title: Are endogenous opiates involved in potentiation of field potentials in the hippocampus of the rat?
abstract: Changes in hippocampal CA1 field potentials during and after tetanic stimulation were studied in rats pretreated with 5 mg/kg s.c. naloxone or saline. Stimuli consisted of successive tetani of increasing frequency; responses at threshold, midrange and asymptotic intensities were sampled. A several fold increase in response amplitude occurred during low frequency stimulation, with no significant differences between the groups. Post-tetanic responses showed depression at the lower frequencies but increases ranging up to 400% at higher frequencies, with the greatest potentiation at threshold; again there were no significant differences between naloxone and saline groups, suggesting that endogenous opiates are not involved.
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004723:Endorphins / Q000502:physiology*; D004745:Enkephalins / Q000502:physiology*; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D004723:Endorphins; D004745:Enkephalins; D011957:Receptors, Opioid; D009270:Naloxone