Is nitric oxide a mediator of the effects of low-intensity electrical stimulation on bone in ovariectomized rats?
Low-intensity electrical stimulation (LIES) may counteract the effects of ovariectomy (OVX) on nitric oxide synthase (NOS) expression, osteocyte viability, bone structure, and microarchitecture in rats (Lirani-Galvão et al., Calcif Tissue Int 84:502-509, 2009). The aim of the present study was to investigate if these effects of LIES could be mediated by NO. We analyzed the effects of NO blockage (by L-NAME) in the response to LIES on osteocyte viability, bone structure, and microarchitecture in OVX rats. Sixty rats (200-220 g) were divided into six groups: sham, sham-L-NAME (6 mg/kg/day), OVX, OVX-L-NAME, OVX-LIES, and OVX-LIES-L-NAME. After 12 weeks, rats were killed and tibiae collected for histomorphometric analysis and immunohistochemical detection of endothelial NOS (eNOS), inducible NOS (iNOS), and osteocyte apoptosis (caspase-3 and TUNEL). In the presence of L-NAME, LIES did not counteract the OVX-induced effects on bone volume and trabecular number (as on OVX-LIES). L-NAME blocked the stimulatory effects of LIES on iNOS and eNOS expression of OVX rats. Both L-NAME and LIES decreased osteocyte apoptosis. Our results showed that in OVX rats L-NAME partially blocks the effects of LIES on bone structure, turnover, and expression of iNOS and eNOS, suggesting that NO may be a mediator of some positive effects of LIES on bone.
Lirani-Galvão
A P R
AP
INSERM Unité 831, Faculté de Médecine R. T. H. Laënnec, rue G. Paradin, 69372, Lyon Cedex 08, France. analirani@hotmail.com
Lazaretti-Castro
M
M
Portero-Muzy
N
N
Bergamaschi
C T
CT
Silva
O L
OL
Carvalho
A B
AB
Delmas
P D
PD
Chavassieux
P
P
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001842:Bone and Bones / Q000378:metabolism; D053148:Caspase 3; D005260:Female; D020287:In Situ Nick-End Labeling; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010011:Osteocytes / Q000378:metabolism / Q000502:physiology; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar
D009569:Nitric Oxide; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D053148:Caspase 3; D019331:NG-Nitroarginine Methyl Ester