Neuropathic and inflammatory antinociceptive effects and electrocortical changes produced by Salvia divinorum in rats.

An extract of Salvia divinorum reduced pain responses in rats with both neuropathic and inflammatory pain. The extract's analgesic effects were blocked by a kappa-opioid receptor antagonist, indicating a kappa-opioid mechanism. The extract also altered brain activity, increasing power spectral density in the anterior cortex and decreasing it in the posterior region, changes that may correlate with the hallucinogenic state seen in humans. The findings suggest Salvia divinorum could be a therapeutic alternative for chronic pain, acting through kappa-opioid receptors.

Study at a glance

Abstract

Salvia divinorum is a medicinal plant traditionally used in hallucinogenic ethnopharmacological practices and for its analgesic and antinflammatory properties. Its active compounds include diterpenes known as salvinorins which act as potent κ opioid receptor agonists. Given its effects in acute animal models of pain, as well as its antinflammatory attributes, we decided to investigate the analgesic effects of an SD extract in neuropathic (sciatic loose nerve ligature) and inflammatory (intra plantar carrageenan) pain models in rats. We also determined in this study the electrocorticographic changes to correlate similar hallucinogenic state and behavior as those produced in humans. Mechanical and thermonociceptive responses, plantar test and von Frey assay, respectively, were measured in adult Wistar rats 30min, 3h and 24h after the intraperitoneal administration of saline or an hydroponic SD extract. We also evaluated carbamazepine and celecoxib, as gold reference drugs, to compare its antinociceptive effects. Our results showed that administration of SD extract induced antialgesic effects in both neuropathic and inflammatory pain models. All those effects were blocked by nor-binaltorphimine (a Kappa opioid receptor antagonist). Moreover, it was observed an increase of the anterior power spectral density and a decrease in the posterior region as electrocorticographic changes. The present investigation give evidence that SD is capable to reduce algesic response associated to neuropathic and inflammatory nociception. This study support therapeutic alternatives for a disabling health problem due to the long term pain with high impact on population and personal and social implications.