Multiple neurotransmitter receptors contribute to the spinal Fos expression.
The aim of this study is to identify the receptors which could potentially mediate the activation of c-Fos. Therefore, the effects of neurotransmitter receptor agonists in the activation of c-Fos in spinal neurons were studied by intrathecal injection of excitatory amino acid (EAA) receptor agonists: N-Methyl-D-Aspartate (NMDA), (S)-alpha-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic acid (AMPA), 2-Carboxyl-3-carboxymethyl-4-isopropenylpyMidine (Kainic acid, KA), (1S-3R)-1-Aminocyclopentane-1, 3-dicarboxylacid (ACPD), and substance-P receptor (neurokinin-1) agonist, [Sar9, Met (O2)11] SP (SarMet-SP). All drugs tested activated the production of c-Fos in spinal dorsal horn neurons. AMPA was found as the most potent agonist tested producing market production of c-Fos particularly in neurons of lamina II at doses of 10 pM per 10-microl injection. At this dose, other agonists were relatively ineffective. At higher doses, AMPA significantly increased the activated cells. NMDA significantly increased c-Fos production to a marked extent only at doses above 10 nM per 10-microl injection. KA and ACPD were least potent of the excitatory amino acid agonists. Injection of SarMet-SP at doses of 1 nM activated Fos selectively in neurons of lamina I. A dose-dependent increase in number of c-Fos-positive cells was observed for AMPA, KA, ACPD, and SarMet-SP, whereas NMDA gave a very strong expression after a high dose with no dose dependency. These finding suggest that multiple neurotransmitter receptors lead to c-Fos production in spinal neurons.
Soygüder
Zafer
Z
University of Yüzüncü Yil, Veterinary Faculty, Department of Anatomy, Van, Turkey. zsoyguder@hotmail.com
D000818:Animals; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000008:administration & dosage; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D007278:Injections, Spinal; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D017981:Receptors, Neurotransmitter / Q000096:biosynthesis* / Q000235:genetics; D013116:Spinal Cord / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D016760:Proto-Oncogene Proteins c-fos; D017981:Receptors, Neurotransmitter