Photoperiod-independent hypothalamic regulation of luteinizing hormone secretion in a free-living sonoran desert bird, the Rufous-winged Sparrow (Aimophila carpalis)

Thomas W. Small*, Peter J. Sharp, George E. Bentley, Robert P. Millar, Kazuyoshi Tsutsui, Elena Mura, Pierre Deviche

*この研究の対応する著者

研究成果: Article査読

57 被引用数 (Scopus)

抄録

We investigated the regulation of luteinizing hormone (LH) in the male Rufous-winged Sparrow,Aimophila carpalis, a resident of the Sonoran desert that breeds after irregular summer rains. Although the testes develop in March due to increasing photoperiod and regress in September due to decreasing photoperiod, LH does not consistently increase in the spring as in other photoperiodic birds. However, throughout the year increased plasma LH is correlated with rainfall. To investigate this rainfall-associated regulation of LH secretion, we quantified immunocytochemical labeling for gonadotropin-releasing hormone I (GnRH-I), proGnRH (the GnRH precursor), and gonadotropin-inhibitory hormone (GnIH) in the hypothalamus of free-living adult males caught before (low LH), and during (high LH) the monsoon rainy season. Compared to pre-monsoon birds, birds caught during the monsoon season had larger immunoreactive GnRH-I (GnRH-I-ir) and proGnRH-ir cell bodies, as well as fewer, less densely labeled proGnRH-ir cell bodies. Birds caught during the monsoon had fewer, less densely labeled GnIH-ir cell bodies than birds caught before the monsoon. Further, there was no GnIH-ir labeling in the median eminence on either capture dates, suggesting that GnIH is not released to the pituitary gland via the portal vein at this time of year, but there were fewer GnIH-ir fibers in the preoptic area of birds caught during the monsoon season. Our data support the hypothesis that environmental factors associated with increased rainfall during the monsoon season stimulate GnRH synthesis and release to increase LH secretion. These data also suggest that GnIH could inhibit GnRH neuronal activity prior to the monsoon season.

本文言語English
ページ(範囲)127-142
ページ数16
ジャーナルBrain, Behavior and Evolution
71
2
DOI
出版ステータスPublished - 2008 2月
外部発表はい

ASJC Scopus subject areas

  • 神経科学(全般)
  • 生態、進化、行動および分類学

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