Genomic glucocorticoid action in embryonic mouse neural stem cells.

Prenatal exposure to synthetic glucocorticoids (sGCs) reprograms brain development and predisposes the developing fetus towards potential adverse neurodevelopmental outcomes. Using a mouse model of sGC administration, previous studies show that these changes are accompanied by sexually dimorphic alterations in the transcriptome of neural stem and progenitor cells (NSPCs) derived from the embryonic telencephalon. Because cell type-specific gene expression profiles tightly regulate cell fate decisions and are controlled by a flexible landscape of chromatin domains upon which transcription factors and enhancer elements act, we multiplexed data from four genome-wide assays: RNA-seq, ATAC-seq (assay for transposase accessible chromatin followed by genome wide sequencing), dual cross-linking ChIP-seq (chromatin immunoprecipitation followed by genome wide sequencing), and microarray gene expression to identify novel relationships between gene regulation, chromatin structure, and genomic glucocorticoid receptor (GR) action in NSPCs. These data reveal that GR binds preferentially to predetermined regions of accessible chromatin to influence gene programming and cell fate decisions. In addition, we identify SOX2 as a transcription factor that impacts the genomic response of select GR target genes to sGCs (i.e., dexamethasone) in NSPCs.

Expression of actin- and oxidative phosphorylation-related transcripts across the cortical visuospatial working memory network in unaffected comparison and schizophrenia subjects.

Visuospatial working memory (vsWM), which is impaired in schizophrenia (SZ), is mediated by a distributed cortical network. In one node of this network, the dorsolateral prefrontal cortex (DLPFC), altered expression of transcripts for actin assembly and mitochondrial oxidative phosphorylation (OXPHOS) have been reported in SZ. To understand the relationship between these processes, and the extent to which similar alterations are present in other regions of vsWM network in SZ, a subset of actin- (CDC42, BAIAP2, ARPC3, and ARPC4) and OXPHOS-related (ATP5H, COX4I1, COX7B, and NDUFB3) transcripts were quantified in DLPFC by RNA sequencing in 139 SZ and unaffected comparison (UC) subjects, and in DLPFC and three other regions of the cortical vsWM network by qPCR in 20 pairs of SZ and UC subjects. By RNA sequencing, levels of actin- and OXPHOS-related transcripts were significantly altered in SZ, and robustly correlated in both UC and SZ subject groups. By qPCR, cross-regional expression patterns of these transcripts in UC subjects were consistent with greater actin assembly in DLPFC and higher OXPHOS activity in primary visual cortex (V1). In SZ, CDC42 and ARPC4 levels were lower in all regions, BAIAP2 levels higher only in V1, and ARPC3 levels unaltered across regions. All OXPHOS-related transcript levels were lower in SZ, with the disease effect decreasing from posterior to anterior regions. The differential alterations in markers of actin assembly and energy production across regions of the cortical vsWM network in SZ suggest that each region may make specific contributions to vsWM impairments in the illness.

Prenatal drug exposure and neurodevelopmental programming of glucocorticoid signalling.

Prenatal neurodevelopment is dependent on precise functioning of multiple signalling pathways in the brain, including those mobilised by glucocorticoids (GC) and endocannabinoids (eCBs). Prenatal exposure to drugs of abuse, including opioids, alcohol, cocaine and cannabis, has been shown to not only impact GC signalling, but also alter functioning of the hypothalamic-pituitary-adrenal (HPA) axis. Such exposures can have long-lasting neurobehavioural consequences, including alterations in the stress response in the offspring. Furthermore, cannabis contains cannabinoids that signal via the eCB pathway, which is linked to some components of GC signalling in the adult brain. Given that GCs are frequently used in pregnancy to prevent complications of prematurity, and also that rates of cannabis use in pregnancy are increasing, the likelihood of foetal co-exposure to these compounds is high and may have additional implications for long-term neurodevelopment. Here, we present a discussion of GC signalling and the HPA axis, as well as the effects of prenatal drug exposure on these pathways and the stress response, and we explore the interactions between GC and EC signalling in the developing brain and potential for neurodevelopmental consequences.

