Molecular and Behavioral Neuroprotective Effects of Clavulanic Acid and Crocin in Haloperidol-Induced Tardive Dyskinesia in Rats

Clavulanic acid (ClvA), a beta-lactamase inhibitor, is being explored for its significant neuroprotective potential. The effects of ClvA were assessed both individually and in combination with crocin (Cr), an antioxidant derived from saffron, in the context of tardive dyskinesia (TD). In rat haloperidol (Hp)-induced-TD (1 mg/kg, i.p. 21 days), the effects of ClvA (50, 100, 150 mg/kg) and Cr (10, 20, 40 mg/kg) were assessed via vacuous chewing movements (VCM) and tongue protrusion (TP). Striatal malondialdehyde (MDA) and glutathione (GSH) were measured spectrophotometrically. Based on the results, ClvA (100 mg/kg) and Cr (10 mg/kg) were determined with sub-effective doses. Glutamate transporter-subtype1 (GLT1), dopamine active transporter (DAT), vesicular monoamine transporter-type2 (VMAT2), Bax/Bcl2, cleaved Caspase3, phosphorylated AKT/AKT, IL1β, and TNFα levels were quantified using western blotting in sub-effective doses and their combination. The behavioral results of catalepsy and orofacial dyskinesia demonstrated model establishment. Hp decreased GLT1 (p < 0.05), DAT (p < 0.01), VMAT2 (p < 0.001), GSH and pAKT/AKT (p < 0.0001); increased TNFα (p < 0.05), IL1β, cleaved Caspase3 (p < 0.001); MDA and Bax/Bcl2 (p < 0.0001). ClvA 100 mg/kg reversed the decreased GLT1 and VMAT2 (p < 0.01), alongside the increased MDA (p < 0.0001) and VCM (p < 0.05). It also increased AKT phosphorylation (p < 0.05). No effects were noted on DAT, GSH, Bax/Bcl2, or inflammatory factors. However, the combination with Cr at 10 mg/kg influenced ClvA on DAT (p < 0.01) and resulted in a significant increase in GSH (p < 0.0001). Additionally, there was a marked decrease in TNFα (p < 0.0001) and IL1β (p < 0.001), enhancing its effects on reducing MDA and increasing pAKT/AKT (p < 0.0001). The combination adversely affected GLT1. ClvA protects against TD via GLT1 and VMAT2; combined with Cr, it enhances antioxidant effects, improves DAT, and requires dose optimization for GLT1 disruption.