Therapeutic Effect of LEV in a Propionic Acid-Induced Autism Model via AMPK/SIRT1 Pathway

In this study, we aimed to evaluate the therapeutic effect of levetiracetam (LEV), an antiepileptic drug used in the treatment of both focal and generalized epilepsy, in a propionic acid (PPA)-induced autism model by assessing social deficits, learning and memory impairments, and their neurochemical correlates. We further examined the involvement of the AMPK/SIRT1 signalling pathway as a potential molecular mechanism.

Thirty male Wistar albino rats were allocated into three groups: normal control (n = 10), PPA + saline (n = 10) and PPA + LEV (n = 10). Autism-like features were induced by intraperitoneal PPA administration (250 mg/kg/day, 5 days). LEV was administered orally (100 mg/kg/day) for 15 days. Behavioural performance (three-chamber sociability test, open-field test, passive avoidance learning), biochemical markers (malondialdehyde [MDA], tumour necrosis factor-alpha [TNF-α], brain-derived neurotrophic factor [BDNF], AMPK, and SIRT1) and histopathological changes (neuronal counts in CA1, CA3, Purkinje cells; GFAP immunostaining) were evaluated.

In the sociability test, social interaction time decreased by 51.6% in the PPA + saline group compared to controls (67.2% ± 2.4% vs. 32.5% ± 2.1%), while LEV increased it by 121.8% vs. PPA + saline (72.1% ± 4.5%). Open-field ambulation decreased by 83% in PPA + saline (17.3 ± 3.2 vs. 2.9 ± 0.8) and increased by 158% with LEV (7.5 ± 2.16). Passive avoidance latency decreased by 76% in PPA + saline (245.9 ± 17.5 s vs. 59.2 ± 20.8 s) and increased by 180% with LEV (165.7 ± 18.3 s). MDA levels increased by 187% in PPA + saline vs. controls (49.9 ± 1.4 vs. 143.5 ± 4.7 nmol/g protein) and decreased by 31% with LEV (98.6 ± 5.4). TNF-α increased by 1012% in PPA + saline (13.1 ± 0.9 vs. 145.8 ± 10.6 pg/mg protein) and decreased by 39% with LEV (88.4 ± 3.9). BDNF decreased by 52% in PPA + saline (5.21 ± 0.9 vs. 2.48 ± 0.3 pg/mg protein) and increased by 88% with LEV (4.66 ± 0.5). AMPK decreased by 62% in PPA + saline (113.5 ± 6.3 vs. 43.2 ± 7.5 pg/mg protein) and increased by 73% with LEV (74.8 ± 2.1). SIRT1 decreased by 75% in PPA + saline (4.65 ± 0.5 vs. 1.17 ± 1.1 pg/mg protein) and increased by 132% with LEV (2.72 ± 0.8). Histologically, CA1 neuronal counts decreased by 35% in PPA + saline (67.2 ± 2.04 vs. 43.8 ± 1.1) and increased by 38% with LEV (60.5 ± 1.3). CA3 neuronal counts decreased by 31% in PPA + saline (48.5 ± 3.2 vs. 33.7 ± 1.9) and increased by 31% with LEV (44.2 ± 0.8). Purkinje cells decreased by 53% in PPA + saline (26.2 ± 0.5 vs. 12.2 ± 0.8) and increased by 68% with LEV (20.5 ± 1.1). GFAP indices in CA1, CA3 and cerebellum were elevated in PPA + saline (31.6 ± 2.4 vs. 47.5 ± 1.2; 33.4 ± 1.1 vs. 48.2 ± 0.7; 21.2 ± 1.6 vs. 32.3 ± 0.9) and reduced with LEV (40.3 ± 0.6; 39.5 ± 0.8; 28.5 ± 1.4, respectively). These therapeutic effects were accompanied by marked upregulation of the AMPK/SIRT1 pathway, which was suppressed in the PPA + saline group.

LEV treatment ameliorated PPA-induced behavioural, biochemical and histological impairments, likely via anti-inflammatory, antioxidant and neuroprotective mechanisms involving activation of the AMPK/SIRT1 pathway. These findings support LEV as a potential therapeutic candidate for autism spectrum disorder.