Abstract
In this study we utilized the technique of simultaneous immunofluorescent double-labeling to investigate possible coexistence of the putative neurotransmitter thyrotropin-releasing hormone (TRH) with serotonin (5-HT) and with substance P (SP) in the intermediolateral cell column (IML) of rat spinal cord. We observed fibers and terminals immunoreactive for both TRH and 5-HT or TRH and SP in IML. In addition, this technique was used in animals in which we retrogradely labeled, with fluorescent tracer dyes, preganglionic sympathetic neurons within IML from either the adrenal medulla or the proximal cut end of the cervical sympathetic trunk. In these animals, fibers and terminals containing these combinations of neurotransmitters appeared to appose identified preganglionic sympathetic neurons in IML. These data represent the first direct immunohistochemical demonstration of fibers and terminals in spinal cord which display coexistence of TRH- with either 5-HT- or SP-immunoreactivity. In addition, the proximity of TRH-immunoreactive fibers and terminals to sympathetic preganglionic neurons in IML support a role for TRH in the regulation of central sympathetic outflow.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 137-143 |
| Number of pages | 7 |
| Journal | Brain Research |
| Volume | 415 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jul 7 1987 |
Bibliographical note
Funding Information:1 Agnati, L.F., Fuxe, K., Benfenati, F., Zini, I. and Htkfelt, T., On the functional role of coexistence of 5-HT and sub-stance P in bulbospinal 5-HT neurons. Substance P reduces affinity and increases density of \[3H\]5-HTb inding sites, A cta Physiol. Scand. , 117 (1983) 299-301. 2 Appel, N.M., Wessendorf, M.W. and Elde, R.P., Coexis-tence of serotonin-and substance P-like immunoreactivity in nerve fibers apposing identified sympathoadrenal pre-ganglionic neurons in rat intermediolateral cell column, Neurosci. Leg., 65 (1986) 241-246. 3 Backman, S.B. and Henry, J.L., Effects of substance P and thyrotropin-releasing hormone on sympathetic pregangli-onic neurones in the upper thoracic intermediolateral nu-cleus of the cat, Can. J. Physiol. Pharmacol., 62 (1984) 248-251. 4 Brown, M.R., Thyrotropin releasing factor: a putative CNS regulator of the autonomic nervous system, Life Sci., 28 (1981) 1789-1795. 5 Erichsen, T.J., Reiner, A. and Karten, H.J., Co-occur-rence of substance P-like and Leu-enkephalin-like immu-noreactivities in neurones and fibres of avian nervous sys-tem, Nature (London), 295 (1982) 407-410. 6 Gilbert, R.F.T., Bennett, G.W. Marsden, C.A. and Em-son, P.C., The effects of 5-hydroxytryptamine-depleting drugs on peptides in the ventral spinal cord, Eur. J. Phar-macol., 76 (1981) 203-210. 7 Gilbert, R.F.T., Emson, P.C. Hunt, S.P., Bennett, G.W., Marsden, C.A., Sandberg, B.E.B., Steinbusch, H.W.M. and Verhofstad, A.A.J., The effects of monoamine neuro-toxins on peptides in the rat spinal cord, Neuroscience, 7 (1982) 69-87. 8 Helke, C.J., Sayson, S.C. Keeler, J.R. and Charlton, C.G., Thyrotropin-releasing hormone-immunoreactive neurons project from the ventral medulla to the intermedio-lateral cell column: partial coexistence with serotonin, Brain Research, 381 (1986) 1-7. 9 Htkfelt, T., Fuxe, K., Johansson, O., Jeffcoate, S. and White, N., Distribution of thyrotropin-releasing hormone The authors wish to express their gratitude to Dr. David Coulter for his generous gift of TRH antiserum, Dr. Lawrence Schmued for his generous gift of Fluoro-Gold and Mr. Gerald Sedgewick for printing the photographs. Support for these studies was provided by NIDA Grants DA 02148 and DA 05275, NIH Grant NS 22665 and the ImmunoNuclear Corporation.
Keywords
- Coexistence
- Immunohistochemistry
- Intermediolateral cell column
- Preganglionic
- Serotonin
- Substance P
- Sympathetic outflow
- Thyrotropin-releasing hormone