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The medial amygdala (MeA) is crucial for sexual behavior; kisspeptin (Kiss1) also plays a role in sexual function. Kisspeptin receptor (Kiss1r) knockout mice display no sexual behavior. Recently Kiss1 and Kiss1r have been discovered in the posterodorsal subnucleus of the medial amygdala (MePD). We hypothesised that Kiss1 in the MePD may have an influence on male sexual behavior. To test this we bilaterally cannulated the MePD and infused kisspeptin-10 in male rats. This caused the rats to have multiple erections, an effect specific to Kiss1 receptor activation, because Kiss1r antagonism blocked the erectile response. When Kiss1 was infused into the lateral cerebroventricle, there were no observed erections. We also measured the plasma levels of LH when Kiss1 is infused into the MePD or lateral cerebroventricle; Kiss1 increased plasma LH to comparable levels when infused into both sites. We conclude that Kiss1 has a role in male sexual behavior, which is specific to the MePD. [ABSTRACT FROM AUTHOR]

Abstract: Because there are sex differences in feeding-related behavior and orexin neurons are involved in feeding, we looked for a possible sex difference in the response of orexin neurons in the lateral hypothalamic area to fasting, using the phosphorylated cyclic AMP response element-binding protein (pCREB) as a marker of neural activity. Intact male and female rats at proestrus, estrus, or diestrus, were fed normally or fasted for 48h. After fasting, they were intravenously injected with saline or glucose and subjected to immunohistochemical processing for the detection of orexin and pCREB. In the rats fed normally and injected with saline, only a small population of orexin neurons expressed pCREB in both male and female rats. However, fasting increased the number of orexin neurons with pCREB (double-stained cells) in female rats regardless of the estrous day but not in male rats, revealing a significant sex difference in the response of orexin neurons to fasting. Glucose injection in fasted rats decreased the number of double-stained cells in female rats, and the magnitude of glucose-dependent decrease was greater at proestrus and estrus than at diestrus 2. We also found that female rats, but not male rats, showed an increase in total food intake after fasting (rebound feeding). We speculate that the demonstrated sex differences in the response of orexin neurons to fasting reflect the vulnerability of feeding mechanisms in females. [Copyright &y& Elsevier]

Abstract: From studies of genetic-knockout animals, brain-derived neurotrophic factor (BDNF), a member of the neurotrophin growth-factor family, has been implicated in both alcohol preference and aggressive behaviour. To test whether a BDNF genetic variant may be associated with alcohol-dependent and violent behaviours, we studied Val66Met polymorphism of the BDNF-gene in 110 cases of alcohol-dependence, in 134 extremely violent convicts, and in 149 individuals without psychosis or mood disorders. We also examined the association of this polymorphism with antisocial personality disorder comorbidity in the extremely violent convicts. The results showed that the genotype and allele frequencies for Val66Met polymorphism at the BDNF-gene site did not differ among the three groups. Furthermore, it was not demonstrated that this polymorphism is associated with antisocial personality disorder comorbidity in the extremely violent convicts. Based on these findings, it seems reasonable to suggest that this BDNF-gene Val66Met polymorphism is unlikely to play a major role in the genetic susceptibility to the traits of alcohol-dependence or violence proneness. [Copyright &y& Elsevier]

To evaluate the role of testosterone in pain modulation, we subcutaneously injected male and female rats with testosterone propionate (TP, 5 mg/kg in oil) or oil for 6 days; on the seventh day, all rats were subjected to the formalin test (10%, 50 μl). Behaviours were recorded in an open field (60 min). At the end of the formalin test, the rats were anaesthetized to collect blood from the abdominal aorta. Among the formalin-induced responses, licking was higher in females than males and was decreased by TP in females; jerking and flexing were only slightly affected by treatment. TP increased testosterone plasma levels in both sexes. These results indicate a role of testosterone in modulating formalin-induced responses. The effects appear to be different in males and females. [Copyright &y& Elsevier]