Effect of methylphenidate on motivation in children with attention-deficit/hyperactivity disorder.

The effects of methylphenidate (MPH) on motivation were examined using a progressive ratio (PR) task in children who were prescribed MPH for the treatment of ADHD. Twenty-one children, 7 to 12 years of age, completed two test sessions, one under the effects of medication and one not. During each session, children pressed a lever to earn nickel reinforcers, where the first press resulted in a reinforcer and 10 additional presses were required for each subsequent reinforcer. Children on MPH had a significantly higher breakpoint than when off medication. This MPH-associated increase in the breakpoint manifested as a significant decrease in the interresponse times (IRT). Further, MPH administration resulted in a significant decrease in IRT variability. In contrast, MPH administration had no significant effects on the means and variability of postreinforcement pause duration. These results suggest that MPH increased motivation in children being treated for ADHD. Further, the inability of MPH to significantly reduce postreinforcement pause duration while simultaneously decreasing IRTs suggests that while MPH may increase motivation to perform an ongoing task, it may have little effect on the initiation of that task.

Chronic oral treatment with isotretinoin alters measures of activity but not anxiety in male and female rats.

Use of the anti-acne drug, Accutane (ACC) (isotretinoin, 13-cis-retinoic acid), has been associated with neuropsychiatric events ranging from depression in animal models to depression and suicide ideation in humans. Our studies, however, have consistently indicated few effects on measures of depression in male and female rats. Still, the comorbidity of depression and anxiety suggests that anxiety assessments in ACC-treated rats could be informative. Such assessments must be balanced with measures of activity since drug-induced activity alterations may impact the expression of anxiety-like behaviors. Here, Sprague-Dawley rats (n=15/sex/dose) were gavaged daily with 0 (soy oil), 7.5, or 30 mg/kg/day ACC beginning on postnatal day (PND) 59. Blood ACC levels similar to humans taking recommended ACC doses are produced by 7.5mg/kg/day. Short-term activity was assessed in open fields prior to ACC treatment (PND 51) and again at PNDs 129 and 164 and in a complex environment at PNDs 66 and PND 184. Long-term residential activity was measured in running wheels (PNDs 85-92) and figure 8 mazes (PNDs 99-106). Anxiety-like behavior was assessed via elevated plus maze (EPM) activity on PND 98 and in a black/white apparatus on PND 125. The typical sex differences in most behaviors were exhibited (i.e., increased EPM open arm entries and overall activity in most measures in females); however, there were no significant effects of ACC treatment on open field activity, complex environment activity, residential running wheel activity, or EPM activity. Residential figure 8 maze activity indicated that male and female rats treated with 30 mg/kg/day were less active on all nights (p<0.05) and females treated with 7.5 or 30 mg/kg/day were less active than same-sex controls on most days (p<0.05). Similarly, rats of both sexes treated with 30 mg/kg/day were significantly less active in the black/white apparatus (p<0.05), entering the darkened area less frequently (p<0.05), although duration in the darkened area did not differ. These data indicate that at blood levels typically achieved by humans (i.e., the 7.5 mg/kg group), there are no significant anxiogenic effects associated with ACC treatment. At higher ACC levels, there are mild effects on activity but these appear to be apparatus- and/or age-specific.

Oral treatment with ACCUTANE does not increase measures of anhedonia or depression in rats.

