Enhanced gene expression of endothelial nitric oxide synthase in brown adipose tissue during cold exposure.
It has been shown that norepinephrine (NE) can mediate vasodilatation by stimulating the production of nitric oxide (NO) in brown adipose tissue (BAT), resulting in an increase in BAT blood flow. We speculated that constitutive NO synthase (NOS) is involved in this NO production. However, it is not known whether constitutive NOS is expressed in BAT. To answer this question, we assessed the expression of two types of constitutive NOS, endothelial (eNOS) and neuronal NOS (nNOS), in BAT of rats. eNOS was abundantly expressed in both BAT and isolated brown adipocytes, whereas nNOS was not. Cold exposure, which is known to stimulate NE release from sympathetic nerve terminals in BAT, led to a significant increase in eNOS mRNA in this tissue. In contrast, very low levels of inducible NOS (iNOS) mRNA were expressed, and cold stimulation failed to increase iNOS mRNA levels in BAT. These results suggest that eNOS is the primary isoform that is responsible for NO production in BAT and that its expression may be under sympathetic control.
Kikuchi-Utsumi
Kazue
K
Department of Physiology 1, Asahikawa Medical University School of Medicine, Asahikawa 078 - 8510, Japan. utsumi@asahikawa-med.ac.jp
Gao
Bihu
B
Ohinata
Hiroshi
H
Hashimoto
Masaaki
M
Yamamoto
Noriyuki
N
Kuroshima
Akihiro
A
D000222:Adaptation, Physiological / Q000502:physiology; D002001:Adipose Tissue, Brown / Q000502:physiology*; D000818:Animals; D003080:Cold Temperature; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar
D012333:RNA, Messenger; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat