Effects of catecholamines on thermoregulation in pigeons.
1 In unanaesthetized pigeons, kept at room temperature (20-23 degrees C) the effects on cloacal temperature were examined of catecholamines, phenoxybenzamine and propranolol, injected into the cerebral ventricles.2 Noradrenaline, adrenaline, dopamine and isoprenaline caused a fall in cloacal temperature.3 Phenoxybenzamine produced a long-lasting small rise in cloacal temperature. This rise is attributed to removal of the hypothermic effect of noradrenaline released continuously from adrenergic neurones ending in the anterior hypothalamus. Propranolol produced a slight fall in cloacal temperature.4 The hypothermic effects of noradrenaline, adrenaline and dopamine were prevented by phenoxybenzamine but not by propranolol. They are therefore attributed to activation of alpha-adrenoceptors.5 The hypothermic effect of isoprenaline was not prevented by either phenoxybenzamine or propranolol. The effect can therefore not be attributed to activation of either alpha or beta-adrenoceptors. Propranolol actually accentuated the isoprenaline-induced hypothermia.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects*; D002395:Catecholamines / Q000008:administration & dosage / Q000494:pharmacology*; D002552:Cerebral Ventricles; D002988:Cloaca / Q000187:drug effects; D010856:Columbidae / Q000502:physiology*; D003864:Depression, Chemical; D004298:Dopamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D007267:Injections; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010643:Phenoxybenzamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013997:Time Factors
D002395:Catecholamines; D010643:Phenoxybenzamine; D011433:Propranolol; D007545:Isoproterenol; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine