Neural regulation of the bovine corpus luteum.
The ovarian noradrenergic stimulation or noradrenaline (NA) administration directly to the ovary in cow increases ovarian oxytocin (OT) release and post-translational processing of OT synthesis within a few minutes has been established in both in vivo and in vitro studies. Furthermore, NA affects progesterone secretion and its synthesis by an increase of cytochrome P450scc and 3beta-hydroxysteroid dehydrogenase activity. This effect is mediated via luteal cell beta(1)- and beta(2)-receptors. Their total amount correlates with peripheral progesterone concentrations during the luteal phase and this reflects the ability of the ovary to react to beta-stimulation. On the other hand, ovarian denervation causes a decrease of steroidogenic activity in the CL, an increase of beta-receptors on luteal cells, a delay in follicular development and the disruption of cyclicity. Moreover, decrease of progesterone secretion by 20-30% was seen after brief pharmacological blockade of ovarian beta-receptors in the mid-cycle of cattle. We assume that tonic beta-stimulation of the CL ensures the basal secretion of progesterone, whereas acute noradrenergic activation supports the CL during stressful situations which could impair its function. Conversely, long-lasting increase in blood catecholamine concentrations markedly decreases the number of beta-receptors in CL, presumably due to their down-regulation. Concentrations of dopamine (DA) within the CL are highly correlated with those of NA during the estrous cycle, and are higher in the newly-formed than in the developed corpus luteum, the regressed corpus luteum or the corpus luteum of pregnant females. Bovine CL can synthesise de novo NA from DA as a precursor. Concluding, presented data indicate that noradrenergic stimulation can be an important part of mechanism supporting secretory function of CL.
Institute of Animal Reproduction and Food Research, Division of Endocrinology and Pathology, The Polish Academy of Sciences, P.O. Box 55, Prawochenskiego 5, 10-718 Olsztyn-Kortowo, Poland. janko@pan.olsztyn.pl
J
J
Kotwica
M
M
Bogacki
R
R
Rekawiecki
D000818:Animals; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000294:innervation* / Q000502:physiology; D005260:Female; D009638:Norepinephrine / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000032:analysis; D013312:Stress, Physiological
D011943:Receptors, Adrenergic, beta; D009638:Norepinephrine