Mn2+ dynamics in manganese-enhanced MRI (MEMRI): Cav1.2 channel-mediated uptake and preferential accumulation in projection terminals.

Manganese-enhanced magnetic resonance imaging (MEMRI) exploits the biophysical similarity of Ca2+ and Mn2+ to map the brain's activity in vivo. However, to what extent different Ca2+ channels contribute to the enhanced signal that MEMRI provides and how Mn2+ dynamics influence Mn2+ brain accumulation after systemic administration of MnCl2 are not yet fully understood. Here, we demonstrate that mice lacking the L-type Ca2+ channel 1.2 (Cav1.2) in the CNS show approximately 50% less increase in MEMRI contrast after repeated systemic MnCl2 injections, as compared to control mice. In contrast, genetic deletion of L-type Ca2+ channel 1.3 (Cav1.3) did not reduce signal. Brain structure- or cell type-specific deletion of Cav1.2 in combination with voxel-wise MEMRI analysis revealed a preferential accumulation of Mn2+ in projection terminals, which was confirmed by local MnCl2 administration to defined brain areas. Taken together, we provide unequivocal evidence that Cav1.2 represents an important channel for neuronal Mn2+ influx after systemic injections. We also show that after neuronal uptake, Mn2+ preferentially accumulates in projection terminals.

Endocannabinoids and stress.

Endogenous cannabinoids play an important role in the physiology and behavioral expression of stress responses. Activation of the hypothalamic-pituitary-adrenal (HPA) axis, including the release of glucocorticoids, is the fundamental hormonal response to stress. Endocannabinoid (eCB) signaling serves to maintain HPA-axis homeostasis, by buffering basal activity as well as by mediating glucocorticoid fast feedback mechanisms. Following chronic stressor exposure, eCBs are also involved in physiological and behavioral habituation processes. Behavioral consequences of stress include fear and stress-induced anxiety as well as memory formation in the context of stress, involving contextual fear conditioning and inhibitory avoidance learning. Chronic stress can also lead to depression-like symptoms. Prominent in these behavioral stress responses is the interaction between eCBs and the HPA-axis. Future directions may differentiate among eCB signaling within various brain structures/neuronal subpopulations as well as between the distinct roles of the endogenous cannabinoid ligands. Investigation into the role of the eCB system in allostatic states and recovery processes may give insight into possible therapeutic manipulations of the system in treating chronic stress-related conditions in humans.

Nurse home visiting and prenatal substance use in a socioeconomically disadvantaged population in British Columbia: analysis of prenatal secondary outcomes in an ongoing randomized controlled trial.

BACKGROUND: Nurse-Family Partnership (NFP) involves public health nurses providing frequent home visits from early pregnancy until children reach age 2 years, focusing on first-time parents experiencing socioeconomic disadvantage. Our aim was to evaluate NFP's effectiveness in improving child and maternal health. METHODS: We conducted an analysis of prenatal secondary outcomes in an ongoing randomized controlled trial in British Columbia; the data used in this analysis were collected from January 2014 to May 2017. Participants were pregnant girls and women aged 14-24 years who were preparing to parent for the first time and experiencing socioeconomic disadvantage. They were randomly allocated 1:1 to the intervention (NFP plus existing services) or control group (existing services). Prespecified prenatal secondary outcome indicators were changes in use of nicotine cigarettes and alcohol use by 34-36-weeks' gestation. We also report on prespecified exploratory cannabis and street drug use measures. We used mixed-effect models for longitudinal and clustered data to estimate intervention effects. Analyses were by intention to treat. RESULTS: The median gestational age at baseline for the 739 participants (368 participants in the intervention group, 371 in the comparison group) was 20 weeks, 6 days. By 34-36 weeks' gestation, NFP significantly reduced cigarette counts (over the past 2 d) (difference in changes [DIC] of count -1.6, 95% confidence interval [CI] -6.4 to -1.3) in those who smoked. NFP also significantly reduced rates of prenatal cannabis use (DIC -6.4, 95% CI -17.0 to -1.7), but not rates of street drug or "any" substance use. While we observed decreased rates of cigarette and alcohol use in both groups (DIC of proportions -2.8, 95% CI -15.3 to 0.6; DIC -0.5, 95% CI -8.7 to 1.8, respectively), these changes were not statistically significant. INTERPRETATION: We found no evidence that NFP was effective in reducing rates of prenatal cigarette and alcohol use; however, it led to reduced prenatal cannabis use, and in smokers it led to modest reductions in cigarette use. NFP may therefore hold promise for reducing some types of prenatal substance use in disadvantaged populations. Trial registration: ClinicalTrials.gov, no. NCT01672060.

