Trophic effect of various neuropeptides on the cultured ventral spinal cord of rat embryo.

We studied the trophic effects of various neuropeptides, including substance P (SP), thyrotropin-releasing hormone (TRH), neurotensin (NT) and bombesin (BN) on explanted cultures of ventral spinal cord from 13- to 14-day-old rat embryos. In groups, receiving one type of drug only, there was a significant neurite-promoting effect (NPE) in SP, TRH and BN-treated cultures. At a concentration of 10(-12) M the most potent effect was shown by SP. However, BN had the most potent action at concentrations greater than 10(-10) M. It also became clear that there were maximum and minimum effective concentrations for these 3 neuropeptides. NT had no NPE at any concentration. There was no additional NPE when any two or all four of these neuropeptides were given simultaneously. Our results demonstrate that BN, SP, and TRH have a trophic effect on ventral spinal cord in cultures, and may contribute to a therapeutic strategy in amyotrophic lateral sclerosis.