# Enhanced Anti-Nociception by Novel Dual Antagonists for 5-HT2AR and mGluR5 in Preclinical Models of Pain

## TL;DR

Researchers found that blocking two brain receptors together can reduce chronic pain more effectively and safely than current treatments like morphine.

## Contribution

The study introduces novel dual antagonists targeting 5-HT2AR and mGluR5, showing enhanced anti-nociception with low abuse potential.

## Key findings

- Dual antagonism of 5-HT2AR and mGluR5 improved anti-allodynic and anti-nociceptive effects compared to monotherapy.
- Novel small molecules inhibited ERK and AKT phosphorylation, reducing excitatory postsynaptic responses.
- Repeated dual antagonist administration maintained efficacy without abuse potential, unlike morphine.

## Abstract

Extensive research has focused on developing anti-nociceptive therapy by targeting specific molecular pathways. Among these, the serotonin 2A receptor (5-HT2AR) and metabotropic glutamate receptor 5 (mGluR5) are recognized as key mediators of neuropathic pain. However, the therapeutic potential of their simultaneous inhibition remains largely unexplored. In this study, we evaluated the efficacy of dual antagonism of 5-HT2AR and mGluR5 using spinal nerve ligation (SNL) and formalin-induced pain models in male Sprague–Dawley rats. Co-administration of selective antagonists significantly enhanced anti-allodynic and anti-nociceptive effects, as evidenced by increased withdrawal thresholds and reduced pain-related behaviors compared to monotherapy. The analgesic efficacy of dual antagonism was comparable to that of gabapentin and morphine. Additionally, novel small molecules designed to concurrently inhibit 5-HT2AR and mGluR5 exerted dose-dependent anti-nociceptive effects by suppressing excitatory postsynaptic responses and inhibiting the phosphorylation of ERK and AKT signaling molecules. Importantly, unlike morphine, repeated administration of the dual antagonist maintained anti-allodynic efficacy with a low potential of abuse. These findings may indicate the promise of simultaneous 5-HT2AR and mGluR5 antagonism as a novel and potentially safer strategy for managing chronic neuropathic pain.