Cardiac and placental mitochondrial characterization in a rabbit model of intrauterine growth restriction.

BACKGROUND: Intrauterine growth restriction (IUGR) is associated with cardiovascular remodeling persisting into adulthood. Mitochondrial bioenergetics, essential for embryonic development and cardiovascular function, are regulated by nuclear effectors as sirtuins. A rabbit model of IUGR and cardiovascular remodeling was generated, in which heart mitochondrial alterations were observed by microscopic and transcriptomic analysis. We aimed to evaluate if such alterations are translated at a functional mitochondrial level to establish the etiopathology and potential therapeutic targets for this obstetric complication. METHODS: Hearts and placentas from 16 IUGR-offspring and 14 controls were included to characterize mitochondrial function. RESULTS: Enzymatic activities of complexes II, IV and II + III in IUGR-hearts (-11.96 ±â€¯3.16%; -15.58 ±â€¯5.32%; -14.73 ±â€¯4.37%; p < 0.05) and II and II + III in IUGR-placentas (-17.22 ±â€¯3.46%; p < 0.005 and -29.64 ±â€¯4.43%; p < 0.001) significantly decreased. This was accompanied by a not significant reduction in CI-stimulated oxygen consumption and significantly decreased complex II SDHB subunit expression in placenta (-44.12 ±â€¯5.88%; p < 0.001). Levels of mitochondrial content, Coenzyme Q and cellular ATP were conserved. Lipid peroxidation significantly decreased in IUGR-hearts (-39.02 ±â€¯4.35%; p < 0.001), but not significantly increased in IUGR-placentas. Sirtuin3 protein expression significantly increased in IUGR-hearts (84.21 ±â€¯31.58%; p < 0.05) despite conserved anti-oxidant SOD2 protein expression and activity in both tissues. CONCLUSIONS: IUGR is associated with cardiac and placental mitochondrial CII dysfunction. Up-regulated expression of Sirtuin3 may explain attenuation of cardiac oxidative damage and preserved ATP levels under CII deficiency. GENERAL SIGNIFICANCE: These findings may allow the design of dietary interventions to modulate Sirtuin3 expression and consequent regulation of mitochondrial imbalance associated with IUGR and derived cardiovascular remodeling.

TRPA1 Channels Mediate Human Gingival Fibroblast Response to Phenytoin.

Drug-induced gingival enlargement (GE) is a frequent adverse effect observed in patients treated with anticonvulsant, immunosuppressant, and some antihypertensive medications-the antiepileptic phenytoin being the main drug associated with GE due to its high incidence (around 50%). The molecular mechanisms behind drug-induced gingival overgrowth are still unknown. By reverse transcription polymerase chain reaction, we demonstrate that the calcium-permeable ion channels TRPA1, TRPV1, and its capsaicin-insensitive isoform TRPV1b are expressed in human gingival fibroblasts (HGFs), the most abundant cellular type in periodontal tissue. Cultured HGFs responded with intracellular calcium elevations to phenytoin and to the canonical TRPA1 agonist allyl isothiocyanate. Application of phenytoin activated a nonselective cationic current in HGFs with a typical signature for TRPA1 channels. Moreover, this activation was blocked by HC030031, a specific TRPA1 blocker. Similarly, the use of shRNAs against hTRPA1 in HGFs reduced TRPA1 expression and activation by phenytoin. In addition, we show that phenytoin increased intracellular calcium levels in cells transfected with mouse or human TRPA1 channels. Responses to phenytoin were not observed in untransfected cells or cells expressing TRPM8 or TRPV1. The activation of HGFs by phenytoin was markedly reduced in the presence of antioxidant vitamins: ascorbic acid, folic acid, and α-tocopherol. By performing cell proliferation assays, we found that phenytoin did not augment the proliferation rate of HGFs. In contrast, alcian blue and picrosirius red staining of long-term HGFs cultures indicated that phenytoin induces extracellular matrix accumulation of collagen. Collectively, these findings support an important role of TRPA1 channels in phenytoin-induced GE, provide insight into the pathophysiologic mechanism, and offer novel therapeutic opportunities for its treatment.