Exposure to ethanol during pregnancy in mice: potential importance of dose for the development of tolerance in offspring

Similar 5F-APINACA Metabolism between CD-1 Mouse and Human Liver Microsomes Involves Different P450 Cytochromes

In 2019, synthetic cannabinoids accounted for more than one-third of new drugs of abuse worldwide; however, assessment of associated health risks is not ethical for controlled and often illegal substances, making CD-1 mouse exposure studies the gold standard. Interpretation of those findings then depends on the similarity of mouse and human metabolic pathways. Herein, we report the first comparative analysis of steady-state metabolism of N-(1-adamantyl)-1-(5-pentyl)-1H-indazole-3-carboxamide (5F-APINACA/5F-AKB48) in CD-1 mice and humans using hepatic microsomes. Regardless of species, 5F-APINACA metabolism involved highly efficient sequential adamantyl hydroxylation and oxidative defluorination pathways that competed equally. Secondary adamantyl hydroxylation was less efficient for mice. At low 5F-APINACA concentrations, initial rates were comparable between pathways, but at higher concentrations, adamantyl hydroxylations became less significant due to substrate inhibition likely involving an effector site. For humans, CYP3A4 dominated both metabolic pathways with minor contributions from CYP2C8, 2C19, and 2D6. For CD-1 mice, Cyp3a11 and Cyp2c37, Cyp2c50, and Cyp2c54 contributed equally to adamantyl hydroxylation, but Cyp3a11 was more efficient at oxidative defluorination than Cyp2c members. Taken together, the results of our in vitro steady-state study indicate a high conservation of 5F-APINACA metabolism between CD-1 mice and humans, but deviations can occur due to differences in P450s responsible for the associated reactions.

Unraveling the molecular mechanisms involved in alcohol intake and withdrawal in adolescent mice exposed to alcohol during early life stages

Alcohol interferes with foetal development and prenatal alcohol exposure can lead to adverse effects known as foetal alcohol spectrum disorders. We aimed to assess the underlying neurobiological mechanisms involved in alcohol intake and withdrawal in adolescent mice exposed to alcohol during early life stages, in discrete brain areas. Pregnant C57BL/6 female mice were exposed to binge alcohol drinking from gestation to weaning. Subsequently, alcohol seeking and taking behaviour were evaluated in male adolescent offspring, as assessed in the two-bottle choice and oral self-administration paradigms. Brain area samples were analysed to quantify AMPAR subunits GluR1/2 and pCREB/CREB expression following alcohol self-administration. We measured the expression of mu and kappa opioid receptors both during acute alcohol withdrawal (assessing anxiety alterations by the EPM test) and following reinstatement in the two-bottle choice paradigm. In addition, alcohol metabolism was analysed by measuring blood alcohol concentrations under an acute dose of 3 g/kg alcohol. Our findings demonstrate that developmental alcohol exposure enhances alcohol intake during adolescence, which is associated with a decrease in the pCREB/CREB ratio in the hippocampus, prefrontal cortex and striatum, while the GluR1/GluR2 ratio showed a decrease in the hippocampus. Moreover, PLAE mice showed behavioural alterations, such as increased anxiety-like responses during acute alcohol withdrawal, and higher BAC levels. No significant changes were identified for mu and kappa opioid receptors mRNA expression. The current study highlights that early alcohol exposed mice increased alcohol consumption during late adolescence. Furthermore, a diminished CREB signalling and glutamatergic neuroplasticity are proposed as underpinning neurobiological mechanisms involved in the sensitivity to alcohol reinforcing properties.

Long lasting effects of rearing by an ethanol-consuming dam on voluntary ethanol consumption by rats

For exposure to alcohol early in life to potentiate alcohol abuse in adolescence or adulthood, consequences of early exposure to alcohol must be of considerable duration. In two experiments using Norway rats as subjects, we examined effects of exposure during weaning to a dam consuming ethanol on adolescents' later affinity for ethanol. In a preliminary experiment, we offered rat pups a choice between 8% ethanol and water for 7 days immediately after they were weaned at 26 days of age. Pups whose dam had ingested 8% ethanol for 6 days either immediately or 1 week before we weaned them drank more ethanol than pups whose dam drank only water during the same period. Independent groups of rats reared by a dam consuming 8% ethanol from postnatal days 18 to 26 and tested 1, 2, 4 or 6 weeks later all drank significantly more 8% ethanol at testing than did pups whose dam drank only water. Our data also provided confirmation of previous reports of an experience-independent greater affinity for ethanol in younger rats.

Impaired development of mitochondria plays a role in the central nervous system defects of fetal alcohol syndrome

BACKGROUND

Alcohol consumption during pregnancy can induce a wide spectrum of adverse effects in offspring. Microcephaly and mental retardation are two major defects of central nervous system (CNS). Most mechanism studies of alcohol-related CNS defects have been focused on the morphologically abnormal tissues, and more attention has been paid to nuclear alteration as opposed to organelle development.

METHODS

A mouse model of fetal alcohol syndrome (FAS) was used to investigate the effect of alcohol on fetal cerebral mitochondria development. Pregnant mice were given different doses of ethanol intragastrically from GD6 to GD15. Fetal cerebral mitochondria were isolated and analyzed on GD18.

RESULTS

Excessive cell apoptosis was found in the cerebra of prenatal alcohol exposure fetuses. Proliferation and differentiation of fetal cerebral mitochondria were inhibited by alcohol. Affected mitochondrial volume constriction and adenosine triphosphate (ATP) accumulation, reduced activities of respiratory chain complex I and IV and ATP synthase were detected in the cerebral tissue without obvious malformed appearance.

