Effects of a single inhalative exposure to formaldehyde on the open field behavior of mice

Learning and memory impairment of mice caused by gaseous formaldehyde

In order to study the e of formaldehyde exposure on learning and memory ability of mice. We used Kun Ming (KM) mice to demonstrate the neurotoxic effects of FA, and Balb/c mice to explore the neurobiological mechanism. The Morris water maze (MWM) test showed that the exposure of gaseous formaldehyde could cause spatial learning and memory impairment in mice. H & E staining showed that in the 3.0 mg/m³ formaldehyde exposed group, the arrangement of pyramidal cells in CA1 area of mouse hippocampus was loose and disordered, the cell morphology was swollen and deformed, and the apical dendrites were shortened or even disappeared. Biochemical indicators revealed high doses of FA exposure could cause oxidative damage in brain. Compared with the control group, there were significant differences in the levels of ROS, MDA, GSH and 8-OHDG in the 3.0 mg/m3 group (P < 0.01), also the monoamine neurotransmitters content and the content of TNF-α, IL-1β and Caspase-3 (P < 0.01). Furthermore, the concentrations of cAMP, cGMP, NO and the activity of NOS in the cerebral cortex, hippocampus and brain stem after high doses of FA exposure were significantly different from those in the control group, indicating that FA exposure could interfere with the transduction of NO/cGMP signaling pathway. The results showed that FA could induce cognitive deficits and this extended investigation found that the toxicity of FA to the mouse nervous system is related to the NO/cGMP and cAMP signaling pathways.

Ectoine alleviates behavioural, physiological and biochemical changes in Daphnia magna subjected to formaldehyde

Ectoine (ECT) is produced by halophilic microorganisms in response to various stressful factors. Its protective properties in bacteria and some populations of isolated cells are known; however, no data are available on its protective influence on aquatic invertebrates subjected to a common pollutant, formaldehyde (FA). The purpose of this study was to determine the effects of FA alone (at 20 and 60 mg/L) and in the combination with various concentrations of ECT (5, 10 and 25 mg/L) at various times of exposure on behavioural, physiological and biochemical parameters of Daphnia magna. Specifically, mortality, heart rate, thoracic limb movement, reduced glutathione (GSH)/oxidised glutathione (GSSG) ratio, catalase (CAT) activity and nitric oxide (NOx) levels were determined. The results showed that both concentrations of FA when administered alone induced significant alterations of the determined parameters. On the other hand, animals treated with the combinations of FA + ECT showed decreased mortalities, attenuated inhibition of heart rates and thoracic limb activities, less decreased GSH/GSSG ratios, lower stimulation of CAT activities and NOx levels when compared to the crustaceans subjected to FA alone. The most distinct attenuation of toxic effects was observed in the combinations in which the highest concentrations of ECT were used. The results suggest that oxidative stress induced by FA in daphnids is likely to be alleviated by the antioxidative action of ECT.

Effects of single episodes of severe stress on the behavior of male and female CBA/Lac and C57BL/6J mice

Experiments were performed to compare the behavior of male and female mice of the inbred strains CBA/Lac and C57BL/6J in the open field test after single episodes of severe stress imposed by forced swimming. Testing was performed 2 h (first test) and one day (second test) after stress. Control animals were intact males and females of these strains, and were also tested in the open field on two sequential days. Both male and female CBA/Lac mice showed increases in the latent period of excursions from the center of the field 2 h after stress. This change persisted to the second test in female CBA/Lac mice. In female C57BL/6J mice, there were changes in four of seven behavioral measures 2 h after stress, though at one day their behavior was as in control individuals. Stress had virtually no effect in males of this strain, only increasing the number of grooming acts in the first test. In addition, detailed analysis of the effects of repeat testing in control and stressed individuals of these mouse strains also revealed interstrain and gender-related differences in the effects of stress. The possible existence of increased basal (trait) and situational (state) anxiety in female C57BL/6J and CBA/Lac mice respectively is discussed.