Inflammation alters somatostatin mRNA expression in sensory neurons in the rat.

Abstract

Proinflammatory neuropeptides, such as substance P and calcitonin gene-related peptide, are up-regulated in primary afferent neurons in acute and chronic inflammation. While these neuropeptides have been intensively studied, potentially anti-inflammatory and/or anti-nociceptive neuropeptides such as somatostatin (SS) have been less widely investigated. Endogenous somatostatin is thought to exert a tonic antinociceptive effect. Exogenous SS is anti-inflammatory and antinociceptive and is thought to exert these actions through inhibition of proinflammatory neuropeptide release. In this study we have compared the expression of somatostatin in two inflammatory models: arthritis, a condition associated with increased nociception, and periodontitis, in which there is little evidence of altered nociceptive thresholds. In acute arthritis (< 24 h) SS mRNA was down-regulated in ipsilateral dorsal root ganglia (DRG; 52 +/- 7% of control, P < 0.05), and up-regulated in contralateral DRG (134 +/- 10% of control; P < 0.05). In chronic arthritis (14 days) this pattern of mRNA regulation was reversed, with SS being up-regulated ipsilaterally and down-regulated contralaterally. In chronic mandibular periodontitis (7-10 days), SS mRNA was up-regulated in only the mandibular division of the ipsilateral trigeminal ganglion (TG) (day 7, 219 +/- 9% and day 10, 217 +/- 12% of control; P < 0.02) but showed no change in other divisions of the trigeminal ganglion or in the mesencephalic nucleus. These data show that antinociceptive and anti-inflammatory neuropeptides are also regulated in inflammation. It is possible that the degree of inflammation and nociception seen may depend on the balance of pro- and anti-inflammatory and nociceptive peptide expression in a particular condition.

• Authors: Seham A Abd El-Aleem, Begonia M Morales-Aza, Daniel S McQueen, Lucy F Donaldson
• Journal: The European journal of neuroscience (Eur J Neurosci) Vol. 21 Issue 1 Pg. 135-41 (Jan 2005) ISSN: 0953-816X [Print] France
• PMID: 15654850 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Polysaccharides
• RNA, Complementary
• RNA, Messenger
• Somatostatin

Topics

• Animals
• Arthritis (chemically induced, genetics, metabolism)
• Disease Models, Animal
• Functional Laterality (physiology)
• Ganglia, Sensory (cytology)
• Gene Expression
• In Situ Hybridization (methods)
• Inflammation (chemically induced, genetics, metabolism)
• Male
• Neurons (metabolism)
• Periodontitis (chemically induced, genetics, metabolism)
• Polysaccharides
• RNA, Complementary (biosynthesis)
• RNA, Messenger (metabolism)
• Rats
• Rats, Wistar
• Somatostatin (genetics, metabolism)
• Time Factors