Regulation of expression of galanin and galanin receptors in dorsal root ganglia and spinal cord after axotomy and inflammation
Annals NY Acad Sci. 1998-12-01; 863(1 GALANIN): 402-413
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1. Ann N Y Acad Sci. 1998 Dec 21;863:402-13.
Regulation of expression of galanin and galanin receptors in dorsal root ganglia
and spinal cord after axotomy and inflammation.
Zhang X(1), Xu ZO, Shi TJ, Landry M, Holmberg K, Ju G, Tong YG, Bao L, Cheng XP,
Wiesenfeld-Hallin Z, Lozano A, Dostrovsky J, Hökfelt T.
(1)Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.
Galanin can normally be detected only in a few dorsal root ganglion (DRG)
neurons, but it is dramatically upregulated after peripheral nerve injury in both
rat and monkey. Galanin is stored in large dense core vesicles, which after
axotomy are often found close to the membrane of afferent nerve endings in the
dorsal horn. In the monkey there is an increase in galanin in many nerve
terminals in the superficial dorsal horn after axotomy, but such an increase is
more difficult to detect in the rat. Galanin is also present in local dorsal horn
neurons, where it is upregulated by peripheral inflammation. Both galanin-R1 and
galanin-R2 receptor mRNAs are expressed in rat DRGs, mainly in, respectively,
large and small DRG neurons. Galanin-R1 receptor mRNA is downregulated in DRG
neurons after axotomy, and a small decrease in galanin-R2 receptor mRNA levels
can also be seen. After peripheral tissue inflammation galanin-R1 receptor mRNA
levels decrease and galanin-R2 receptor mRNA levels increase. The present results
show that galanin and galanin receptors are present in sensory and local dorsal
horn neurons and are regulated by nerve injury and inflammation. Galanin may
therefore be involved in processing of pain information, primarily exerting
analgesic effects. Whereas local dorsal horn neurons represent a defense system
against inflammatory pain, we have proposed that a second defense system, against
neuropathic pain, is intrinsic to DRG neurons.
PMID: 9928186 [Indexed for MEDLINE]