Association of detrusor underactivity with aging and metabolic syndrome: suggestions from animal models

Detrusor underactivity, a condition in which the bladder muscle does not contract strongly or long enough to empty the bladder completely or within the normal time frame, is a common cause of lower urinary tract symptoms in older individuals of both sexes. Although aging is a known risk factor for detrusor underactivity, its pathophysiological mechanisms are not fully understood. Therefore, establishing animal models that closely mimic the pathophysiology of detrusor underactivity in humans is necessary to elucidate these mechanisms. Metabolic syndrome is a cluster of several risk factors, including obesity, hyperlipidemia, hyperglycemia, and hypertension, which are associated with the development of diabetes, cardiovascular disease, and lower urinary tract dysfunction in both sexes. Notably, bladder dysfunction resulting from detrusor underactivity is observed at an earlier age in animal models with diabetes mellitus than in those without. Recently, detrusor underactivity-like phenotypes have been observed at a relatively early age in animal models with metabolic syndrome, involving obesity, hyperlipidemia, and hypertension, compared with those without. Therefore, this review introduces the association of detrusor underactivity with aging and metabolic syndrome, as well as possible pathophysiological mechanisms for detrusor underactivity from reports of various animal models. Notably, metabolic syndrome may accelerate the onset of age-related detrusor underactivity, and further analysis of old animal models with metabolic syndrome may help elucidate the pathogenesis of detrusor underactivity in humans.