Catecholamines regulate the steroidogenesis by luteal cells from early pregnant pig

Luteal cells (10(6)/chamber) from pregnant pigs (Day 18, n = 5) were incubated in a perfusion system with a flow rate of 0.11 ml/min and samples collected every 10 min. This medium 199 had been supplemented with 1% BSA, 0.1% ascorbic acid and 10 mM Hepes buffer. The effects in vitro of adrenergic agonists (adrenaline, noradrenaline and isoproterenol) at concentrations of 10(-5) M on progesterone (P4) production by pig luteal cells were studied. The alpha or beta receptors were blocked by pretreatment of the luteal cells with phentolamine or propranolol for 30 min and then the cells were treated with adrenergic agonists for 60 min followed by a further 80 min with medium alone. The steroidogenic response to noradrenaline in terms of increased P4 production was greater than that for adrenaline and isoproterenol (P less than 0.05). Response to both natural and synthetic catecholamines was suppressed by pretreatment of luteal cells with propranolol but after pretreatment with phentolamine all the agonists significantly (P less than 0.05) elevated P4 production. The results demonstrate that catecholamines can affect steroidogenesis in luteal cells from the early pregnant pig and their action is mediated by beta adrenergic receptors.