Normobaric hyperoxic stress in budgerigars: non-enzymic antioxidants

Area of Science:

• Biochemistry
• Physiology
• Avian Biology

Background:

• Non-enzymic antioxidants play a crucial role in mitigating oxidative stress.
• Understanding the impact of hyperoxia on these protective compounds is vital for avian health.

Purpose of the Study:

• To evaluate the effects of varying durations of oxygen exposure on pulmonary and blood non-enzymic antioxidant concentrations in budgerigars (Melopsittacus undulatus).

Main Methods:

• Budgerigars were exposed to acute (3h), repeated acute (3x3h), or chronic (72h) normobaric hyperoxia.
• Pulmonary and plasma concentrations of glutathione, uric acid, alpha- and gamma-tocopherol, and carotenoids were measured.

Main Results:

• Increased duration of oxygen exposure led to a higher ratio of oxidized to reduced glutathione.
• Significant reductions in uric acid, alpha- and gamma-tocopherol, and carotenoids were observed, especially after chronic exposure.
• Acute and repeated acute exposures showed altered glutathione and reduced alpha-tocopherol, indicating oxygen stress.

Conclusions:

• Chronic oxygen exposure depletes non-enzymic antioxidants in budgerigars, signifying exhaustion of defense mechanisms.
• The findings suggest a progression from oxygen stress to oxygen toxicity with extended hyperoxic conditions.
• These results highlight the vulnerability of avian antioxidant systems to hyperoxia.