In vitro and in vivo evidence for the existence of presynaptic muscarinic cholinergic receptors in the rat hippocampus.
The intrahippocampal injection of kainic acid cleared 50% of muscarinic receptors and favored the detection of a further 20% loss in hippocampal presynaptic muscarinic receptors produced by electrolytic lesion of the medial septal nucleus as determined by Scatchard analysis of the saturation isotherms of [3H]dexetimide binding. In accordance, a decrease of about 20% in the in vivo accumulation of [3H]dexetimide in the hippocampus was found in animals lesioned in the medial septal nucleus. This effect occurred at both the dose of 5 micrograms/kg and at the saturating dose of 100 micrograms/kg of [3H]dexetimide. The results suggest that the loss was due to decreased receptor number rather than decreased receptor affinity.
D000818:Animals; D001921:Brain / Q000502:physiology; D003909:Dexetimide / Q000378:metabolism; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D007608:Kainic Acid / Q000633:toxicity; D007700:Kinetics; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
D011976:Receptors, Muscarinic; D003909:Dexetimide; D007608:Kainic Acid