Postsynaptic 5-HT1A receptors mediate 5-hydroxytryptamine release in the amygdala through a feedback to the caudal linear raphe

Using brain microdialysis, it was demonstrated that the release of 5-hydroxytryptamine (5-HT) in the central nucleus of the amygdala is under inhibitory control of somatodendritic and postsynaptic 5-HT1A receptors. Systemic administration of flesinoxan, a selective 5-HT1A receptor agonist, significantly reduced the extracellular levels of 5-HT in the central nucleus of the amygdala. This effect could be completely antagonized by the 5-HT1A receptor antagonist N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)-N-(2-pyridyl)cyclohexane carboxamine trihydrochloride (WAY 100635). Local administration of these compounds by reversed microdialysis into the raphe nuclei revealed that extracellular 5-HT levels in the central nucleus of the amygdala can be regulated through 5-HT1A receptors in the caudal linear raphe nucleus, but not in the dorsal and median raphe nuclei. Interestingly, administration of flesinoxan into the central nucleus of the amygdala also decreased dialysate 5-HT levels both locally and in the caudal linear raphe nucleus. The former effect could be blocked by pretreatment with WAY 100635 when applied into the central nucleus of the amygdala, but not when applied into the caudal linear raphe nucleus. These data provide circumstantial evidence for the existence of a 5-HT1A receptor mediated feedback loop from the central nucleus of the amygdala to the caudal linear raphe nucleus. (C) 1997 Elsevier Science B.V

MHPG and heart rate as correlates of nonresponse to drug therapy in panic disorder patients - A preliminary report

Little is known about biological predictors of treatment response in panic disorder (PD). In the present study heart rate, blood pressure, plasma cortisol and plasma MHPG were investigated at baseline in a sample of 44 PD patients as possible predictors for nonresponse to treatment. We used a strict definition of nonresponse to find patients who did not respond at all after 12 weeks of treatment with brofaromine or fluvoxamine. Patients were considered nonresponders when they fulfilled two criteria: they did not show a 50% reduction of agoraphobic avoidance and they still experienced panic attacks at endpoint. The variables that differed significantly between the groups were used to predict nonresponse to drug therapy. Using this strict definition of nonresponse, 15 patients (32.6%) were considered nonresponders. These patients were characterised by a higher plasma MHPG concentration and a higher heart rate at baseline. These variables were subsequently used to predict nonresponse

Clinical effects of buspirone in social phobia:A double-blind placebo-controlled study

Background: The results of open pilot studies suggest that the serotonin-1A (5-HT1A) receptor agonist buspirone might be effective in social phobia. Method: In the present study, the efficacy of buspirone was investigated in patients with social phobia using a 12-week double-blind placebo-controlled design. Thirty social phobic patients (DSM-IV) were treated with either buspirone 30 mg daily or placebo. Efficacy of treatment was measured using the Social Phobia Scale (subscores anxiety and avoidance) and the Hamilton Rating Scale for Anxiety. Results: Taking a reduction of 50% or more on the Social Phobia Scale as a criterion for clinically relevant improvement, only 1 patient on buspirone and 1 on placebo were classified as responder to treatment. A subjective and clinically relevant improvement was reported by 4 patients (27%) on buspirone and 2 patients (13%) on placebo. There were no statistically significant differences between buspirone and placebo on any of the outcome measures. Generally speaking, buspirone was well tolerated. Conclusion: The results of the study do not support the results of open studies, in which a reduction of social anxiety and social avoidance was reported in patients with social phobia treated with buspirone

MHPG and heart rate as correlates of nonresponse to drug therapy in panic disorder patients - A preliminary report

Little is known about biological predictors of treatment response in panic disorder (PD). In the present study heart rate, blood pressure, plasma cortisol and plasma MHPG were investigated at baseline in a sample of 44 PD patients as possible predictors for nonresponse to treatment. We used a strict definition of nonresponse to find patients who did not respond at all after 12 weeks of treatment with brofaromine or fluvoxamine. Patients were considered nonresponders when they fulfilled two criteria: they did not show a 50% reduction of agoraphobic avoidance and they still experienced panic attacks at endpoint. The variables that differed significantly between the groups were used to predict nonresponse to drug therapy. Using this strict definition of nonresponse, 15 patients (32.6%) were considered nonresponders. These patients were characterised by a higher plasma MHPG concentration and a higher heart rate at baseline. These variables were subsequently used to predict nonresponse

Responders and non-responders to drug treatment in social phobia: Differences at baseline and prediction of response

Differences between responders and non-responders to drug therapy were investigated in social phobia. Two previously published studies were pooled to obtain data of 30 patients who were treated for 12 weeks with brofaromine or fluvoxamine. Four criterion variables were used to divide patients in responders and non-responders. Depending on the criterion variable up to 72% of the patients were regarded as responders. Non-responders differed from responders in that they had a higher heart rate and a higher blood pressure. They were also characterised by higher scores on several psychometric scales, indicative of illness severity