Chronic intermittent nicotine treatment dose-dependently alters serotonergic neurons response to citalopram in the rat.
Pharmacol Biochem Behav
; 89(3): 338-44, 2008 May.
Article
em En
| MEDLINE
| ID: mdl-18262640
ABSTRACT
Acetylcholine nicotinic systems and serotonergic systems are known to interact. In rodents, acute and chronic nicotine treatments have consequences on several aspects of the activity of dorsal raphe serotonin (DRN 5-HT) neurons. One hypothesis is that states of functioning of DRN 5-HT neurons (firing rate and sensitivity) vary as a function of nicotine dose and mode of administration during chronic nicotine treatment. In the present study, the firing rate and sensitivity of DRN 5-HT neurons were investigated using single (0.5 and 1 mg/kg) or multiple (3 injections of 0.7 mg/kg) daily injections of nicotine over 10 days. The sensitivity of neurons was tested by the cumulative dose of the selective serotonin reuptake inhibitor citalopram necessary to inhibit their firing. The activity of neurons was tested during treatment, and then 24 and 48 h after nicotine withdrawal. The results show that, on day 10, DRN 5-HT neurons were desensitized (reduced response to citalopram) after chronic single daily injection treatments with the high dose of nicotine (1 mg/kg), while their sensitivity remained unaltered after single daily injections with the low dose (0.5 mg/kg), and after the multiple daily injection paradigm. None of the treatments altered the firing rate of DRN 5-HT neurons. The dose-dependent and time-dependent alterations of serotonergic neurons sensitivity after chronic nicotine treatments are likely the consequences of long-term adaptations of nicotinic receptors. The desensitization of DRN 5-HT neurons after chronic single daily injections of 1 mg/kg of nicotine suggests an antidepressant-like effect of chronic nicotine.
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Núcleos da Rafe
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Citalopram
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Serotonina
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Inibidores Seletivos de Recaptação de Serotonina
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Nicotina
Limite:
Animals
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article