Neuronal gap junctions in the mouse main olfactory bulb: morphological analyses on transgenic mice

Area of Science:

• Neuroscience
• Cell Biology
• Anatomy

Background:

• The olfactory bulb processes sensory information through complex neuronal networks.
• Gap junctions facilitate direct electrical and chemical communication between neurons.
• Understanding neuronal connectivity is crucial for deciphering olfactory processing.

Purpose of the Study:

• To investigate the structural characteristics of extraglomerular gap junction-forming processes in the mouse olfactory bulb.
• To identify the cell types expressing connexin 36 in the olfactory bulb.
• To characterize the neuronal populations involved in extraglomerular communication.

Main Methods:

• Electron microscopy was used to analyze extraglomerular gap junction structures.
• Transgenic mice with histological reporters replacing the connexin 36 coding sequence were utilized.
• Immunofluorescence labeling was performed to identify cell types and protein expression.

Main Results:

• Mitral/tufted cell somata, dendrites, and axon hillocks formed gap junctions and mixed synapses with interneuronal processes extraglomerularly.
• Connexin 36 was found in mitral cells, tufted cells, presumed granule cells, and periglomerular cells.
• Interneurons expressing connexin 36 in the periglomerular region and granule cell layer represent distinct, potentially uncharacterized neuronal populations.

Conclusions:

• Mitral/tufted cells establish gap junctions with a variety of extraglomerular neurons.
• Extraglomerular gap junctions involve periglomerular cells and a novel class of neurons.
• Connexin 36 plays a significant role in extraglomerular communication within the olfactory bulb.