Adrenergic enhancement of inhibitory transmission in the accessory olfactory bulb.
Noradrenergic modulation of dendrodendritic synapses between the mitral and granule cells in the accessory olfactory bulb (AOB) is postulated to play a key role in the formation of memory in olfactory-mediated behaviors. Current models propose that noradrenaline (NA) increases excitation of mitral/tufted cells (M/TCs) by decreasing the release of GABA from granule cells. However, surprisingly little is known about the actions of NA at the cellular level in the AOB. Here, in recordings from AOB slices, we show that NA decreases the firing frequency of M/TCs in response to stimulation. This effect is attributable to an increase in the GABA inhibitory input to M/TCs. Application of NA (10 microM) produced an approximately 20-fold increase in the frequency of GABA-induced miniature IPSCs (mIPSCs) without changing their amplitude. A pharmacological analysis indicated that the increase in mIPSCs frequency results from activation of alpha1 adrenergic receptors. In addition to increasing the mIPSC frequency, NA also potentiated GABA inhibitory currents induced by direct stimulation of granule cells. Together, our results suggest that NA increases the release of GABA from granule cells by acting on presynaptic receptors. Thus, the role of the noradrenergic activity in the AOB may be opposite than suggested previously: we find that the overall effect of NA in the AOB is inhibition of M/TCs.
Department of Biological Sciences, Columbia University, New York, New York 10027, USA. rca23@columbia.edu
Ricardo C
RC
Araneda
Stuart
S
Firestein
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism; D005260:Female; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D009830:Olfactory Bulb / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000378:metabolism; D012903:Smell / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
C547714:Adra1a protein, mouse; D018340:Receptors, Adrenergic, alpha-1; D005680:gamma-Aminobutyric Acid; D009638:Norepinephrine