Increased tissue content of long-chain acylcarnitines may induce mitochondrial and cardiac damage by stimulating ROS production. N⁶-trimethyllysine dioxygenase (TMLD) is the first enzyme in the carnitine/acylcarnitine biosynthesis pathway. Inactivation of the TMLHE gene (TMLHE KO) in mice is expected to limit long-chain acylcarnitine synthesis and thus induce a cardio- and mitochondria-protective phenotype. TMLHE gene deletion in male mice lowered acylcarnitine concentrations in blood and cardiac tissues by up to 85% and decreased fatty acid oxidation by 30% but did not affect muscle and heart function in mice. Metabolome profile analysis revealed increased levels of polyunsaturated fatty acids (PUFAs) and a global shift in fatty acid content from saturated to unsaturated lipids. In the risk area of ischemic hearts in TMLHE KO mouse, the OXPHOS-dependent respiration rate and OXPHOS coupling efficiency were fully preserved. Additionally, the decreased long-chain acylcarnitine synthesis rate in TMLHE KO mice prevented ischaemia-reperfusion-induced ROS production in cardiac mitochondria. This was associated with a 39% smaller infarct size in the TMLHE KO mice. The arrest of the acylcarnitine biosynthesis pathway in TMLHE KO mice prevents ischaemia-reperfusion-induced damage in cardiac mitochondria and decreases infarct size. These results confirm that the decreased accumulation of ROS-increasing fatty acid metabolism intermediates prevents mitochondrial and cardiac damage during ischaemia-reperfusion.

As traumatic brain injury (TBI) is one of the major causes of permanent disability, there is increasing interest in the long-term outcome of TBI. While motor deficits, cognitive impairment and longer-term risks of neurodegenerative disease are well-established consequences in animal models of TBI, pain is discussed less often despite its high prevalence. The current study addresses the need to characterize the extent of chronic pain and long-term behavioral impairments induced by moderate lateral fluid percussion injury (latFPI) in mice up to 12 months post-TBI and evaluates the validity of the model. Adult male BALB/c mice were subjected to latFPI, and the results were compared with outcomes in sham-operated mice. Mouse behavior was assessed at 1 and 7 days and 1, 3, 6, 9, and 12 months post-injury using sensory-motor (neurological severity score, NSS), cold (acetone) and mechanical sensitivity (von Frey), depressive-like behavior (tail suspension), locomotor (open field), motor coordination (rotarod) and cognitive (Morris water maze, y-maze, passive avoidance) tests. Animals with TBI demonstrated significantly higher NSS than the sham-operated group for up to 9 months after the injury. Cold sensitization was significantly increased in the contralateral hind paw in the TBI group compared to that of the sham group at 3, 6, and 9 months after TBI. In the von Frey test, the withdrawal threshold of the contralateral and ipsilateral hind paws was reduced at 6 months after TBI and lasted for up to 12 months post-injury. latFPI induced progressive depressive-like behavior starting at 6 months post-injury. No significant deficits were observed in memory, motor coordination or locomotion over the 12-month assessment period. The present study demonstrates that moderate TBI in mice elicits long-lasting impairment of sensory-motor function, results in progressive depression and potentiates peripheral pain. Hence, the latFPI model provides a relevant preclinical setting for the study of the link between brain injury and chronic sequelae such as depression and peripheral pain.

Neuroprotective effects of Sigma-1 receptor (S1R) ligands have been observed in multiple animal models of neurodegenerative diseases. Traumatic brain injury (TBI)-related neurodegeneration can induce long-lasting physical, cognitive, and behavioral disabilities. The aim of our study was to evaluate the role of S1R in the development of neurological deficits after TBI. Adult male wild-type CD-1 (WT) and S1R knockout (S1R-/-) mice were subjected to lateral fluid percussion injury, and behavioral and histological outcomes were assessed for up to 12 months postinjury. Neurological deficits and motor coordination impairment were less pronounced in S1R-/- mice with TBI than in WT mice with TBI 24 h after injury. TBI-induced short-term memory impairments were present in WT but not S1R-/- mice 7 months after injury. Compared to WT animals, S1R-/- mice exhibited better motor coordination and less pronounced despair behavior for up to 12 months postinjury. TBI induced astrocyte activation in the cortex of WT but not S1R-/- mice. S1R-/- mice presented a significantly reduced GFAP expression in Bergmann glial cells in the molecular layer of the cerebellum compared to WT mice. Our findings suggest that S1R deficiency reduces TBI-induced motor coordination impairments by reducing GFAP expression in Bergmann glial cells in the cerebellum.

Altered neuronal Ca²⁺ homeostasis and mitochondrial dysfunction play a central role in the pathogenesis of traumatic brain injury (TBI). R-Phenibut ((3R)-phenyl-4-aminobutyric acid) is an antagonist of the α₂δ subunit of voltage-dependent calcium channels (VDCC) and an agonist of gamma-aminobutyric acid B (GABA-B) receptors. The aim of this study was to evaluate the potential therapeutic effects of R-phenibut following the lateral fluid percussion injury (latFPI) model of TBI in mice and the impact of R- and S-phenibut on mitochondrial functionality in vitro. By determining the bioavailability of R-phenibut in the mouse brain tissue and plasma, we found that R-phenibut (50mg/kg) reached the brain tissue 15min after intraperitoneal (i.p.) and peroral (p.o.) injections. The maximal concentration of R-phenibut in the brain tissues was 0.6μg/g and 0.2μg/g tissue after i.p. and p.o. administration, respectively. Male Swiss-Webster mice received i.p. injections of R-phenibut at doses of 10 or 50mg/kg 2h after TBI and then once daily for 7 days. R-Phenibut treatment at the dose of 50mg/kg significantly ameliorated functional deficits after TBI on postinjury days 1, 4, and 7. Seven days after TBI, the number of Nissl-stained dark neurons (N-DNs) and interleukin-1beta (IL-1β) expression in the cerebral neocortex in the area of cortical impact were reduced. Moreover, the addition of R- and S-phenibut at a concentration of 0.5μg/ml inhibited calcium-induced mitochondrial swelling in the brain homogenate and prevented anoxia-reoxygenation-induced increases in mitochondrial H₂O₂ production and the H₂O₂/O ratio. Taken together, these results suggest that R-phenibut could serve as a neuroprotective agent and promising drug candidate for treating TBI.

Sigma-1 receptor (Sig1R) has been proposed as a therapeutic target for neurological, neurodegenerative, and psychiatric disorders, including depression and anxiety. Identifying metabolites that are affected by Sig1R absence and cross-referencing them with specific mood-related behaviors would be helpful for the development of new therapies for Sig1R-associated disorders. Here, we examined metabolic profiles in the blood and brains of male CD-1 background Sig1R knockout (KO) mice in adulthood and old age and correlated them with the assessment of depression- and anxiety-related behaviors. The most pronounced changes in the metabolic profile were observed in the plasma of adult Sig1R KO mice. In adult mice, the absence of Sig1R significantly influenced the amino acid, sphingolipid (sphingomyelin and ceramide (18:1)), and serotonin metabolic pathways. There were higher serotonin levels in plasma and brain tissue and higher histamine levels in the plasma of Sig1R KO mice than in their age-matched wild-type counterparts. This increase correlated with the reduced behavioral despair in the tail suspension test and lack of anhedonia in the sucrose preference test. Overall, these results suggest that Sig1R regulates behavior by altering serotonergic and histaminergic systems and the sphingolipid metabolic pathway.