GABAB receptor expression and function in olfactory receptor neuron axon growth

✍ Scribed by Priest, Catherine A. ;Puche, Adam C.

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 382 KB
• Volume: 60
• Category: Article
• ISSN: 0022-3034
• DOI: 10.1002/neu.20011

✦ Synopsis

Neurotransmitters have been implicated in regulating growth cone motility and guidance in the developing nervous system. Anatomical and electrophysiological studies show the presence of functional GABA B receptors on adult olfactory receptor neuron (ORN) nerve terminals. Using antisera against the GABA B R1a/b receptor isoforms we show that developing mouse olfactory receptor neurons express GABA B receptors from embryonic day 14 through to adulthood. GABA B receptors are present on axon growth cones from both dissociated ORNs and olfactory epithelial explants. Neurons in the olfactory bulb begin to express glutamic acid decarboxylase (GAD), the synthetic enzyme for GABA, from E16 through to adulthood. When dissociated ORNs were cultured in the presence of the GABA B receptor agonists, baclofen or SKF97541, neurite outgrowth was significantly reduced. Concurrent treatment of the neurons with baclofen and the GABA B receptor antagonist CGP54626 prevented the inhibitory effects of baclofen on ORN neurite outgrowth. These results show that growing ORN axons express GABA B receptors and are sensitive to the effects of GABA B receptor activation. Thus, ORNs in vivo may detect GABA release from juxtaglomerular cells as they enter the glomerular layer and use this as a signal to limit their outgrowth and find synaptic targets in regeneration and development.