Vasopressin’s Depolarizing Action on Neonatal Rat Spinal Lateral Horn Neurons May Involve Multiple Conductances

Kolaj, Miloslav; Renaud, Leo P.

doi:10.1007/978-1-4615-4871-3_26

Cited by 2 publications

(1 citation statement)

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“…This AHP is inhibited by noradrenaline (Yoshimura et al 1987 a ; Huangfu et al 1992; Jansen et al 1995 b ) suggesting that co‐activation of the A5 noradrenergic neurons might potentiate the sympathoactivation caused by high frequency stimulation of the C1 cells. The sympathetic preganglionic neurons receive many additional inputs, for example from the non‐catecholaminergic portion of the bulbospinal RVLM projection, the hypothalamus or the serotonergic neurons of the raphe (Jansen et al 1995 b ; Kolaj & Renaud, 1998; Madden & Morrison, 2006). Each of these inputs could, in theory, up‐ or down‐regulate the sympathoexcitatory effect of the C1 cells simply by altering the intrinsic properties of the preganglionic neurons.…”

Section: Discussionmentioning

confidence: 99%

Photostimulation of channelrhodopsin‐2 expressing ventrolateral medullary neurons increases sympathetic nerve activity and blood pressure in rats

Abbott

Stornetta

Socolovsky

et al. 2009

The Journal of Physiology

112

146

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To explore the specific contribution of the C1 neurons to blood pressure (BP) control, we used an optogenetic approach to activate these cells in vivo. A lentivirus that expresses channelrhodopsin-2 (ChR2) under the control of the catecholaminergic neuron-preferring promoter PRSx8 was introduced into the rostral ventrolateral medulla (RVLM). After 2-3 weeks, ChR2 was largely confined to Phox2b-expressing neurons (89%). The ChR2-expressing neurons were non-GABAergic, non-glycinergic and predominantly catecholaminergic (∼54%). Photostimulation of ChR2-transfected RVLM neurons (473 nm, 20 Hz, 10 ms, ∼9 mW) increased BP (15 mmHg) and sympathetic nerve discharge (SND; 64%). Light pulses at 0.2-0.5 Hz evoked a large sympathetic nerve response (16 × baseline) followed by a silent period (1-2 s) during which another stimulus evoked a reduced response. Photostimulation activated most (75%) RVLM baroinhibited neurons sampled with 1/1 action potential entrainment to the light pulses and without accommodation during 20 Hz trains. RVLM neurons unaffected by either CO 2 or BP were light-insensitive. Bötzinger respiratory neurons were activated but their action potentials were not synchronized to the light pulses. Juxtacellular labelling of recorded neurons revealed that, of these three cell types, only the cardiovascular neurons expressed the transgene. In conclusion, ChR2 expression had no discernable effect on the putative vasomotor neurons at rest and was high enough to allow precise temporal control of their action potentials with light pulses. Photostimulation of RVLM neurons caused a sizable sympathoactivation and rise in blood pressure. These results provide the most direct evidence yet that the C1 neurons have a sympathoexcitatory function.

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