Journal
GENERAL AND COMPARATIVE ENDOCRINOLOGY
Volume 170, Issue 2, Pages 276-282Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ygcen.2010.08.005
Keywords
Lamprey gonadotropin-releasing hormone-I; Lamprey gonadotropin-releasing hormone-II; Lamprey gonadotropin-releasing hormone-III; GnRH; Lamprey; Petromyzon marinus; Seasonal changes of GnRH; Estradiol; Ovarian and testicular morphology; Temperature changes on neuroendocrine system
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Funding
- NSF [0421923, 0849569]
- REU Supplement
- Direct For Biological Sciences
- Division Of Integrative Organismal Systems [0421923] Funding Source: National Science Foundation
- Direct For Biological Sciences
- Division Of Integrative Organismal Systems [0849569] Funding Source: National Science Foundation
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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 (IGnRH-II), was identified in lampreys and suggested to have a hypothalamic role in reproduction (Kavanaugh et al., 2008). To further understand the role of IGnRH-II, changes in ovarian morphology, brain gonadotropin-releasing hormone (IGnRH-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 showed significant correlations between water temperature, fluctuation of brain GnRHs, plasma estradiol and reproductive stages during this time. In males, IGnRH-I concentration increased early in the season, peaked, then declined with a subsequent increase with the final maturational stages. In comparison, IGnRH-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 IGnRH-II or increase of IGnRH-III at spermiation. In females, IGnRH-III concentration peaked in mid-season with a drop at ovulation while IGnRH-I remained unchanged during the season. In contrast, IGnRH-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 there are seasonal and differential changes of the three GnRHs during this final reproductive period suggesting specific roles for each of the GnRHs in male and female reproduction. (C) 2010 Elsevier Inc. All rights reserved.
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