Interneurons and the GABA neurotransmitter (40X)

Interneurons and the GABA neurotransmitter of the cerebellum. Image copyright: University of Oslo, CC BY-NC-ND 4.0. (Tissue stain: Beroxydase/benzidine).

This is a section from the cerebellum of a rat. Immunocytochemical detection of the presence of the inhibitory neurotransmitter GABA. Antibodies have been made against GABA (actually against the conjugate of GABA and albumin), which recognizes and binds to GABA bound to proteins in the brain tissue. Anti-GABA molecules are then coupled with peroxidase-labeled anti-antibody. The peroxidase (pepper peroxidase) is then detected with benzidine, which produces a brown reaction product.

GABA is synthesized in the boutons. It is therefore really more unexpected that the cell bodies of the interneurons contain so much GABA, than that the cell bodies of the Purkinje cells contain little GABA. The reason for this difference is not known, but possibly it is related to a difference in the length of the axon the shorter the axon, the more GABA is found in the cell body (in addition to in the boutons).