title: Effect of Isoflurane Anesthesia on Circadian Metabolism and Physiology in Rats.
abstract: Isoflurane anesthesia alters the blood levels of several neuroendocrine hormones associated with normal metabolism and physiology and increases stress, but the effect of brief CO2 anesthesia on these parameters is unknown. In this study, we examined the effects of isoflurane (4%) compared with brief CO2 (70% CO2, 30% air) anesthesia on circadian rhythms of plasma measures of physiology and metabolism. Adult male Sprague-Dawley rats (Crl:SD; n = 6 per group) were maintained on a 12:12-h light:dark (300 lx; lights on, 0600) photoperiod. After 1 wk of acclimation, a series of 6 low-volume blood draws were collected by cardiocentesis under anesthesia using isoflurane (10 min or less) compared with CO2 (1 min or less) at a single circadian time point every 4 d (0400, 0800, 1200, 1600, 2000, or 2400) over 3 wk to assess arterial blood glucose, lactic acid, and potassium and plasma melatonin, leptin, insulin, total fatty acids, and corticosterone concentrations. Results revealed that plasma levels (mean ± SEM) of melatonin were low (11 ± 1 pg/mL) during the light phase in both groups but were significantly lower during the dark phase in the isoflurane group (48 ± 6 pg/mL) compared with the CO2 group (162 ± 18 pg/mL). In addition, prominent circadian rhythms of arterial plasma levels of corticosterone, glucose, total fatty acids, lactic acid, and potassium were altered in the isoflurane group compared with the CO2 group. These findings demonstrate that the normal circadian rhythms of endocrine physiology and metabolism observed during brief CO2 anesthesia in rats are markedly disrupted by isoflurane anesthesia.
authors.affiliation: Departments of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana;, Email: mwren@tulane.edu.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Wren-Dail
authors.affiliation: Departments of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Dauchy
authors.affiliation: Departments of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: David E
authors.initials: DE
authors.lastname: Blask
authors.affiliation: Departments of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Hill
authors.affiliation: Section of Laboratory Animal Medicine, IIT Research Institute, Chicago, Illinois.
authors.forename: Tara G
authors.initials: TG
authors.lastname: Ooms
authors.affiliation: Departments of Comparative Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Lynell M
authors.initials: LM
authors.lastname: Dupepe
authors.affiliation: Division of Veterinary Medicine, Tulane National Primate Research Center, Covington, Louisiana.
authors.forename: Rudolf P
authors.initials: RP
authors.lastname: Bohm
mesh_terms: D000758:Anesthesia / Q000379:methods / Q000662:veterinary; D018685:Anesthetics, Inhalation / Q000009:adverse effects / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects; D057906:Circadian Clocks / Q000187:drug effects*; D003345:Corticosterone / Q000097:blood; D005227:Fatty Acids / Q000097:blood; D007328:Insulin / Q000097:blood; D007530:Isoflurane / Q000009:adverse effects / Q000494:pharmacology*; D019344:Lactic Acid / Q000097:blood; D020738:Leptin / Q000097:blood; D008297:Male; D008550:Melatonin / Q000097:blood; D009490:Neurosecretory Systems / Q000187:drug effects; D017440:Photoperiod; D011188:Potassium / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018685:Anesthetics, Inhalation; D001786:Blood Glucose; D005227:Fatty Acids; D007328:Insulin; D020738:Leptin; D019344:Lactic Acid; D007530:Isoflurane; D008550:Melatonin; D011188:Potassium; D003345:Corticosterone