Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC315
Prenatal exposure of pregnant rats to cigarette smoke and nicotine: effect on nitric oxide and fasting glycemia in treated and untreated neonates with vitamin C
O. O. Obembe1, V. O. Ukwenya3, A. O. Ige2, I. P. Oyeyipo1, A. A. Fasanmade2
1. Department of Physiology, Osun State University, Osogbo, Osun, Nigeria. 2. Department of Physiology, University of Ibadan, Ibadan, Oyo, Nigeria. 3. Department of Anatomy, Bowen University, Iwo, Osun, Nigeria.
Smoking remains a serious public health problem. It is still unclear whether the injurious effect of cigarette smoking in pregnancy are due to nicotine, and if so, what the effects are. The effects of cigarette smoking on nitric oxide (NO) pathways and nitric oxide synthase (NOS) isoenzymes are controversial and may vary according to the disease, model or location of the NOS. It has been documented that cigarette smoke inhibits NO production in active and passive smokers(1). This study investigated the effects on plasma nitric oxide and fasting glycemia in neonates from pregnant rats exposed to cigarette smoke and nicotine, postnatally treated and untreated with vitamins C. Fifteen female wistar rats weighing 250-300g were divided into three groups of five rats each .Group A rats were exposed to idling cigarette smoke in an ad hoc chamber for 30 min per day from day 0 to day 20 of gestation. Group B received 0.25 mg/kg body weight of nicotine intramuscularly while Group C served as the Control. After mating and gestation, litters from each group were randomly subdivided into two groups of ten neonates each. Group A: A1 and A2, Group B: B1, and B2, Group C: C1 and C2. Groups A1, B1 and C1 received 50 mg/kg B.W Vitamin C (50mg/kg body wt administered orally in a suspension) for 4 weeks after birth while Groups A2 and B2 and C2 did not receive any. Plasma nitric oxide and fasting glycemia were estimate in blood samples obtained from these animals (taken from heart puncture after 1.9% ether anaesthesia). Values are means ± S.E.M., compared by ANOVA. Results show that the neonates of animals exposed to cigarette smoke had a significantly higher nitric oxide concentration (21.00±1.29 μM) than those from not exposed ones (10.75±2.95 μM) and a significantly lower fasting glycemia (61.00 +2.03 mg/ dL) when compared with the control (75.50 + 3.73 mg/dl). In contrast, prenatal exposure to nicotine neither had a significant effect on nitric oxide concentration (12.50+2.10 μM) nor on fasting glycemia (74.17+3.48 mg/dl) when compared with the control (10.75+2.95 μM) and (75.50+3.73 mg/dl), respectively. While the effects of cigarette smoke shown here could not be attributed to the pharmacological activity of nicotine, they may be related to the formation of smoking induced oxidative free radicals, since the administration of an antioxidant as vitamin C reversed them.
Where applicable, experiments conform with Society ethical requirements