Korean J Physiol Pharmacol.  1999 Aug;3(4):365-373.

The role of somatostatin in nociceptive processing of the spinal cord in anesthetized cats

Affiliations
  • 1Department of Physiology and Biophysics, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul, 110-799 South Korea.
  • 2Department of Physiology, Dankook University College of Medicine, Chunan 330-715South Korea.
  • 3Department of Physiology, Kangwon University College of Medicine, Chunchon 200-701, Korea.

Abstract

Somatostatin (SOM) is one of the major neuropeptides in dorsal root ganglion cells, but its role in spinal nociceptive process has not been well known. In present study we aimed to investigate the effect of SOM on the response of dorsal horn neurons to the various types of peripheral nociceptive stimuli in anesthetized cats. Using carbon-filament microelectrode, the single cell activities of wide dynamic range neurons were recorded from the lumbosacral enlargement after noxious mechanical (squeeze), thermal (radiant heat lamp) and cold (dry ice) stimulation to the receptive field. Sciatic nerve was stimulated electrically to evoke A delta- and C-nociceptive responses SOM analogue, octreotide (10 mug/kg), was applied intravenously and the
results
were compared with those of morphine (2 mg/kg, MOR) Systemic SOM decreased the cellular responses to the noxious heat and the mechanical stimulation, but increased those to the cold stimulation. In the responses to the electric stimuli of sciatic nerve, A delta-nociceptive response was increased by SOM, while C-nociceptive response was decreased. On the other hand, MOR inhibited the dorsal horn cell responses to all the noxious stimuli. From the above results, it is concluded that SOM suppresses the transmission of nociceptive heat and mechanical stimuli, especially via C-fiber, while it facilitates those of nociceptive cold stimuli via A delta-fiber.

Keyword

Somatostatin; Wide dynamic range (WDR) cell; Noxious stimulation; A delta-fiber; C-fiber
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