Endogenous BDNF regulates inhibitory synaptic transmission in the ventromedial nucleus of the hypothalamus

J Neurophysiol. 2012 Jan;107(1):42-9. doi: 10.1152/jn.00353.2011. Epub 2011 Oct 12.

Abstract

Output from steroidogenic factor-1 (SF-1) neurons in the ventromedial nucleus of the hypothalamus (VMH) is anorexigenic. SF-1 neurons express brain-derived neurotrophic factor (BDNF) that contributes to the regulation of food intake and body weight. Here I show that regulation of GABAergic inputs onto SF-1 neurons by endogenous BDNF determines the anorexigenic outcome from the VMH. Single-cell RT-PCR analysis reveals that one-third of SF-1 neurons express BDNF and that only a subset of BDNF-expressing SF-1 neurons coexpresses the melanocortin receptor type 4. Whole cell patch-clamp analysis of SF-1 neurons in the VMH shows that exogenous BDNF significantly increases the frequency of spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs). This enhancement of GABA drive readily decreases the excitability of SF-1 neurons. However, treatment with BDNF has no significant effect on the frequency of TTX-independent GABAergic IPSCs. Moreover, TrkB receptors are not localized at the postsynaptic sites of GABAergic synapses on SF-1 neurons as there is no change in the amplitude of miniature IPSCs in the presence of BDNF. Dual patch-clamp recordings in mouse hypothalamic slices reveal that stimulation of one SF-1 neuron induces an increase in sIPSC frequency onto the neighboring SF-1 neuron. More importantly, this effect is blocked by a tyrosine kinase inhibitor. Hence, this increased GABA drive onto SF-1 neurons may, in part, explain the cellular mechanisms that mediate the anorexigenic effects of BDNF.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain-Derived Neurotrophic Factor / metabolism*
  • Inhibitory Postsynaptic Potentials / physiology*
  • Mice
  • Mice, Transgenic
  • Neural Inhibition / physiology*
  • Neuronal Plasticity / physiology*
  • Synaptic Transmission / physiology*
  • Ventromedial Hypothalamic Nucleus / physiopathology*

Substances

  • Brain-Derived Neurotrophic Factor