Anxiolytic and Antidepressant‐Like Effects of a Probiotic Mixture HMLH123 Potentially via the Serotonergic Pathway in Wistar Rats

Anxiety and depression are a major health problem worldwide with increasing prevalence and limitations in pharmacologic treatment. The gut-brain axis has emerged as a potential therapeutic target, with probiotics showing promise in the regulation of mental health. To evaluate the anxiolytic and antidepressant-like effects of a probiotic mixture HMLH123 and its pharmacologic interaction with fluoxetine, 60 male Wistar rats were divided into six experimental groups that received either vehicle, fluoxetine (0.5 or 1 mg/kg), probiotic mixture HMLH123 200 μL to a concentration of 10⁹ CFU/mL (Lactiplantibacillus sp. LH01, Lactiplantibacillus sp. LH02, and Lactiplantibacillus sp. LH3), or a combination of fluoxetine and probiotic mixture HMLH123. Behavioral assessments included the locomotor activity test (LAT), the elevated plus maze (EPM), and the forced swim test (FST). Data were analyzed using one-way ANOVA with a significance level of p ≤ 0.05. Administration of probiotic mixture HMLH123 or in combination with fluoxetine significantly increased the time spent in the open arms of the EPM, indicating anxiolytic-like effects. In the FST, groups treated with probiotic mixture HMLH123 showed reduced immobility time and increased swimming behavior, suggesting a possible modulation of the serotonergic system. These findings support the potential of probiotic mixture HMLH123 as a preclinical alternative approach for the treatment of anxiety and depression. While no synergistic interaction with fluoxetine was observed, treatment with the probiotic mixture showed positive effects independently. Further research should explore its mechanisms of action and therapeutic applications as a standalone intervention.