Reports of depression and/or suicide with ACCUTANE (13-cis-retinoic acid (13-cis-RA)) use prompted studies in a rodent model to ascertain its potential effects. Previously, there were no effects on measures of anhedonia (intake of a saccharin-flavored solution) and depression (forced swim test (FST) behaviors) in rats treated with 7.5 or 22.5 mg/kg 13-cis-RA [S.A. Ferguson, F.J. Cisneros, B. Gough, J.P. Hanig, K.J. Berry, Chronic oral treatment with 13-cis-retinoic acid (isotretinoin) or all-trans-retinoic acid does not alter depression-like behaviors in rats, Toxicol. Sci. 87 (2005) 451-459.]. Here, dose and temporal thresholds were investigated by increasing the maximum 13-cis-RA dose to 30 mg/kg, extending treatment duration, and measuring behaviors repeatedly. Beginning on post-natal day 59, male and female Sprague-Dawley rats were gavaged with soybean oil, 7.5 or 30 mg/kg/day of 13-cis-RA for approximately 19 weeks. FST behaviors were measured after 24, 82, and 131 treatment days and saccharin intake (0.03% solution) was measured at baseline and after 14, 35, 56, and 112 treatment days. Body weight and food intake were not altered by treatment. FST durations of swim, climb/struggle, and immobility were unaffected by 13-cis-RA at any time during treatment. More males than females required "rescue" in the FST but there was no treatment effect on number of rats requiring early removal. 13-cis-RA treatment had no effects on saccharin intake at any time. Given that the 7.5 mg/kg dose produces serum levels which parallel those of humans [S.A. Ferguson, P.H. Siitonen, F.J. Cisneros, B. Gough, J.F. Young, Steady state pharmacokinetics of oral treatment with 13-cis-retinoic acid or all-trans-retinoic acid in male and female adult rats, Basic Clin. Pharmacol. Toxicol 98 (2006) 582-587.], these results are quite relevant. Combined with previous results, these results provide further evidence that 13-cis-RA does not produce behavioral alterations indicative of depression in rats.

Baseline behavior, but not sensitivity to stimulant drugs, differs among spontaneously hypertensive, Wistar-Kyoto, and Sprague-Dawley rat strains.

Deficits in temporal processing are implicated in Attention Deficit Hyperactivity Disorder (ADHD) for which the most common rodent model is the Spontaneously Hypertensive Rat (SHR). To assess strain differences in temporal processing, males and females of the SHR, Wistar-Kyoto (WKY), and Sprague-Dawley (SD) strains were compared on two timing tasks: one requiring maintenance of a lever press for 10-14 s (TRD, temporal response differentiation) and the other requiring withholding of a lever press for 10-14 s (DRL, differential reinforcement of low rates). Performance of the progressive ratio (PR) task more directly assessed food-motivated behavior. Strains did not differ in task acquisition; however, steady state TRD and DRL performance of the SHR and WKY strains was less accurate which was related to increased burst (non-timing related) responses in those strains relative to the SD. PR performance demonstrated that the SHR and WKY strains exhibited higher response rates and breakpoints than the SD. Subsequently, methylphenidate (1, 3.25, 4.50, 7.50, and 12.0 mg/kg) and d-amphetamine (0.1, 0.25, 0.65, 1.0, and 2.0 mg/kg) were administered intraperitoneally pre-testing. Both drugs disrupted TRD and DRL performances by increasing burst response frequency; however, the strains were not differentially sensitive to either drug. Strain differences were generally maintained throughout the drug and extinction portions of the study. These results indicate increased similarity between the SHR and WKY strains relative to the SD in performance of timing and motivation tasks. Further, the current results do not support continued use of the SHR as a model for ADHD.

Oral Accutane (13-cis-retinoic acid) has no effects on spatial learning and memory in male and female Sprague-Dawley rats.

