BDNF Influences the Excitability of Subfornical Organ Neurons

Abstract

Brain‐derived neurotrophic factor (BDNF) is a peptide known to be involved in several mammalian physiological processes. Expression of BDNF transcripts has been identified in the subfornical organ (SFO), a circumventricular organ involved in fluid balance and energy homeostasis. Microarray analysis has demonstrated that levels of transcript expression in the SFO are differentially regulated by fluid and food deprivation, with levels of BDNF expression increasing significantly in response to dehydration, and decreasing in response to starvation (Hindmarch et al 2008). The current study was therefore undertaken in order to determine the effects of BDNF on the excitability of SFO neurons. We used the whole‐cell patch clamp technique to determine the influence of BDNF on the membrane potential of dissociated SFO neurons as well as that of SFO neurons in slice preparation. We found that 86% of dissociated neurons responded when treated with BDNF (2 nM), all of which depolarized (mean 14 mV). Additionally, 75% of neurons tested in the slice preparation responded when treated with BDNF (2 nM). Of these, 67% showed a depolarization (mean 12 mV) and 33% hyperpolarized (mean ‐18 mV). This study suggests the SFO as a potential central nervous system site at which BDNF may act directly to influence homeostatic regulation.Supported by the Canadian Institutes for Health Research