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Inhibitory effect of cysteamine on nociceptive responses of dorsal horn neurons in spinal cord of cats

Yang Huanqiao, Zhao Zhiqi, Liu Yun

Shanghai Brain Besearch Institute, Chinese Acadmey of Science. Shanghai 200031, China；Shanghai Institute of Physioloyg, Chinese Academy of Sciences. Shanghai 200031, China；Shanghai Medical College for Continuing Education. Shanghai 200232

Abstract

The effect of somatostatin depletor cysteamine on the noeiceptive responses of
neurons in laminae Ⅳ-Ⅵ of spinal cord was studied in 16 pentobarbitone anesthetized and spinal cord transected (at Ll)cats. Intravenous injection of cysteamine. (50 mg/kg) markedly inhibited responses of the neurons produced by noxious heating (50℃) of glabrous skin of the plantar region，but not C fibre responses induced by electrical stimulation of unmyelinated fibers of the tibial nerve. However，C responses in 8/13 neurons tested were significantly inhibited by large dose cysteamine(100 mg/kg). Following micropressure ejection of cysteamine(20 psig) into the substantia gelatinosa where somatostatinontaining fibers terminate，heating responses were significantly
inhibited in all laminae Ⅳ-Ⅵ neurons whereas C responses was only weakly inhibited in 7/13. neurons. The results suggest that depletion of spinal somatostatin may be involved in cysteamine-induced inhibition of spinal nociception. The possible mechanism underlying the stronger cysteamine- induced inhibition of heating response was discussed.

Key words: Spinal dorsal horn neuron;Cysteamine;Somatostatin;Naciceptive response

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Citing This Article：

Yang Huanqiao, Zhao Zhiqi, Liu Yun. Inhibitory effect of cysteamine on nociceptive responses of dorsal horn neurons in spinal cord of cats. Acta Physiol Sin 1993; 45 (1): (in Chinese with English abstract).