Immunoreactivity of Somatostatin Receptor Subtype 2 in Dorsal Root Ganglia in the Rat / 대한정형외과학회잡지

PURPOSE: Somatostatin has been suggested to play a role in the transmission of neurotransmitters and in the modulation of pain. Of the different subtypes of somatostatin receptors 2, sstr2A and sstr2B are important in the modulation and transmission of pain. The present study was carried out to investigate sstr2 immunoreactivity in rat. MATERIALS AND METHODS: Dorsal root ganglia (DRG) cells at the L4-L6 levels of the spinal cord of 10 rats (Sprague-Dawley, 200-250 g) were examined for sstr2 by immunohistochemistry. RESULTS: In the control group, sstr2A immunoreactivity was strongly positive in the dense network within laminae I and II of the dorsal horn at spinal levels (L4-L6). In contrast to sstr2A, sstr2B immunoreactivity was observed throughout laminae III-VI. In the DRG, sstr2A and sstr2B immunoreactivities were mainly found in medium-sized neurons. CONCLUSIONS: The distribution of sstr2A immunoreactive cells among sstr2 in the dorsal root ganglia (L4-6) resembles that of somatostatin. Incontrast to sstr2A, sstr2B immunoreactivity showed a different distribution. The presence of sstr2A at laminae I and II, and sstr2B at laminae III-VI of the dorsal horn may modulate sensory functions at these different regions of the spinal cord. Considering different actions according to the receptors of the neurotransmitter, the functions of the isoforms of sstr2 appear variable in terms of modulating and transmitting pain.

Differential Expression of Somatostatin Receptor Subtype 2 in Dorsal Root Ganglia after Ischemic Injury in the Rat / 대한정형외과학회잡지

PURPOSE: The somatostatin has been suggested to play a role in the transmission of neurotransmitters and the modulation of pain. Therefore, this study was carried out to investigate the spatial and temporal alterations of sstr2 (somatostatin receptors 2) immunoreactivity after an ischemic injury in rats. MATERIALS AND METHODS: Fifty-five rats (Sprague-Dawley, 200-250 g) were assigned to the experimental group, the other five to the control group. In the experimental group, an occlusion of the left common iliac artery was made using an aneurysm clip. Ten groups were classified according to the time after ischemiareperfusion. Dorsal root ganglia (DRG) cells in the L4, L5, L6 levels of the spinal cord, from the rats were examined the sstr2 using an immunohistochemistry technique. RESULTS: The sstr2A/B immunoreactivity (IR) appeared in the DRG after ischemia-reperfusion. The number of sstr2A- and sstr2B-IR neurons were markedly lower in the group of rats 12 hours after ischemia-reperfusion. In the group of rats one day after ischemia-reperfusion, the sstr2A- and sstr2B-IR neurons began to recover in both number and immunoreactivity. Furthermore, 3 days after ischemia-reperfusion, sstr2A/B immunoreactivity decreased in number and immunoreactivity, and 7 days after ischemia-reperfusion, very weak immunoreactivity was observed in the cytoplasm. CONCLUSION: The sstr2A/B immunoreactivity of the DRG exhibited different appearance according to the post-traumatic compartment syndrome or ischemic injury of the leg. In addition, the chronological alterations of sstr2A and sstr2B immunoreactivities may be important in controlling the pain after a transient ischemia-reperfusion event.