Effect of Chronic Nicotine Exposure on Maternal Renal Adaptations in Pregnant Rats: The Possible Role of Nitric Oxide

Abstract Background: Nicotine exposure during pregnancy contin-ues to be a widespread public health problem, impacting both fetal and postnatal health. Although the deleterious effects of nicotine on fetal development and the newborn have been extensively investigated, few studies have focused on its negative effects on the maternal adaptations to pregnancy especially relevant on renal functions. Aim of Study: To study the effects of chronic nicotine exposure on the maternal renal adaptations during pregnancy and the possible underlying mechanisms. Material and Methods: Thirty six adult virgin female albino rats, divided into two main groups, each subdivided into three subgroups; all received treatment for four weeks. Group I (virgin): Subdivided into; saline treated: Received daily subcutaneous saline injections, nicotine treated: Received daily nicotine bitartrate (1mg/kg) subcutaneous injections, combined with transdermal nicotine patches (5.2mg nico-tine/day) application, and nicotine and L-arginine treated: Received the same nicotine therapy plus 0.25% L-arginine added to drinking. Group II (pregnant): Subdivided into; saline treated: Received daily subcutaneous injections of saline (2 weeks prior to mating and 1 st two weeks of gestation), nicotine treated: Received daily subcutaneous injections of nicotine bitartrate (1mg/kg), with transdermal nicotine patches, and nicotine and L-arginine treated): Received same nicotine therapy plus 0.25% L-arginine added to drinking water. Results: Physiological effects of the pregnancy on renal function were significantly improved by L-argini ne. Similarly, nicotine exposure to virgin group produced a significant increase in serum and urinary Na+, significant decrease in renal total protein, nitric oxide with renal oxidative stress compared to their control group. Co-administration of nicotine and L-arginine to virgin group produced a significant decrease in serum Na+, urinary albumin and renal MDA levels, and significant increase in the urinary Na+ level, renal total protein, NO and GSH levels compared to the virgin nicotine group. Similarly, nicotine administration to pregnant group produced a significant increase in serum and urinary Na+, FENa, urinary albumin levels, together with significant de-crease in GFR, UFR and renal total protein, NO and GSH levels. While co-administration of nicotine and L-arginine to pregnant group produced a significant decrease in serum Na+, FENa, urinary albumin levels, with significant increase in the GFR, UFR and renal total protein, NO and GSH levels. Conclusion: We concluded that chronic nicotine exposure potentially impaired maternal renal adaptation to pregnancy which was improved greatly by L-arginine, implicating NO as crucial player.