Neuroanatomical Substrate for the Inhibition of Gonadotrophin Secretion in Goldfish: Existence of a Dopaminergic Preoptico-Hypophyseal Pathway
作者:
Olivier Kah,
Joseph G. Dulka,
Pierrette Dubourg,
Jean Thibault,
Richard E. Peter,
期刊:
Neuroendocrinology
(Karger Available online 1987)
卷期:
Volume 45,
issue 6
页码: 451-458
ISSN:0028-3835
年代: 1987
DOI:10.1159/000124774
出版商: S. Karger AG
关键词: Dopamine;Tyrosine hydroxylase;Gonadotrophin release;Pituitary;Neuroendocrine control;Reproduction;Goldfish;Teleost
数据来源: Karger
摘要:
To investigate the existence of a dopaminergic preoptico-hypophyseal pathway in the goldfish, electrolytic lesions were placed in the rostral preoptic area and their effects on gonadotrophin levels and pituitary innervation examined. In a first experiment, the fish were sacrificed 2 days after surgery and the pituitary studied by electron microscopy. Numerous exocytosis profiles were observed in the gonadotrophs, confirming the large increase in serum gonadotrophin levels measured in the animals. In addition, type A and B degenerating fibers were detected in the neurohypophysis and the pars distalis, in particular at the level of the gonadotrophs. In the second experiment, the distribution of tyrosine hydroxylase-immunopositive fibers was studied in the pituitary of controls and lesioned animals. It was found that lesioning the anterior ventral preoptic region resulted in the disappearance of all positive fibers in the pars distalis, while those in the neurointermediate lobe appeared unaffected. The presence of a large group of catecholaminergic perikarya in the destroyed area was confirmed in control animals. These results and other data strongly support the existence of a dopaminergic preoptico-hypophyseal pathway, providing a morphological support for the inhibitory effect of dopamine on the release of anterior pituitary hormones in teleosts, in particular gonadotrophin.
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