Localization and release of 5-hydroxytryptamine thyrotrophin releasing hormone and substance P in rat ventral spinal cord.
1. The highest spinal cord levels of 5-hydroxytryptamine (5-HT) and thyrotrophin releasing hormone (TRH) were found in the ventral lumbar cord, in contrast to substance P which was found predominantly in the dorsal cord. 2. 5,6- and 5,7-dihydroxytryptamine, administered into the lateral ventricles reduced 5-HT in the dorsal and ventral spinal cord by up to 90%. 3. There was a parallel reduction in substance P and TRH in ventral spinal cord while methionine-enkephalin and somatostatin in ventral and dorsal cord increased. 4. Reserpine and tetrabenazine depleted 5-HT and partially depleted substance P and TRH in the ventral cord, but had no effect on either methionine-enkephalin or somatostatin. 5. The rates of loss and recovery, after reserpine and tetrabenazine, of 5-HT were different from those of the two peptides. 6. Endogenous 5-HT and TRH release from slices of lumbar cord was enhanced by high potassium. 7. p-Chloroamphetamine and fenfluramine increased 5-HT release but reduced or had no effect on TRH release. The effect of p-chloroamphetamine on TRH release was not dependent on either the presence of 5-HT or 5-HT receptor activity. 8. The results are discussed in terms of the possible co-existence, co-storage and release of 5-HT, substance P and TRH in descending bulbospinal neurones.
D000818:Animals; D004102:Dihydroxytryptamines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
D004102:Dihydroxytryptamines; D012701:Serotonin; D013373:Substance P; D013973:Thyrotropin-Releasing Hormone