Synergistic effects of prenatal nicotine exposure and post-weaning high-fat diet on hypercholesterolaemia in rat offspring of different sexes

Prenatal smoke (Nicotine) exposure and offspring's metabolic disease susceptibility in adulthood

Exposure to smoking (nicotine) during pregnancy not only directly affects fetal development, but also increases susceptibility to metabolic diseases in adulthood, but the mechanism of action remains unclear. Here, we review epidemiological and laboratory studies linking these relationships. In addition to the direct effect of nicotine on the fetus, intrauterine neuroendocrine-metabolic programming mediated by maternal glucocorticoid overexposure also plays an important role, involving glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis, hypothalamic-pituitary-adrenal (HPA) axis, renin-angiotensin system (RAS) and other endocrine systems. Epigenetics is involved in intrauterine neuroendocrine-metabolic programming, metabolic disease susceptibility and multigenerational inheritance. There are "two programming" and "two strikes" mechanisms for the occurrence of fetal-originated metabolic diseases in adulthood. These innovative research summaries and academic viewpoints provide experimental and theoretical basis for systematically elucidating the occurrence and development of fetal-originated metabolic diseases.

Loss of the Protective Effect of Estrogen Contributes to Maternal Gestational Hypertension-Induced Hypertensive Response Sensitization Elicited by Postweaning High-Fat Diet in Female Offspring

Background

A recent study conducted in male offspring demonstrated that maternal gestational hypertension (MHT) induces hypertensive response sensitization (HTRS) elicited by postweaning high‐fat diet (HFD). In this study, we investigated the sensitizing effect of MHT on postweaning HFD‐induced hypertensive response in female rat offspring and assessed the protective role of estrogen in HTRS.

Methods and Results

The results showed that MHT also induced a sensitized HFD‐elicited hypertensive response in intact female offspring. However, compared with male offspring, this MHT‐induced HTRS was sex specific in that intact female offspring exhibited an attenuated increase in blood pressure. Ovariectomy significantly enhanced the HFD‐induced increase in blood pressure and the pressor response to centrally administered angiotensin II or tumor necrosis factor‐α in offspring of normotensive dams, which was accompanied by elevated centrally driven sympathetic activity, upregulated mRNA expression of prohypertensive components, and downregulated expression of antihypertensive components in the hypothalamic paraventricular nucleus. However, when compared with HFD‐fed ovariectomized offspring of normotensive dams, the MHT‐induced HTRS and pressor responses to centrally administered angiotensin II or tumor necrosis factor‐α in HFD‐fed intact offspring of MHT dams were not potentiated by ovariectomy, but the blood pressure and elicited pressor responses as well as central sympathetic tone remained higher.

Conclusions

The results indicate that in adult female offspring MHT induced HTRS elicited by HFD. Estrogen normally plays a protective role in antagonizing HFD prohypertensive effects, and MHT compromises this normal protective action of estrogen by augmenting brain reactivity and centrally driven sympathetic activity.

Tobacco smoking during breastfeeding increases the risk of developing metabolic syndrome in adulthood: Lessons from experimental models

Metabolic syndrome (MetS) is characterized by increased abdominal fat, dyslipidemia, diabetes mellitus and hypertension. A high MetS prevalence is strongly associated with obesity. Obesity is a public health problem in which several complex factors have been implicated, including environmental pollutants. For instance, maternal smoking seems to play a role in obesogenesis in childhood. Given the association between endocrine disruptors, obesity and metabolic programming, over the past 10 years, our research group has contributed to studies based on the hypothesis that early exposure to nicotine/tobacco causes offspring to become MetS-prone. The mechanism by which tobacco smoking during breastfeeding induces metabolic dysfunctions is not completely understood; however, increased metabolic programming has been shown in studies that focus on this topic. Here, we reviewed the literature mainly based in light of our latest data from experimental models. Nicotine or tobacco exposure during breastfeeding induces several endocrine dysfunctions in a sex- and tissue-specific manner. This review provides an updated summary regarding the hypothesis that early exposure to nicotine/tobacco causes offspring to become MetS-prone. An understanding of this issue can provide support to prevent long-term disorders, mainly related to the risk of obesity and its comorbidities, in future generations.

