Benzodiazepine receptors modulating serotonergic neurotransmission in rat hippocampus do not desensitize after long-term diazepam treatment.
Previous studies have shown in the rat that long-term diazepam treatment induces a desensitization of gamma-aminobutyric acid (GABA) benzodiazepine receptors which modulate serotonergic (5-HT) neuron firing activity in the dorsal raphe. We have examined the effect of a 21-day treatment with diazepam (5 mg/kg/day, i.p.) on the benzodiazepine receptors (BZR) which modulate the efficacy of the electrical stimulation of the ascending 5-HT pathway in suppressing the firing activity of rat dorsal hippocampus pyramidal neurons. The efficacy of the stimulation was not modified 24 h after the last dose of diazepam. Moreover, the potentiating effect of acute diazepam (1 mg/kg, i.v.) on the efficacy of the stimulation was similar in diazepam- and vehicle-treated rats. These results indicate that GABA-benzodiazepine receptors that modulate the release of 5-HT in the rat dorsal hippocampus are not desensitized by long-term diazepam treatment.
Lista
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A
Department of Psychiatry, McGill University, Montreal, Que., Canada.
Blier
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P
de Montigny
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C
D000818:Animals; D003975:Diazepam / Q000494:pharmacology*; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D007478:Iontophoresis; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*; D013997:Time Factors
D011963:Receptors, GABA-A; D012701:Serotonin; D003975:Diazepam