angiotensin-i and Pain

We have previously demonstrated that the phosphorylation of p38 MAPK, through spinal AT

Topics: Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Diminazene; Disease Models, Animal; Formaldehyde; Humans; Injections, Spinal; Male; Mice; Microglia; Neurons; Nociception; p38 Mitogen-Activated Protein Kinases; Pain; Peptide Fragments; Peptidyl-Dipeptidase A; Phosphorylation; Proto-Oncogene Mas; Proto-Oncogene Proteins; Receptors, G-Protein-Coupled; Spinal Cord

Angiotensin-(1-7) is a bioactive component of the renin-angiotensin system that is formed endogenously and induces nitric oxide release in several tissues. The L-arginine/NO/cyclic GMP pathway and ATP-sensitive K+ channels have been proposed as the mechanism of action for the peripheral antinociception of several groups of drug and endogenous substances, including opioids, non-steroidal analgesics, acetylcholine and others. The aim of the present study was to investigate the involvement of the L-arginine/NO/cGMP and KATP+ pathway on antinociception induced by angiotensin-(1-7). Paw pressure in rats was used to induce hyperalgesia via an intraplantar injection of prostaglandin E2 (2 μg/paw). Ang-(1-7) (2, 3 and 4 μg/paw) elicited a local peripheral antinociceptive effect that was antagonized by the nonselective NO synthase (NOS) inhibitor L-NOarg and the selective neuronal NOS (nNOS) inhibitor L-NPA. The selective inhibition of endothelial (eNOS) and inducible (iNOS) NOS by L-NIO and L-NIL, respectively, was ineffective at blocking the effects of a local Ang-(1-7) injection. In addition, the level of nitrite in the homogenized paw tissue, as determined by a colorimetric assay, indicated that exogenous Ang-(1-7) is able to induce NO release. The soluble guanylyl cyclase inhibitor ODQ and the specific blocker of ATP-sensitive K+ channels glibenclamide (40, 80 and 160 μg/paw) antagonized the Ang-(1-7) response. The results provide evidence that Ang-(1-7) most likely induces peripheral antinociceptive effects via the L-arginine/NO/cGMP pathway and KATP+ pathway activation.

Topics: Adenosine Triphosphate; Analgesics; Angiotensin I; Animals; Arginine; Cyclic GMP; Dinoprostone; Dose-Response Relationship, Drug; Hyperalgesia; KATP Channels; Male; Nitric Oxide; Pain; Pain Measurement; Peptide Fragments; Rats; Rats, Wistar