Long-term antidepressant treatment restores clonidine's effect on growth hormone secretion in a genetic animal model of depression.
We have recently demonstrated that various doses of clonidine failed to increase growth hormone (GH) in Fawn-hooded (FH) rats (a rat strain suggested to represent a genetic model of depression). In the present study, we investigated whether long-term antidepressant treatment might normalize clonidine's effect on GH secretion in male FH rats. Long-term (16 days) treatment with the tricyclic antidepressant, imipramine (5 mg/kg/day), the 5-HT uptake inhibiting antidepressant, fluoxetine (2.5 mg/kg/day), and the noradrenergic uptake inhibiting antidepressant, desipramine (5 mg/kg/day), accentuated clonidine's effect on GH levels. On the other hand, long-term treatment with the monoamine oxidase type-A inhibiting antidepressant, clorgyline (1 mg/kg/day) and the alpha 2-noradrenergic antagonists, yohimbine and 1-phenylpiperazine (1 mg/kg/day, each) did not modify clonidine's effect. These findings suggest enhancement of 5-HT2c receptor-mediated function following long-term treatment with uptake inhibiting antidepressants in a genetic animal model of depression.
Aulakh
C S
CS
Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, MD 20892-1264, USA.
Mazzola-Pomietto
P
P
Murphy
D L
DL
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D018687:Antidepressive Agents, Second-Generation / Q000494:pharmacology; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology*; D003010:Clorgyline / Q000494:pharmacology; D003866:Depressive Disorder / Q000235:genetics* / Q000378:metabolism*; D003891:Desipramine / Q000494:pharmacology; D005260:Female; D005473:Fluoxetine / Q000494:pharmacology; D013006:Growth Hormone / Q000378:metabolism*; D008297:Male; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D058647:Adrenergic alpha-2 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D000928:Antidepressive Agents; D018687:Antidepressive Agents, Second-Generation; D000929:Antidepressive Agents, Tricyclic; D008996:Monoamine Oxidase Inhibitors; D005473:Fluoxetine; D013006:Growth Hormone; D003010:Clorgyline; D003000:Clonidine; D003891:Desipramine