Effects of naloxone on l-clausenamide-induced long-term potentiation in dentate gyrus of anesthetized rats.

AIM

To investigate the mechanisms of l-clausenamide-induced long-term potentiation (LTP) in the dentate gyrus of anesthetized rats.

METHODS

Extracellular recording technique was used to record the population spike (PS) in the dentate gyrus of anesthetized rats.

RESULTS

I.c.v. injection of naloxone 1 nmol, affecting neither the basal PS amplitude nor the LTP induced by tetanus, reduced the l-clausenamide-potentiated LTP only when it was administrated prior to clausenamide. Naloxone 1 nmol (i.c.v.), administrated 10 min before l-clausenamide, reduced the PS amplitude at 20 min, 55 min, and 90 min after i.c.v. injection of l-clausenamide 4 nmol from 138% +/- 10%, 170% +/- 10%, and 169% +/- 12% to 111% +/- 7%, 124% +/- 14%, and 123% +/- 11%, respectively. All P < 0.01 (n = 8). The same dose of naloxone (i.c.v.), delivered 10 min after l-clausenamide, did not affect the l-clausenamide-induced potentiation.

CONCLUSION

The activation of opioid receptors contributes to the induction of l-clausenamide-induced LTP of synaptic transmission in dentate gyrus of anesthetized rats.