Amphetamine, but not methylphenidate, increases ethanol intake in adolescent male, but not in female, rats

Introduction: There has been an increasing interest in analyzing the interactions between stimulants and ethanol during childhood and adolescence. Stimulants are used to treat attention-deficit hyperactivity disorder (ADHD) in these developmental stages, during which ethanol initiation and escalation often occur. Methods: This study assessed the effects of repeated d-amphetamine (AMPH) or methylphenidate (MPH) treatment during adolescence [male and female Wistar rats, between postnatal day (PD) 28 to PD34, approximately] on the initiation of ethanol intake during a later section of adolescence (PD35 to PD40). Results: Amphetamine and MPH exerted reliable acute motor stimulant effects, but there was no indication of sensitized motor or anxiety responses. MPH did not affect dopamine (DA) levels, whereas AMPH significantly reduced insular levels of DA in both sexes and norepinephrine levels in females only. Repeated treatment with AMPH, but not with MPH, enhanced ethanol intake during late adolescence in male, but not in female, rats. Conclusion: A short treatment with AMPH during adolescence significantly altered DA levels in the insula, both in male and females, and significantly enhanced ethanol intake in males. The present results suggest that, in adolescent males, a very brief history of AMPH exposure can facilitate the initiation of ethanol intake.Fil: Ruiz, Paul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina. Universidad de la República; UruguayFil: Calliari, Aldo. Universidad de la República; UruguayFil: Genovese, Patricia. Universidad de la República; UruguayFil: Scorza, Cecilia. Instituto de Investigaciones Biológicas "Clemente Estable"; UruguayFil: Pautassi, Ricardo Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina. Universidad Nacional de Córdoba. Facultad de Psicología; Argentin

Long-Lasting Effects of Prenatal Ethanol Exposure on Fear Learning and Development of the Amygdala

Prenatal ethanol exposure (PrEE) produces developmental abnormalities in brain and behavior that often persist into adulthood. We have previously reported abnormal cortical gene expression, disorganized neural circuitry along with deficits in sensorimotor function and anxiety in our CD-1 murine model of fetal alcohol spectrum disorders, or FASD (El Shawa et al., 2013; Abbott et al., 2016). We have proposed that these phenotypes may underlie learning, memory, and behavioral deficits in humans with FASD. Here, we evaluate the impact of PrEE on fear memory learning, recall and amygdala development at two adult timepoints. PrEE alters learning and memory of aversive stimuli; specifically, PrEE mice, fear conditioned at postnatal day (P) 50, showed deficits in fear acquisition and memory retrieval when tested at P52 and later at P70–P72. Interestingly, this deficit in fear acquisition observed during young adulthood was not present when PrEE mice were conditioned later, at P80. These mice displayed similar levels of fear expression as controls when tested on fear memory recall. To test whether PrEE alters development of brain circuitry associated with fear conditioning and fear memory recall, we histologically examined subdivisions of the amygdala in PrEE and control mice and found long-term effects of PrEE on fear memory circuitry. Thus, results from this study will provide insight on the neurobiological and behavioral effects of PrEE and provide new information on developmental trajectories of brain dysfunction in people prenatally exposed to ethanol

Ontogeny of one-trial behavioral sensitization in preweanling, adolescent, and adult rats: Differential effects of cocaine and methamphetamine

The purpose of this thesis was to assess the ontogeny of cocaine- and methamphetamine-induced one-trial locomotor sensitization in preweanling, adolescent, and adult rats. Subjects were 336 male and female rats of Sprague-Dawley descent that were raised at California State University, San Bernardino (CSUSB)