Descriptions of psychiatric effects with Accutane (13-cis-retinoic acid (13-cis-RA)) use prompted a series of studies in a rodent model to ascertain its cognitive effects. Previously, we reported no effects on measures of anhedonia and depression in rats treated with 7.5, 22.5, or 30 mg/kg 13-cis-RA [S.A. Ferguson, F.J. Cisneros, B. Gough, J.P. Hanig, K.J. Berry, Chronic oral treatment with 13-cis-retinoic acid (isotretinoin) or all-trans-retinoic acid does not alter depression-like behaviors in rats, Toxicol. Sci. 87 (2005) 451-459 [16]; S.A. Ferguson, F.J., Cisneros, J.P. Hanig, K.J. Berry, Chronic oral treatment with Accutane (13-cis-retinoic acid) does not increase measures of anhedonia or depression in male and female Sprague-Dawley rats, (in preparation) [19]]. Here, we assessed spatial learning and memory in male and female Sprague-Dawley rats gavaged daily beginning on postnatal day (PND) 59 with vehicle control (soybean oil), 7.5 or 30 mg/kg of 13-cis-RA. We have reported that 7.5 mg/kg produces serum levels of 13-cis-RA comparable to those of humans prescribed Accutane [S.A. Ferguson, P.H. Siitonen, F.J. Cisneros, B. Gough, J.F. Young, Steady state pharmacokinetics of oral treatment with 13-cis-retinoic acid or all- trans-retinoic acid in male and female adult rats, Basic Clin. Pharmacol. Toxicol. 98 (2006) 582-587 [18]]. Three behavioral tasks assessed spatial learning and memory after chronic 13-cis-RA treatment: the escape-reinforced Morris water maze (PNDs 111-115), the food-reinforced 8-arm radial maze (PNDs 132-136), and the water-reinforced NCTR complex maze (PNDs 153-157). Behaviors were measured after a minimum of 52 and maximum of 94 days of 13-cis-RA treatment. 13-cis-RA treatment had no effects on performance of the 8-arm radial maze or the NCTR complex maze. Treatment effects on Morris water maze performance were negligible and neither dose-related nor consistent. Performances of the control group were quite similar to those previously described in this laboratory. These results indicate that chronic 13-cis-RA treatment in male and female rats has few effects on measures of spatial learning and memory.

Chronic oral treatment with 13-cis-retinoic acid (isotretinoin) or all-trans-retinoic acid does not alter depression-like behaviors in rats.

Oral treatment with the anti-acne drug Accutane (isotretinoin, 13-cis-retinoic acid) has been associated with suicide ideation and depression. Here, depression-like behaviors (i.e., behavioral despair and anhedonia) were quantified in adult Sprague-Dawley rats gavaged daily beginning at postnatal day (PND) 82 with 13-cis-RA (7.5 or 22.5 mg/kg) or all-trans-retinoic acid (10 or 15 mg/kg ). Tested at PND 130-131 in the Forced Swim Test, 7.5 mg/kg 13-cis-RA marginally decreased immobility and slightly increased climb/struggle durations whereas neither all-trans-retinoic acid group differed from controls. Voluntary saccharin solution (0.03%) intake at PND 102-104 and PND 151-153 was not different from controls in any treated group, although all RA-treated groups had lower intakes. Swim speed in a water maze at PND 180 was similar across groups, indicating no RA-induced differences in physical ability. Open field activity was mildly decreased at PND 91 in 7.5 mg/kg-treated males only, but it was within the control range at PND 119, 147, and 175. Thus, at serum levels similar to those in humans receiving the drug, chronic 13-cis-RA treatment did not severely affect depression-like behaviors in rats. These data do not substantiate the hypothesis of 13-cis-RA-induced depression.

Behavioral effects of prenatal folate deficiency in mice.

BACKGROUND: Folate supplementation decreases the incidence of birth defects such as neural tube defects (NTDs). We and others have shown that gestational dietary folate deficiency that does not produce overt NTDs can alter fetal neural histology. Accordingly, murine offspring were examined for the possible functional consequences of prenatal folate deficiency. METHODS: CD-1 mice were fed a diet of chow containing 400, 600, or 1200 nmol of folic acid/kg of chow for eight weeks prior to breeding and until GD18, at which time all dams were placed on folate-replete chow. Behavioral tests of male and female offspring included righting reflex, negative geotaxis, forelimb hanging, motor coordination, open field activity, and elevated plus maze activity. RESULTS: Of greatest significance, the adult offspring that were prenatally folate-deficient exhibited more anxiety-related behavior in the elevated plus maze. Offspring of the 400 nmol of folic acid/kg of chow diet group exhibited significantly shorter durations in the open arms and longer durations in the closed arms. Further, these two behaviors were dose-related. There was also a trend for the prenatally folate-deficient adult mice to exhibit more thigmotaxis (wall-hugging) behavior in the open field, entering the central area less frequently than controls. There were few other differences in tested behaviors between folate-deficient and folate-replete mice. CONCLUSIONS: Prenatal folate deficiency that is repleted at birth can manifest later with increased anxiety 9-12 weeks after birth.