title: Serotonergic effects on feeding, but not hypothalamus-pituitary-adrenal secretion, are altered in ovine pregnancy.
abstract: In ovine pregnancy, as in human pregnancy, hypothalamus-pituitary-adrenal activity is chronically increased. These studies were designed to test the hypotheses that expression of serotonergic genes and responsiveness to serotonin are increased in pregnancy. We tested the stimulatory effect of an acute, intracerebroventricular injection of the serotonin reuptake inhibitor fluoxetine on plasma ACTH and cortisol in ewes during late pregnancy or postpartum. We also tested the effect of lower-dose, longer-term stimulation by intracerebroventricular infusion of fluoxetine in pregnant and nonpregnant ewes over 6 days. Overall, we found that the stimulatory effect of fluoxetine on ACTH and cortisol was not significantly different between late-gestation and nonpregnant ewes, although the effect of acute fluoxetine administration was inversely related to plasma progesterone concentrations. Also, there were no differences in hypothalamic expression of the glucocorticoid and mineralocorticoid receptors, corticotropin-releasing hormone, AVP, the serotonin reuptake transporter, or the serotonin [5-hydroxytryptamine (5-HT)] receptors 5-HT(1A) and 5-HT(2A) with pregnancy or fluoxetine treatment. However, chronic fluoxetine infusion reduced food intake in the nonpregnant, but not pregnant, ewes. Expression of proopiomelanocortin mRNA in the hypothalamus was reduced in pregnant compared with nonpregnant ewes. Our results indicate that pregnancy does not increase responsiveness of ACTH and cortisol to serotonergic stimulation but, rather, that progesterone reduces the ACTH response. In addition, we found a reduced ability of serotonin to inhibit feeding in the pregnant ewes, consistent with a reduction in anorexic mechanisms in the pregnant state.
authors.affiliation: Box 100274, Dept. of Physiology and Functional Genomics, Univ. of Florida, Gainesville, FL 32610, USA. melland@ufl.edu
authors.forename: Melissa
authors.initials: M
authors.lastname: Lingis
authors.forename: Elaine
authors.initials: E
authors.lastname: Richards
authors.forename: Dana
authors.initials: D
authors.lastname: Perrone
authors.forename: Maureen
authors.initials: M
authors.lastname: Keller-Wood
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D005473:Fluoxetine / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D006400:Hematocrit; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D007276:Injections, Intraventricular; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D049590:Postpartum Period / Q000502:physiology; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D011333:Pro-Opiomelanocortin / Q000235:genetics; D012701:Serotonin / Q000502:physiology*; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D012756:Sheep
chemical_list: D000324:Adrenocorticotropic Hormone; D005473:Fluoxetine; D006854:Hydrocortisone; D011333:Pro-Opiomelanocortin; D012701:Serotonin; D017367:Selective Serotonin Reuptake Inhibitors