Nicotine activates and up-regulates nicotinic acetylcholine receptors in bronchial epithelial cells

The 5-HT4 receptor agonist mosapride attenuates NSAID-induced gastric mucosal damage

BACKGROUND

The cholinergic anti-inflammatory pathway is a novel physiological mechanism found at various locations in the body where the nicotinic regulation of inflammatory cells through the autonomic nervous system is involved. In this study, we tested the hypothesis that cholinergic nerve stimulation by a 5-HT(4) agonist may modulate the progression of gastric mucosal ulcers induced by nonsteroidal anti-inflammatory drugs (NSAIDs).

METHODS

Acute gastric ulcers were induced in rats by the oral administration of indomethacin.

RESULTS

Gastric damage analysis indicated that pretreatment with mosapride, a selective 5-HT(4) agonist, at 0.25, 0.5, and 0.75 mg/kg, inhibited the mucosal damage induced by indomethacin. In gastric emptying analysis, an evacuation effect was observed in the 3.0 mg/kg mosapride pretreatment group, but this effect was not observed in the lower dose (0.5 mg/kg) group. The antiulcerogenic activity of mosapride treatment (at 0.5 mg/kg) was blocked by a 5-HT(4)-specific antagonist, GR113808 (1 mg/kg, i.v.). Additionally, we demonstrated that methyllycaconitine (0.29 and 0.87 mg/kg i.p.), a selective inhibitor of alpha7 nicotinic acetylcholine (ACh) receptors (alpha7nAChRs), ablated the antiulcerogenic action of mosapride.

CONCLUSIONS

These results suggest that the mucosal protective action of mosapride may be mediated by an action on immune cells through the acceleration of ACh release from parasympathetic nerves via the activation of 5-HT(4) receptors, followed by activation of the nicotinic anti-inflammatory system. It appears that the alpha7nAChR may be involved in the antiulcerogenic action of mosapride.

Control of lung epithelial growth by a nicotinic acetylcholine receptor: the other side of the coin

This Commentary provides a perspective on an article in the current issue of the American Journal of Pathology by Maouche et al, which demonstrates that alpha7 nicotinic acetylcholine receptors play a key role in regulating airway regeneration by limiting basal epithelial cell proliferation.

Alpha9 nicotinic acetylcholine receptors and the treatment of pain

Chronic pain is a vexing worldwide problem that causes substantial disability and consumes significant medical resources. Although there are numerous analgesic medications, these work through a small set of molecular mechanisms. Even when these medications are used in combination, substantial amounts of pain often remain. It is therefore highly desirable to develop treatments that work through distinct mechanisms of action. While agonists of nicotinic acetylcholine receptors (nAChRs) have been intensively studied, new data suggest a role for selective antagonists of nAChRs. alpha-Conotoxins are small peptides used offensively by carnivorous marine snails known as Conus. A subset of these peptides known as alpha-conotoxins RgIA and Vc1.1 produces both acute and long lasting analgesia. In addition, these peptides appear to accelerate the recovery of function after nerve injury, possibly through immune mediated mechanisms. Pharmacological analysis indicates that RgIA and Vc1.1 are selective antagonists of alpha9alpha10 nAChRs. A recent study also reported that these alpha9alpha10 antagonists are also potent GABA-B agonists. In the current study, we were unable to detect RgIA or Vc1.1 binding to or action on cloned GABA-B receptors expressed in HEK cells or Xenopus oocytes. We review the background, findings and implications of use of compounds that act on alpha9* nAChRs.(1).