Effect of repeated electroconvulsive shocks on serotonergic neurons.
The hypothermia induced by the serotonin (5-HT)1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) was attenuated in rats that had received a course of six electroconvulsive shocks (ECS) over a two-week period. The firing activity of dorsal raphe 5-HT neurons, as well as their responsiveness to microiontophoretic applications of 5-HT and 8-OH-DPAT, was unaltered in ECS-treated rats. The electrically evoked overflow of [3H]5-HT from preloaded slices of guinea pig hypothalamus was unchanged after the same ECS treatment. The concentration-effect curves of the 5-HT autoreceptor agonist 5-carboxyamidotryptamine (0.1-100 nM) were similar in slices prepared from control and ECS-treated guinea pigs. In addition, the reduction in the evoked [3H]5-HT overflow obtained by increasing the stimulation frequency from 1 to 5 Hz, which is due to a greater activation of terminal 5-HT autoreceptors at the higher frequency, was not altered by the ECS treatment. The enhancing effects of the 5-HT autoreceptor antagonist methiothepin (0.1-1 microM) and of the 5-HT3 agonist 2-methyl-5-HT (0.1-1 microM) on the evoked [3H]5-HT overflow were unaltered by the ECS treatment. These results thus indicate that repeated ECS attenuates the 8-OH-DPAT-induced hypothermia in rats, as previously reported, but does not affect the firing activity of 5-HT neurons and the sensitivity of their somatodendritic 5-HT1A autoreceptors in the dorsal raphe. The function of 5-HT terminals in the guinea pig hypothalamus was also unaffected by repeated ECS. In conclusion, repeated ECS does not affect the function of 5-HT neurons at the cell body and nerve terminal.
Blier
P
P
McGill University, Department of Psychiatry, Montréal, Qué., Canada.
Bouchard
C
C
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001933:Brain Stem / Q000502:physiology / Q000648:ultrastructure; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D004565:Electroconvulsive Therapy; D006168:Guinea Pigs; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D007035:Hypothermia / Q000139:chemically induced / Q000209:etiology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D014316:Tritium; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; D014316:Tritium; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin