Nitric oxide may mediate nipple erection.
The nipple is a specialized structure that can become erect by cold, sexual  arousal, breast-feeding, or other tactile stimulations, which can induce the  milk ejection reflex and sexual arousal because of intense sensory  innervation. The studies that have been conducted thus far to identify the  mechanism of nipple erection (NE) are not sufficient. It has been stated that  NE occurs via activation of the sympathetic nervous system and smooth muscle  contraction. The purposes of this study were to investigate the existence of  nitric oxide synthase (NOS) in the nipple-areola complex (NAC) to explain the  NE mechanism. Considering that smooth muscle relaxation might be effective in  NE, endothelial and neuronal NOS expression and localization were investigated  via immunohistochemical methods on sagittal sections from 17 human NACs. The  results of this study indicate that eNOS is expressed in the vascular  endothelium, ductal epithelium, and smooth muscles, whereas nNOS is expressed  in the neural fibers, smooth muscles, ductal epithelium, and vascular  endothelium in the NAC. Sinusoidal spaces with endothelial layers similar to  those found in penile cavernosal tissue are not found in the NAC. Various  mediators are known to affect the function of the NAC smooth muscles; however,  this study demonstrates that enzymes (eNOS and nNOS) that synthesize nitric  oxide are expressed in the NAC.
Department of Urology, Istanbul Faculty of Medicine, Istanbul University, 34390, Capa - Istanbul, Turkey. dr_murat3@hotmail.com
Murat
M
Tezer
Yasemin
Y
Ozluk
Oner
O
Sanli
Oktar
O
Asoglu
Ates
A
Kadioglu
D000328:Adult; D000368:Aged; D004730:Endothelium, Vascular / Q000201:enzymology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D042361:Mammary Glands, Human / Q000201:enzymology; D008875:Middle Aged; D009130:Muscle, Smooth / Q000201:enzymology; D009417:Nerve Tissue / Q000201:enzymology; D009558:Nipples / Q000098:blood supply / Q000201:enzymology* / Q000294:innervation; D009569:Nitric Oxide / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000032:analysis*; D052250:Nitric Oxide Synthase Type III / Q000032:analysis*; D012677:Sensation; D015398:Signal Transduction
D009569:Nitric Oxide; C496320:NOS1 protein, human; C496314:NOS3 protein, human; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III