Effects of neurotrophins on gastrointestinal myoelectric activities of rats

Aim: To observe the effects of mouse nerve growth factor (NGF), rat recombinant brain derived neurotrophic factor (rm-BDNF) and recombinant human neurotrophin-3 (rh-NT-3) on the gastrointestinal motility and the migrating myoelectric complex (MMC) in rat. Methods: A randomized, double-blinded, placebo-controlled experiment was performed. 5-7 days after we chronically implanted four or five bipolar silver electrodes on the stomach, duodenum, jejunum and colon, 21 experimental rats were coded and divided into 3 groups and injected NGF, rm-BDNF, rh-NT-3 or placebo respectively via tail vein at a dose of 20 μg.kg^-1. The gastrointestinal myoelectrical activity was recorded 2 hours before and after the test substance infusions in these consciously fasting rats. Results: The neurotrophins-induced pattern of activity was characterized by enhanced spiking activity of different amplitudes at all recording sites, especially in the colon. In the gastric antrum and intestine, only rh-NT-3 had increased effects on the demographic characteristics of electrical activities (P<0.05), but did not affect the intervals of MMCs. In the colon, all the three kinds of neurotrophins could significantly increase the frequency, amplitude and duration levels of spike bursts, and also rh-NT-3 could prolong the intervals of MMC in the transverse colon (25±11 min vs 19±6 min, P<0.05). In the distal colon rh-NT-3 could evoke phase III-like activity and disrupt the MMC pattern, which was replaced by a continuously long spike bursts (LSB) and irregular spike activity (ISA) for 48±6 min. Conclusion: Exogenous neurotrophic factors can stimulate gut myoelectric activities in rats.