This study elucidated the potential antidepressant-like effect of prolonged Ropren® administration (8.6 mg/kg, orally, once daily for 28 days) using a β-amyloid (25-35) rat model of Alzheimer's disease following gonadectomy. The experimental model was created by intracerebroventricular injection of β-amyloid (25-35) into gonadectomized (GDX) rats and GDX rats with testosterone propionate (TP, 0.5 mg/kg, subcutaneous, once daily, 28 days) supplementation. Ropren® was administered to the GDX rats and GDX rats treated with TP. Depression-like behavior was assessed in the forced swimming test, and the spontaneous locomotor activity was assessed using the open-field test. The corticosterone and testosterone levels in the blood serum before and after FST were measured in all experimental groups. Treatment with Ropren® significantly decreased the immobility time of GDX rats with β-amyloid (25-35) in the forced swimming test. Coadministration of Ropren® with TP exerted a markedly synergistic antidepressant-like effect in the GDX rats with β-amyloid (25-35 on the same model of depression-like behavior testing. Ropren® administered alone or together with TP significantly enhanced crossing, frequency of rearing, and grooming of the GDX rats with β-amyloid (25-35) in the open-field test. Moreover, Ropren® administered alone or together with TP significantly decreased the elevated corticosterone levels in the blood serum of GDX rats with β-amyloid (25-35) following the forced swimming test. These results indicate that Ropren® has a marked antidepressant-like effect in the experimental model of Alzheimer's disease in male rats with altered levels of androgens.
Keywords: Alzheimer’s disease; Depression-like behavior; Gonadectomy; Polyprenols; Ropren®; Testosterone.