showed a marked reduction in response amplitude for both rod- and cone-mediated potentials. However, despite the histological and electrophysiological changes, there was no evidence of gross abnormalities in the visual cycle. After bleaching a significant fraction of the available rhodopsin, electroretinogram amplitude and rhodopsin density gradually increased toward their pre-bleach levels, and the rates of recovery were even more rapid than those seen in wild-type (IRBP+/+) mice.

Severe cryptosporidial infections were produced in gamma interferon (IFN-γ) knockout mice. Mean oocyst shedding increased from 332 to 30717 oocysts/100 μl of faecal suspension between day 4 and 9 after administration of 1×105 oocysts/mouse. No significant differences in oocyst shedding were observed in mice after being inoculated with 1×105, 1×104 or 1×103 oocysts/mouse (P>0·05). Infected mouse weights decreased an average 3–4 g before death or euthanization. Histological studies revealed heavy parasite colonization in small intestinal epithelium (approximately 250 organisms/high-power field at ×400). Mesenteric lymph nodes in infected mice were markedly enlarged compared to controls (P<0·05). Both CD4+ and CD8+ T cell populations increased in spleens of infected mice while the B cell population increased in mesenteric lymph nodes from infected mice. No significant proliferation was observed when pooled lymphocytes from infected mice were exposed to C. parvum antigens in vitro. Addition of recombinant mouse IFN-γ did not restore antigen responsiveness. While lymphoproliferative responses to specific antigen were not significant in the short period following infection, this mouse model provides unique features to study the characteristics of acute infection and the immune response against C. parvum.