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Immunocytochemical localization of somatostatin receptor sst 2A in the rat spinal cord and dorsal root ganglia
Author(s) -
Schulz Stefan,
Schreff Matthias,
Schmidt Harald,
Händel Manuela,
Przewlocki Ryszard,
Höllt Volker
Publication year - 1998
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.1998.00386.x
Subject(s) - somatostatin , spinal cord , somatostatin receptor , receptor , nociception , neuroscience , biology , medicine , chemistry , anatomy , endocrinology
Intrathecal administration of octreotide, a stable somatostatin analogue, provides pain relief in patients, and locally applied somatostatin inhibits firing of nociceptive dorsal horn neurons. In the present study, we have raised polyclonal antibodies that specifically detect the somatostatin receptor sst 2A and used these antisera for immunocytochemical localization of the receptor protein in the rat spinal cord and dorsal root ganglia. In the superficial layers of the dorsal horn, sst 2A ‐like immunoreactivity (Li) formed a dense network consisting of neuronal perikarya and dendrites which were often closely apposed by, but not co‐contained within, somatostatin‐14‐immunoreactive nerve fibres and terminals. sst 2A ‐Li was resistant to dorsal rhizotomy and did not colocalize with either substance P or calcitonin gene‐related peptide suggesting that sst 2A ‐Li was not located to primary afferents, but rather confined to second‐order spinal neurons. The position of sst 2A ‐Li perikarya and dendrites in the dorsal horn appeared to be similar to those containing μ‐opioid receptor‐Li; however, double labelling experiments revealed no instances of coexistence of these two receptors. sst 2A ‐Li was also observed in the dorsal root ganglia predominantly targeted to the somatic plasmalemma of medium size neurons distinct from those expressing somatostatin‐14 or δ‐opioid receptors. Thus, the present results not only provide a morphological substrate for spinal octreotide analgesia but also show that somatostatin and opioids are poised to modulate nociceptive transmission by distinct anatomical systems.