Exogenous ketosis fails to mitigate cardiac dysfunction, mitochondrial and inflammatory dysregulation in acute doxorubicin-induced cardiotoxicity

Background Doxorubicin (DOX)-induced cardiotoxicity is driven by mitochondrial dysfunction, oxidative stress and inflammatory activation. In pathological conditions, the heart undergoes metabolic remodelling, increasing its reliance on ketone bodies (KB) as an auxiliary energy substrate. Although exogenous KB have demonstrated cardioprotective effects in models of cardiac remodelling, their impact on the DOX-induced cardiac injury remains undefined. Purpose To determine whether exogenous ketosis modulates mitochondrial regulatory pathways, redox balance and inflammatory signalling in acute DOX-induced cardiotoxicity. Methods Male Wistar rats (n = 64) were allocated to six groups: Control, DOX, KB1 (1,3-butanediol 5 g/kg), KB2 (1,3-butanediol 10 g/kg), DOX+KB1 and DOX+KB2. 1,3-Butanediol was administered by oral gavage once a day, for two weeks, to induce ketosis. Acute cardiotoxicity was triggered by a single intraperitoneal DOX injection (20 mg/kg). Forty-eight hours post-DOX injection, cardiac function was assessed by echocardiography and invasive left ventricular haemodynamics. Myocardial oxidative stress markers were quantified spectrophotometrically, and protein expression of mitochondrial dynamics, metabolic regulators and inflammatory mediators was analysed by Western blotting. Statistical analysis: Two-way ANOVA. Results Rats receiving KB exhibited reduced food and water intake, accompanied by a decrease in body weight. Blood ketone levels increased at 4 and 8 hours following KB administration, with a more pronounced rise at 8 hours in animals receiving 10 g/kg (Figure 1A). DOX-treated animals showed a higher E/E′ ratio and reduced S′ on echocardiography, together with decreased +dP/dt and –dP/dt during left ventricular pressure assessment, indicating both systolic and diastolic dysfunction (Figure 1B). Myocardial troponin T levels were reduced following DOX administration, suggesting myocardial injury. DOX treatment decreased myocardial expression of the mitochondrial fusion protein mitofusin 2 and increased protein levels of TNF-α, Keap1 and NF-κB, which are associated with inflammatory signalling and oxidative stress regulation (Figure 2). Catalase activity was increased in rats that received DOX, without effects of KB (C: 2.41 ± 0.73; D: 3.71 ± 2.02; KB1: 2.62 ± 1.45; KB2: 4.35 ± 1.40; DKB1: 3.65 ± 1.07; DKB2: 1.81 ± 0.53 U/mg protein; p_DOX < 0.001; p_KB = 0.358; p_interaction = 0.790). No significant differences were observed in superoxide dismutase activity, malondialdehyde levels, carbonylated proteins, or myocardial expression of AMPK, SIRT3, DRP1, IL-10, PGC-1α and PPAR-γ. Conclusions Acute DOX cardiotoxicity is characterised by early disruption of mitochondrial fusion machinery and activation of pro-inflammatory and redox-sensitive pathways. Despite inducing systemic ketosis, exogenous KB supplementation failed to modulate these molecular perturbations or preserve cardiac function.Figure 1Figure 2