Meeting Abstract
P1.14 Monday, Jan. 4 Changes in Brain Concentrations of GnRH-I, -II, and –III During the Final Reproductive Period in Adult Male and Female Sea Lamprey SOWER, STACIA A.*; BALZ, EILEEN; MACDONALD, CARYN; KAVANAUGH, SCOTT I.; University of New Hampshire, Durham; University of New Hampshire Durham; University of New Hampshire, Durham; University of New Hampshire, Durham sasower@cisunix.unh.edu
Sea lampreys are anadromous and semelparous, i.e., they spawn only once in their lifetime, after which they die. Sexual maturation is thus a synchronized process coordinated with the life stages of the lamprey. Recently, a novel gonadotropin-releasing hormone, lamprey GnRH-II, was identified in lampreys and suggested to have a hypothalamic role in reproduction (Kavanaugh et al., 2008). To further understand the role of lGnRH-II, changes in ovarian morphology, brain gonadotropin-releasing hormone (GnRH-I, -II, and -III), and plasma estradiol were examined during the final two months of the reproductive season of adult male and female sea lamprey. The results show significant correlations between water temperature, fluctuation of brain GnRHs and plasma estradiol during this time. In males, lGnRH-I concentration increased early in the season, peaked, then declined with a subsequent increase with the final maturational stages. In comparison, lGnRH-II and –III concentrations were also elevated early in the season in males, dropped and then peaked in mid-season with a subsequent decline of lGnRH-II or increase of lGnRH-III at spermiation. In females, lGnRH-III concentration peaked in mid-season with a drop at ovulation while lGnRH-I remained unchanged during the season. In contrast, lGnRH-II concentrations in females were elevated at the beginning of the season and then dropped and remained low during the rest of the season. In summary, these data provide evidence that lampreys have three hypothalamic GnRHs and that these GnRHs change in a differential manner during this final reproductive period. Supported by NSF Grants 0421923, 0849569, NSF REU supplement and NH AES Hatch 332 to SAS.
