The Effect of Antidepressant Treatment on Beta-Adrenergic Receptor Responsiveness in Patients with Major Depression

Baek, Hye Kyung; Kim, Eui Jung; Yu, Bum Hee

Abstract

Many studies have reported reduced beta-adrenergic receptor responsiveness in major depression, but there were few studies to see the effect of antidepressant treatment on beta-adrenergic receptor function in depressed patients. This study examined beta-adrenergic receptor responsiveness in patients with major depression before and after antidepressant treatment. After careful psychiatric interviews by two experienced psychiatrists, twenty depressed patients (Hamilton Depression Rating Scale scores>18) were randomly assigned to 8 weeks of double-blind treatment with either milnacipran or sertraline. Twenty normal control subjects who had no previous history of major medical and psychiatric illness were matched with the patients considering age, sex and body mass index. The Hamilton Depression Rating Scale (HAM-D), Montgomery-Asberg Depression Rating Scale (MADRS) and Hamilton Anxiety Rating Scale (HAM-A) were performed to assess clinical change of depression in the patients before and after treatment. We measured the lymphocyte cyclic AMP ratio (ratio of isoproterenol-stimulated cAMP/ basal cAMP), beta-adrenergic receptor density (Bmax) and receptor affinity (Kd) in all subjects. Depressed patients showed much lower HAM-D scores (25.7+/-4.8 vs. 14.3+/-9.1, p=0.002), MADRS scores (34.3+/-5.7 vs. 21.5+/-13.1, p=0.005) and HAM-A scores (31.4+/-7.9 vs. 22.1+/-13.5, p=0.040) after 8 weeks of antidepressant treatment than those before treatment. There were statistically significant differences in the means of Bmax and Kd between control subjects and patients before treatment. Contrary to our expectation, there was no statistically significant difference in the means of cAMP ratio between the two groups. Lymphocyte Bmax (4.90+/-3.08 vs. 8.13+/-3.08, p=0.027) and Kd (63.61+/-6.52 vs. 70.89+/-9.40, p=0.029) in the patients increased after antidepressant treatment. This result suggests that antidepressant treatment increases beta-adrenergic receptor responsiveness in depressed patients.