Background: The heart is under the influence of neurotrophins (NTs) secreted from peripheral sympathetic nerves, including brain derived neurotrophic factor (BDNF). BDNF is indispensible for cardiac development and vascular wall integrity. Yet, whether BDNF signaling plays a role in governing cardiac function in response to stress is unclear.
Hypothesis: BDNF signaling contributes to maintain proper cardiac structure/function in pressure overloaded mice.
Results: BDNF expression is markedly down-regulated in hearts subjected to transverse aortic constriction (TAC). Cardiac specific over-expression of BDNF (BDNF-TG) or administration of a BDNF-mimetic agonist (LM22A-4) preserved cardiac function against pressure overload. In contrast, cardiac-selective deletion of the BDNF receptor, Tropomyosin related kinase receptor B (TrkB), further exacerbated heart failure. In neurons, BDNF up-regulates Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) that regulates energy metabolism and mitochondrial function/biogenesis. Oxidative stress is a major negative modulator of PGC-1a expression/activity. Exposing neonatal rat ventricular myocytes (NRVMs) to hydrogen peroxide downregulated PGC-1α, and BDNF restored it to normal levels, with a concomitant up-regulation of downstream genes involved in both mitochondrial biogenesis and oxidative stress, resulting in attenuated ROS production and increased mitochondrial biogenesis. Consistent with the cultured myocyte findings, PGC-1α and downstream genes were up-regulated in BDNF-TG mice subjected to TAC, associated with attenuated oxidative stress and improved mitochondrial biogenesis; whereas TrkB-/- mice subjected to TAC displayed further decreased PGC-1α expression with worsened oxidative stress and impaired mitochondrial biogenesis.
Conclusion: Our data show that BDNF confers protection against pressure overload via enhanced PGC-1α signaling that in turn prevents oxidative stress and improves mitochondrial biogenesis. Our data suggest BDNF/trkB is a promising new therapeutic avenue to prevent or retard heart failure.