LACK OF OVARIAN-STEROID HORMONE REGULATION OF NOREPINEPHRINE TRANSPORTER MESSENGER-RNA EXPRESSION IN THE NONHUMAN PRIMATE LOCUS-COERULEUS

Decreases in ovarian steroids can negatively affect mood, and drugs wh ich block the norepinephrine transporter (NET) or the serotonin transp orter (SERT) alleviate depression. However, the respective contributio n of the noradrenergic and serotonergic systems may vary depending upo n the etiology of the depression. We previously demonstrated that E an d P alter gene expression for tryptophan hydroxylase (TPH) and for the serotonin reuptake transporter (SERT) in raphe neurons of the rhesus monkey. In this study, we questioned whether the noradrenergic system contributes to depression related to the reproductive function in wome n, using a non-human primate model of the menstrual cycle. The effect of estrogen (E) or E plus progesterone (P) on the expression of the NE T gene in the locus coeruleus (LC) was examined with in situ hybridiza tion for NET mRNA. In addition, we questioned whether the neurons of t he LC contain nuclear E or P receptors (ER/PR). Hence, immunocytochemi stry for ER and PR were performed on adjacent sections. Treatment grou ps consisted of monkeys (n = 4 per treatment) which were ovariectomize d/hysterectomized (spayed), E-treated (28 days) and E + P-treated (14 days E, +14 days E + P). Expression of mRNA far NET was unchanged at a ny level of the LC due to steroid treatment p > .05). Neither ER nor P R were detected in the LC of any treatment group. Therefore, E and P i n a treatment paradigm which mimics the menstrual cycle do not directl y regulate NET mRNA expression in the non-human primate LC. In additio n, the noradrenergic neurons of the primate LC lack nuclear receptors for ovarian steroids. These data suggest that the noradrenergic system may not contribute significantly to depression related to changes in ovarian hormones. (C) 1997 Elsevier Science Ltd.