Melatonin prevents hyperglycemia in a model of sleep apnea.
OBJECTIVE
Obstructive sleep apnea is a common disorder associated with aging and obesity. Apneas cause repeated arousals, intermittent hypoxia, and oxidative stress. Changes in glucolipidic profile occur in apnea patients, independently of obesity. Animal models of sleep apnea induce hyperglycemia. This study aims to evaluate the effect of the antioxidants melatonin and N-acetylcysteine on glucose, triglyceride, and cholesterol levels in animals exposed to intermittent hypoxia.


METHODS
Two groups of Balb/c mice were exposed to intermittent hypoxia (n = 36) or sham intermittent hypoxia (n = 36) for 35 days. The intermittent hypoxia group underwent a total of 480 cycles of 30 seconds reducing the inspired oxygen fraction from 21% to 7 ± 1% followed by 30 seconds of normoxia, during 8 hours daily. Melatonin or N-acetylcysteine were injected intraperitonially daily from day 21 on.


RESULTS
At day 35, glucose levels were significantly higher in the intermittent hypoxia group than in the control group. The intermittent hypoxia groups receiving N-acetylcysteine and vehicle showed higher glucose levels than the group receiving melatonin. The lipid profile was not affected by intermittent hypoxia or antioxidant administration.


CONCLUSIONS
The present results suggest that melatonin prevents the well-recognized increase in glucose levels that usually follows exposure to intermittent hypoxia. Further exploration of the role of melatonin in sleep apnea is warranted.
Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Renata Schenkel Rivera
RS
Kaminski
Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Denis
D
Martinez
UFRGS, Porto Alegre, RS, Brazil.
Micheli
M
Fagundes
UFRGS, Porto Alegre, RS, Brazil.
Emerson Ferreira
EF
Martins
Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Carolina Caruccio
CC
Montanari
Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Darlan Pase
DP
Rosa
Cardiology Division, Hospital de Clinicas de Porto Alegre, UFRGS, Porto Alegre, RS, Brazil.
Cintia Zappe
CZ
Fiori
Universidade Luterana do Brasil, Canoas, RS, Brazil.
Norma Possa
NP
Marroni
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight / Q000187:drug effects; D002784:Cholesterol / Q000097:blood; D004195:Disease Models, Animal; D016166:Free Radical Scavengers / Q000494:pharmacology; D006943:Hyperglycemia / Q000188:drug therapy*; D000860:Hypoxia / Q000097:blood / Q000188:drug therapy*; D008550:Melatonin / Q000494:pharmacology*; D008807:Mice, Inbred BALB C; D020181:Sleep Apnea, Obstructive / Q000188:drug therapy*; D013997:Time Factors; D014280:Triglycerides / Q000097:blood
D000975:Antioxidants; D001786:Blood Glucose; D016166:Free Radical Scavengers; D014280:Triglycerides; D002784:Cholesterol; D008550:Melatonin; D000111:Acetylcysteine