Onuf's nucleus controls rhabdosphincter motor neurons and has been shown to contain a dense array of 5-HT (serotonin) and NE terminals. 5-HT and NE were shown to inhibit bladder activity. In 2005, researchers Wolfgang H. Jost and Parvaneh Marsalek used serotonin norepinephrine reuptake inhibitors (SNRI) to increase the synaptic levels of both 5-HT and NE in the synaptic cleft. Duloxetine hydrochloride, a SNRI, has been shown to increase bladder capacity and sphincteric muscle activity in animals and humans exhibiting irritated bladder function. Duloxetine is the first medication developed to help SUI. This is promising because Duloxetine also showed no effect on bladder contraction force or duration which suggests that Duloxetine is affecting the sensory limb of the urination process. 5-HT and NE do not function through direct excitation of motor neurons but facilitate the effects of glutamate. When glutamatergic activation in sphincter motor neurons is absent there is no effect of NE or 5-HT (seen during micturition contraction).