Abstract
The dorsal motor nucleus of the vagus (DMV) is a key integrative point of the parasympathetic neuronal network localized in the dorsal vagal complex. Activity of neurons in the DMV is closely regulated by synaptic inputs, and regulation of excitatory and inhibitory synapsis by transient receptor potential vanilloid type 1 (TRPV1) has been demonstrated. Activation of TRPV1 by heat, protons, endovanilloids, endocannabinoids, and inflammatory mediators is well established. In our study we hypothesized that TRPV1 contributes to the synaptic transmission of DMV neurons at physiological range of temperature without additional stimuli. Using whole-cell patch-clamp recordings we evaluated the effect of a rapid increase of temperature on excitatory and inhibitory neurotransmission and the contribution of TRPV1 to this response. Rapid increase of temperature from 25 to 37°C increased the frequency of miniature excitatory post-synaptic currents (mEPSC) by 351.7%. The frequency of miniature inhibitory post-synaptic currents (mIPSC) also increased by 184.7%. 5′-iodoresiniferatoxin (5′-iRFT), a selective TRPV1 antagonist, prevented the increase of mEPSC and mIPSC frequency. In summary, our data demonstrate that at physiological range of temperature TRPV1 contributes to presynaptic neurotransmission of DMV neurons.
Highlights
The dorsal vagal complex (DVC) is a main parasympathetic autonomic center
We found that the potentiation of excitatory and inhibitory neurotransmission to dorsal motor nucleus of the vagus (DMV) neurons was a result of thermal activation of presynaptic TRPV1 receptors
Our results suggest that rapid increase of temperature form 25 to 37◦C potentiate presynaptic release of inhibitory neurotransmitters to DMV neurons in TRPV1-dependent manner
Summary
The dorsal vagal complex (DVC) is a main parasympathetic autonomic center. It encompasses the nucleus of the solitary tract (NTS), the dorsal motor nucleus of the vagus nerve (DMV), and the area postrema (AP) (Bailey, 2008). The DMV sends vagal projections to postganglionic neurons innervating subdiaphragmatic organs (Browning and Travagli, 2011), thereby regulating the function of the gastrointestinal tract, the cardiovascular system, and the respiratory system (Bauer et al, 2005; Shoudai et al, 2010; Cavanaugh et al, 2011; Zsombok et al, 2011b). TRPV1 is expressed in the cerebral cortex, the hypothalamus, the brainstem and the hindbrain, as shown by different methods (Cristino et al, 2006; Derbenev et al, 2006; Pingle et al, 2007; Cavanaugh et al, 2011; Zsombok et al, 2011b; Gao et al, 2012)
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