Effect of Catecholamines on the Secretory Function of the Bovine Corpus Luteum

Abstract

ContentsAdrenergic innervation of the ovary is crucial for the corpus luteum (CL) secretory function in many species. Noradrenergic stimulation of the ovary or noradrenaline (NA) treatment causes a prompt increase in progesterone and ovarian oxytocin (OT) secretion during the entire luteal phase. Ths effect is medated via luteal cell 8-recep tors. Their amount correlates with peripheral progesterone concentrations on days 4, 8 and 12 of the oestrous cycle. NA also stimulates progesterone and OT synthesis by activating 38-hydroxysteroid dehydrogenase (38-HSD) and peptidyl glycine-a-amidating monooxygenase (PGA), respectively, withn the luteal cell. On the other hand, ovarian denervation in the rat and ewe causes many morphe logical and functional changes, i.e. a decrease of luteal steroidogenic activity, an increase in the number of B-receptors on luteal cells, disruption of cyclicity, delay of follicular development, etc. Furthermore, a brief blockade of ovarian 8-receptors in mid cycle in cattle decreases progesterone secretion by up to 40%. It was also dmovered that NA can be synthesised within the CL from dopamine @A) and moreover, NA does appear to activate tyrosine hydroxylase converting tyrosine to DOPA, which is transformed further to dopamine. It is suggested that (1) constant 8-stimulation of the CL ensures basal secretion of progesterone, whereas short-term noradrenergtc system activation prevents and even supports CL function; (2) activation of the noradrenergic system and its concomitant influence on ovarian and peripheral vasculature, lipolysis and luteal cell enzyme activity causes a prompt response of the CL to brief stressful situations which could impair its function and (3) NA affects its own synthesis within the CL. Ovarian innervationThe extrinsic autonomic nerves reach the ovary via the nerve in the suspensory ligament (superior ovarian nerve) innervating predominantly the endocrine component, and the ovarian plexus which innervates mamly the ovarian vasculature (Lawrence and Burden 1980). Ovarian NA content which reflects ovarian innervation increased in rats (Ben-Jonatan et al. 1984) during sexual maturation and declines during agmg (Ferrante et a]. 1990). NA and DA, which is a NA precursor, were found in bovine CL and ovarian stroma, and DA concentrations were much hgher in the early luteal phase than during the rest of the cycle or pregnancy penning- Kendall et al. 1991). In addition, follicular differentiation in newborn rats depends on direct neurogenic influence when ovaries are insensitive to gonadotrophins (Malamed et a]. 1992). The increase in ovarian NA and DA content in cyclic rats with lesions in the amygdaloid complex suggests that the amygdaloid catecholaminergtc system exerts an inhibitory ef€ect on ovarian catecholamines (Leret et al. 1992). Likewise, in rats with posterior hypothalamic lesions inflicted on the day of birth, NA Concentrations at puberty were markedly higher than in intact controls (Ivanisevic-Mdovanovic et al. 1993). Thus, the peripheral noradrenergic s...

Norepinephrine stimulates progesterone production in highly estrogenic bovine granulosa cells cultured under serum-free, chemically defined conditions

“…In addition, few studies have evaluated the effects of NE on the synthesis of the key ovarian hormones progesterone (P4) and estradiol (E2). Norepinephrine has been previously shown to induce P4 production in the bovine corpus luteum [11,12]. However, the effects of NE in E2 production by ovarian follicular granulosa cells (GCs) have not been demonstrated in mammalian species, despite the known elevation of catecholamine levels in the estrogenic pre-ovulatory phase of the rodent estrous cycle [13] and the presence of high concentrations of NE in the follicular fluid and follicular wall of both, small antral and pre-ovulatory follicles of cows [14].…”

Beta-Adrenergic Receptors in Corpora Lutea from Different Stages of the Estrous Cycle in Conscious and Slaughtered Cattle1

“…Accepting this hypothesis, it is possible to explain the prompt CL response to catecholamine challenge in vivo [27,36] in contrast to the response in vitro [5]. Furthermore, when the early stages of CL formation and its importance in early pregnancy are taken into account, this catecholamine mechanism influences CL secretion and supports its normal function, regardless of blood pressure changes in the general circulation [39].…”

Influence of dopamine as noradrenaline precursor on the secretory function of the bovine corpus luteum in vitro

“…Results from studies on other species have suggested that dopamine can affect this process directly through specific dopamine receptors (Clarke et al, 1979;Hilditch & Drew, 1985;Cameron et al, 1992), indirectly through the adrenoceptors by way of a cross-reaction (Weiner, 1985) or finally dopamine can be converted to NA in the process catalysed by dopamine-f-hydroxylase (Levin et al, 1960). Dopamine, which is a precursor for NA, was discovered to be present in bovine corpus luteum (CL) (Battista et al, 1989;Denning-Kendall et al, 1991) and was found to stimulate OT secretion from CL in conscious heifers (Kotwica et al, 1995). NA influences the concomitant secretion of progesterone and ovarian OT during all stages of oestrous cycle in cattle (Kotwica et al, 1991; by acting through the fl-adrenoceptors (Godkin et al, 1977;.…”