Postnatal Neuro-Behavioral Effects of Prenatal Ethanol Exposure in a Mouse Model

Alcohol consumption during pregnancy can produce developmental abnormalities in offspring brain and behavior that often persist into adulthood, resulting in lifelong neurobehavioral anomalies. Fetal alcohol spectrum disorders, or FASD, is an umbrella term that describes a range of adverse developmental conditions caused by prenatal alcohol, or ethanol exposure (PrEE), with epidemiological studies recently reporting up to 5% of children being diagnosed with some form of FASD. PrEE can manifest in a host of physical, cognitive, emotional and behavioral impairments, arising from underlying neurobiological damage in various brain regions, including the neocortex. In order to study the affects of PrEE on brain biology and behavior, our laboratory created a CD-1 mouse model of FASD, implementing a maternal voluntary consumption of 25% ethanol solution paradigm throughout gestation. In preliminary studies, our laboratory was first to demonstrate disrupted targeting of ipsilateral intraneocortical connections (INCs) within sensori-motor regions of neocortex, altered gene expression patterns, coupled with altered cortical thickness and subcortical anatomy in newborn PrEE mice and abnormal behavior in older PrEE mice (El Shawa et al., 2013; Abbott et al., 2016). Chapter one of this dissertation extends initial studies investigating structural differences between newborn PrEE and control mice by examining the long-term effects of PrEE on brain anatomy throughout development, in weanling and early adult PrEE mice, with results revealing long-term alterations in cortical anatomy and abnormal subcortical development from the in utero ethanol exposure. Furthermore, we examine and discuss behavioral implications of PrEE-induced cortical and subcortical damage in young adult mice. In chapter two, we investigate whether aberrant INCs and altered gene expression patterns found in the PrEE newborn are transient or persist into prepubescence. Here, we discuss the maintenance of PrEE-induced changes in gene expression and altered behavior through prepubescence, albeit recovery of ectopic cortical connectivity observed at birth. Finally, chapter three evaluates the impact of PrEE on components of brain and behavior involved in fear learning and memory recall. Specifically, we assess the long-term effects of early ethanol exposure on a Pavlovian fear-conditioning paradigm, with results indicating that PrEE significantly alters learning and memory of aversive stimuli in adulthood when conditioned earlier in development. In addition, we review the outcome of PrEE on brain regions involved in fear learning and emotion regulation in adulthood. Further identification of the biological and behavioral phenotypes resulting from PrEE in this dissertation will contribute greatly toward discerning solutions in minimizing the severity and/or ameliorating ethanol-induced neurobehavioral damage

Rapid Changes in Cortical and Subcortical Brain Regions after Early Bilateral Enucleation in the Mouse.

Functional sensory and motor areas in the developing mammalian neocortex are formed through a complex interaction of cortically intrinsic mechanisms, such as gene expression, and cortically extrinsic mechanisms such as those mediated by thalamic input from the senses. Both intrinsic and extrinsic mechanisms are believed to be involved in cortical patterning and the establishment of areal boundaries in early development; however, the nature of the interaction between intrinsic and extrinsic processes is not well understood. In a previous study, we used a perinatal bilateral enucleation mouse model to test some aspects of this interaction by reweighting sensory input to the developing cortex. Visual deprivation at birth resulted in a shift of intraneocortical connections (INCs) that aligned with ectopic ephrin A5 expression in the same location ten days later at postnatal day (P) 10. A prevailing question remained: Does visual deprivation first induce a change in gene expression, followed by a shift in INCs, or vice versa? In the present study, we address this question by investigating the neuroanatomy and patterns of gene expression in post-natal day (P) 1 and 4 mice following bilateral enucleation at birth. Our results demonstrate a rapid reduction in dorsal lateral geniculate nucleus (dLGN) size and ephrin A5 gene expression 24-hours post-enucleation, with more profound effects apparent at P4. The reduced nuclear size and diminished gene expression mirrors subtle changes in ephrin A5 expression evident in P1 and P4 enucleated neocortex, 11 and 8 days prior to natural eye opening, respectively. Somatosensory and visual INCs were indistinguishable between P1 and P4 mice bilaterally enucleated at birth, indicating that perinatal bilateral enucleation initiates a rapid change in gene expression (within one day) followed by an alteration of sensory INCs later on (second postnatal week). With these results, we gain a deeper understanding of how gene expression and sensory input together regulate cortical arealization and plasticity during early development

The effects of lifelong blindness on murine neuroanatomy and gene expression.

