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

  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},
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

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

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

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

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

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)

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 ...



Photoperiodic control of the development of the LHRH neurosecretory system of European starlings (Sturnus vulgaris) during puberty and the onset of photorefractoriness.

The results suggest that gonadal regression is initiated by a reduction in L HRH synthesis and possibly, in addition, an external inhibitory influence on LHRH release.

Changes in brain GnRH associated with photorefractoriness in house sparrows (Passer domesticus).

The results are consistent with the idea that house sparrows become absolutely refractory, regardless of whether exposed to a decline in photoperiod, and suggest that relative refractoriness may induce gonadal regression through a cessation of GnRH secretion, whereas absolute ref tractoriness involves down-regulation of peptide production.

Immunohistochemical demonstration of proGnRH and GnRH in the preoptic-basal hypothalamus of the primate.

Using immunohistochemical techniques, it is observed that in serial and the same sections through the preoptic-basal hypothalamus (POA-BH), the precursor molecule was primarily present in the cell soma, whereas GnRH was found in thecells, nerve fibers, and terminals of the same neurons.

Photoperiodism in Japanese quail: the termination of seasonal breeding by photorefractoriness

  • J. RobinsonB. Follett
  • Biology
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  • 1982
Results suggest that the physiological basis of refractoriness lies either in the neural circuits regulating neurohormone secretion or in the photoperiodic clock mechanism itself.

Integration of photoperiodic and food cues to time changes in reproductive physiology by an opportunistic breeder, the red crossbill, Loxia curvirostra (Aves: Carduelinae)

  • T. Hahn
  • Biology, Environmental Science
  • 1995
Captive crossbills held on natural photoperiod, constant temperature, and ad libitum food express cycles of gonadal development, secretion of luteinizing hormone (LH), fat deposition, body mass, hematocrit, and molt, which shows that changing food availability is not necessary for expression of a seasonal cycle.

Effects of ovariectomy on GnRH mRNA , Ottawa : University of Ottawa Press , Comparative endocrinology of proGnRH and GnRH levels in the preoptic hypothalamus of the photorefractoriness

  • J Endocr
  • 1987

Photoperiodic control of the termination release in a long-distance migratory bird, the garden warbler (Sylvia of reproduction in Japanese quail (Coturnix japonica)

  • Proc R Soc borin), under constant photoperiods. J Endocr
  • 1990

Endocrine Localisation of a peptide sequence contained in the precursor tochanges associated with the termination of photorefractoriness by gonadotrophin releasing hormone ( GnRH )

  • Brain Res
  • 1987

Plasma prolactin and gonadotrophins during gonadal development and the onset of photorefractoriness in Statistical analysis male and female starlings ( Sturnus vulgaris ) on artificial photoperiods

  • Data on testicular mass , cell numbers , cell area and optical density of J Endocr
  • 1983