标题：Raphe pallidus modulates Botzinger complex-induced inhibition of the phrenic nerve activity in rats.
作者：Yu SY;Wang GM;Wang H;Zhang H;Li Q
作者机构：[Yu, S.-Y] Department of Physiology, Shandong University, School of Medicine, Jinan, Shandong Province, China, Key Laboratory of Medical Neurology of 更多
通讯作者地址：[Yu, SY]Shandong Univ, Dept Physiol, Sch Med, Jinan 250100, Shandong, Peoples R China.
来源：The European Journal of Neuroscience
关键词：Botzinger complex; phrenic nerve; raphe pallidus; rat; serotonin
摘要：The raphe pallidus (RPa) and Botzinger complex (BotC) represent two important nuclei which project to spinal phrenic motor neurons. Stimulation of the RPa produces facilitative effects on respiratory activity, whereas stimulation of the BotC induces inhibitory effects on respiratory activity. In the present study, we examined the modulatory effects of serotonergic (5-hydroxytryptamine, 5-HT) RPa neurons on the inhibitory response of the phrenic nerve activity elicited from the BotC in rats. Experiments were performed on spontaneously breathing, urethane-anesthetized adult rats. Either high-frequency stimulation or glutamatergic chemical activation of the RPa region significantly attenuated the BotC-induced inhibition of the phrenic nerve. This attenuation showed a post-stimulation time and intensity dependency. Pharmacological experiments showed that intravenous injection of methysergide, a broad-spectrum antagonist of 5-HT receptors, markedly reduced the respiratory facilitation induced by electrical stimulation of the RPa. Furthermore, microinjections of methysergide into the cerebrospinal fluid around the phrenic motor nucleus (PMN) region at spinal cord segments C4 and C5 significantly decreased the RPa-related attenuation effects on BotC-evoked inhibition of phrenic nerve discharge. These results suggest that RPa serotonergic neurons could modulate the inhibition of phrenic nerve activity induced by BotC. Moreover, as the relevant 5-HT receptors for RPa\'s modulatory effects are located in the cervical spinal cord, 5-HT may, in part, function as a modulator to suppress the BotC neuronal activity via direct RPa-PMN and BotC-PMN convergent projection pathways to phrenic motoneurons.