Involvement of Supraspinal Imidazoline Receptors and Descending Monoaminergic Pathways in Tizanidine-Induced Inhibition of Rat Spinal Reflexes

Journal of Pharmacological Sciences

Hideki Ono¹  Motoko Honda¹  Mitsuo Tanabe¹  Yurika Kino¹ 

[1] Laboratory of CNS Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University

关键词: tizanidine;    spinal reflex;    6-hydroxydopamine;    5;    6-dihydroxytryptamine;    imidazoline receptor;   

DOI  :  10.1254/jphs.FP0050520

学科分类：药学

来源: Nihon Yakuri Gakkai Henshuubu / Japanese Pharmacological Society

【 摘 要 】

References(34)Cited-By(9)The neuronal pathways involved in the muscle relaxant effect of tizanidine were examined by measurement of spinal reflexes in rats. Tizanidine (i.v. and intra-4th ventricular injection) decreased the mono- and disynaptic (the fastest polysynaptic) reflexes (MSR and DSR, respectively) in non-spinalized rats. Depletion of central noradrenaline by 6-hydroxydopamine abolished the depressant effect of tizanidine on the MSR almost completely and attenuated the effect on the DSR. Co-depletion of serotonin by 5,6-dihydroxytryptamine and noradrenaline resulted in more prominent attenuation of tizanidine-induced inhibition of the DSR. Supraspinal receptors were then studied using yohimbine- and some imidazoline-receptor ligands containing an imidazoline moiety. Idazoxan (I1, I2, I3, and α2), efaroxan (I1, I3, and α2), and RX821002 (I3 and α2), but not yohimbine, an α2-adrenergic receptor antagonist with no affinity for I receptors, antagonized the inhibitory effects of tizanidine. Thus, supraspinal I receptors (most likely I3) and descending monoaminergic influences are necessary for tizanidine-induced inhibition of spinal segmental reflexes.

【 授权许可】

Unknown