Effects of electrical stimulation of the striatum on bladder activity in cats

Abstract

Parkinson's disease (PD) affects the nigrostriatal projections leading to micturition disturbance in most cases. Overactive bladder (OAB) symptoms such as urinary urgency or urgent urinary incontinence are common amongst PD patients. Several urodynamic studies have revealed that detrusor overactivity causes OAB symptoms in PD patients. We assert that striatal dysfunction might contribute to the pathogenesis of detrusor overactivity in PD patients. However, the role of the striatum in bladder contraction remains unclear. We generated spontaneous isovolumetric bladder contractions in 12 ketamine-anesthetized adult male cats and subsequently performed electrical stimulation and extracellular single-unit recording in the striatum. Electrical stimulation applied to the posterior ventral caudate nucleus and the adjacent putamen reduced inhibition of the spontaneous bladder contraction. None of the responses were facilitatory. Electrical stimulation was most effective at an amplitude of 70-400 microA. Forty-six neurons that exhibited correlation to spontaneous bladder contraction were recorded in the striatum. Thirty-five neurons were found to be tonically active throughout the bladder relaxation phase, and the remaining 11 neurons were active during the bladder contraction phase. These particular neurons were located within the area in which spontaneous bladder contraction was inhibited by electrical stimulation. Electrical stimulation was found to inhibit bladder contraction, and a correlation was observed between spontaneous bladder relaxation/contraction and neuronal firing in the posterior ventral striatum.