Login to Access Video or Poster Abstract: MP85-06
Sources of Funding: P20 DK103086

Introduction

Lower urinary tract symptoms (LUTS) are common and poorly understood; treatment is often ineffective. Failure of neural control of bladder function likely contributes to LUTS symptoms in many patients. Prior studies have shown that the pontine micturition center (PMC) directly controls voiding. Within the PMC corticotropin releasing hormone neurons (PMC^CRH) project axons directly to spinal sacral cord nuclei that control bladder contraction. Here we show that PMC^CRH neurons are critical for voiding, and identify neurons, particularly in the ventrolateral periaqueductal gray (PAG_VL) which directly modulate PMC^CRH and alter voiding.

Methods

We inject adeno-associated viruses expressing proteins in a Cre-dependent fashion into anatomically defined regions of mice expressing Cre recombinase in specific neural types, to cause highly selective expression of these probes in target neuron populations. We monitor conscious voiding with micturition video thermography (MVT), and CMG under anesthesia while monitoring/stimulating specific neuron groups.

Results

Stimulating PMC^CRH neurons using designer receptors exclusively activated by designer drugs (DREADDs) produces urinary frequency in awake mice and on anesthetized CMG. Also, ablating PMC^CRH neurons by selective expression of diphtheria toxin A disrupts normal voiding and the normal CMG voiding reflex. To identify neurons which provide input to PMC^CRH, we used modified rabies virus and cholera toxin B labeling of PMC^CRH and confirmed our results with viral anterograde tracing. Afferents to PMC^CRH are located in PAG_VL, the preoptic area, the lateral hypothalamic area, and other sites. Because sacral afferents sensing bladder filling project to PAG_VL we determined the impact of stimulating Glutamatergic or GABA-ergic neurons (PAG_VL^GLUT or PAG_VL^GABA) in this region. Chemogenetic or optogenetic stimulation of PAG_VL^GLUT neurons leads to voiding and detrusor contraction. By contrast, chemogenetic or optogenetic activation of PAG_VL^GABA inhibits voiding and delays detrusor contraction on CMG.

Conclusions

1. PMC^CRH are driver neurons for detrusor contraction/voiding. 2. PAG_VL^GLUT project to PMC^CRH, and when fired drive voiding/detrusor contraction. 3. PAG_VL^GABA project to PMC^CRH and inhibit voiding/detrusor contraction. PAG_VL, which receives bladder-based sacral afferents, likely controls bladder filling, and is a potential target in efforts to control urge incontinence and urgency symptoms of LUTS.

Funding

P20 DK103086