Skip to main content
. 2020 May 25;5(5):484–497. doi: 10.1016/j.jacbts.2020.03.007

Figure 1.

Figure 1

Chemogenetic Hypothalamic Oxytocin Neuron Activation Restores Oxytocin Release to Cardiac Vagal Neurons in Heart Failure

(A) Three-dimensional (3D) confocal image showing sniffer CHO cell (red) expressing R-GECO and oxytocin receptor in close proximity to channelrhodopsin expressing PVN oxytocinergic nerve fibers (green) projecting to brainstem DMNX cardiac vagal neurons. Scale bar represents 10 microns. (B) Optogenetic stimulation of ChR2 expressing PVN oxytocin fibers projecting to cardiac vagal neurons evokes an increase in intracellular calcium response in sniffer CHO cells that were significantly blunted in animals with HF at 6 weeks post-TAC. These responses were restored in the treatment group upon chemogenetic activation of DREADDs-expressing PVN oxytocin neurons starting at 4 weeks post-TAC. DREADDS was activated by daily intraperitoneal injections of CNO (1 mg/kg) to treatment animals, whereas Sham and TAC animals received saline injections. Responses representative of 1 sniffer CHO cell are shown. (C) Quantitative histograms showing increase in fluorescence in CHO cells evoked by photostimulation of PVN oxytocin fibers at various time points of disease progression (2, 4, 6, 8, and 10 weeks post-TAC/Sham) in Sham, TAC, and 4 to 10 weeks post-TAC in treatment-group animals. Responses in Sham animals were not different in all time points. TAC animals displayed blunted responses at 6 and 10 weeks post-TAC compared with 2 weeks post-TAC. Similar to Sham animals, responses were not different in treatment animals at all time points. Data were analyzed using mixed-effects model with Tukey’s postmultiple comparison test. Numbers in parentheses indicate number of cells. Number of animals in each group of animals at each time point are Sham (n = 3 at all points except 6 weeks [n=4]); TAC (n = 3 except at 8 weeks [n = 4]); treatment (n = 3 at all time points); ∗p < 0.05; ∗∗∗p < 0.001. CHO, Chinese hamster ovary; DREADDs, designer receptors exclusively activated by designer drugs; HF, heart failure; PVN, paraventricular nucleus of the hypothalamus; R-GECO, red fluorescent genetically encoded Ca2+ indicators; TAC, transascending aortic constriction.