Exposure to Hypobaric Hypoxia and Reoxygenation Induces Transient Anxiety-Like Behavior in Rat

Abstract

Chronic exposure to hypobaric hypoxia (HH) causes memory impairment and prolonged state of mental confusion. However, effect of high altitude exposure on mood state and its underlying mechanisms have been poorly studied. Present study was undertaken to investigate the mood state alteration following chronic exposure to HH. Male Sprague Dawley rats were divided into five groups and exposed to hypoxia for 3, 7, 14 and 21 days in an animal decompression chamber at an altitude of 25,000ft. Anxiety-and depression-like behaviors were assessed by using various mazes along with changes in serotonin and glutamate level. Our study revealed a decrease in exploratory, grooming and rearing behavior in open field test following initial exposure to HH for 7 days without affecting the locomotory behavior. Initial exposure to HH-decreased time spent in open arm of elevated plus maze indicating induction of anxiety-like behavior which normalized on prolonged hypoxic exposure for 21 days. Hypoxic exposure for 7 days induced anhedonia and increased despair behavior in rat while there was steady improvement in these behaviors when exposed for 21 days. Decrease in serotonin level was noted in hippocampus along with elevated corticosterone and glutamate level which gradually decreased on prolonged exposure to HH. These findings suggest that initial exposure to HH increases transient anxiety-like behavior in rats followed by gradual improvement in mood state on prolonged exposure. Further, the study also indicates the involvement of serotonergic system in mood state alteration at high altitude following chronic exposure and reoxygenation.

Mammalian-unique eIF4E2 maintains GSK3β proline kinase activity to resist senescence against hypoxia

“…For comparison, the effect of e2-I injection under normoxic conditions is negligible. Consistent with previous reports (Baitharu et al, 2013), hypoxia decrease the rearing counts of mice ( Fig EV6A). And the e2-I injection further decreased the rearing counts of mice to half, compared with scrambled peptide injection ( Fig EV6A).…”

Neuroprotective Role of L-NG-Nitroarginine Methyl Ester (L-NAME) against Chronic Hypobaric Hypoxia with Crowding Stress (CHC) Induced Depression-Like Behaviour

“…Prolonged exposure to hypobaric hypoxia is known to causes glutamate excitotoxicity, hippocampal neurodegeneration and cognitive dysfunction [ 22 , 27 ]. Recent study by Baitharu et al (2013) showed that hypobaric hypoxia induced alteration in mood state is transient in nature which get normalised with prolonged exposure [ 28 , 32 ].Further, prolonged hypoxic exposure causes decrease in food and water intake and consequent loss of body weight [ 33 , 34 ]. Exposure to restraint or immobilisation stress has been reported to induce psychosocial disorders in animal [ 35 ].…”

“…Induction of behavioural impairment along with structural as well as morphological alterations in various brain regions following exposure to chronic restraint/crowding stress is well documented. Though effect of hypobaric hypoxia on mood state alteration have been shown to be transient in nature [ 28 ], Combination of hypoxia and crowding stress could exert robust influence on mood state and precipitate anxiety and depression like behaviour following prolonged exposure. Keeping in mind the elevated nitric oxide level in the brain following hypoxic exposure, we attempted to explore the relationship between the nitric oxide and microglial activation following CHC stress exposure and further evaluated the therapeutic efficacy of L-NAME in ameliorating CHC induced depressive mood state.…”

Angelica gigas ameliorate depression-like symptoms in rats following chronic corticosterone injection

“…The rats was placed in one corner of the open filed and its activity during the subsequent 5 min was assessed. Locomotion (central zone crossing) and time spent in central and peripheral zone were observed [ 24 ].…”