Effects of age and of chronic antidepressant treatment on [3H]tryptamine and [3H]dihydroalprenolol binding to rat cortical membranes.
1. The effects of age and of chronic antidepressant treatment on [3H]tryptamine and [3H]dihydroalprenolol binding site density were measured in brain cortical membranes from male Sprague-Dawley rats. 2. The density but not the affinity of [3H]tryptamine binding sites was increased in 18-month-old rats relative to 3-month-old rats. Neither the density nor the affinity of [3H]dihydroalprenolol binding sites was affected by age. 3. Chronic administration (28 days s.c. via Alzet osmotic minipumps) of tricyclic antidepressant drugs (daily doses: imipramine.HCl, 30 mg kg-1; desipramine.HCl, 10 mg kg-1; clomipramine.HCl, 10 mg kg-1) resulted in decreases in [3H]dihydroalprenolol binding site density but no changes in [3H]tryptamine binding site density; no changes in affinity of either site were observed. 4. Chronic administration (s.c. via Alzet osmotic minipumps) of monoamine oxidase inhibitor antidepressant drugs (daily doses: tranylcypromine.HCl, 0.5 and 1.0 mg kg-1; phenelzine sulfate, 5 and 10 mg kg-1, each for 28 days; clorgyline.HCl, 1.0 mg kg-1; (-)-deprenyl.HCl, 1.0 mg kg-1, each for 14 days) resulted in decreases in [3H]tryptamine binding site density, without any effects on the affinity of this site. In addition, each of these monoamine oxidase inhibitors except (-)-deprenyl resulted in a decrease in [3H]dihydroalprenolol binding site density. No affinity changes were observed. 5. These data indicate that the [3H]tryptamine binding site exhibits physiological changes with aging and is differentially sensitive to the actions of tricyclic antidepressants and monoamine oxidase inhibitor antidepressants, respectively.
Department of Psychiatry, University of Alberta, Edmonton, Canada.
D D
DD
Mousseau
D J
DJ
McManus
G B
GB
Baker
A V
AV
Juorio
W G
WG
Dewhurst
A J
AJ
Greenshaw
D000367:Age Factors; D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism*; D004082:Dihydroalprenolol / Q000378:metabolism*; D008297:Male; D008995:Monoamine Oxidase / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D011985:Receptors, Serotonin / Q000378:metabolism*; D014363:Tryptamines / Q000378:metabolism*
D000928:Antidepressive Agents; D011943:Receptors, Adrenergic, beta; D011985:Receptors, Serotonin; D014363:Tryptamines; C028413:dihydroalprenolol receptor; C030820:tryptamine; D004082:Dihydroalprenolol; D008995:Monoamine Oxidase