Behavioural teratogenic effects of prenatal nicotine exposure in mice offspring
Dept. of Anatomy, Faculty of Basic Medical Sciences, Univers
Dept. of Anatomy, Faculty of Basic Medical Sciences, University of Calabar, Calabar - Nigeria
Last modified: June 12, 2006
Introduction: Maternal nicotine use impacts directly and indirectly on the developing foetus, Newborn, infant and child. Earlier studies has shown that chronic nicotine treatments of pregnant rats throughout gestation produced subtle neurological changes, which manifested themselves as behavioural or electrophysiological alteration in the offspring. This study therefore was conducted to determine the behavioural teratogenic effects on the mouse offspring of dams injected intraperitoneally with subteratogenic doses of nicotine during neurogenesis, by using a behavioural test battery system.
Methods: The behavioural teratogenic effects of prenatal nicotine exposure on 5 parameters in male albino mice were assessed. Twenty virgin female albino mice weighing between 30g to 38g were used for this study. The animals were divided into 2 groups of 10 mice each (A and B). Each group was kept in a separate plastic cage. The mice were fed with commercial mice feed and tap water ad libitum throughout the experimental period. The females were caged overnight with sexually mature male mice of the same strain. The presence of sperm (tailed structures) in the vaginal smears obtained the following morning confirmed coitus and the sperm positive day was designated as day zero of pregnancy. Dams in group A were injected intraperitonially with 0.5 mg/kg/day of nicotine dispersed in distilled water on gestation days 9 – 12. Dams in group B served as control received only the vehicle on corresponding days. The dams were allowed to deliver spontaneously. At 4 days after birth, litters were culled randomly to group of 10 foetuses; at 21 days, they were weaned, separated by sex and housed 6 per cage. Before weaning the offspring were examined to test their surface righting reflex (5 days of age), cliff avoidance response (6 days) and negative geotaxis response (7 days). After weaning, the males were examined using the open field maze (7 weeks), and the shuttle- box-avoidance learning test.
Results: The results showed that the avoidance learning of the mice in the treatment group A was significantly poorer than that of the control group B. There were also significant differences between group A and B offspring for the surface righting and negative geotaxis responses.
Discussion: The findings suggest that prenatal exposure to nicotine may retard early response development; impair learning ability, development of motor coordination and developmental pattern of behaviour of offspring of albino mice exposed to nicotine during pregnancy.
Final Summary: Prenatal exposed of mice to Nicotine at a dose tower than that which cause gross malformation or growth retardation altered neurobehavioral performance in the offspring in their pre-weaning and post-weaning periods.
Keywords: Behavioural teratology; Nicotine; Albino mice