Stress-induced 5-HT1A receptor desensitization: protective effects of Ginkgo biloba extract (EGb 761).
The effects of sub-chronic cold stress on the functioning of hippocampal 5-HT1A receptors in old isolated rats and the possible protective effects of Ginkgo biloba extract (EGb 761) were investigated. Cold exposure during five days, produced a significant reduction of the inhibitory effect of 8-hydroxy-2-(di-n-propylamino)tetraline (8-OH-DPAT) on forskolin-stimulated adenylyl cyclase activity. In contrast, neither the affinity nor the density of hippocampal [3H]8-OH-DPAT binding sites were affected indicating that the reduced sensitivity of 5-HT1A receptors induced by stress is probably due to a modification of their coupling mechanisms to adenylyl cyclase. The stress-induced desensitization of 5-HT1A receptors was prevented by the administration of EGb 761 (50 mg/kg per os/14 days). These results clearly indicate that 5-HT1A receptors are desensitized by stress and point out the reduced capacity of old rats to cope with the adverse effects of a chronic stressor. EGb 761 appears to restore the age-related decreased capacity to adapt to a chronic stressor.
Bolaños-Jiménez
F
F
Unité de Pharmacologie Neuro-Immuno-Endocrinienne, Institut Pasteur, Paris, France.
Manhães de Castro
R
R
Sarhan
H
H
Prudhomme
N
N
Drieu
K
K
Fillion
G
G
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000494:pharmacology*; D020441:Ginkgo biloba; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D013315:Stress, Psychological / Q000188:drug therapy / Q000378:metabolism*; D000096983:Ginkgo Extract
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D016166:Free Radical Scavengers; D010936:Plant Extracts; D011985:Receptors, Serotonin; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract