BARON, MP*; SOWER, SA; University of New Hampshire; University of New Hampshire: Lamprey Estrogen Receptor Expression by In Situ Hybridization in the Brain and Pituitary of Adult Sea Lamprey.
Across all vertebrates, gonadotropin-releasing hormone (GnRH) is the key hormone in regulating the hypothalamic-pituitary-gonadal axis in reproductive processes. Two forms of GnRH (lamprey GnRH I & III) have been identified in the sea lamprey (Petromyzon marinus) and have been shown by immunocytochemistry and in situ hybridization to be expressed in the hypothalamo-neurohypophysial system. In most other vertebrates, estrogen has been shown to exert negative/positive feedback on GnRH, directly or indirectly. The recent cloning of the cDNA of an estrogen receptor (ER) in lamprey by Thornton (2001) has presented the opportunity to investigate ER expression in lamprey. The objective of this study was to examine possible interactions between ER and GnRH I & III in lamprey by determining ER expression in relation to GnRH using in situ hybridization. Following hybridization with radiolabeled (35S) RNA probes, ER mRNA expression was observed in the lamprey optic lobe, hypothalamus, and ventral hindbrain. Expression of ER in close proximity to hypothalamic GnRH neurons supports the possibility that the ER may influence GnRH function in lamprey. (Supported by NSF 0421923 to SAS)