CONCLUSIONS

Impaired mitochondria development plays a role in the CNS defects induced by prenatal alcohol exposure.

Effects of prenatal ethanol exposure on later sensitivity to the low-dose stimulant actions of ethanol in mouse offspring: possible role of catecholamines

The purpose of this study was to examine whether prenatal ethanol (EtOH) exposure alters later sensitivity to the low-dose stimulant effects of EtOH. Because the locomotor stimulant effects of EtOH are thought to be mediated, at least in part, by activation of brain monoamine systems, and because prenatal EtOH exposure has been shown to alter brain monoamine activity, it was hypothesized that prenatal EtOH exposure may alter sensitivity to the stimulant actions of EtOH. To test this hypothesis, sensitivity to the locomotor stimulant effects of various challenge doses of EtOH was examined in male and female offspring from prenatal alcohol (A), pair-fed (PF), and lab chow (LC) groups at different ages. In addition, to address the hypothesis further, sensitivity to the catecholamine synthesis inhibitor alpha-methyl-p-tyrosine (AMPT) was examined in these offspring, as well. Results indicated that male offspring prenatally exposed to EtOH exhibited reduced baseline activity and a blunted stimulant response to all challenge doses of EtOH (0.75-1.5 g/kg) in comparison with control offspring at 30 days of age, but these effects appeared to "normalize" at 70 days of age. Female EtOH-exposed offspring also exhibited a reduced baseline level of activity relative to control offspring, as well as a blunted stimulant response to the lowest challenge dose of EtOH (0.75 g/kg) at 30 days of age, and these effects persisted into adulthood. The stimulant response to higher doses of EtOH did not significantly differ among prenatal treatment groups in young or adult female offspring. However, because baseline activity was significantly lower in female EtOH-exposed offspring than control offspring, the stimulant response to these doses of EtOH (1.125 and 1.5 g/kg) was relatively greater than that for PF and LC offspring. Importantly, none of the differences in performance among the prenatal treatment groups could be attributed to an alteration in EtOH pharmacokinetics, because blood EtOH levels measured immediately following the 10-min test session were similar for all prenatal treatment groups across all of the EtOH test doses. Further, a similar response profile as that observed following EtOH challenge at 70 days of age was obtained following phenobarbital challenge (10-40 mg/kg). Finally, whereas AMPT (50-400 mg/kg) dose-dependently antagonized the stimulant effects of EtOH in all prenatal treatment groups, this effect of AMPT was significantly greater in mice prenatally exposed to EtOH in comparison with control offspring.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute alcohol intoxication paired with aversive reinforcement: ethanol odor as a conditioned reinforcer in rat pups

Previous research has suggested that infant rats process ethanol sensory properties during acute alcohol intoxication. The present study was designed in order to examine if alcohol odor could act as an aversive conditioned stimulus after the organism experiences the state of intoxication paired with nociceptive stimulation (footshock). In a first experiment 11-day-old pups received intragastric alcohol administration (1.5 g/kg). At different postabsorptive intervals footshock was presented (0-30, 30-60, 60-90, or 90-120 min). An explicitly unpaired control group which experienced footshock prior to the state of intoxication was also employed. All animals were subsequently tested in terms of alcohol intake and ethanol locational odor preferences. Both assessments indicated that pups which were exposed to the unconditioned peripheral stimulus 30-60 min after receiving ethanol expressed strong alcohol aversions. In a second experiment pups were exposed to footshock during this postabsorptive interval. Twenty four hours later, pups experienced ambient ethanol odor paired with soft or rough texture surfaces. Differential texture aversions were registered in experimental animals when compared with controls which suffered the state of intoxication explicitly unpaired with footshock, or unpaired presentations of ethanol odor and the tactile stimuli under consideration. These results appear to support the hypothesis concerning orosensory processing during an acute state of intoxication. Additionally it seems that the hedonic value of sensory attributes of this drug varies as a function of associative processes occurring during such a state.

Sensorimotor maturation and alcohol responsiveness in rats prenatally exposed to alcohol during gestational day 8

On gestational day 8, pregnant Sprague-Dawley derived rats received two intraperitoneal injections of 0.015 ml/g body weight of a 24% v/v ethanol solution representing an absolute alcohol dose of 2.82 g/kg per administration (ETOH Group). Control females were injected with similar volumes of saline (SAL Group) or did not receive any type of intraperitoneal administration of drugs (AC Group). In comparison with the control treatments, the ethanol treatment did not affect long-term maternal body weight gain during pregnancy, total length of gestation, probability of delivery, number of pups born per litter or the offsprings' preference of alcohol odor. Nevertheless, this ethanol insult was sufficient to significantly reduce body weights at birth and to retard the ontogeny of some sensorimotor patterns among offspring, as assessed through the Righting Reflex, Horizontal Screen Test and opening of the external auditory canals. The maturation of other reflexes (Cliff Aversion and Negative Geotaxis) appeared to be retarded indirectly as an outcome of the maternal injection procedure, with ETOH and SAL pups exhibiting similar developmental delays when compared with AC animals. During adulthood, rats prenatally exposed to alcohol exhibited a decreased hypothermic response to an intoxicating dose of alcohol as well as significant increases in voluntary alcohol consumption in comparison with both control conditions. Collectively, these results suggest that relatively acute alcohol exposure early in gestation may not only affect normal patterns of development but also later responsiveness to this pharmacological agent.