The distributions of the duplicate estrogen receptors ER- beta a andER- beta b in the forebrain of the Atlantic croaker (Micropogoniasundulatus): evidence for subfunctionalization after gene duplication

摘要

Teleost fishes have three distinct estrogen receptor (ER) subtypes: ER- alpha , ER- beta a (or ER- gamma ) and ER- beta b. ER- beta a and ER- beta b arose from a duplication of an ancestral ER- beta gene early in the teleost lineage. Here, we describe the distribution of the three ER mRNAs in the hypothalamus and cerebellum of the Atlantic croaker to address two issues: the specific functions of multiple ERs in the neuroendocrine system and the evolution and fate of duplicated genes. ER- alpha was detected in nuclei of the preoptic area (POA) and hypothalamus previously shown to possess ER- alpha s in teleosts. AcER- beta b, but not ER- beta a, labelling was detected in the magnocellular neurons of the POA, nucleus posterior tuberis, the nucleus recessus posterior and cerebellum. By contrast, acER- beta a, but not ER- beta b, was detected in the dorsal anterior parvocellular POA and suprachiasmatic nucleus. Both ER- beta s were found in posterior parvocellular and ventral anterior POA nuclei, the ventral hypothalamus, and periventricular dorsal hypothalamus. The differences we observed in ER subtype mRNA distribution within well-characterized brain nuclei suggest that ER- beta a and ER- beta b have distinct functions in the neuroendocrine control of reproduction and behavior, and provide evidence that the teleost ER- beta paralogues have partitioned functions of the ancestral ER- beta gene they shared with tetrapods.