Chronic imipramine enhances 5-HT(1A) and 5-HT(2) receptors-mediated inhibition of panic-like behavior in the rat dorsal periaqueductal gray.
Electrical stimulation of the dorsal periaqueductal gray (DPAG) has been used to induce panic-like behavior in rats. In the present study, we investigated the effect of chronic imipramine treatment on the sensitivity of different 5-HT receptor subtypes in inhibiting aversion induced by electrical stimulation of this brain area. For that, the effects of intra-DPAG administration of the endogenous agonist 5-HT (20 nmol), the 5-HT(1A) receptor agonist 8-OH-DPAT (8 nmol) and the 5-HT(2A/2C) receptor agonist DOI (16 nmol) were measured in female Wistar rats given either chronic injection of imipramine (15 mg/kg, 3 weeks, ip) or saline. The results showed that the three receptor agonists raised the threshold of aversive electrical stimulation in both groups of animals, but this antiaversive effect was significantly higher in rats treated with imipramine. Treatment with imipramine did not change the basal threshold of aversive electrical stimulation measured before intra-DPAG injection of the 5-HT agonists. The results suggest that sensitization of both 5-HT(1A) and 5-HT(2) receptors within the DPAG may be involved in the beneficial effect of imipramine in panic disorder (PD).
Jacob
Cláudia A
CA
Laboratório de Psicologia Comparada, Universidade Estácio de Sá (UNESA), Rio de Janeiro, CEP, Brazil.
Cabral
Alfredo H C L
AH
Almeida
Leandro P
LP
Magierek
Valeska
V
Ramos
Patrício L
PL
Zanoveli
Janaína M
JM
Landeira-Fernandez
Jesus
J
Zangrossi
Hélio
H
Nogueira
Regina L
RL
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage / Q000494:pharmacology; D000662:Amphetamines / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D004558:Electric Stimulation; D004924:Escape Reaction / Q000187:drug effects; D005260:Female; D007099:Imipramine / Q000008:administration & dosage / Q000494:pharmacology*; D008845:Microinjections; D010200:Panic / Q000187:drug effects*; D010487:Periaqueductal Gray / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000187:drug effects*; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology
D000662:Amphetamines; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D007099:Imipramine; C015952:4-iodo-2,5-dimethoxyphenylisopropylamine