کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2800687 1156121 2012 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Variation in the gonadotrophin-releasing hormone-1 and the song control system in the tropical breeding rufous-collared sparrow (Zonotrichia capensis) is dependent on sex and reproductive state
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی علوم غدد
پیش نمایش صفحه اول مقاله
Variation in the gonadotrophin-releasing hormone-1 and the song control system in the tropical breeding rufous-collared sparrow (Zonotrichia capensis) is dependent on sex and reproductive state
چکیده انگلیسی

Seasonal breeding in temperate zone vertebrates is characterised by pronounced variation in both central and peripheral reproductive physiology as well as behaviour. In contrast, many tropical species have a comparatively longer and less of a seasonal pattern of breeding than their temperate zone counterparts. These extended, more “flexible” reproductive periods may be associate with a lesser degree of annual variation in reproductive physiology. Here we investigated variation in the neuroendocrine control of reproduction in relation to the changes in the neural song control system in a tropical breeding songbird the rufous-collared sparrows (Zonotrichia capensis). Using in situ hybridization, we show that the optical density of GnRH1 mRNA expression is relatively constant across pre-breeding and breeding states. However, males were found to have significantly greater expression compared to females regardless of breeding state. Both males and females showed marked variation in measures of peripheral reproductive physiology with greater gonadal volumes and concentrations of sex steroids in the blood (i.e. testosterone in males; estrogen in females) during the breeding season as compared to the pre-breeding season. These findings suggest that the environmental cues regulating breeding in a tropical breeding bird ultimately exert their effects on physiology at the level of the median eminence and regulate the release of GnRH1. In addition, histological analysis of the song control system HVC, RA and Area X revealed that breeding males had significantly larger volumes of these brain nuclei as compared to non-breeding males, breeding females, and non-breeding females. Females did not exhibit a significant difference in the size of song control regions across breeding states. Together, these data show a marked sex difference in the extent to which there is breeding-associated variation in reproductive physiology and brain plasticity that is dependent on the reproductive state in a tropical breeding songbird.


► Seasonal change in GnRH1 mRNA and song nuclei were examined in Rufous-collared sparrow.
► GnRH1 mRNA is higher in male compared to female sparrows.
► GnRH1 mRNA is constitutively expressed in the POA regardless of breeding state.
► Female sparrows do not exhibit plasticity in HVC, RA, or Area X volumes.
► Data highlight sex differences for the neural integration of environmental cues.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: General and Comparative Endocrinology - Volume 178, Issue 1, 1 August 2012, Pages 1–7
نویسندگان
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