Midbrain cholinergic mechanisms regulating cardiovascular responses during hypothalamic defence reaction.
1. Hind limb blood flow and arterial blood pressure were recorded during aggressive behaviour induced on electrical stimulation of the anterior hypothalamic area and the central gray, in anaesthetised cats. 2. Bilateral microinfusions of atropine sulphate (20 ug/ul) were made in the midbrain central gray, and the effect on the behavioural and cardiovascular components recorded. 3. Atropine sulphate was found to decrease the hind limb vascular conductance obtained on stimulation of the hypothalamic and the midbrain defence areas. 4. It was found that the recovery of the behavioural components of aggression required at least 1-5 days as compared to the cardiovascular components which reappeared after 3 weeks of atropine sulphate microinfusions. 5. These results suggest that although the cholinergic muscarinic mechanisms play an important role in eliciting both the behavioural and the cardiovascular responses from the same site, yet the two mechanisms may operate differently.
Dawra
P S
PS
Department of Physiology, All India Institute of Medical Sciences, New Delhi.
Rao
S P
SP
Manchanda
S K
SK
Tandon
O P
OP
D000374:Aggression / Q000187:drug effects; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D004558:Electric Stimulation; D005260:Female; D006614:Hindlimb / Q000098:blood supply; D007032:Hypothalamus, Anterior / Q000502:physiology*; D008297:Male; D010487:Periaqueductal Gray / Q000187:drug effects / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects
D011976:Receptors, Muscarinic; D001285:Atropine