The gonadotropin releasing hormone (GnRH) system in the hypothalamus is often considered the final point in integration of environmental cues as they pertain to the reproductive axis. However, cues such as stress and food availability are detectable in the plasma (as glucocorticoid and metabolic fuel fluctuations). Vertebrate gonads express glucocorticoid receptor, therefore we hypothesized that the gonads can detect and respond directly to cues of stress. We provide evidence here that, in addition to regulation by the brain, the gonads of European starlings (Sturnus vulgaris) respond directly to fluctuations in corticosterone and metabolic fuels by modulating sex steroid secretion. Using a 4-h gonad culture, we show that physiologically-relevant concentrations of corticosterone and metabolic stress (via use of the glucose utilization inhibitor 2-deoxy-D-glucose and the fatty acid oxidation inhibitor ethyl 2-mercaptoacetate (2DG/MA)) can directly decrease testosterone and estradiol secretion from luteinizing hormone and follicle-stimulating hormone (LH/FSH)-stimulated testes and ovaries. This effect is regulated seasonally. Prior to the breeding season, testes and ovaries respond to corticosterone and 2DG/MA by significantly decreasing gonadal steroid release. Within the breeding season, the testes do not respond to these cues of stress, while the ovaries respond only to corticosterone. This seasonal difference in response may be due in part to the influence of these cues of stress on gonadal neuropeptide expression: corticosterone upregulates GnIH expression in the testes while metabolic stress upregulates GnIH in the ovaries. Thus the gonads can directly respond to fluctuations in corticosterone and metabolic fuels during a time of critical importance to the onset of breeding.

Background: HCN channels influence neuronal excitability. Results: Filamin-A (FLNa) facilitated selective, reversible dynamin-dependent internalization of HCN1 and reduced I h . In hippocampal neurons, dominant-negative FLNa enhanced native HCN1, and decoy peptides disrupting HCN1-FLNa binding reduced channel clustering and augmented endogenous I h . Conclusion: FLNa modulates neuronal excitability via dynamin-mediated HCN1 endocytosis. Significance: Novel roles for FLNa in mature neuronal function are presented.

No abstract

No abstract

Poor career prospects a r e often cited as one of the maln reasons for the dwindling number of physics majors. This is more myth than reality. Recent developments in Malaysia show that there a r e openings lor physics graduates hitherto unexplored. Surveys carried out elsewhere show that physicists are In demand and In some cases there might be a shortage in the future.