Brain Activity after Intermittent Hypoxic Brain Condition in Rats

Abstract

Hypoxic brain injury is accompanied by a decrease in various functions. It is also known that obstructive sleep apnea (OSA) can cause hypoxic brain injury. This study aimed to produce a model of an intermittent hypoxic brain condition in rats and determine the activity of the brain according to the duration of hypoxic exposure. Forty male Sprague–Dawley rats were divided into four groups: the control group (n = 10), the 2 h per day hypoxia exposure group (n = 10), the 4 h per day hypoxia exposure group (n = 10), and the 8 h per day hypoxia exposure group (n = 10). All rats were exposed to a hypoxic chamber containing 10% oxygen for five days. Positron emission tomography–computed tomography (PET-CT) brain images were acquired using a preclinical PET-CT scanner to evaluate the activity of brain metabolism. All the rats were subjected to normal conditions. After five days, PET-CT was performed to evaluate the recovery of brain metabolism. Western blot analysis and immunohistochemistry were performed with vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF). The mean SUV was elevated in the 2 h per day and 4 h per day groups, and all brain regions showed increased metabolism except the amygdala on the left side, the auditory cortex on the right side, the frontal association cortex on the right side, the parietal association cortex on the right side, and the somatosensory cortex on the right side immediately after hypoxic exposure. However, there was no difference between 5 days rest after hypoxic exposure and control group. Western blot analysis revealed the most significant immunoreactivity for VEGF in the 2, 4, and 8 h per day groups compared with the control group and quantification of VEGF immunohistochemistry showed more expression in 2 and 4 h per day groups compared with the control group. However, there was no significant difference in immunoreactivity for BDNF among the groups. The duration of exposure to hypoxia may affect the activity of the brain due to angiogenesis after intermittent hypoxic brain conditions in rats.

Circulating ADAMTS13 Levels Are Associated with an Increased Occurrence of Obstructive Sleep Apnea

“…Abu et al found that tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) (an efficient inhibitor of several members of the ADAM and ADAMTS) had powerful regulatory effects on anti-inflammatory and antiangiogenic activities [ 48 ]. Meanwhile, OSA is associated with angiogenesis [ 49 ]. Mun et al revealed that rats with an intermittent hypoxic brain condition stimulated vascular proliferation for spontaneous recovery through VEGF elevation [ 49 ].…”

“…Meanwhile, OSA is associated with angiogenesis [ 49 ]. Mun et al revealed that rats with an intermittent hypoxic brain condition stimulated vascular proliferation for spontaneous recovery through VEGF elevation [ 49 ].…”

Regulation of Genes Related to Cognition after tDCS in an Intermittent Hypoxic Brain Injury Rat Model

“…The humidity was measured and maintained at 40–50% by circulating gas through the freezer and using silica gel. The ambient temperature was kept at 22–24 °C [ 19 ].…”