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={D. M. Parry and Arthur R. Goldsmith and Robert Peter Millar and L 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. 
Hypothalamic GnRH-I and its precursor during photorefractoriness onset in free-living male Dark-eyed Juncos (Junco hyemalis) of different year classes.
TLDR
Age-class differences in the transition to photorefractoriness do not appear to result from differences in GnRH-I synthesis, and the regulation of Gn RH-I secretion by non-photoperiodic factors may determine photoreFractoriness onset. Expand
Cloning of gonadotropin-releasing hormone I complementary DNAs in songbirds facilitates dissection of mechanisms mediating seasonal changes in reproduction.
TLDR
In situ hybridization using radiolabeled cRNA probes demonstrated GNRH1 mRNA expression primarily in the POA, consistent with previous studies on the distribution of the GnRH1-immunoreactive cell bodies, and provided evidence for photoperiod-dependent regulation of GN RH1 mRNA in male starlings. Expand
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. Expand
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TLDR
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Interspecific Variation in Photo-Induced GnRH Plasticity among Nomadic Cardueline Finches
TLDR
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Photoperiodically Driven Changes in Fos Expression within the Basal Tuberal Hypothalamus and Median Eminence of Japanese Quail
TLDR
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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. Expand
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. Expand
Identification of European starling GnRH-I precursor mRNA and its seasonal regulation.
TLDR
It is indicated that GnRH-I mRNA synthesis commences but is variable in photosensitive birds, stabilizes in photostimulated birds, then ceases when birds become photorefractory. Expand
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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References

SHOWING 1-10 OF 24 REFERENCES
Photoperiodic control of the development of the LHRH neurosecretory system of European starlings (Sturnus vulgaris) during puberty and the onset of photorefractoriness.
TLDR
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. Expand
Changes in brain GnRH associated with photorefractoriness in house sparrows (Passer domesticus).
TLDR
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. Expand
Immunohistochemical demonstration of proGnRH and GnRH in the preoptic-basal hypothalamus of the primate.
TLDR
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. Expand
Photoperiodism in Japanese quail: the termination of seasonal breeding by photorefractoriness
  • J. Robinson, B. Follett
  • Biology, Medicine
  • Proceedings of the Royal Society of London. Series B. Biological Sciences
  • 1982
TLDR
Results suggest that the physiological basis of refractoriness lies either in the neural circuits regulating neurohormone secretion or in the photoperiodic clock mechanism itself. Expand
Recovery of photosensitivity in photorefractory starlings is not prevented by testosterone treatment.
TLDR
In the castrated birds given empty capsules plasma luteinizing hormone (LH) rose from basal levels after 20-30 days and reached a high plateau level at about 40 days; this return of a "castration response" indicates a quite rapid recovery of photosensitivity under short days. Expand
Integration of photoperiodic and food cues to time changes in reproductive physiology by an opportunistic breeder, the red crossbill, Loxia curvirostra (Aves: Carduelinae)
TLDR
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. Expand
Gen Compa 25 Hahn TP, Ball GF. Neuroendocrine basis of reproductive flexibility
  • Endocr
  • 1995
Neuroendocrine basis of reproductive flexibility
  • Endocr
  • 1995
GnRH expression in photorefractory dark - eyed Juncos ( Junco hyem - Immunocytochemical studies on the LHRH system of the Japanese alis )
  • Gen Comp Endocr
  • 1994
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
...
1
2
3
...