1. The effects of intracerebroventricular administration of Tyr-D-Arg-Phe-beta-Ala-NH2 (TAPA), a novel dermorphin analog, on plus-maze learning and spontaneous alternation performance were investigated in mice. 2. The pre- or posttraining or preretention administration of TAPA (0.3-3.0 ng) alone failed to affect transfer latency of plus-maze learning, whereas TAPA (3 ng) produced a significant decrease in percent alternation without affecting total arm entries. 3. beta-Funaltrexamine (5 micrograms) almost completely reversed the TAPA (3 ng)-induced decrease in percentage of alternation. 4. These results suggest that stimulation of mu-opioid receptors disrupts spontaneous alternation performance associated with spatial working memory.
Analgesics, Opioid Animals