Abstract
The efficacy of antidepressants has been linked in part to their ability to reduce activity of the hypothalamic-pituitary-adrenal (HPA) axis; however, the mechanism by which antidepressants regulate the HPA axis is largely unknown. Given that recent research has demonstrated that endocannabinoids can regulate the HPA axis and exhibit antidepressant potential, we examined the hypothesis that the endocannabinoid system is regulated by long-term antidepressant treatment. Three-week administration of the tricyclic antidepressant desipramine (10 mg/kg/day) resulted in a significant increase in the density of the cannabinoid CB(1) receptor in the hippocampus and hypothalamus, without significantly altering endocannabinoid content in any brain structure examined. Furthermore, chronic desipramine treatment resulted in a reduction in both secretion of corticosterone and the induction of the immediate early gene c-fos in the medial dorsal parvocellular region of the paraventricular nucleus of the hypothalamus (PVN) following a 5 min exposure to swim stress. Acute treatment with the CB(1) receptor antagonist, AM251 (1 mg/kg), before exposure to swim stress, completely occluded the ability of desipramine to reduce both corticosterone secretion and induction of c-fos expression in the PVN. Collectively, these data demonstrate that CB(1) receptor density in the hippocampus and hypothalamus is increased by chronic tricyclic antidepressant treatment, and suggest that this upregulation could contribute to the ability of tricyclic antidepressants to suppress stress-induced activation of the HPA axis.
Publication types
-
Research Support, N.I.H., Extramural
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Antidepressive Agents, Tricyclic / pharmacology*
-
Cannabinoid Receptor Modulators / agonists*
-
Cannabinoid Receptor Modulators / metabolism
-
Cortisone / metabolism
-
Depressive Disorder, Major / drug therapy*
-
Depressive Disorder, Major / metabolism
-
Depressive Disorder, Major / physiopathology
-
Desipramine / pharmacology
-
Disease Models, Animal
-
Drug Administration Schedule
-
Endocannabinoids*
-
Gene Expression Regulation / drug effects
-
Gene Expression Regulation / physiology
-
Hippocampus / drug effects
-
Hippocampus / metabolism
-
Hippocampus / physiopathology
-
Hypothalamo-Hypophyseal System / drug effects*
-
Hypothalamo-Hypophyseal System / metabolism
-
Hypothalamo-Hypophyseal System / physiopathology
-
Male
-
Norepinephrine / metabolism
-
Paraventricular Hypothalamic Nucleus / drug effects
-
Paraventricular Hypothalamic Nucleus / metabolism
-
Piperidines / pharmacology
-
Proto-Oncogene Proteins c-fos / drug effects
-
Proto-Oncogene Proteins c-fos / metabolism
-
Pyrazoles / pharmacology
-
Rats
-
Rats, Sprague-Dawley
-
Receptor, Cannabinoid, CB1 / agonists*
-
Receptor, Cannabinoid, CB1 / antagonists & inhibitors
-
Receptor, Cannabinoid, CB1 / metabolism
-
Stress, Psychological / drug therapy*
-
Stress, Psychological / metabolism
-
Stress, Psychological / physiopathology
-
Up-Regulation / drug effects
-
Up-Regulation / physiology
Substances
-
Antidepressive Agents, Tricyclic
-
Cannabinoid Receptor Modulators
-
Endocannabinoids
-
Piperidines
-
Proto-Oncogene Proteins c-fos
-
Pyrazoles
-
Receptor, Cannabinoid, CB1
-
AM 251
-
Desipramine
-
Cortisone
-
Norepinephrine