Postnatal expression and denervation induced up-regulation of aquaporin-5 protein in rat sweat gland.
The evolution of aquaporin-5 (AQP5) expression during postnatal development has not been defined in the sweat gland. Previous studies have suggested that AQP isoforms in several peripheral targets are regulated by a neural mechanism. We have examined, in rat sweat glands, the expression of AQP5 during postnatal development and the effects of denervation on AQP5 expression. Both AQP5 mRNA and protein begin to be expressed at postnatal day 10, before sweat-secretory responsiveness first appears; this expression coincides with the occurrence of vasoactive intestinal peptide (VIP) immunoreactivity. Early noradrenergic and later cholinergic interaction between sweat glands and their innervation are disrupted by neonatal chemical sympathectomy or postnatal severance of the sciatic nerve. Examination of such denervated developing rats has shown that secretory responsiveness fails to arise later in the adults, and AQP5 immunostaining increases in the denervated glands, whereas gland morphogenesis and the occurrence of AQP5 expression proceed normally. Immunobloting has revealed an increase of AQP5 abundance after the denervated mature glands lose their secretory ability. These findings suggest that AQP5 protein is necessary for sweat secretion, and that the expression of AQP5 in rat sweat glands is independent of sympathetic innervation. Our data also indicate that factor(s) regulating the normal morphological development of sweat gland might be responsible for controlling AQP5 expression.
Ma
Lei
L
Department of Neurology, Xijing Hospital, Fourth Military Medical University, 17 Changle West Road, Xi'an, 710032, People's Republic of China.
Huang
Yuan-Gui
YG
He
Hua
H
Deng
Yan-Chun
YC
Zhang
Hai-Feng
HF
Che
Hong-Lei
HL
Tian
Ji-Yu
JY
Zhao
Gang
G
D000818:Animals; D000831:Animals, Newborn; D051402:Aquaporin 5 / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000378:metabolism / Q000473:pathology; D013545:Sweat Glands / Q000254:growth & development / Q000294:innervation* / Q000378:metabolism* / Q000473:pathology; D013563:Sympathectomy, Chemical
D051402:Aquaporin 5; D012333:RNA, Messenger