# Serotonergic Signaling Rewired: A Lipid Raft-Controlled Model of Synaptic Transmission Grounded in the Fundamental Parameters of Biological Systems

## TL;DR

This paper proposes a new model of serotonin signaling involving lipid rafts, suggesting serotonin can persist longer in the brain and affecting how antidepressants work.

## Contribution

The novel contribution is a model where serotonin signaling is regulated by lipid rafts, extending beyond traditional synaptic transmission.

## Key findings

- Serotonin can be stored in neuronal and glial membranes, prolonging its availability.
- Lipid rafts regulate serotonin bioavailability through cholesterol-dependent insertion.
- Antidepressants like fluoxetine affect serotonin signaling via lipid raft interactions.

## Abstract

Serotonergic signaling is traditionally conceived as a transient, vesicle-mediated process restricted to the synaptic cleft. Here, we propose an expanded model in which serotonin can also be inserted into the plasma membrane of neurons and glial cells, forming a stable, membrane-associated reservoir that prolongs its availability beyond classical synaptic timescales. In this framework, the synapse emerges not as a simple neurotransmitter–receptor interface but as a dynamic, multiscale medium where membrane order, hydration, and quantum-level processes jointly govern information flow. Two temporal “tunnels” appear to regulate serotonin bioavailability: its aggregation in synaptic vesicles during exocytosis, and its cholesterol-dependent insertion into neuronal and glial membranes at the tripartite synapse. Lipid raft microdomains enriched in cholesterol and gangliosides thus act as active regulators of a continuum between transient and constitutive serotonin signaling. This extended serotonergic persistence prompts a reconsideration of current pharmacological models and the action of antidepressants such as fluoxetine, which not only inhibits the serotonin transporter (SERT) but also accumulates in lipid rafts, perturbs raft organization, and alters serotonin–cholesterol equilibria, contributing to SERT-independent effects. Grounded in the recently established fundamental parameters of biological systems, this model invites a broader, quantum-informed rethinking of synaptic transmission.