The effect of cholinergic, GABAergic, serotonergic, and glutamatergic receptor modulation on posttrial memory processing in the hippocampus

Though the hippocampus is widely recognized as important in learning and me mory, most of the evidence for this comes from animal lesion and human path ological studies. Due to the relatively small number of drugs that have bee n tested in the hippocampus for their ability to alter posttrial memory pro cessing, there is a general impression that memory processing involves only a few neurotransmitters. We have evaluated the effects of cholinergic, GAB Aergic, serotonergic, and glutamatergic receptor agonists and antagonists f or their ability to facilitate or impair retention. CD-I mice received acut e intrahippocampal drug infusion following footshock avoidance training in a T-maze. Retention was tested 1 week after training and drug administratio n. The results indicate that receptor agonists of acetylcholine and glutama te improved retention, while antagonists impaired retention. However, scopo lamine did not impair retention, but M1 and M2 antagonists did. Receptor ag onists of serotonin and GABA impaired retention, while antagonists improved retention. Drugs acting on 5-HT-1 and 5-HT-2 as well as GABAA and GABAB re ceptor subtypes did not differentially effect retention, (C) 2000 Academic Press.