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The selective 5--HT_(1A) receptor antagonist WAY--100635 increases neuronal activity of the basolateral nucleus of the amygdala in 6--hydroxydopamine--lesioned rats

Zhang Qiaojun, Wu Zhongheng, Liu Jian, Wang Tao, Wang Shuang, Han Lingna

Department of Neurology, the Second Hospital, School of Medicine, Xi'an Jiaotong University.Xi'an 710004,Shaanxi

Abstract

In the present study, extracellular recording was used to examine the neuronal activity of the basolateral nucleus (BL) of theamygdala and the effects of systemic administration of the selective 5-HT_(1A) receptor antagonist WAY-100635 on the neuronal activityin the normal rats and rats with 6-hydroxydopamine (6-OHDA)-produced lesions in the substantia nigra pars compacta (SNc), Theresults showed that the firing rates of BL projection neurons and intemeurons were (0.39±0.04) Hz and (0.83±0.16) Hz in the normalrats, and (0.32±0.04) Hz and (0.53±0.12) Hz in 6-OHDA-lesioned rats. There was no significant difference in the firing rates of BL projection neurons and interneurons between the normal and 6-OHDA-lesioned rats. In the normal rats, all BL projection neurons firedin burst; 94% of BL interneurons fired in burst and 6% fired irregularly. In 6-OHDA-lesioned rats, 85% of BL projection neurons displayed a burst fLdng pattern and 15% fired irregularly; 86% of BL intemeurons had a burst firing pattern and 14% fired irregularly.The distribution of firing patterns of projection neurons and interneurons in the BL in 6-OHDA-lesioned rats did not differ from thatin the normal rats. Systemic administration of WAY-100635 at 0.1 mg/kg body weight did not change the mean firing rates of projectionneurons and interneurons in the BL in both normal and 6-OHDA-lesioned rats, However, a higher dose of WAY-100635 at 0.5 mg/kgbody weight significantly decreased the mean firing rate of BL projection neurons from (0.43±0.07) to (0.15±0.02) Hz in the normalrats (P<0.01), but significantly increased the activity of BL projection neurons in 6-OHDA-lesioned rats from (0.37±0.08) to (0.69±0.18) Hz (P<0.004). The mean firing rates of BL interneurons in the normal and 6-OHDA-lesioned rats did not change after adminis-tration of a higher dose of WAY-100635 at 0.5 mg/kg body weight. These results demonstrate that the activity of BL neurons aftersubstantia nigra dopaminergic lesion in the SNc is regulated by activation of intrinsic and extrinsic inputs, and that 5-HT_(1A) receptorssignificantly contribute to the regulation of the activity of BL projection neurons in both normal and 6-OHDA-lesioned rats. Furthermore,WAY-100635 induced an increase in the mean firing rate of projection neurons in the BL in 6-OHDA-lesioned rats, suggesting that 5-HT_(1A) receptor is likely to play a role in generating affective symptoms in Parkinson's disease.

Key words: basolateral amygdala complex;5-HT_(1A) receptor;WAY-100635;6-hydroxydopamine;Parkinson's disease;Electrophysiology

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Citing This Article：

Zhang Qiaojun, Wu Zhongheng, Liu Jian, Wang Tao, Wang Shuang, Han Lingna. The selective 5--HT_(1A) receptor antagonist WAY--100635 increases neuronal activity of the basolateral nucleus of the amygdala in 6--hydroxydopamine--lesioned rats. Acta Physiol Sin 2008; 60 (2): 259-269 (in Chinese with English abstract).