Cholinergic dysfunction is a central feature of many neurodegenerative and age-related cognitive disorders. Experimental blockade of muscarinic acetylcholine receptors with scopolamine (SCO) is a widely used pharmacological model to induce transient cognitive impairment in animals. Glibenclamide (GD), a sulfonylurea antidiabetic agent, has been proposed to possess neuroprotective properties. The interplay between cholinergic blockade and monoaminergic systems may underlie cognitive changes in this model, motivating investigation of GD's effects on behavior and brain monoamines.
The study aimed to evaluate behavioral and neurochemical effects of chronic glibenclamide administration in a rat model of SCO-induced cognitive impairment, assessing whether GD modulates monoaminergic neurotransmission and influences memory and learning deficits produced by muscarinic blockade.
Adult male Wistar rats were allocated to four experimental groups: control (saline), SCO (1 mg/kg), GD (50 µg/kg), and combined GD+SCO. The study employed chronic GD administration, with SCO used to induce cholinergic-related cognitive deficits. Both behavioral testing and biochemical analyses were performed to link functional outcomes to underlying neurochemical changes.
Cognitive and anxiety-related behaviors were evaluated using three standard tests: the Morris water maze (MWM) to assess spatial learning and memory consolidation, the Y-maze for working memory, and the elevated plus maze (EPM) for anxiety-like behavior. In the MWM, reported outcome measures included area under the curve (AUC) during acquisition and time spent in the target quadrant during probe testing.
Monoamine neurotransmitters — dopamine (DA), norepinephrine (NE), serotonin (5-HT) — and their metabolites were quantified in two brain regions, the striatum and the hippocampus, using high-performance liquid chromatography (HPLC). Specific metabolite changes reported included homovanillic acid (HVA) levels.
Expression levels of key monoamine-metabolizing enzymes—monoamine oxidase A (MAO-A), monoamine oxidase B (MAO-B), and catechol-O-methyltransferase (COMT)—were assessed by reverse transcription quantitative PCR (RT-qPCR) in relevant brain tissues.
Scopolamine produced measurable impairment in spatial learning and memory in the MWM, evidenced by an increased AUC during acquisition and reduced time spent in the target quadrant on probe testing. SCO did not significantly affect working memory in the Y-maze or anxiety-like behavior in the EPM according to the reported results. Chronic GD administration alone improved memory consolidation but was associated with impaired spatial learning performance. In animals receiving both GD and SCO, GD partially moderated SCO-induced memory deficits.
Region-specific changes in monoaminergic markers were observed. GD alone increased striatial dopamine (DA) levels while decreasing hippocampal DA. SCO reduced hippocampal homovanillic acid (HVA) and serotonin (5-HT). The combination of GD and SCO partially restored striatal 5-HT levels that had been affected by SCO. At the mRNA level, GD elevated MAO-B expression in the striatum, whereas SCO decreased MAO-A expression in the hippocampus. COMT expression changes were analyzed but specific shifts were not detailed in the abstract.
The authors interpret the findings as evidence that glibenclamide modulates monoaminergic systems in a region-specific manner under conditions of cholinergic dysfunction. GD produced a dual profile: it improved memory consolidation (a beneficial effect) yet impaired spatial learning and reduced hippocampal monoamines (an adverse effect). The partial restoration of memory consolidation in SCO-treated rats suggests some capacity of GD to counteract aspects of cholinergic blockade, while the regional decreases in hippocampal monoamines and altered enzyme expression indicate complex neuromodulatory actions that may underlie mixed behavioral outcomes.
Details beyond the reported behavioral and biochemical outcomes—such as exact timing of treatments, full dose–response relationships, sample sizes, statistical values, and long-term effects—were not provided in the abstract. The reported results derive from an animal model and require cautious extrapolation to clinical contexts. The data highlight that repurposing antidiabetic agents like GD for cognitive dysfunction warrants careful evaluation given region-specific and bidirectional effects on neurotransmitter systems.
Reported keywords include COMT, Cognitive impairment, Dopamine, Glibenclamide, Hippocampus, MAO-A, MAO-B, Monoamines, Morris water maze, Scopolamine, Serotonin, and Striatum. Overall, GD alters monoaminergic neurotransmission differentially across brain regions and partially restores memory consolidation in a scopolamine model while impairing spatial learning, underscoring a complex, dual role documented in this study.