Sensory experience selectively regulates transmitter synthesis enzymes in interglomerular circuits

Brain Res. 2011 Mar 25;1382:70-6. doi: 10.1016/j.brainres.2011.01.068. Epub 2011 Jan 26.

Abstract

Sensory experience influences brain organization and function. A particularly striking example is in the olfactory bulb where reduction of odorant sensory signals profoundly down-regulates dopamine in glomerular neurons. There are two large populations of glomerular inhibitory interneurons: (1) GABAergic periglomerular (PG) cells, whose processes are limited to a single glomerulus, regulate intraglomerular processing and (2) DAergic-GABAergic short axon (SA) cells, whose processes contact multiple glomeruli, regulate interglomerular processing. The inhibitory neurotransmitter GABA is synthesized from L-glutamic acid by the enzyme glutamic acid decarboxylase (GAD) of which there are two major isoforms: GAD65 and GAD67. GAD65 is expressed in uniglomerular PG cells. GAD67 is expressed by SA cells, which also co-express the rate-limiting enzyme for dopamine synthesis, tyrosine hydroxylase (TH). Deafferentation or sensory deprivation decreases TH expression but it is not known if sensory input alters GAD isoforms. Here we report that either deafferentation or reduction of sensory input by nares occlusion significantly reduced GAD67 protein and the number of SA cells expressing GAD67. However, neither manipulation altered GAD65 protein or the number of GAD65 PG cells. These findings show that sensory experience strongly impacts transmitter regulation in the circuit that controls neural processing across glomeruli but not in the circuit that regulates intraglomerular processing.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Denervation / methods
  • Dopamine / biosynthesis
  • Down-Regulation / physiology
  • Gene Expression Regulation, Enzymologic / physiology
  • Glutamate Decarboxylase / metabolism*
  • Interneurons / cytology
  • Interneurons / enzymology*
  • Learning / physiology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Neural Inhibition / physiology
  • Neural Pathways / cytology
  • Neural Pathways / enzymology
  • Neuronal Plasticity / physiology
  • Neuropil / cytology
  • Neuropil / enzymology
  • Olfactory Bulb / physiology*
  • Olfactory Nerve / surgery
  • Olfactory Nerve Injuries
  • Smell / physiology
  • Synaptic Transmission / physiology
  • gamma-Aminobutyric Acid / biosynthesis*

Substances

  • gamma-Aminobutyric Acid
  • Glutamate Decarboxylase
  • glutamate decarboxylase 1
  • glutamate decarboxylase 2
  • Dopamine