Prenatal Effects of Nicotine on Obesity Risks: A Narrative Review

Behavioral and Pharmacokinetic Assessment of Nicotine e-Cigarette Inhalation in Female Rats

INTRODUCTION

Nicotine and tobacco use remain high both globally and in the United States, contributing to large health care expenditures. With a rise in e-cigarette use, it is important to have clinically relevant models of inhaled nicotine exposure.

AIMS AND METHODS

This study aims to extend prior preclinical nicotine inhalation animal data to females and provide both behavior and serum pharmacokinetics. We tested two inhalation doses of nicotine (24 mg/mL and 59 mg/ mL) and compared these to injected doses (0.4 mg/kg and 1 mg/kg). In addition, we assessed locomotor behavior after the same doses. Blood was collected at 10- and 120-minutes post-administration. We assessed nicotine and cotinine serum concentrations by LC-MS/MS.

RESULTS

Showed that while nicotine serum concentrations for the respective high and low-dose administrations were similar between both routes of administration, the route had differential effects on locomotor behavior. Inhaled nicotine showed a dose-dependent decrease in locomotor activity while injected doses showed the opposite trend.

CONCLUSIONS

Our results indicate that the route of administration is an important factor when establishing preclinical models of nicotine exposures. Given that the overall use of e-cigarettes in vulnerable populations is on the rise, our study provides important behavioral and pharmacokinetic information to advance our currently limited understanding of the effects of nicotine vapor exposure.

IMPLICATIONS

This study highlights behavioral differences between different routes of administration of similar doses of nicotine. Using a low and high dose of nicotine, we found that nicotine serum concentrations were similar between the different routes of administration. Our results indicate that different routes of administration have opposing effects on locomotor activity. These findings provide important implications for future behavioral models.

Vaporized nicotine in utero results in reduced birthweight, increased locomotion, and decreased voluntary exercise, dependent on sex and diet in offspring

Rationale Clinical research has shown that prenatal exposure to nicotine may result in increased obesity risk later in life. Preclinical research has corroborated this finding, but few studies have investigated inhaled nicotine or the interaction with diet on obesity risk. Objective The aim of this study was to investigate the effects of prenatal nicotine exposure on both direct and indirect obesity measures, with both sex and diet as factors. Methods Pregnant rats were exposed to either vehicle or nicotine vapor (24 mg/mL or 59 mg/mL) throughout the entire gestational period. Offspring from each treatment group were given either a normal diet or a high fat diet starting at postnatal day 22. Caloric intake, body weight, spontaneous locomotion, sleep/wake activity, and voluntary exercise were measured throughout adolescence. Pregnancy weight gain and pup birthweights were collected to further measure developmental effects of prenatal nicotine exposure. Results Both maternal weight gain during pregnancy and pup weight at birth were decreased with prenatal nicotine exposure. Early adolescent males showed increased spontaneous activity in the open field following prenatal nicotine exposure compared to vehicle counterparts, particularly those given high-fat diet. Additionally, high dose nicotine prenatal treated males ran significantly less distance on the running wheel in late adolescence compared to vehicle counterparts, in the normal diet group only. Conclusion The results presented here show decreased birthweight, hyperactivity, and decreased voluntary exercise in adolescence following prenatal nicotine exposure in dose, sex, and diet dependent manners, which could lead to increased obesity risk in adulthood.

Vaporized Δ9-THC in utero results in reduced birthweight, increased locomotion, and altered wake-cycle activity dependent on dose, sex, and diet in the offspring

AIMS

Preclinical studies have found that chronic ∆9-tetrahydrocannabinol (THC) treatment is directly associated with weight gain when introduced during adolescence and adulthood, but the effect of prenatal THC is unclear. Clinical studies have demonstrated prenatal exposure to THC is a prospective predictor of increased health risks associated with obesity. Our study aims to examine prenatal THC impact on obesity risks in males and females throughout adolescence using a clinically relevant inhalation model.

METHODS

Pregnant rats were exposed to one of the following from gestational day 2 through birth: 10 mg THC, 40 mg THC, or air. Daily 10-min inhalations were conducted in each animal from 0900 to 1200. Offspring from each treatment group were given either a high-fat diet (HFD) or a normal diet (ND). Food and bodyweights were collected daily, while circadian activity, locomotion, and exercise were measured periodically (PND 21-60). Pregnancy weight gain and birth weight were collected to determine early-life developmental effects.

RESULTS

Rats prenatally treated with low-dose THC (LDTHC) generally had lower dark-cycle activity compared with control counterparts, but this altered activity was not observed at the higher dose of THC (HDTHC). In terms of open-field activity, THC doses displayed a general increase in locomotion. In addition, the LDTHC male rats in the ND showed significantly greater exploratory behavior. Prenatal THC had dose-dependent effects on maternal weight gain and birth weight.

CONCLUSIONS

Overall, our findings indicate there are some activity-related and developmental effects of prenatal THC, which may be related to obesity risks later in life.

Prenatal oxidative stress and rapid infant weight gain

BACKGROUND AND OBJECTIVES

Infant weight patterns predict subsequent weight outcomes. Rapid infant weight gain, defined as a >0.67 increase in weight-for-age z-score (WAZ) between two time points in infancy, increases obesity risk. Higher oxidative stress, an imbalance between antioxidants and reactive oxygen species, has been associated with low birthweight and paradoxically also with later obesity. We hypothesized that prenatal oxidative stress may also be associated with rapid infant weight gain, an early weight pattern associated with future obesity.

METHODS

Within the NYU Children's Health and Environment Study prospective pregnancy cohort, we analyzed associations between prenatal lipid, protein, and DNA urinary oxidative stress biomarkers and infant weight data. Primary outcome was rapid infant weight gain (>0.67 increase in WAZ) between birth and later infancy at the 8 or 12 month visit. Secondary outcomes included: very rapid weight gain (>1.34 increase in WAZ), low (<2500 g) or high (≥4000 g) birthweight, and low (< -1 WAZ) or high (>1 WAZ) 12 month weight.

RESULTS

Pregnant participants consented to the postnatal study (n = 541); 425 participants had weight data both at birth and in later infancy. In an adjusted binary model, prenatal 8-iso-PGF2α, a lipid oxidative stress biomarker, was associated with rapid infant weight gain (aOR 1.44; 95% CI: 1.16, 1.78, p = 0.001). In a multinomial model using ≤0.67 change in WAZ as a reference group, 8-iso-PGF2α was associated with rapid infant weight gain (defined as >0.67 but ≤1.34 WAZ; aOR 1.57, 95% CI: 1.19, 2.05, p = 0.001) and very rapid infant weight gain (defined as >1.34 WAZ; aOR 1.33; 95% CI: 1.02, 1.72, p < 0.05) Secondary analyses detected associations between 8-iso-PGF2α and low birthweight outcomes.

CONCLUSIONS

We found an association between 8-iso-PGF2α, a lipid prenatal oxidative stress biomarker, and rapid infant weight gain, expanding our understanding of the developmental origins of obesity and cardiometabolic disease.