Substance P enhancement of passive and active avoidance conditioning in mice.
In a series of seven experiments we explored the effects of peripherally administered substance P on passive and active avoidance conditioning in mice of two genotypes. The peripheral post-trial administration of substance P significantly enhanced the retention of a single-trial passive avoidance task. This effect was dose dependent; 1 ng/g of substance P enhanced the retention of this habit, whereas higher and lower doses were either less effective or ineffective. In heterogeneous strain (HS) mice, substance P administered before training on an active avoidance task did not alter the rate at which these animals learned this habit. However, animals that had been trained with substance P were significantly more resistant to extinction than were animals that had been injected with vehicle. Similarly, C57Bl/6J mice that had been treated with substance P immediately after active avoidance training were more resistant to extinction than were mice that had been given control injections. The enhancement of retention of the passive avoidance habit with substance P was reversed in animals that had been pretreated with naltrexone. Substance P enhancement of the retention of the passive avoidance habit, and its reversal with naltrexone, was observed in both sham operated and adrenalectomized mice.
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009271:Naltrexone / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology*
D013373:Substance P; D009271:Naltrexone