Effect of Prolactin and Bromocriptine Administration on Testicular Metabolism in Albino Rats

Reddy, Y. Dhananjaya; Govindappa, S

doi:10.3109/13813458509104511

Cited by 1 publication

(1 citation statement)

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“…Because prolactin is luteotropic in mink and circulating concentrations of the hormone increase before progesterone, it is also possible that prolactin affects uterine glycogen metabolism. Prolactin receptors have been detected in the mink uterus and ovaries [ 50 , 51 ], and the hormone has been shown to stimulate glycogenolysis in the rat epididymis [ 52 ].…”

Section: Discussionmentioning

confidence: 99%

Uterine glycogen metabolism in mink during estrus, embryonic diapause and pregnancy

Dean

Hunt

McDougall

et al. 2014

Journal of Reproduction and Development

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We have determined uterine glycogen content, metabolizing enzyme expression and activity in the mink, a species that exhibits obligatory embryonic diapause, resulting in delayed implantation. Gross uterine glycogen concentrations were highest in estrus, decreased 50% by diapause and 90% in pregnancy (P ≤ 0.05). Endometrial glycogen deposits, which localized primarily to glandular and luminal epithelia, decreased 99% between estrus and diapause (P ≤ 0.05) and were nearly undetectable in pregnancy. Glycogen synthase and phosphorylase proteins were most abundant in the glandular epithelia. Glycogen phosphorylase activity (total) in uterine homogenates was higher during estrus and diapause, than pregnancy. While glycogen phosphorylase protein was detected during estrus and diapause, glycogen synthase was almost undetectable after estrus, which probably contributed to a higher glycogenolysis / glycogenesis ratio during diapause. Uterine glucose-6-phosphatase 3 gene expression was greater during diapause, when compared to estrus (P ≤ 0.05) and supports the hypothesis that glucose-6-phosphate resulting from phosphorylase activity was dephosphorylated in preparation for export into the uterine lumen. The relatively high amount of hexokinase-1 protein detected in the luminal epithelia during estrus and diapause may have contributed to glucose trapping after endometrial glycogen reserves were depleted. Collectively, our findings suggest to us that endometrial glycogen reserves may be an important source of energy, supporting uterine and conceptus metabolism up to the diapausing blastocyst stage. As a result, the size of uterine glycogen reserves accumulated prior to mating may in part, determine the number of embryos that survive to the blastocyst stage, and ultimately litter size.

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Section: Discussionmentioning

confidence: 99%