MODULATION OF ACETYLCHOLINE METABOLISM IN HIPPOCAMPAL CHOLINERGIC PATHWAY BY INTRASEPTALLY INJECTED SUBSTANCE-P

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 206  (1) , 21-28
Abstract
Intraventricular injection of substance P induced a dose-dependent decrease of acetylcholine (ACh) turnover rate (TRACh) in the hippocampus of rats. The highest dose used (20 nmol) decreased the hippocampal TRACh to 40% of the control value. No changes in the ACh or choline content were detected in the various brain areas 40 min after injection, but after 70 min an increase in ACh content in diencephalon was significant. Local injection of substance P into the medial nuclei of the septum decreased significantly the hippocampal TRACh. Neither intraventricular injection nor injection into the periaqueductal grey of high doses of substance P (30 nmol) induced analgesia, whereas .beta.-endorphin (1 nmol) and morphine (15 nmol) were effective. No specific change in the electroencephalograph pattern recorded from either cortex or hippocampus could be detected within the 1st 2 h after intraventricular injection of substance P. Substance P may serve as a neurotransmitter or a neuromodulator in the mammalian CNS.