# Peptide Modulator of TRPV1 Channel Increases Long-Term Potentiation in the Hippocampus and Reduces Anxiety and Fear in Mice Under Acute Stress

## TL;DR

A peptide that modulates the TRPV1 channel improves brain function and reduces anxiety and fear in mice under acute stress.

## Contribution

The study shows that intranasal delivery of a TRPV1 peptide modulator reduces anxiety and enhances hippocampal function in mice.

## Key findings

- APHC3 significantly enhanced long-term potentiation and Paired-Pulse Ratio in the hippocampus.
- Intranasal APHC3 showed a moderate anxiolytic effect in mice.
- Both intranasal and intramuscular APHC3 reduced acute stress as effectively as a reference drug.

## Abstract

One of the attractive targets for the relief of stress conditions is TRPV1, which is expressed mostly in primary afferent neurons (nociceptors) and in the central nervous system, mainly in the cortex and hippocampus. We evaluated the action of a potent low-molecular-weight antagonist of TRPV1 (AMG517) and peptide modulator of this channel (APHC3) on long-term potentiation (LTP) and Paired-Pulse Ratio (PPR) in the CA3-CA1 region of the hippocampus of mice. In vivo, we used intranasal administration to provide effective peptide delivery into the brain and analyzed the effects of APHC3 in acute stress tests in comparison with intramuscular administration of APHC3, AMG517, and the reference anxiolytic drug Fabomotizole (Fab). In electrophysiology studies, APHC3 significantly enhanced LTP and PPR, while AMG517 enhanced only PPR. Intranasal administration of APHC3 to mice provided a moderate anxiolytic effect in the single dose (0.01 mg/kg). Intramuscular administration of APHC3 and AMG517 significantly reduced acute stress in mice equal to the reference drug Fab. Thus, TRPV1 modulation in either the peripheral or central nervous system is sufficient to produce an anxiolytic-like effect, likely through distinct underlying mechanisms.