Paternal cadmium exposure increases the susceptibility to diet-induced testicular injury and spermatogenic disorders in mouse offspring

The impairments of gestational cadmium (Cd) exposure on testicular development and male fertility in offspring have been reported. Here, we investigated the effect of paternal low-concentration cadmium exposure on testicular development and spermatogenesis in offspring. Five-week-old male mice were exposed to cadmium chloride (100 mg/L) in drinking water for 20 weeks. Results presented that Cd did not affect the testicular histology and sperm count in mice. After mating with untreated females, pregnant mice and pups were then evaluated. No significant difference in the rate for successful pregnancy and the body weight of pups was observed in Cd-exposed mice compared to the controls. Male offspring were given with a chow and high-fat diet from postnatal day (PND) 35 to PND70. Our data indicated that high-fat diet obviously decreased No. of sperm in epididymides of adult offspring due to paternal Cd exposure. Testicular histology revealed that the percentage of seminiferous tubules in stages IX-XII and the atypical residual bodies positive tubules in CdH (paternal cadmium exposure and pubertal high-fat diet) group were higher than these in CdC (paternal cadmium exposure and pubertal chow diet) group. Further analysis demonstrated that high-fat diet markedly accelerated testicular apoptosis, as determined by TUNEL assay and immunostaining for cleaved caspase-3, in male offspring due to paternal Cd exposure. Collectively, high-fat diet exacerbates the damage of testicular development and spermatogenesis in offspring due to paternal cadmium exposure.

Comparison of Protective Effects of Electroacupuncture at ST 36 and LU 5 on Pulmonary and Hypothalamic Pituitary Adrenal Axis Changes in Perinatal Nicotine-Exposed Rats

BACKGROUND

Maternal smoking and/or exposure to environmental tobacco smoke continue to be significant factors in fetal and childhood morbidity and are a serious public health issue worldwide. Nicotine passes through the placenta easily with minimal biotransformation, entering fetal circulation, where it results in many harmful effects on the developing offspring, especially on the developing respiratory system.

OBJECTIVES

Recently, in a rat model, electroacupuncture (EA) at maternal acupoints ST 36 has been shown to block perinatal nicotine-induced pulmonary damage; however, the underlying mechanism and the specificity of ST 36 acupoints for this effect are unknown. Here, we tested the hypothesis that compared with EA at ST 36, EA at LU 5 acupoints, which are on lung-specific meridian, will be equally or more effective in preventing perinatal nicotine-induced pulmonary changes.

METHODS

Twenty-four pregnant rat dams were randomly divided into 4 groups: saline ("S"), nicotine ("N"), nicotine + ST 36 (N + ST 36), and nicotine + LU 5 (N + LU 5) groups. Nicotine (1 mg/kg, subcutaneously) and EA (at ST 36 or LU 5 acupoints, bilaterally) were administered from embryonic day 6 to postnatal day 21 once daily. The "S" group was injected saline. As needed, using ELISA, western analysis, q-RT-PCR, lung histopathology, maternal and offspring hypothalamic pituitary adrenal axes, offspring key lung developmental markers, and lung morphometry were determined.

RESULTS

With nicotine exposure, alveolar count decreased, but mean linear intercept and septal thickness increased. It also led to a decrease in pulmonary function and PPARγ and an increase of β-catenin and glucocorticoid receptor expression in lung tissue and corticosterone in the serum of offspring rats. Electroacupuncture at ST 36 normalized all of these changes, whereas EA at LU 5 had no obvious effect.

CONCLUSION

Electroacupuncture applied to ST 36 acupoints provided effective protection against perinatal nicotine-induced lung changes, whereas EA applied at LU 5 acupoints was ineffective, suggesting mechanistic specificity and HPA axis' involvement in mediating EA at ST 36 acupoints' effects in mitigating perinatal nicotine-induced pulmonary phenotype. This opens the possibility that other acupoints, besides ST 36, can have similar or even more robust beneficial effects on the developing lung against the harmful effect of perinatal nicotine exposure. The approach proposed by us is simple, cheap, quick, easy to administer, and is devoid of any significant side effects.