| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1994: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
|
|---|
| Research Abstract |
Studies have been carried out to clarify the role of emotional factors e.g., anxiety and fear underling the production of antinociception (stress-induced analgesia, SIA) and the blockade of the development of tolerance to morphine antinociception by exposure to psychological (PSY) stress using the communication box. 1. Both PSY-SIA and the suppression of the development of morphine tolerance were completely extinguished by diazepam (DZP), suggesting an essential role of emotional factors in the underlying mechanisms. Methysergide, buspirone, ritanserin and Y-25,130 dose-dependently suppressed both the production of PSY-SIA and the blockade of tolerance development by PSY-stress, while neither (<plus-minus>) pindolol nor imipramine was inffective. Thus, it is suggested that 5-HT receptor (5-HT_<1A>,5-HT_2 and 5-HT_3 but not5-HT_<1B>) -mediated mechanisms participate in the appearance of various responses to PSY stress, and furthermore, to observe the extinguishable effect of drugs on th
… More
e stress-induced responses, e.g., analgesia and suppression of the development of morphine tolerance, would be valid for a new method for screening anxiolytic drugs in mice. 2. The development of antinociceptive tolerance to morphine was significantly delayd in the presence of inflammatory pain induced by formalin. While indomethacin and aspirin had no effects on the delay of the development of morphine tolerance, diazepam completely abolished the delay. These results suggest that pain associated anxiety participates in the delay of the development of morphine tolerance. 3. In an elevated plus maze method, PSY-stress produced the anxiogenic effect. 4. Exposure to PSY-stress induced a significant place aversion in the conditioned place preference method, while the stress potentiated the reinforcing effect of morphine. 5. Pre-training PSY-stress in the one trial passive avoidance learning task resulted in enhanced test latency. Naloxone did not affect the facilitatory effects, suggesting different mechanisms are involved in stress-induced memory modification and the production of SIA. Less
|
