Got pure blood in fetal rats?

Exposure to nicotine during pregnancy and altered learning and memory in the rat offspring

INTRODUCTION

Prenatal exposure to nicotine can cause many fetal developmental problems. This study determined the influence of nicotine during pregnancy on the development of cognitive behavior in the offspring.

METHODS

Nicotine was administered to pregnant rats through implanted osmotic mini-pumps at 6mg/kg/day and flow rate of 60 μl/day for whole pregnancy from gestational day 4. Fetal and offspring body and brain weight was measured. Learning and memory were tested in adult offspring with Morris water maze; Learning and memory-related receptors were measured.

RESULTS

The results showed that exposure to prenatal nicotine (PN) not only caused fetal growth restriction, but also had long-term effects on learning and memory in the offspring. The PN offspring exhibited longer escape latency regardless of sex. The number of passing the platform was significantly less in the PN offspring than that of the control. The expression of messenger RNA (mRNA) and protein of N-methyl-D-aspartic acid receptor (NMDAR) in the hippocampus was significantly increased, whereas alpha7 nicotinic acetylcholine receptor (α7 nAChR) protein was decreased with unchanged α7 nAChR mRNA in the PN offspring.

CONCLUSION

The data provided novel information on the PN-affected development in learning and memory in the offspring, suggesting that α7 nAChR and NMDAR1 in the hippocampus might be the targets for actions of PN in association with memory impairment.

Prenatal water deprivation alters brain angiotensin system and dipsogenic changes in the offspring

OBJECTIVE

Central renin-angiotensin system (RAS) plays an important role in regulating body fluid balance. The present study determined the effect of maternal dehydration on brain expression levels of angiotensinogen, angiotensin II receptor subtypes, and dipsogenic responses in offspring.

METHODS

Pregnant rats were deprived of water during late gestation. Expressions of brain angiotensinogen, angiotensin II receptors, and dipsogenic responses were determined.

RESULTS

Maternal water deprivation significantly decreased fetal body and brain weight, and body and tail length. Fetal plasma sodium, osmolality, and hematocrit were increased. Both AT(1)R and AT(2)R protein abundance was significantly increased in the fetal brain, associating with increased mRNA levels of AT(1a)R and AT(2)R. Additionally, angiotensinogen mRNA was increased. In adult offspring, prenatal dehydration resulted in significant increases in AT(1)R protein and AT(1a)R mRNA, as well as angiotensinogen mRNA in the forebrain in both males and females. In contrast, AT(2)R mRNA and protein were increased only in males. Prenatal dehydration resulted in a significant increase in intracerebroventricular angiotensin II-induced water intake in male, but not female, offspring.

CONCLUSION

The results provided new information that antenatal water deprivation induces a reprogramming of brain RAS and Ang II receptor expression patterns and alters the central Ang II-mediated dipsogenic response in offspring in a sex-dependent manner.

Prenatal dehydration alters renin-angiotensin system associated with angiotensin-increased blood pressure in young offspring

The renin-angiotensin system (RAS) has an important role in cardiovascular homeostasis. This study determined the influence of water deprivation during pregnancy on the development of the RAS in rats, and examined blood pressure (BP) in the adolescent offspring. Pregnant rats were water deprived for 3 days at late gestation, and we examined fetal cardiac ultrastructure, as well as heart angiotensin (Ang) II receptor protein and mRNA, liver angiotensinogen and plasma Ang II concentrations. We also tested cardiovascular responses to i.v. Ang II in the young offspring. In utero exposure to maternal water deprivation significantly decreased fetal body and heart weight, and increased fetal plasma sodium and osmolality. Fetal liver angiotensinogen mRNA, plasma Ang I and Ang II concentrations were also increased. Although fetal AT(1a) and AT(1b) receptor mRNA and AT(1) protein were not changed, AT(2) receptor mRNA and protein levels in the heart were significantly increased following maternal dehydration. Prenatal exposure to maternal water deprivation had no effect on baseline BP; however, it significantly increased BP in response to i.v. Ang II infusion, and decreased baroreflex sensitivity in the offspring. In addition, the heart AT(2) receptor mRNA and protein were higher in the offspring exposed to prenatal dehydration. The results of this study demonstrate that prenatal dehydration affected the RAS development associated with an Ang II-increased BP in fetal origin.

The effect of prenatal nicotine on expression of nicotine receptor subunits in the fetal brain

Previous studies have suggested that prenatal exposure to nicotine is associated with abnormal development in fetuses, including fetal brain damage. The present study determined the effect of maternal administration of nicotine during different gestational periods on brain nicotine receptor subunits in fetal rats. Subcutaneous injections of nicotine in maternal rats from the early and middle gestation decreased fetal blood PO2, increased fetal blood PCO2 and hemoglobin, and decreased fetal brain weight. The nicotinic acetylcholine receptor (nAChRs) mRNA abundance in the fetal brain was significantly changed by prenatal treatment with nicotine during pregnancy. Fetal alpha2, alpha4, alpha7, and beta2 units were significantly increased in the brain by prenatal exposure to nicotine in rat fetuses. However, the expression of mRNA of fetal brain alpha3, alpha5, beta3, and beta4 units were not changed. The results showed that prenatal nicotine can change the development of both alpha and beta subunits of nAChRs in the fetal brain at gene level in association with restriction of fetal brain growth and in utero hypoxia.

The effect of prenatal nicotine on mRNA of central cholinergic markers and hematological parameters in rat fetuses

A number of studies have demonstrated the influence of nicotine on fetal development. This study determined the expression of choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), and high-affinity choline transporter (CHT1) in the forebrain and hindbrain following chronic prenatal nicotine exposure in the rat fetus (maternal rats were subcutaneously injected with nicotine at different gestation periods). We also measured the effect of chronic nicotine exposure on fetal blood pO(2), pCO(2), pH, Na(+) and K(+) concentrations, as well as lactic acid levels. Maternal nicotine exposure during pregnancy was associated with a decrease in fetal pO(2) coupled with a significant increase in pCO(2) and lactic acid as well as restricted fetal growth. Additionally, maternal nicotine administration also reduced ChAT, VAChT, and CHT1 mRNA levels in the fetal brain. Nicotine-induced fetal hypoxic responses and reduced cholinergic marker expression in the brain were more severe when nicotine was started in early gestation. Our results provide new information about the effects of repeated exposure to nicotine in utero on the expression of central ChAT, VAChT, and CHT1 in the rat fetus. These results indicate that repeated hypoxic episodes or/and a direct effect of nicotine on the central cholinergic system during pregnancy may contribute to brain developmental problems in fetal origin.