title: Attenuation of brain hyperbaric oxygen toxicity by fasting is not related to ketosis.
abstract: The effect of 24 h of fasting and changes in blood glucose and beta-hydroxybutyrate (BHB) level on latency to seizures in hyperbaric oxygen (HBO2) was studied. Conscious, unrestrained rats implanted with cortical electroencephalogram electrodes were exposed to 0.5 MPa (gauge pressure) O2 until seizures were observed. Fasting for 24 h significantly (P < 0.01) decreased blood glucose (from 8.6 +/- 0.9 in fed to 6.9 +/- 0.7 mM in the fasted group), increased blood BHB (0.07 +/- 0.02 mM to 0.38 +/- 0.10 mM, respectively), and prolonged the latency to seizures compared with normally fed animals (21.0 +/- 9.8 vs. 34.6 +/- 17.7 min, P < 0.05). Injection of the ketone precursor 1,3-butanediol (BD) to the fed animals increased blood BHB level to 0.72 +/- 0.32; however, seizure latency remained the same as in fed animals. Restoration of blood glucose in fasted animals to the same level as in the fed group did not reverse the protection achieved by fast; instead it increased the latency to seizures. The results indicate that the protection against HBO2 seizures by fasting in short starvation is not related to the increase in circulating ketone bodies or decrease in blood glucose.
authors.affiliation: Naval Medical Research Center, Bethesda, Maryland 20889-5607, USA.
authors.forename: M
authors.initials: M
authors.lastname: Chavko
authors.forename: J C
authors.initials: JC
authors.lastname: Braisted
authors.forename: A L
authors.initials: AL
authors.lastname: Harabin
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D002072:Butylene Glycols / Q000008:administration & dosage / Q000378:metabolism; D004569:Electroencephalography; D005215:Fasting / Q000502:physiology*; D006931:Hyperbaric Oxygenation / Q000009:adverse effects*; D007003:Hypoglycemia / Q000209:etiology* / Q000503:physiopathology; D007657:Ketone Bodies / Q000378:metabolism*; D007662:Ketosis / Q000150:complications*; D008297:Male; D010313:Partial Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D013047:Specific Pathogen-Free Organisms
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D002072:Butylene Glycols; D007657:Ketone Bodies; C028491:1,3-butylene glycol; D020155:3-Hydroxybutyric Acid