Mammalian neocortical development is regulated by neural patterning mechanisms, with distinct sensory and motor areas arising through the process of arealization. This development occurs alongside developing central or peripheral sensory systems. Specifically, the parcellation of neocortex into specific areas of distinct cytoarchitecture, connectivity and function during development is reliant upon both cortically intrinsic mechanisms, such as gene expression, and extrinsic processes, such as input from the sensory receptors. This developmental program shifts from patterning to maintenance as the animal ages and is believed to be active throughout life, where the brain’s organization is stable yet plastic. In this study, we characterize the long-term effects of early removal of visual input via bilateral enucleation at birth. To understand the long-term effects of early blindness we conducted anatomical and molecular assays 18 months after enucleation, near the end of lifespan in the mouse. Bilateral enucleation early in life leads to long-term, stable size reductions of the thalamic lateral geniculate nucleus (LGN) and the primary visual cortex (V1) alongside a increase in individual whisker barrel size. Neocortical gene expression in the aging brain has not been previously identified; we document cortical expression of multiple regionalization genes. Expression patterns of Ephrin A5, COUP-TFI, and RZRß and patterns of intraneocortical connectivity are altered in the neocortices of aging blind mice. Sensory inputs from different modalities during development likely play a major role in the development of cortical areal and thalamic nuclear boundaries. We suggest that early patterning by prenatal retinal activity combined with persistent gene expression within the thalamus and cortex is sufficient to establish and preserve a small but present LGN and V1 into late adulthood

Analysis of dLGN reduction and <i>ephrin A5</i> expression in control and enucleated brains.

<p>(A) P1 cells stained with DAPI within the dLGN. Decreased nuclear size observed in enucleated cases (79.34 ± 3.462% <i>P</i> < 0.001), when compared to control animal baseline levels. (B) P4 cells stained with DAPI within the dLGN. dLGN size of enucleated animals (69.15 ± 2.938%; <i>P</i> < 0.0001) is significantly different from controls. (C) Area of <i>ephrin A5</i> expression in P1 dLGN. <i>Ephrin A5</i> expression within the dLGN of enucleated animals (78.98 ± 5.723%; <i>P</i> < 0.05) is significantly different than controls. (D) Area of <i>ephrin A5</i> expression in P4 dLGN. Percentage of <i>ephrin A5</i> expression in enucleated dLGN (73.52 ± 6.190%; <i>P</i> < 0.01) is significantly different when compared to controls. DAPI: P1 and P4, n = 6 control and n = 6 enucleates; <i>Ephrin A5</i>: P1 n = 7 control and n = 7 enucleates, P4 n = 6 control and n = 6 enucleates. All data are presented as percentage of mean control measure.</p

Neocortical gene expression of <i>ephrin A5</i> at P1 in control and enucleated mice.

<p><i>In situ</i> RNA hybridization was used to determine the distribution of transcripts for <i>ephrin A5</i> at P1 in control (A1-A3) and enucleated (B1-B3) brains as labeled. All panels are low magnification views of one hemisphere after sectioning at 100μm in the coronal plane, shown in a rostral to caudal (left to right) series. Cortical <i>Ephrin A5</i> expression in control animals (A1-A3) was found predominantly in middle layers of the somatosensory-motor amalgam (A1), somatosensory (A2) and visual cortices (A3), with some extension of deep layer transcripts detected in the somatosensory and visual cortex. Expression was similar, but reduced in experimental cases (B1-B3). ROIs within the somatosensory-motor amalgam (C1), somatosensory (C2) and visual cortices (C3) all revealed significant reductions in <i>ephrin A5</i> transcript coverage (control 32.42 ± 1.199% and enucleated 25.84 ± 0.0.919%; D2, control 50.96 0078 1.741% and enucleated 31.64 ± 3.587%; D3, control 40.98 ± 1.568% and enucleated 27.07 ± 4.310%). All sections are oriented with dorsal (D) up and medial (M) to the left. S: somatosensory cortex; V: visual cortex; s-m: somatosensory-motor amalgam. Scale bar = 500μm. * = <i>P</i> < 0.05, *** = <i>P</i> < 0.001; n = 6 controls and n = 6 enucleates.</p

Analysis of dye labeling in control and enucleated brains.

<p>(A) Distance to midline in P1 control and enucleated mice. No significant difference in somatosensory border distance from midline was detected between groups (control, 0.43 ± 0.01 mm, n = 9; enucleated, 0.45 ± 0.03 mm, n = 8; P = 0.50). (B) Distance to midline in P4 control and enucleated mice. Somatosensory border distance from midline was did not differ significantly between groups (control, 0.51 ± 0.03 mm, n = 11; enucleated, 0.45 ± 0.03 mm, n = 13; P = 0.20).</p