The effect of selective serotonergic neurotoxin treatment on tachykinin levels in the rat ventral spinal cord.
The levels of 5-hydroxytryptamine and tachykinin neuropeptides substance P, neurokinin A, neurokinin B and neuropeptide K were measured in the spinal cord of rats treated by intraventricular injection of the selective serotonergic neurotoxin 5,7-dihydroxytryptamine. The spinal cord levels of 5-hydroxytryptamine as measured by high performance liquid chromatography with electrochemical detection decreased by more than 90% in the ventral and dorsal cord compared to controls. The levels of substance P as measured by radioimmunoassay were significantly reduced (66%, P less than 0.01) in the ventral lumbar cord only. In this region, neurokinin A, neurokinin B and neuropeptide K levels were determined by combined high performance liquid chromatography and radioimmunoassay. The neurotoxin treatment also caused a significant reduction of neurokinin A (72% reduction, P less than 0.01) and a non-significant reduction of neuropeptide K, but virtually no change in the neurokinin B level. Immunohistochemical studies of the ventral lumbar cord of sham-operated animals showed immunoreactivity for 5-hydroxytryptamine as well as for substance P and neurokinin A in nerve fibres around motor neurons. In neurotoxin-treated rats this region was devoid of immunohistochemically detectable substance P- and neurokinin A-positive fibres and showed very sparse or no 5-hydroxytryptamine immunoreactivity. We conclude that among the tachykinins both neurokinin A and substance P, but probably not neurokinin B, co-exist with 5-hydroxytryptamine in nerve terminals in the rat ventral spinal cord.
Franck
J
J
Department of Physiology, Karolinska Institutet, Stockholm, Sweden.
Brodin
E
E
Fried
K
K
Rosén
A
A
Yamamoto
Y
Y
Fried
G
G
D015116:5,7-Dihydroxytryptamine / Q000633:toxicity*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D015288:Neurokinin A / Q000032:analysis; D015287:Neurokinin B / Q000032:analysis; D009479:Neuropeptides / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000032:analysis; D013116:Spinal Cord / Q000737:chemistry / Q000187:drug effects*; D013373:Substance P / Q000032:analysis; D015320:Tachykinins / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics
D009479:Neuropeptides; D015320:Tachykinins; C045206:neuropeptide K; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D013373:Substance P; D015288:Neurokinin A; D015287:Neurokinin B