Search

Background: We recently showed that alcohol and cannabis can interact prenatally, and in a recent review paper, we identified parvalbumin-positive (PV) interneurons in the hippocampus as a potential point of convergence for these teratogens., Methods: A 2 (Ethanol [EtOH], Air) × 2 (tetrahydrocannabinol [THC], Vehicle) design was used to expose pregnant Sprague-Dawley rats to either EtOH or air, in addition to either THC or the inhalant vehicle solution, during gestational days 5-20. Immunohistochemistry was performed to detect PV interneurons in 1 male and 1 female pup from each litter at postnatal day 70., Results: Significant between-group and subregion-specific effects were found in the dorsal cornu ammonis 1 (CA1) subfield and the ventral dentate gyrus (DG). In the dorsal CA1 subfield, there was an increase in the number of PV interneurons in both the EtOH and EtOH +THC groups, but a decrease with THC alone. There were fewer changes in interneuron numbers overall in the DG, though there was a sex difference, with a decrease in the number of PV interneurons in the THC-exposed group in males. There was also a greater cell layer volume in the DG in the EtOH +THC group than the control group, and in the CA1 region in the EtOH group compared to the control and THC groups., Conclusions: Prenatal exposure to alcohol and THC differentially affects parvalbumin-positive interneuron numbers in the hippocampus, indicating that both individual and combined exposure can impact the balance of excitation and inhibition in a structure critically involved in learning and memory processes., (© 2021 by the Research Society on Alcoholism.)

Background: Marijuana and alcohol are both substances that, when used during pregnancy, may have profound effects on the developing fetus. There is evidence to suggest that both drugs have the capacity to affect working memory, one function of the hippocampal formation; however, there is a paucity of data on how perinatal exposure to alcohol or cannabis impacts the process of adult neurogenesis., Methods: This systematic review examines immunohistochemical data from adult rat and mouse models that assess perinatal alcohol or perinatal marijuana exposure. A comprehensive list of search terms was designed and used to search 3 separate databases. All results were imported to Mendeley and screened by 2 authors. Consensus was reached on a set of final papers that met the inclusion criteria, and their results were summarized., Results: Twelve papers were identified as relevant, 10 of which pertained to the effects of perinatal alcohol on the adult hippocampus, and 2 pertained to the effects of perinatal marijuana on the adult hippocampus. Cellular proliferation in the dentate gyrus was not affected in adult rats and mice exposed to alcohol perinatally. In general, perinatal alcohol exposure did not have a significant and reliable effect on the maturation and survival of adult born granule neurons in the dentate gyrus. In contrast, interneuron numbers appear to be reduced in the dentate gyrus of adult rats and mice exposed perinatally to alcohol. Perinatal marijuana exposure was also found to reduce inhibitory interneuron numbers in the dentate gyrus., Conclusions: Perinatal alcohol exposure and perinatal marijuana exposure both act on inhibitory interneurons in the hippocampal formation of adult rats. These findings suggest simultaneous perinatal alcohol and marijuana exposure (SAM) may have a dramatic impact on inhibitory processes in the dentate gyrus., (© 2020 by the Research Society on Alcoholism.)

Background: The hippocampus is particularly vulnerable to the teratogenic effects of prenatal ethanol exposure (PNEE), and hippocampal structural and functional deficits are thought to contribute to the learning and memory deficits that are a hallmark feature of fetal alcohol spectrum disorders., Methods: Sprague Dawley dams were exposed to a liquid diet that contained EtOH (35.5% EtOH-derived calories) throughout gestation, and then, PNEE juvenile (P21-28) male and female offspring were used for in vitro electrophysiological recordings. We examined long-term potentiation (LTP), long-term depression (LTD), and depotentiation in the medial perforant path input to the dentate gyrus (DG) to determine the impact of PNEE on the dynamic range of bidirectional synaptic plasticity in both sexes., Results: PNEE reduced the responsiveness of the DGs of male but not in female offspring, and this effect was no longer apparent when GABAergic signaling was inhibited. There was also a sex-specific LTD impairment in males, but increasing the duration of the conditioning stimulus could overcome this deficit. The magnitude of LTP was also reduced, but in both sexes following PNEE. This appears to be an increase in the threshold for induction, not in capacity, as the level of LTP induced in PNEE animals was increased to control levels when additional conditioning stimuli were administered., Conclusions: These data are the first to describe, in a single study, the impact of PNEE on the dynamic range of bidirectional synaptic plasticity in the juvenile DG in both males and in females. The data suggest that PNEE increases the threshold for LTP in the DG in both sexes, but produces a sex-specific increase in the threshold for LTD in males These alterations reduce the dynamic range for synaptic plasticity in both sexes., (© 2019 by the Research Society on Alcoholism.)

