The effect of periovulatory imbalance of prolactin on the expression of prolactin receptors in rat ovary cells |
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Authors: | T Kotok R L Bogorad A N Smirnov V M Turovetskii O V Smirnova |
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Institution: | (1) Hebrew University of Jerusalem, 12065, 91120 Jerusalem, Israel;(2) Moscow State University, Vorob’evy gory, 119899 Moscow, Russia |
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Abstract: | Using the technique of immunohistochemistry in combination with cytophotometry, we have studied the effect of periovulatory
hyper- and hypoprolactinemia on the expression of prolactin receptors in various cell types of rat ovaries during early estrus.
It has been shown that intense specific staining of oocytes is positively controlled by prolactin. The maximal intensity of
specific staining was found in cells of the cumulus and the inner layer of granulosa cells in mature follicles; staining intensity
gradually diminished towards the outer boundary cell layer. Postovulatory follicles are distinct from those mature follicles
in which there was no ovulation in their more intense manifestation of prolactin receptors in cells of the inner layer and
cumulus, as well as in increased positive staining (after prolactin administration) only in the granulosa layer cells closest
to theca. In follicles which did not ovulate by the time of the early estrus, prolactin administration leads to a proportional
growth of specific immunoreactivity in all cell layers of the granulosa. The administration of bromocryptin, an inhibitor
of prolactin secretion, leading to a 10-fold decrease in the prolactin level in the blood, results in a twofold decrease in
the intensity of specific staining of all cell layers of the granulosa in either type of follicle. Corpora lutea of the previous
cycle have irregularly positioned luteocytes with weak and strong specific staining, the intensity of which is not changed
in response to prolactin and diminishes slightly after the administration of bromocryptin. We conclude that the most intense
changes in the content of prolactin receptors under the conditions of imbalance of this hormone during the periovulatory period
are observed in those follicles where the oocyte did not ovulate by the time of early estrus. |
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Keywords: | ovulation ovaries prolactin receptors prolactin bromocryptin rat |
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