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