Following the masters: portrait viewing and appreciation is guided by selective detail.

A painted portrait differs from a photo in that selected regions are often rendered in much sharper detail than other regions. Artists believe these choices guide viewer gaze and influence their appreciation of the portrait, but these claims are difficult to test because increased portrait detail is typically associated with greater meaning, stronger lighting, and a more central location in the composition. In three experiments we monitored viewer gaze and recorded viewer preferences for portraits rendered with a parameterised non-photorealistic technique to mimic the style of Rembrandt (DiPaola, 2009 International Journal of Art and Technology 2 82-93). Results showed that viewer gaze was attracted to and held longer by regions of relatively finer detail (experiment 1), and also by textural highlighting (experiment 2), and that artistic appreciation increased when portraits strongly biased gaze (experiment 3). These findings have implications for understanding both human vision science and visual art.

Precipitated withdrawal counters the adverse effects of subchronic cannabinoid administration on male rat sexual behavior.

In the present study, sexual behavior of male rats was assessed following prolonged treatment with the CB(1) receptor agonist, HU-210 (0.1mg/mg/day for 10 days) under conditions of drug maintenance, spontaneous withdrawal and precipitated withdrawal (induced via administration of the CB(1) receptor antagonist AM251; 1mg/kg). Following subchronic cannabinoid treatment, sexual activity in male rats was impaired under both the drug maintenance and spontaneous withdrawal conditions, as revealed by a reduction in frequency of both intromissions and ejaculations. Notably, the induction of precipitated drug withdrawal reversed the negative effects of subchronic HU-210 treatment on sexual activity as seen by a reversal of the suppression of ejaculations. These data illustrate that, contrary to expectations, the impairments in male sexual activity following protracted cannabinoid administration are not due to drug withdrawal, per se, but are likely mediated by neuroadaptive changes provoked by repeated drug exposure.

Estrogenic regulation of limbic cannabinoid receptor binding.

Sex differences have been identified in many of the behavioral and physiological effects of cannabinoids. While estrogen has been linked to some of these variations, the effects of estrogen on cannabinoid receptor binding have not been characterized within regions of the brain specifically implicated in stress responsivity and emotional behavior. To examine sex differences, and the role of estradiol, in regulation of the cannabinoid receptor, we compared the binding site density of the cannabinoid receptor within the amygdala, hippocampus and hypothalamus in males, cycling females, ovariectomized (OVX) females and estradiol-treated OVX females (OVX+E). Our data reveal that males and OVX females have higher amounts of hypothalamic and lower amounts of amygdalar cannabinoid receptor binding relative to both cycling females and OVX+E females. Within the hippocampus, ovariectomy resulted in an upregulation of cannabinoid receptor binding. These data provide a putative biochemical mechanism mediating the observed behavioral and physiological sex differences in the effects of cannabinoids, particularly with respect to stress and emotional behavior.

Protracted cannabinoid administration elicits antidepressant behavioral responses in rats: role of gender and noradrenergic transmission.

Research has shown that enhancement of cannabinoid CB(1) receptor activity elicits an antidepressant-like response in the forced swim test (FST); however, the effects of chronic administration of cannabinoid agents in the FST are not well characterized. In Experiment 1, the CB(1) receptor agonist HU-210 (0.1 mg/kg) was administered for 10 days to male rats, following which animals were exposed to the FST. In Experiment 2, the same protocol was utilized; however, prior to the FST animals were co-treated with either prazosin (1 mg/kg; an alpha(1)-adrenoreceptor antagonist) or propranolol (2.5 mg/kg; a beta-adrenoreceptor antagonist). In Experiment 3, the same protocol was employed in both male and female rats, and the role of drug withdrawal was examined by administration of the CB(1) receptor antagonist AM251 (1 mg/kg) prior to the FST. Experiment 1 revealed that HU-210 administration evoked a reduction in immobility and increase in struggling that was identical to that produced by the antidepressant desipramine (10 mg/kg). Experiment 2 revealed that this effect was attenuated by both alpha- and beta-adrenoreceptor antagonists, suggesting noradrenergic involvement in this antidepressant-like profile. Experiment 3 demonstrated that HU-210 administration produced an antidepressant response in both males and females, which was attenuated by the induction of precipitated withdrawal. These results show that protracted administration of a CB(1) receptor agonist produces an antidepressant-like response in the FST in both sexes, which appears to involve the noradrenergic system.