Physiology and Behavior, cilt.312, 2026 (SCI-Expanded, SSCI, Scopus)
Obesity and excessive weight gain have emerged as significant global health concerns in recent years and are often comorbid with numerous contemporary diseases, including cardiovascular disorders, diabetes, and cognitive impairments. L-carnitine, a vital cofactor in mitochondrial energy metabolism, possesses potent antioxidant and anti-inflammatory properties that merit investigation for mitigating obesity-associated neuronal damage. Consequently, this study investigated the potential neuroprotective effects of L-carnitine on anxiety- and depression-like behaviors in adolescent rats subjected to neonatal monosodium glutamate (MSG) exposure, a model known to induce obesity and associated neurobehavioral alterations. Neonatal rats received MSG (4 g/kg, s.c.) on alternate postnatal days (PND) 2–10. Subsequently, L-carnitine (200 mg/kg) was administered via oral gavage daily from PND 60 to 81 (subchronic treatment). Anxiety- and depression-like behaviors were assessed using the Forced Swim Test (FST), Elevated Plus Maze (EPM), and Open Field Test (OFT). All molecular and histological analyses were conducted in the prefrontal cortex (PFC), a region selected for its susceptibility to excitotoxicity and critical role in emotional regulation. Oxidative stress was evaluated through measurements of total oxidant and antioxidant levels. To elucidate the underlying molecular mechanisms, gene expression analyses focused on neuronal survival and apoptosis (BDNF, Bax, Bcl-2), while immunohistochemical evaluations targeted neuroinflammation and cell death pathways (TNF-α, Caspase-3, IL-1β, and Bcl-2). The findings reveal that neonatal MSG exposure leads to pronounced anxiety- and depression-like behaviors, accompanied by metabolic dysregulation, oxidative stress, neuroinflammation, and apoptosis. Although L-carnitine treatment did not reverse obesity-related metabolic alterations, it exhibited notable sustained anxiolytic effects. The neuroprotective potential of L-carnitine was further supported by its ability to reduce cortical neuroinflammation and neurodegerenative damage through suppression of proinflammatory cytokines and restoration of antioxidant balance. Overall, this study offers valuable insights into the cognitive, genetic, and histological outcomes associated with obesity-related mood disturbances and contributes to understanding the complex biological mechanisms underlying these conditions.