Antenatal glucocorticoid treatment induces adaptations in adult midbrain dopamine neurons, which underpin sexually dimorphic behavioral resilience

We demonstrated previously that antenatal glucocorticoid treatment (AGT, gestational days 16-19) altered the size and organization of the adult rat midbrain dopaminergic (DA) populations. Here we investigated the consequences of these AGT-induced cytoarchitectural disturbances on indices of DA function in adult rats. We show that in adulthood, enrichment of striatal DA fiber density paralleled AGT-induced increases in the numbers of midbrain DA neurons, which retained normal basal electrophysiological properties. This was co-incident with changes in (i) striatal D2-type receptor levels (increased, both sexes); (ii) D1-type receptor levels (males decreased; females increased); (iii) DA transporter levels (males increased; females decreased) in striatal regions; and (iv) amphetamine-induced mesolimbic DA release (males increased; females decreased). However, despite these profound, sexually dimorphic changes in markers of DA neurotransmission, in-utero glucocorticoid overexposure had a modest or no effect on a range of conditioned and unconditioned appetitive behaviors known to depend on mesolimbic DA activity. These findings provide empirical evidence for enduring AGT-induced adaptive mechanisms within the midbrain DA circuitry, which preserve some, but not all, functions, thereby casting further light on the vulnerability of these systems to environmental perturbations. Furthermore, they demonstrate these effects are achieved by different, often opponent, adaptive mechanisms in males and females, with translational implications for sex biases commonly found in midbrain DA-associated disorders

Trajectories of dementia-related cognitive decline in a large mental health records derived patient cohort

Background: Modeling trajectories of decline can help describe the variability in progression of cognitive impairment in dementia. Better characterisation of these trajectories has significant implications for understanding disease progression, trial design and care planning. Methods: Patients with at least three Mini-mental State Examination (MMSE) scores recorded in the South London and Maudsley NHS Foundation Trust Electronic Health Records, UK were selected (N = 3441) to form a retrospective cohort. Trajectories of cognitive decline were identified through latent class growth analysis of longitudinal MMSE scores. Demographics, Health of Nation Outcome Scales and medications were compared across trajectories identified. Results: Four of the six trajectories showed increased rate of decline with lower baseline MMSE. Two trajectories had similar initial MMSE scores but different rates of decline. In the faster declining trajectory of the two, a higher incidence of both behavioral problems and sertraline prescription were present. Conclusions: We find suggestive evidence for association of behavioral problems and sertraline prescription with rate of decline. Further work is needed to determine whether trajectories replicate in other datasets

Sex-specific disruption of murine midbrain astrocytic and dopaminergic developmental trajectories following antenatal GC treatment

The mammalian midbrain dopaminergic systems arising in the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) are critical for coping behaviours and are implicated in neuropsychiatric disorders where early life challenges comprise significant risk factors. Here, we aimed to advance our hypothesis that glucocorticoids (GCs), recognised key players in neurobiological programming, target development within these systems, with a novel focus on the astrocytic population. Mice received antenatal GC treatment (AGT) by including the synthetic GC, dexamethasone, in the mothers' drinking water on gestational days 16-19; controls received normal drinking water. Analyses of regional shapes and volumes of the adult SNc and VTA demonstrated that AGT induced long-term, dose-dependent, structural changes that were accompanied by profound effects on astrocytes (doubling/tripling of numbers and/or density). Additionally, AGT induced long-term changes in the population size and distribution of SNc/VTA dopaminergic neurons, confirming and extending our previous observations made in rats. Furthermore, glial/neuronal structural remodelling was sexually dimorphic and depended on the AGT dose and sub-region of the SNc/VTA. Investigations within the neonatal brain revealed that these long-term organisational effects of AGT depend, at least in part, on targeting perinatal processes that determine astrocyte density and programmed cell death in dopaminergic neurons. Collectively, our characterisation of enduring, AGT-induced, sex-specific cytoarchitectural disturbances suggests novel mechanistic links for the strong association between early environmental challenge (inappropriate exposure to excess GCs) and vulnerability to developing aberrant behaviours in later life, with translational implications for dopamine-associated disorders (such as schizophrenia, ADHD, autism, depression), which typically show a sex bia

Expansion of guidance for the day 8 initiation dose of paliperidone palmitate to avoid a missed dose

Mahesh N Samtani,1 Isaac Nuamah,1 Srihari Gopal,1 Bart Remmerie,2 Jennifer Kern Sliwa,3 Larry Alphs31Janssen Research and Development, LLC, NJ, USA; 2Janssen Research and Development, LLC, Division of Janssen Pharmaceutica NV, Beerse, Belgium; 3Janssen Scientific Affairs, LLC, NJ, USABackground: Paliperidone palmitate (PP) is a long-acting injectable formulation of an atypical antipsychotic, paliperidone. Its dose can be expressed in milligram or milligram equivalents (mg eq) of active paliperidone (39, 78, 117, 156, and 234 mg of PP correspond to 25, 50, 75, 100, and 150 mg eq of paliperidone). The recommended initiation dosing regimen for PP is 150 [day 1]/100[day 8] mg eq. Labeling guidance allowed a ± 2 day window for the day 8 injection that provides more flexibility with patient scheduling and avoids missing the day 8 initiation dose. Recently, expansion of the day 8 dosing window from ±2 to ±4 days has been approved in the United States based on results obtained from the model-based simulations and review of safety data presented here.Methods: The predicted exposure for the recommended initiation regimen of PP was compared with day 1/day 4, and day 1/day 12 dosing scenarios; each scenario was compared with the highest clinically evaluated initiation regimen (150[day 1]/150[day 8] mg eq) and to the recommended 6 mg/day oral dose of extended-release paliperidone.Results: Simulated exposures with PP 150 mg eq on day 1 and 100 mg eq on days 4, 8, or 12 overlap considerably, with ±3 ng/mL variation in median maximum plasma concentrations. Based upon pharmacokinetic bridging/bracketing, the peak concentration with PP 150/100 mg eq [days 1/4] was lower than that with the highest initiation regimen. Exposures for PP 150 mg eq on day 1 and 100 mg eq on days 4, 8, or 12 were maintained close to those of 6 mg of paliperidone extended-release.Conclusion: These simulations indicate that using the expanded dosing window of ±4 days has little effect on paliperidone exposure. A review of the overall pattern of treatment-emergent adverse events did not identify any new safety risks associated with the expanded dosing window.Keywords: dosing window expansion, initiation regimen, long-acting-injectable, pharmacokinetic bridging, paliperidone palmitate, population pharmacokinetic

Erratum

Samtani MN, Sheehan JJ, Fu D-J, Remmerie B, Sliwa JK, Alphs L. Management of antipsychotic treatment discontinuation and interruptions using model-based simulations. Clin Pharmacol. 2012;4:25–40. The video abstract was not included on page 25 for this paper.Read the original article &nbsp