Alteration of blood glucose levels in the rat following exposure to hyperbaric oxygen

Abstract

Findings regarding blood glucose level (BGL) on exposure to hyperbaric oxygen (HBO) are contradictory. We investigated the influence of HBO on BGL, and of BGL on latency to central nervous system oxygen toxicity (CNS-OT). The study was conducted on five groups of rats: Group 1, exposure to oxygen at 2.5 atmospheres absolute (ATA), 90 min/day for 7 days; Group 2, exposure to oxygen once a week from 2 to 6 ATA in increments of 1 ATA/wk, for a period of time calculated as 60% of the latency to CNS-OT (no convulsions); Group 3, exposure to 6 ATA breathing a gas mixture with a pO2 of 0.21; Group 4, received 10 U/kg insulin to induce hypoglycemia before exposure to HBO; Group 5, received 33% glucose to induce hyperglycemia before exposure to HBO. Blood samples were drawn before and after exposures for measurement of BGL. No change was observed in BGL after exposure to oxygen at 2.5 ATA, 90 min/day for 7 days. BGL was significantly elevated after exposure to oxygen at 6 ATA until the appearance of convulsions, and following exposure to 4, 5, and 6 ATA without convulsions (P< 0.01). No change was observed in BGL after exposure to 6 ATA breathing a gas mixture with a pO2 of 0.21. Hypoglycemia shortened latency to CNS oxygen toxicity, whereas hyperglycemia had no effect. Our results demonstrate an influence of HBO exposure on elevation of BGL, starting at 4 ATA. This implies that BGL may serve as a marker for the generation of CNS-OT.

Ameliorating effect of ketogenic diet on acute status epilepticus: Insights into biochemical and histological changes in rat hippocampus

“…At day 21, ketosis was confirmed by measuring β‐hydroxybutyrate and glucose levels in two drops of blood taken from the tail vein of KD fed rats using FreeStyle optium neo blood ketone and glucose monitoring system obtained from Abbott Diabetes Care Inc. (USA). In our study, all rats in KD and KD + SE groups showed hypoglycemia (42.6 ± 4.01 & 44.3 ± 3.9 mg/dl, respectively) and ketosis (blood β‐hydroxybutyrate = 4.61 ± 0.39 & 5.61 ± 0.47 mmol/L, respectively) which were in line with Eynan et al (2015) and Linard et al (2010) respectively. KD was noted to cause a significant weight loss when consumed by normal or epileptic rats.…”

Hyperbaric oxygen therapy reduces renal lactate production

“…Another study reported unaltered blood glucose levels when exposing healthy rats to HBO up to 4 ATA (Eynan et al. ). In that study, pressure above 4 ATA was reported to increase blood glucose levels; therefore, it was suggested that HBO therapy induces glycogen depletion and insulin resistance mediated by the sympathetic nervous system.…”

“…; Eynan et al. ) used a very short time interval between HBO therapy and the subsequent examination of its effects. The difference between the acute and delayed examinations suggests a potentially delayed conditioning effect of the HBO therapy, which might differentiate the acute and long‐term HBO effects.…”

Comparative Response of Brain to Chronic Hypoxia and Hyperoxia

“…This notation comprises the fraction of O 2 in inspired air in the case of in vivo studies, the O 2 content in the atmosphere where cells are cultured in the case of in vitro studies, etc. F I O 2 values <0.21 and >0.21 refer to hypoxia and hyperoxia, respectively] under hyperbaric conditions (2.5 atm) reduces the blood glucose level in rats [ 15 ], only a few studies have examined the effects of hyperoxia on bioenergetics metabolism. The prevalent context of such studies is a post-stroke situation where hyperoxia is used as part the therapeutic interventions aimed at salvaging neurons at risk.…”