Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

L-Homocysteic acid (L-HCA) is a sulfated amino acid which is present in mammalian striatum and is a putative excitatory striatal neurotransmitter. In the present study we examined the histologic and neurochemical effects of L-HCA induced striatal lesions to determine how closely changes resemble those of Huntington's disease (HD). Increasing doses of L-HCA injected into the anterior striatum resulted in dose-dependent reductions in both substance P-like immunoreactivity (SP-LI) and gamma-aminobutyric acid (GABA) while there was a relative sparing of both somatostatin-like immunoreactivity (SS-LI) and neuropeptide Y-like immunoreactivity (NPY-LI). Immunocytochemical studies showed a relative sparing of NADPH-diaphorase neurons (which colocalize with SS and NPY) within regions in which there was a significant depletion of enkephalin stained neurons. The lesions were blocked by pretreatment with MK-801, a systemically effective non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors or coinjection of equimolar concentrations of 2-amino-5-phosphonovalerate (APV). These findings are similar to those produced with the NMDA agonist quinolinic acid, and suggest that other endogenous NMDA agonists, such as L-HCA, could be potential excitotoxins in HD.
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PMID:Homocysteic acid lesions in rat striatum spare somatostatin-neuropeptide Y (NADPH-diaphorase) neurons. 168 75

The purpose of this study was to determine the distribution of cells in the medial reticular formation (MRF) and the pontomedullary locomotor strip (PLS), which can induce locomotion when activated. Controlled microinjections of neuroactive substances (Goodchild et al., 1982) into the MRF or PLS were made in order to activate cell bodies in those areas. The ability of trigeminal receptive field stimulation to induce locomotion before and after drug infusion into the PLS was also assessed since the PLS and the spinal nucleus of the trigeminal nerve are similar in their anatomical distribution. Experiments were performed on precollicular-postmamillary decerebrate cats walking on a treadmill. Injections of glutamic acid (GA; 500 nmol) into the MRF produced locomotion that was antagonized by infusion of glutamic acid diethyl ester into the same spot. Decreases in the current threshold for locomotion produced by electrical stimulation of the MRF were observed when the MRF was infused with either GA (40-80 nmol), DL-homocysteic acid (DL-HCA; 200 nmol), or picrotoxin (PIC; 15 nmol). Injections of GA (100 nmol), DL-HCA (700 nmol), PIC (10-50 nmol), and substance P (2 nmol) into the PLS also produced locomotion. Locomotion produced by injections of PIC into the PLS was blocked by infusion of equal amounts of muscimol or GABA. Effective PLS injection sites were all confined to the trigeminal spinal nucleus or immediately ventral and medial to this in the adjacent lateral reticular formation. Trigeminal nerve peripheral field stimulation evoked locomotion after microinjection of PIC into the PLS, although this same facial stimulus was not effective prior to drug injection. We conclude that the MRF and PLS regions of the cat brain stem contain cells that produce locomotion when chemically stimulated, and we suggest that the PLS is closely related to or synonymous with the spinal nucleus of the trigeminal nerve. Furthermore, we suggest that stimulation of trigeminal afferents is analogous to stimulation of segmental afferent pathways in the production of locomotion (Sherrington, 1910; Jankowska et al., 1967; Afelt, 1970; Budakova, 1972; Grillner and Zangger, 1979).
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PMID:Locomotion produced in mesencephalic cats by injections of putative transmitter substances and antagonists into the medial reticular formation and the pontomedullary locomotor strip. 289 14