The predicted outcome of SP binding to NK1R is pain, as shown in numerous studies43 and a link between the neuropeptide response and lower urinary tract symptoms has previously been documented in models of pelvic pain, interstitial cystitis and UTI where an increase in SP-reactive varicose nerve fibers has been observed within the lamina propria, additionally, Duell et al. detected an increase in Tac1 gene expression after bladder infection in mice44,45. Here, TACR1 is linked to interstitial cystitis.