Blood-labyrinth barrier (BLB)

Blood-labyrinth barrier Overview

The **blood-labyrinth barrier** (BLB) is not a molecule or receptor, but rather a unique anatomical and physiological barrier system located in the inner ear, specifically in the **stria vascularis** and other cochlear regions[1][3][7]. The BLB is formed by **endothelial cells** joined by tight junctions, **pericytes**, a **basement membrane**, and **perivascular-resident macrophage-like melanocytes**. Its core function is to **limit and regulate the exchange of solutes, metabolites, and toxins between the bloodstream and the inner ear fluids (endolymph, perilymph)**[5][6][7]. It is equivalent in concept to the blood-brain barrier, but specifically maintains the composition and homeostasis of cochlear fluids necessary for hearing[1][3]. The barrier helps protect the ear from systemic toxins and supports essential functions like nutrient supply, ion absorption, and waste excretion[6][7]. BLB dysfunction is a pathological feature in conditions such as Meniere’s disease, sensorineural hearing loss, noise- and drug-induced hearing loss, and autoimmune diseases affecting the ear[2][3][7]. There is **no single molecular target, receptor, or gene designated as "BLB"**. The BLB is considered an *anatomical barrier* and *physiological entity*, not a druggable target like an enzyme or receptor[1][2][5][7]. Recent therapeutic research aims to exploit or traverse the BLB for targeted drug delivery, for example, nanoparticle-based therapies or agents capable of modulating BLB permeability[1][6][7]. However, there are **no drugs that interact directly with "the BLB" as a target**, and it is **not classified under molecular families like receptors, enzymes, or transporters**. **Note:** - This entry is **incorrect if used as a therapeutic molecular target** or if assigned as a classic receptor, enzyme, or transporter. - If you are seeking *molecular targets* within the BLB (like tight junction proteins, transporters, or signaling molecules), further specificity is required.

Mechanism of Action

Biological Functions

Safety Considerations