Ultrastructural Evidence for Changes in Synaptic Input to the Hypothalamic Luteinizing Hormone‐Releasing Hormone Neurons in Photosensitive and Photorefractory Starlings

@article{Parry1993UltrastructuralEF,
  title={Ultrastructural Evidence for Changes in Synaptic Input to the Hypothalamic Luteinizing Hormone‐Releasing Hormone Neurons in Photosensitive and Photorefractory Starlings},
  author={D. M. Parry and Arthur R. Goldsmith},
  journal={Journal of Neuroendocrinology},
  year={1993},
  volume={5}
}
Neural input to the hypothalamic luteinizing hormone‐releasing hormone (LHRH) neurons was investigated in male starlings (Sturnus vulgaris) using electron microscopy combined with immunocytochemistry. Birds (4 to 6 in each group) were sampled at four stages of a photoperiodically induced reproductive cycle: (a) sexually immature but photosensitive, under short days; (b) during sexual maturation after 7 to 25 long days; (c) during gonadal regression after 35 to 50 long days; and (d) when fully… 

Prenatal testosterone masculinizes synaptic input to gonadotropin-releasing hormone neurons in sheep.

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The number of synapses on GnRH neurons from male, female, and androgenized female lambs was similar to that from male lambs, suggesting that prenatal steroids give rise to sex differences in synaptic input to Gn RH neurons.

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TLDR
It was found that preoptic GnRH neurons in breeding season ewes received more than twice the mean number of synaptic inputs per unit of plasma membrane as Gn RH neurons in anestrous animals, and significant seasonal differences were seen in both axodendritic and axosomatic inputs.

Seasonal Differences in the Secretion of Luteinising Hormone and Prolactin in Response to N‐Methyl‐dl‐Aspartate in Starlings (Sturnus vulgaris)

  • A. Dawson
  • Biology
    Journal of neuroendocrinology
  • 2005
TLDR
It is suggested that high circulating prolactin may fine‐tune the timing of gonadal regression in advance of the inhibition of cGnRH‐I synthesis, to confirm that photorefractoriness is associated with a lack of releasable cGN RH‐I, but that decreased synthesis of cNHR‐I is not the proximate cause of regression.

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

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TLDR
It is suggested that the development of absolute and relative photorefractoriness may be initiated by increased plasma prolactin, and that increased Prolactin maintains relative, but not absolute photoreFractoriness.

Effects of N-Methyl-d-Aspartate on Luteinizing Hormone Release and Fos-Like Immunoreactivity in the Male White-Crowned Sparrow (Zonotrichia leucophrys gambelii)1.

TLDR
Using the excitatory amino acid glutamate agonist N-methyl-d-aspartate (NMDA), plasma LH levels in White-crowned sparrows were significantly elevated regardless of the reproductive or photoperiodic condition, and NMDA significantly induced Fos-like immunoreactivity (FLI) within the infundibular nucleus and median eminence.

Molecular neuroendocrine mechanisms controlling photoperiodically regulated release of gonadotropin releasing hormone

TLDR
It is suggested that the development of absolute and relative photorefractoriness may be initiated by increased plasma prolactin, and that increased Prolactin maintains relative, but not absolute photoreFractoriness.

The effects of nerve growth factor and anti-nerve growth factor antibody on the neuroendocrine reproductive system in the European starling Sturnus vulgaris

Abstract Thyroidectomy of starlings causes them to remain in breeding condition indefinitely; deactivation of gonadotrophin-releasing hormone neurons that is characteristic of photorefractoriness

Anatomical localization of the effects of reproductive state, castration, and social milieu on cells immunoreactive for gonadotropin‐releasing hormone‐I in male European starlings (Sturnus vulgaris)

TLDR
The findings indicate that social context and hormonal milieu have profound effects on GnRH‐I immunoreactivity in addition to the previously described effects of reproductive state and suggest that gonadal hormones and female presence independently regulate Gn RH‐I cells in specific regions of the POA in male starlings.

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TLDR
Comparisons between animals of differing reproductive status are needed to determine whether alterations in synaptic inputs, glial ensheathment, or L HRH‐LHRH appositions, may underlie seasonal changes in the activity of LHRH neurons.

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TLDR
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TLDR
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TLDR
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TLDR
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TLDR
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