CORTISOL, HYPOTHERMIC, AND BEHAVIORAL-RESPONSES TO IPSAPIRONE IN PATIENTS WITH BIPOLAR DEPRESSION AND NORMAL CONTROLS

To examine if 5-HT1A receptor function is involved in the pathophysiol ogy of bipolar depression, we measured the cortisol, hypothermic and b ehavioral responses to ipsapirone, a 5-HT1A receptor agonist, in 8 pat ients with bipolar depression and 26 normal controls. After obtaining blood samples for baseline cortisol levels and measuring baseline body temperature, a single dose of 0.3 mg/kg of ipsapirone was administere d orally to all the subjects, and further blood and temperature readin gs were obtained every 30 min for 3 h. The results showed that the adm inistration of ipsapirone led to a significant increase in cortisol re lease and a significant decrease in body temperature both in bipolar d epressed patients and normal controls. There was no significant differ ence in the cortisol or hypothermic responses to ipsapirone between gr oups. However, there was a significant positive correlation between th e Hamilton Depression Rating (HAMD) scores and the hypothermic respons e in the depressed patients, while the HAMD scores were not significan tly correlated with the cortisol response. Comparing our findings with those of previous studies, we suggest that the alterations in 5-HT1A receptor sensitivity in depressed patients may be related to the sever ity of depression, and they may only occur in more severely depressed patients.