[Effect of TRH and its analog DN-1417 on anoxia-induced amnesia in mice].

The effect of neuropeptides and their analogs on anoxia-induced amnesia was examined using one-trial passive avoidance task in mice. Anoxia, produced by the exposure to CO2 immediately after the acquisition of avoidance response, induced amnesia which is shown by a short latency to enter from the safety compartment into the shocked compartment in the retention test conducted 24 hr later. In these anoxia-treated animals, thyrotropin-releasing hormone (TRH: 10-20 mg/kg), its analog DN-1417 (10-20 mg/kg) and ACTH 4-10 (66 micrograms/body), which were given sc 15-60 min before the retention test, markedly prolonged the latency in a dose-dependent manner, indicating a reversal of the amnesia. Arginine- and lysine-vasopressin also reversed the amnesia at a dose of 100 micrograms/body. These results suggest that TRH and DN-1417, known to reverse the amnesia produced by the protein synthesis inhibitor cycloheximide, have ameliorating effects on the retrieval process of memory.