Glutamatergic Inputs Contribute to Phasic Activity in Vasopressin Neurons
Journal of Neuroscience. 2010-01-27; 30(4): 1221-1232
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1. J Neurosci. 2010 Jan 27;30(4):1221-32. doi: 10.1523/JNEUROSCI.2948-09.2010.
Glutamatergic inputs contribute to phasic activity in vasopressin neurons.
Israel JM(1), Poulain DA, Oliet SH.
(1)Inserm Unité 862, Neurocentre Magendie, Université de Bordeaux, 33077
Many neurons in the CNS display rhythmic patterns of activity to optimize
excitation-secretion coupling. However, the mechanisms of rhythmogenesis are only
partially understood. Magnocellular vasopressin (VP) neurons in the hypothalamus
display a phasic activity that consists of alternative bursts of action
potentials and silent periods. Previous observations from acute slices of adult
hypothalamus suggested that VP cell rhythmicity depends on intrinsic membrane
properties. However, such activity in vivo is nonregenerative. Here, we studied
the mechanisms of VP neuron rhythmicity in organotypic slice cultures that,
unlike acute slices, preserve functional synaptic connections. Comparative
analysis of phasic firing of VP neurons in vivo, in acute slices, and in the
cultures revealed that, in the latter, the activity was closely related to that
observed in vivo. It was synaptically driven, essentially from glutamatergic
inputs, and did not rely on intrinsic membrane properties. The glutamatergic
synaptic activity was sensitive to osmotic challenges and kappa-opioid receptor
activation, physiological stimuli known to affect phasic activity. Together, our
data thus strongly suggest that phasic activity in magnocellular VP neurons is
controlled by glutamatergic synaptic inputs rather than by intrinsic properties.
PMID: 20107050 [Indexed for MEDLINE]