NEUROLOGICAL, HAEMATOLOGICAL AND HISTOLOGICAL EFFECTS OF CHRONIC EXPOSURE TO NITROUS OXIDE IN WISTAR ALBINO RATS

Objectives: The objectives of the study were to investigate the neurological, hematological, and histological effects of chronic exposure to nitrous oxide (N₂O) in male Wistar albino rats. Methodology: 12 adults, male, Wistar albino rats (150-200g) were divided into 2 groups of 6 animals each. Group 1 served as control. Group 2 received N₂O + O₂ (70:30 mixture) for 1 h every day for 60 days. Neurological assessments were done by forced swim test, tail suspension test, actophotometer, rotarod, and elevated plus maze models at baseline and every 2 weeks, after that for 60 days. Complete blood count, liver function tests, renal function tests, and serum methemoglobin levels were assessed at baseline and on day 60. Rats were sacrificed on the 60^th day, and histopathological examination of liver, kidney, spleen, and brain was done. Results: On comparing the results with the control group, the following changes were observed in nitrous oxide exposed rats. A: The duration of immobility was significantly reduced in forced swim test and tail suspension test, implying antidepressant-like activity. B: The activity of the animals was significantly reduced in actophotometer model, implying a reduction in the locomotor activity. C: No significant changes were observed in rotarod and elevated plus maze. D: Serum methemoglobin was significantly elevated. E: Histopathological examination showed hepatitis and interstitial nephritis. Conclusion: Chronic nitrous oxide exposure resulted in significant neurological changes, methemoglobinemia, hepatitis and interstitial nephritis. Hence healthcare workers such as dentists, doctors and paramedical staff need to take necessary precautions to prevent chronic occupational exposure of nitrous oxide.