Does chronic formaldehyde exposure worsen hippocampal damage in rats with reduced blood flow to the brain?

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This study evaluated the effect of chronic formaldehyde (FA) exposure on the hippocampus in a rat model of chronic cerebral hypoperfusion—chronically reduced blood flow to the brain.

Seventy-two male Sprague-Dawley rats were randomly divided into four groups: (A) sham-operated bilateral common carotid artery occlusion (BCCAO) with room air inhalation; (B) BCCAO with room air inhalation; (C) sham-operated BCCAO with FA inhalation at a concentration of 10 mL vapor m−3, 1 hour per day for 90 days; and (D) BCCAO with FA inhalation.

After 30 days of FA exposure, rats in groups C and D showed decreased mobility, reddened conjunctivae, and overreaction. At 90 days after FA exposure, malondialdehyde (MDA) levels were significantly increased in group D.

Compared with group B or C, group D showed increased Bax protein expression and significantly decreased Bcl-2 and NR2B protein expression. Neuronal nuclear antigen (NeuN)-positive cells were significantly decreased in group D. Neuronal loss, oxidative stress, and protein-expression changes were more prominent at 90 days after FA exposure, especially in group D.

The researchers proposed that oxidative stress-induced neuronal damage in the hippocampus may be a possible mechanism of neurotoxicity from chronic FA exposure. They concluded that chronic FA exposure caused more neuronal damage in the chronic cerebral hypoperfusion rat model.