The mechanisms by which prolonged estrogen exposures, such as estrogen therapy and pregnancy, reduce thymus weight, cellularity, and CD4 and CD8 phenotype expression, have not been well defined. In this study, the roles played by the membrane estrogen receptor, G protein-coupled receptor 30 (GPR30), and the intracellular estrogen receptors, estrogen receptor alpha (ERalpha) and beta (ERbeta), in 17beta-estradiol (E2)-induced thymic atrophy were distinguished by construction and the side-by-side comparison of GPR30-deficient mice with ERalpha and ERbeta gene-deficient mice. Our study shows that whereas ERalpha mediated exclusively the early developmental blockage of thymocytes, GPR30 was indispensable for thymocyte apoptosis that preferentially occurs in T cell receptor beta chain(-/low) double-positive thymocytes. Additionally, G1, a specific GPR30 agonist, induces thymic atrophy and thymocyte apoptosis, but not developmental blockage. Finally, E2 treatment attenuates the activation of nuclear factor-kappa B in CD25(-)CD4(-)CD8(-) double-negative thymocytes through an ERalpha-dependent yet ERbeta- and GPR30-independent pathway. Differential inhibition of nuclear factor-kappaB by ERalpha and GPR30 might underlie their disparate physiological effects on thymocytes. Our study distinguishes, for the first time, the respective contributions of nuclear and membrane E2 receptors in negative regulation of thymic development.

Data from our lab indicate that the orexin system is involved in the regulation of both conditioned and unconditioned responding for palatable foods. Anticipation of food rewards activates orexin receptor containing neurons within the paraventricular nucleus of the thalamus (PVT). The PVT regulates mesolimbic dopamine neurochemistry through direct connections with the nucleus accumbens and modulates the processing of cognitive-emotional information, suggesting that the PVT may represent a unique brain region with the capacity to mediate orexinergic effects on brain dopamine and behavior. Here, we tested the hypothesis that PVT orexin signaling mediates mesolimbic dopamine and reward-based feeding. To do this we used a behavioral pharmacological approach in tandem with central genetic manipulation of the orexin-1 receptor in the PVT. Data from these studies indicate that orexin-A action in the PVT increases dopamine levels in the nucleus accumbens. In addition, endogenous orexin signaling in the PVT mediates locomotor activity and hedonic feeding responses. Together these data highlight the PVT as a critical site capable of mediating orexin action on brain dopamine and reward-based feeding.

A series of 5-keto-substituted 7-tert-buty1-2,3-dihydro-3,3- dimethylbenzofurans (DHDMBFs) were prepared and evaluated as potential nonsteroidal antiinflammatory and analgesic agents. Interest in this class of compounds arose when a DHDMBF was found to be an active metabolite of the di-tert-butylphenol antiinflammatory agent tebufelone. We have now found that a variety of 5-keto-substituted DHDMBFs have good in vivo antiinflammatory and analgesic activity after oral administration. These compounds inhibit both cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) in vitro. The cyclooxygenase inhibition was found to be selective for the cyclooxygenase-2 isoform, and this combination of COX-2/5-LOX inhibition may be responsible for the gastrointestinal safety of compounds such as 30.

No abstract

Aims/hypothesis We examined the physiological mechanisms by which cannabinoid receptor 1 (CB1) antagonism improves glucose metabolism and insulin sensitivity independent of its anorectic and weight-reducing effects, as well as the effects of CB1 antagonism on brown adipose tissue (BAT) function. Methods Three groups of diet-induced obese mice received for 1 month: vehicle; the selective CB1 antagonist SR141716; or vehicle/pair-feeding. After measurements of body composition and energy expenditure, mice underwent euglycaemic-hyperinsulinaemic clamp studies to assess in vivo insulin action. In separate cohorts, we assessed insulin action in weight-reduced mice with diet-induced obesity (DIO), and the effect of CB1 antagonism on BAT thermogenesis. Surgical denervation of interscapular BAT (iBAT) was carried out in order to study the requirement for the sympathetic nervous system in mediating the effects of CB1 antagonism on BAT function.Results Weight loss associated with chronic CB1 antagonism was accompanied by increased energy expenditure, enhanced insulin-stimulated glucose utilisation, and marked activation of BAT thermogenesis. Insulin-dependent glucose uptake was significantly increased in white adipose tissue and BAT, whereas glycogen synthesis was increased in liver, fat and muscle. Despite marked weight loss in the mice, SR141716 treatment did not improve insulin-mediated suppression of hepatic glucose production nor increase skeletal muscle glucose uptake. Denervation of iBAT blunted the effect of SR141716 on iBAT differentiation and insulin-mediated glucose uptake. Conclusions/interpretation Chronic CB1 antagonism markedly enhances insulin-mediated glucose utilisation in DIO mice, independent of its anorectic and weight-reducing effects. The potent effect on insulin-stimulated BAT glucose uptake reveals a novel role for CB1 receptors as regulators of glucose metabolism.