The morphologic effects of histamine on the lateral cochlear wall

Area of Science:

• Otoacoustic emissions and inner ear physiology
• Histamine's effects on cochlear microcirculation
• Cellular mechanisms in the cochlea

Background:

• The lateral cochlear wall, comprising the stria vascularis, spiral ligament, and spiral prominence, is crucial for cochlear function.
• Understanding the impact of vasoactive substances like histamine on cochlear structures is vital for auditory health research.
• Previous studies have suggested histamine's role in cochlear fluid balance and vascular regulation.

Purpose of the Study:

• To investigate the morphologic and histochemical effects of intravenous histamine on the chinchilla lateral cochlear wall.
• To determine histamine's influence on stria vascularis vessel permeability and cellular glycogen levels.
• To elucidate the mechanisms by which histamine affects the inner ear's microenvironment.

Main Methods:

• Morphologic and histochemical examination of chinchilla cochlear tissue.
• Administration of various doses of intravenous histamine.
• Utilizing horseradish peroxidase as a protein tracer to assess vessel permeability.
• Microscopic analysis of ultrastructure, vessel transport, and cellular glycogen content.

Main Results:

• Histamine did not alter the fundamental ultrastructure of the lateral cochlear wall.
• A time- and dose-dependent increase in stria vascularis vessel permeability to horseradish peroxidase was observed.
• The mechanism of transport across the stria vascularis remained a large pore system, unaffected by histamine.
• Histamine induced glycogen depletion in stria marginal cells, with apparent mobilization into intercellular spaces.

Conclusions:

• Histamine administration alters stria vascularis permeability in a dose- and time-dependent manner.
• Glycogen depletion in stria marginal cells suggests a metabolic response to histamine.
• The basic cellular architecture of the cochlear lateral wall is resilient to acute histamine exposure.