Support for a Physiological Role of Endogenous Catecholamines in the Stimulation of Bovine Luteal Progesterone Production1

Abstract

To determine if catecholamines were present in bovine luteal tissue, corpora lutea (CL) were obtained during the mid-luteal phase (Days 10-12) and the concentration of dopamine (DA) and norepinephrine (NE) was determined by high-performance liquid chromatography. Both DA and NE were detected in luteal tissue at mean concentrations of 41.9 +/- 5.73 and 10.2 +/- 2.51 ng/g for DA and NE, respectively. These concentrations represented a luteal content of 306.6 +/- 66.88 ng/CL for DA and 70.5 +/- 16.88 ng/CL for NE. In vitro, DA at concentrations of 1.0 mM to 0.01 mM stimulated the production of progesterone (P4, p less than 0.05). The response to DA was inhibited by propranolol (a beta-adrenergic receptor antagonist, p less than 0.05) but not by phentolamine, phenoxybenzamine (alpha-adrenergic receptor antagonists), or haloperidol (a DA receptor antagonist, p greater than 0.05). Neither L-tyrosine nor L-dopa altered P4 production (p greater than 0.05). Inhibition of DA beta-hydroxylase, the enzyme that catalyzes the conversion of DA to NE by FLA-63 blocked the DA-induced increases in luteal P4 production (p less than 0.05). These results demonstrate the existence of DA and NE in bovine luteal tissue and indicate that exogenous DA can be converted to NE in luteal tissue. The results support a physiological role for catecholamines in the stimulation of bovine luteal function.

Concentrations of catecholamines, ascorbic acid, progesterone and oxytocin in the corpora lutea of cyclic and pregnant cattle

“…The lack of correlation between ascorbic acid and catecholamines in our study sug [3,21,35] and pigs [31]. The ability of PGF to stimulate ascorbate secretion implies that this process is crucial for luteal regression.…”

“…We also found that the amount of DA in the CL is two to four times higher than NA. The high correlation between DA and NA (r = 0.66) and the presence of dopamine (3-hydroxylase in bovine CL reported in another study [3], provide evidence that NA could be synthesised de novo in this tissue as shown earlier by Kotwica et al [19]. The origin of DA in bovine CL is not clear.…”

“…The origin of DA in bovine CL is not clear. Battista et al [3] and Denning-Kendall et al [6] [24] provide evidence for the involvement of ascorbic acid in the stimulation of progesterone synthesis and OT secretion from bovine granulosa cells in vitro [25]. Thus, maximal luteal and follicular function was associated with increased concentrations of total ascorbate within the tissue in pigs [30] and in cattle [26], although its precise role in steroidogenesis has not been established [22].…”

“…and in vitro [3,5]. Moreover, noradrenaline (NA) is synthesised in bovine CL from its precursor dopamine (DA) [19].…”

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;.…”