Propranolol Induced Changes in Plasma Catecholamine, Corticosterone, T₄, T₃and Prolactin Levels in the Pigeon

Abstract

Concentrations of plasma noradrenaline, adrenaline, corticosterone, thyroxine (T4), triiodothyronine (T3) and prolactin were measured in pigeons at 22 degrees C after intravenous injection of propranolol (1 mg/kg). An increase in catecholamines occurred in 5 or 15 min. T4, T3 and prolactin increased within 30 and 60 min after injection, however, after correction for the differences in plasma protein content, only the concentration of prolactin was significantly above the control values. It is concluded that the impairment of heat production produced by propranolol in birds is not primarily induced by inhibition of the secretion or release of these hormones.

Stress and adrenal function

“…Increased corticosterone concentrations occur in birds treated with catecholamines or adrenergic drugs (Freeman and Manning, '79a, 1980;Hissa et al, 1982), and the potentiated corticosterone responses to adrenocorticotrophin (ACTH) in birds pretreated with noradrenaline, adrenaline, and adrenergic drugs (Rees, Harvey, and Phillips, unpublished observations), suggests that catecholamines may increase corticosterone secretion by a peripheral mechanism or by increasing adrenal sensitivity to ACTH.…”

“…The immediate release of noradrenaline and adrenaline may also stimulate adrenocortical activity, in advance of the stimulation that follows the activation of the hypothalamo-pituitary-adrenal axis (HPA), because certain stressors increase the plasma corticosterone concentration (Beuving and Vonder,'78;Harvey et al, '80) before HPAinduced corticosterone secretion would be expected. Increased corticosterone concentrations occur in birds treated with catecholamines or adrenergic drugs (Freeman and Manning, '79a, 1980;Hissa et al, 1982), and the potentiated corticosterone responses to adrenocorticotrophin (ACTH) in birds pretreated with noradrenaline, adrenaline, and adrenergic drugs (Rees, Harvey, and Phillips, unpublished observations), suggests that catecholamines may increase corticosterone secretion by a peripheral mechanism or by increasing adrenal sensitivity to ACTH.…”