Background: The consumption of alcohol during pregnancy can result in abnormal fetal development and impaired brain function in humans and experimental animal models. Depending on the pattern of consumption, the dose, and the period of exposure to ethanol (EtOH), a variety of structural and functional brain deficits can be observed., Methods: This study compared the effects of EtOH exposure during distinct periods of brain development on oxidative damage and endogenous antioxidant status in various brain regions of adult female and male Sprague Dawley rats. Pregnant dams and neonatal rats were exposed to EtOH during one of the following time windows: between gestational days (GDs) 1 and 10 (first trimester equivalent); between GDs 11 and 21 (second trimester equivalent); or between postnatal days (PNDs) 4 and 10 (third trimester equivalent)., Results: EtOH exposure during any of the 3 trimester equivalents significantly increased lipid peroxidation in both the cornus ammonis (CA) and dentate gyrus (DG) subregions of the hippocampus, while also decreasing the levels of the endogenous antioxidant glutathione in the hippocampal CA and DG subregions as well as the prefrontal cortex of young adult animals (PND 60)., Conclusions: These results indicate that EtOH exposure during restricted periods of brain development can have long-term consequences in the adult brain by dysregulating its redox status. This dysfunction may underlie, at least in part, the long-term alterations in brain function associated with fetal alcohol spectrum disorders., (Copyright © 2016 by the Research Society on Alcoholism.)

Background: Prenatal ethanol (EtOH) exposure results in a spectrum of structural, cognitive, and behavioral abnormalities, collectively termed "fetal alcohol spectrum disorders" (FASDs). The hippocampal formation, an area of the brain strongly linked with learning and memory, is particularly vulnerable to the teratogenic effects of EtOH. Prenatal EtOH exposure can lead to long-lasting impairments in the ability to process spatial information, as well as produce long-lasting deficits in the ability of animals to exhibit long-term potentiation (LTP), a biological model of learning and memory processing. These deficits also have the ability to facilitate EtOH and/or other drug abuse later in life. This study sought to determine prenatal EtOH exposure altered the effects of acute EtOH application on synaptic plasticity., Methods: Prenatal EtOH exposure was modeled using a liquid diet where dams were given 1 of 3 diets: (i) a liquid diet containing EtOH (35.5% EtOH-derived calories), (ii) a liquid diet, isocaloric to the EtOH diet, but with maltose-dextrin substituting for the EtOH-derived calories, and (iii) an ad libitum diet of standard rat chow. Extracellular recordings from transverse brain slices (350 μm) prepared from 50- to 70-day-old rats, following prenatal EtOH exposure (gestational day 1 to 21). LTP was examined in the dentate gyrus following acute EtOH exposure (0, 20, or 50 mM) in these slices., Results: Prenatal EtOH exposure attenuated LTP in the adult dentate gyrus. In control offspring, acute application of EtOH in adulthood attenuated (20 mM) or blocked (50 mM) LTP. Conversely, the effect of acute EtOH application on LTP was not as pronounced in prenatal EtOH offspring., Conclusions: Prenatal EtOH exposure alters the sensitivity of the adult dentate gyrus to acute EtOH application producing a long-lasting tolerance to the inhibitory effects of EtOH. This decreased sensitivity may provide a mechanism promoting the formation of drug-associated memories and help explain the increased likelihood of developing an alcohol dependency often observed in individuals with FASDs., (Copyright © 2013 by the Research Society on Alcoholism.)