Regulation of the NRG1/ErbB4 Pathway in the Intrinsic Cardiac Nervous System Is a Potential Treatment for Atrial Fibrillation

Figures

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  FIGURE 1. Flow diagram of the present study. RAP was performed after saline, NRG1 or NRG1 plus ERA microinjection into four atrial GP and LOM, except in the control group. ERP and ΣWOV at atrial and pulmonary vein sites were examined at baseline, the end of 3rd hour and the end of the 6th hour. ARGP function and neural activity were examined at baseline and the end of 6th hour, respectively. GP tissues were excised for histological studies at the end of the 6th hour.

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  FIGURE 2. Changes in ERP and ΣWOV. (A–G) The ERP changes at different time points in the control group, RAP group, NRG1 group and NRG1 + ERA group. (H) The ΣWOV changes at different time points in the four groups. The ERP was shortened, and ΣWOV was widened in atrial and pulmonary vein sites in the RAP group. NRG1 alleviated the effect of RAP, and ERA blocked the beneficial effects of NRG1 on ERP and ΣWOV. ∗p < 0.05 vs. NRG1 group. #p < 0.05 vs. RAP group. ΔP < 0.05 vs. the NRG1 group.

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  FIGURE 3. Changes in ARGP function. (A) The position of ARGP. (B) Representative example of the SR slowing response to ARGP stimulation. (C) ARGP function assessed using the SR slowing responses to ARGP stimulation before and after 6 h of RAP. (D) Percent of maximal SR change induced by different interventions after 6 h of RAP. § P < 0.05 vs. baseline; ∗P < 0.05 vs. the control group; #P < 0.05 vs. the RAP group; ΔP < 0.05 vs. the NRG1 group.

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  FIGURE 4. Changes in ARGP neural activity. (A) Representative ARGP neural activity in the control, RAP group, NRG1 group and NRG1 + ERA group. (B) Quantitative analysis of the frequency of ARGP neural spikes. (C) Quantitative analysis of the amplitude of ARGP neural spikes. ∗P < 0.05 vs. the control group; #P < 0.05 vs. the RAP group; ΔP < 0.05 vs. the NRG1 group.

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  FIGURE 5. Changes in c-fos and NGF expression. (A) Representative examples of the protein levels of c-fos and NGF. (B) Quantitative analysis of the protein expression levels of c-fos and NGF. ∗P < 0.05 vs. the control group; #P < 0.05 vs. the RAP group; ΔP < 0.05 vs. the NRG1 group.

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  FIGURE 6. Parvalbumin (PAV) and ErbB4 staining before and after 6 h of RAP. (A) Representative example of PAV-immunoreactive neurons (40×, red) within the ARGP. (B) Quantitative analysis of the PAV-positive neurons. (C) Representative example of ErbB4-immunoreactive neurons (40×, green) within the ARGP. (D) Quantitative analysis of the ErbB4 positive cells. ∗p < 0.05 vs. control group.

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  FIGURE 7. Schematic diagram illustrating the involvement of PAV-positive neurons in the genesis of AF. (A) The position of four major GP and LOM. (B) PAV-positive neurons (inhibitory neurons) play an important role in modulating the GP neural activity in normal conditions. (C) AF simulated by RAP suppressed PAV-positive neurons, diminished evoked GABA release, and increased GP neural activity and promoted AF. (D) Pretreatment with NRG1 activated PAV-positive neurons and enhanced evoked GABA release via ErbB4 receptors, which suppressed RAP-induced GP activation and AF.