Role of androgens in the regulation of urotensin II precursor mRNA expression in the rat brainstem and spinal cord

International audienceIt has been reported that both urotensin II precursor (pro UII) mRNA and androgen receptors (ARs) are highly expressed in rat brainstem motor nuclei and ventral horn of the spinal cord. In order to determine the possible involvement of androgens in regulation of pro UII mRNA expression, we have studied the co-localization of pro UII mRNA and AR immunoreactivity and the effect of castration and dihydrotestosterone (DHT) replacement therapy on pro UII mRNA in the rat facial nucleus and ventral horn of the spinal cord. By in situ hybridization, pro UII mRNA was only detected in motoneurons in both the facial nucleus and ventral horn of the spinal cord. Double-labelling studies revealed that the vast majority (over 95%) of motoneurons immunostained for AR also expressed pro UII mRNA in both areas examined. Three weeks after castration, pro UII mRNA expression, as measured by semi-quantitative in situ hybridization, was increased by 17% and 58% in the ventral horn of the spinal cord and the facial nucleus, respectively. The administration of DHT completely prevented the stimulating effect of castration. These results indicate that circulating androgens are exerting a down-regulation of pro UII expression possibly by a direct action at the level of motoneurons. The physiological relevance of these new findings remains to be fully explored

Evaluation of ovarian POMC mRNA through quantitative RT-PCR analysis in Rana esculenta

International audienceThe evaluation of changes in the expression of specific genes requires accurate measurement of the corresponding mRNA concentration, especially when the gene is expressed at a very low level. We previously showed that the proopiomelanocortin (POMC) gene is expressed in the ovary of the frog Rana esculenta, and, to evaluate its mRNA content in frog ovary, we have now developed a sensitive quantitative RT-PCR method. This study provides evidence for the validation of this method and for the effects of captivity and hypophysectomy on POMC gene expression in the ovary of this anuran. Our data indicate that ovarian POMC gene is involved in short-term captivity stress response and seems not influenced by pituitary. These results are discussed taking into account the knowledge of the role played by opioids in stress response; moreover, a local control of POMC gene expression is also suggested

Expression of Proopiomelanocortin and Its Cleavage Enzyme Genes in Rana esculenta and Xenopus laevis Gonads

International audienceProopiomelanocortin (POMC) is the precursor protein of different hormones and neuropeptides, and the POMC-derived peptides are produced through proteolytic cleavage. Prohormone convertase PC1 and PC2 are enzymes responsible for the cleavage of the POMC prohormone. The coexpression of POMC, PC1, and PC2 genes was previously described in the brain and the pituitary gland of Rana esculenta and Xenopus laevis, but no data are available for the gonad. The present work demonstrates a gonadal POMC convertase gene expression in Rana esculenta and Xenopus laevis