Prostaglandins E2 and F2alpha and gross behavioural effects of cholinomimetic substances injected into the cerebral ventricles of unanesthetized cats.

Abstract

Abstract Prostaglandin E 2 in a dose of 0.001 mg injected intraventricularly into conscious cats did not produce any gross behavioural changes. The gross behavioural effects of cholinomimetic substances (methacholine, carbachol, physostigmine and pilocarpine) were markedly potentiated when injected 15min after 0.001 mg of PGE 2 . Emotional behaviour, autonomie changes and motor phenomena evoked by carbachol and physostigmine were maximally potentiated, whereas emotional behaviour produced by methacholine and pilocarpine were less potentiated. Acetylcholinesterase activity in the thalamus, hypothalamus and caudate nucleus was significantly inhibited 15 min after intraventricular injection of PGE 2 (0.001 mg). The same dose of PGE 2 had no effect on acetylcholinesterase activity in the hippocampus in the cat brain. Prostaglandin F 2α (PGF 2α ) when injected intraventricularly into conscious cats in a dose of 0.1 mg did not produce any significant gross behavioural changes. The gross behavioural effects of methacholine, carbachol, physostigmine and pilocarpine injected 15 min after PGF 2 were markedly potentiated. Acetylcholinesterase activity in the caudate nucleus, thalamus and hypothalamus, but not in the hippocampus, was significantly inhibited 15 min after the intraventricular injection of PGF 2α (0.1 mg). This finding corresponds well with the observation that PGE 2 strongly potentiated the gross behavioural effects of cholinomimetic substances, especially motor phenomena and emotional changes. It is concluded that the potentiating effect of prostaglandins E 2 and F 2α of gross behavioural changes induced by cholinomimetic substances can be, at least partly, due to acetylcholinesterase inhibition in some areas of the cat brain.