Immunocytochemical Localization of GnRH Precursor in the Hypothalamus of European Starlings during Sexual Maturationand Photorefractoriness

@article{Parry1997ImmunocytochemicalLO,
  title={Immunocytochemical Localization of GnRH Precursor in the Hypothalamus of European Starlings during Sexual Maturationand Photorefractoriness},
  author={Dilys M. Parry and Arthur R. Goldsmith and Robert P. Millar and Linda M. Glennie},
  journal={Journal of Neuroendocrinology},
  year={1997},
  volume={9}
}
Immunocytochemistry with quantitative image analysis, for both GnRH and its precursor proGnRH‐GAP, was used in male European starlings (Sturnus vulgaris) to investigate four stages of a photoperiodically‐induced reproductive cycle. Four different groups of birds were examined: photosensitive but sexually immature, sexually mature, undergoing gonadal regression, and after the completion of regression and fully photorefractory. 

Photoperiodic Condition Is Associated with Region-Specific Expression of GNRH1 mRNA in the Preoptic Area of the Male Starling (Sturnus vulgaris)1

TLDR
Detailed analysis of the rostrocaudal and mediolateral distribution revealed that breeding birds had greater numbers of cells expressing GNRH1 mRNA in the medial intermediate, mediocaudal, and lateral intermediate preoptic area compared with prebreeding and nonbreeding birds.

Variation in Gonadotrophin‐Releasing Hormone‐1 Gene Expression in the Preoptic Area Predicts Transitions in Seasonal Reproductive State

TLDR
It is demonstrated that the recovery of photorefractoriness involves an increase in gnrh1 mRNA expression and expands upon previous knowledge that the development of photosensitivity is associated with an increase with both the precursor proGnRH1‐GAP and GnRH1 peptides in the POA.

Interspecific Variation in Photo-Induced GnRH Plasticity among Nomadic Cardueline Finches

TLDR
Patterns of decrease in GnRH immunoreactivity, gonadal regression and molt suggest that some form of refractoriness to photostimulation develops on constant long days, and relatively small differences in the response of the neuroendocrine system to stimulatory cues such as day length may lead to remarkably different capabilities for reproductive flexibility even within a closely related family of birds.

Photoperiodically Driven Changes in Fos Expression within the Basal Tuberal Hypothalamus and Median Eminence of Japanese Quail

TLDR
The FLI induction parallels LH changes, suggesting that gene expression may be involved in events preceding photostimulation and is the earliest photoperiodically stimulated physiological change yet reported.

Gonadotropin-inhibitory hormone in seasonally-breeding songbirds: neuroanatomy and functional biology

TLDR
Direct effects of GnIH upon reproductive physiology and behavior are demonstrated, possibly at multiple physiological levels and over different time-frames, as well as in the midbrain on or close to GnRH-II neurons.

Photoperiod-Independent Hypothalamic Regulation of Luteinizing Hormone Secretion in a Free-Living Sonoran Desert Bird, the Rufous-Winged Sparrow (Aimophila carpalis)

TLDR
The data support the hypothesis that environmental factors associated with increased rainfall during the monsoon season stimulate GnRH synthesis and release to increase LH secretion and suggest that GnIH could inhibit GnRH neuronal activity prior to themonsoon season.

Identification of European starling GnRH-I precursor mRNA and its seasonal regulation.

Photorefractoriness and seasonal changes in the brain in response to changes in day length in American goldfinches (Carduelis tristis)

We examined neural and gonadal responses to photoperiod in a late-summer-breeding finch, the American goldfinch (Carduelis tristis). First we measured seasonal changes in the gonads of free-living ...
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