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. 2017 May 18;8:15097. doi: 10.1038/ncomms15097

Figure 2. Recruitment of vagal activity increases exercise capacity.

Figure 2

(a) Photomicrographs of coronal sections of the rat brainstem taken at low (left) and high (right) magnification illustrating representative examples of CHIEFtdTomato expression in the caudal region of the DVMN (Bregma level: −13.8 mm) 6 weeks after microinjections of PRSx8-ChIEFtdTomato-LVV. Neurons display specific membrane localization of the transgene. Arrows point at ventrally projecting axons of the transduced DVMN neurons (forming the efferent vagus nerve). XII, hypoglossal motor nucleus; NTS, nucleus of the solitary tract. Scale bars: 500 μm (left), 200 μm (right). (b) Schematic drawing of the experimental setup. The rat brain drawn in saggital projection shows the approximate positioning of the chronic optrode implant. (c) Illustration of the experimental protocols. ChIEF, animals transduced to express ChIEFtdTomato in the DVMN. eGFP, animals transduced to express eGFP in the DVMN. (d) Exercise capacity of rats transduced to express eGFP or ChiEFtdTomato by the DVMN neurons before and after 4 days of light stimulation of the dorsal brainstem as well as of a separate group of naive animals before and after 4 daily sessions of treadmill exercise training. Data are presented as individual values and means±s.e.m. Comparisons are made using ANOVA. (e) Summary data showing LV ejection fraction at baseline and in response to β-adrenoceptor stimulation (administration of dobutamine) in rats transduced to express eGFP or ChiEFtdTomato by the DVMN neurons after 4 days of light stimulation of the dorsal brainstem and in naive animals following four daily sessions of exercise training. Data are presented as individual values and means±s.e.m. Comparisons are made using ANOVA. (f) Left: representative immunoblots showing GRK2 and β-arrestin 2 expression in LV lysates of rats transduced to express eGFP or ChiEFtdTomato by the DVMN neurons after 4 days of light stimulation of the dorsal brainstem. Right: summary data illustrating means±s.e.m. of the densitometry of GRK2 and β-arrestin 2 relative expression. *P<0.05 (ANOVA).