Zhang H, Ouyang S, Huang WF. Effects of intracerebral microinjection of 5-hydroxytryptamine and its blocking agents and intracerebral microelectric stimulation on gastric electrical activity in rabbits.
Shijie Huaren Xiaohua Zazhi 2009;
17:3189-3196. [DOI:
10.11569/wcjd.v17.i31.3189]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To observe the effects of microinjection of 5-hydroxytryptamine (5-HT) and its blocking agents into the paraventricular nucleus (PVN) and nucleus raphe magnus (RM) and microelectric stimulation of the PVN on gastric electrical activity (GEA) in rabbits, and explore the central role of the PVN in controlling gastrointestinal movement.
METHODS: The stereopositioning of the PVN and RM was performed using a stereo positioner (model SN-2). Microinjection of 5-HT and its blocking agents ondansetron and cyproheptadine into the PVN and RM and electrical stimulation of the PVN were then performed. GEA was measured using four bipolar serosal electrodes (gastric body I-III and gastric antrum) in a rabbit. The parameters of GEA detected included average frequency, phase difference, the ratio of negative phase, amplitude, etc.
RESULTS: Paraventricular injection of 2 μg of 5-HT accelerated the electric frequencies of gastric body I-II and gastric antrum, and the change in the electric frequency of gastric body II was statistically significant (4.44 ± 0.09 vs 4.24 ± 0.09,P = 0.034). Subsequent microinjection of 5 μg of ondansetron slowed down the frequencies of gastric body I-III and gastric antrum, and the changes in the frequencies of gastric body II-III were statistically significant (P = 0.032 and 0.043, respectively). Microinjection of 5 μg of cyproheptadine following 5-HT injection accelerated the electric frequencies of gastric body I-II and gastric antrum, and the change in the electric frequency of gastric body II was statistically significant (P = 0.044). Elelctric stimulation of the PVN slowed down the frequencies of gastric body I and III and gastric antrum, and the changes in the frequencies of gastric body I and III were statistically significant (P = 0.030 and 0.029, respectively). Microinjection of 10 μg of 5-HT into the RM significantly slowed down the frequency of gastric body II (4.13 ± 0.11 vs 4.33 ± 0.09, P = 0.021), while subsequent injection of 10 μg of cyproheptadine accelerated the frequency of gastric body II (P= 0.034). Electrical stimulation of the PVN following microinjection of 10 μg of 5-HT into the RM slowed down the frequencies of II-III and gastric antrum, and the change in the frequency of gastric antrum was statistically significant (3.93 ± 0.14 vs 4.46 ± 0.14, P = 0.006).
CONCLUSION: Microinjection of 5-HT into the PVN mainly exerts stimulating effects on GEA, in which the 5-HT3 receptor pathway may play an important role. Microinjection of 5-HT into the RM exerts inhibitory effects on GEA, in which 5-HT2 receptor may play an important role. There is a synergistic effect between microinjection of 5-HT into the RM and microelectric stimulation of the PVN. These results further demonstrate the existence of "a descending inhibitory system and a descending exciting system" in the central nervous system, both of which modulate GEA together.
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