Mechanism of action of noradrenaline on secretion of progesterone and oxytocin by the bovine corpus luteum in vitro

Authors: Miszkiel, Grazdotyna; Kotwica, J.

Source: Acta Veterinaria Hungarica, Volume 49, Number 1, 31 January 2001 , pp. 39-51(13)

Publisher: Akademiai Kiado

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Abstract:

The present studies were conducted: (1) to determine which bgr-adrenoceptor subtypes are involved in progesterone and oxytocin (OT) secretion, (2) to examine whether noradrenaline (NA) acts directly on the cytochrome P-450scc and 3bgr-hydroxysteroid dehydrogenase (3bgr-HSD), and (3) to study the effect of prostaglandin F2agr (PGF2agr) on NA-stimulated steroidogenesis in luteal cells. The effect of NA on progesterone secretion from luteal slices of heifers on days 8–12 of the oestrous cycle was blocked by both atenolol (bgr1-antagonist) and ICI 118.551 hydrochloride (bgr2-antagonist). OT secretion was blocked only after treatment with ICI 118.551 hydrochloride (P < 0.05). Dobutamine (10–4–10–6M), a selective bgr1 agonist and salbutamol (10–4–10–6M), a selective bgr2 agonist, both increased progesterone production (P < 0.01) with an efficiency comparable to that produced by NA (P < 0.01). The increase of OT content in luteal slices was observed only after treatment with salbutamol at the dose of 10–5M (P < 0.01). Dobutamine had no effect on OT production at any dose. A stimulatory effect of NA on cytochrome P-450scc activity (P < 0.05) was demonstrated using 25-hydroxycholesterol as substrate. 3bgr-HSD activity also increased following NA (P < 0.01) or pregnenolone (P < 0.05) and in tissue treated with pregnenolone together with NA (P < 0.01). PGF decreased progesterone synthesis (P < 0.05) and 3bgr-HSD activity (P < 0.01) in tissue treated with NA. We conclude that NA stimulates progesterone secretion by luteal bgr1- and bgr2-adrenoceptors, while OT secretion is probably mediated only via the bgr2-receptor. NA also increases cytochrome P-450scc and 3bgr-HSD activity. PGF inhibits the luteotropic effect of NA on the luteal tissue.

Keywords: oxytocin; progesterone; corpus luteum; Cattle; noradrenaline

Document Type: Research article

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