Haloperidol, spiperone, pimozide and aripiprazole reduce intracellular dopamine content in PC12 cells and rat mesencephalic cultures: Implication of inhibition of vesicular transport

Utility of Extrapolating Human S1500+ Genes to the Whole Transcriptome: Tunicamycin Case Study

The TempO-Seq S1500+ platform(s), now available for human, mouse, rat, and zebrafish, measures a discrete number of genes that are representative of biological and pathway co-regulation across the entire genome in a given species. While measurement of these genes alone provides a direct assessment of gene expression activity, extrapolating expression values to the whole transcriptome (~26 000 genes in humans) can estimate measurements of non-measured genes of interest and increases the power of pathway analysis algorithms by using a larger background gene expression space. Here, we use data from primary hepatocytes of 54 donors that were treated with the endoplasmic reticulum (ER) stress inducer tunicamycin and then measured on the human S1500+ platform containing ~3000 representative genes. Measurements for the S1500+ genes were then used to extrapolate expression values for the remaining human transcriptome. As a case study of the improved downstream analysis achieved by extrapolation, the “measured only” and “whole transcriptome” (measured + extrapolated) gene sets were compared. Extrapolation increased the number of significant genes by 49%, bringing to the forefront many that are known to be associated with tunicamycin exposure. The extrapolation procedure also correctly identified established tunicamycin-related functional pathways reflected by coordinated changes in interrelated genes while maintaining the sample variability observed from the “measured only” genes. Extrapolation improved the gene- and pathway-level biological interpretations for a variety of downstream applications, including differential expression analysis, gene set enrichment pathway analysis, DAVID keyword analysis, Ingenuity Pathway Analysis, and NextBio correlated compound analysis. The extrapolated data highlight the role of metabolism/metabolic pathways, the ER, immune response, and the unfolded protein response, each of which are key activities associated with tunicamycin exposure that were unrepresented or underrepresented in one or more of the analyses of the original “measured only” dataset. Furthermore, the inclusion of the extrapolated genes raised “tunicamycin” from third to first upstream regulator in Ingenuity Pathway Analysis and from sixth to second most correlated compound in NextBio analysis. Therefore, our case study suggests an approach to extend and enhance data from the S1500+ platform for improved insight into biological mechanisms and functional outcomes of diseases, drugs, and other perturbations.

Dopaminergic impact of cART and anti-depressants on HIV neuropathogenesis in older adults

The success of combination antiretroviral therapy (cART) has transformed HIV infection into a chronic condition, resulting in an increase in the number of older, cART-treated adults living with HIV. This has increased the incidence of age-related, non-AIDS comorbidities in this population. One of the most common comorbidities is depression, which is also associated with cognitive impairment and a number of neuropathologies. In older people living with HIV, treating these overlapping disorders is complex, often creating pill burden or adverse drug-drug interactions that can exacerbate these neurologic disorders. Depression, NeuroHIV and many of the neuropsychiatric therapeutics used to treat them impact the dopaminergic system, suggesting that dopaminergic dysfunction may be a common factor in the development of these disorders. Further, changes in dopamine can influence the development of inflammation and the regulation of immune function, which are also implicated in the progression of NeuroHIV and depression. Little is known about the optimal clinical management of drug-drug interactions between cART drugs and antidepressants, particularly in regard to dopamine in older people living with HIV. This review will discuss those interactions, first examining the etiology of NeuroHIV and depression in older adults, then discussing the interrelated effects of dopamine and inflammation on these disorders, and finally reviewing the activity and interactions of cART drugs and antidepressants on each of these factors. Developing better strategies to manage these comorbidities is critical to the health of the aging, HIV-infected population, as the older population may be particularly vulnerable to drug-drug interactions affecting dopamine.

Nafion-Radical Hybrid Films on Carbon Nanotube Transistors for Monitoring Antipsychotic Drug Effects on Stimulated Dopamine Release

We developed floating electrode-based carbon nanotube biosensors for the monitoring of antipsychotic drug effects on the dopamine release from PC12 cells under potassium stimulation. Here, carbon nanotube field-effect transistors with floating electrodes were functionalized with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^•) radicals by Nafion films. This method allows us to build selective biosensors for dopamine detection with a detection limit down to 10 nM even in the presence of other neurotransmitters such as glutamate and acetylcholine, resulting from the selective interaction between ABTS^• radicals and dopamine. The sensors were also utilized to monitor the real-time release of dopamine from PC12 cells upon the stimulation of high-concentrated potassium solutions. Significantly, the antipsychotic effects of pimozide on the dopamine release from potassium-stimulated PC12 cells could also be evaluated in a concentration-dependent manner by using the sensors. The quantitative and real-time evaluation capability of our strategy should provide a versatile tool for many biomedical studies and applications.

Effect of acute millimeter wave exposure on dopamine metabolism of NGF-treated PC12 cells

Several forthcoming wireless telecommunication systems will use electromagnetic frequencies at millimeter waves (MMWs), and technologies developed around the 60-GHz band will soon know a widespread distribution. Free nerve endings within the skin have been suggested to be the targets of MMW therapy which has been used in the former Soviet Union. So far, no studies have assessed the impact of MMW exposure on neuronal metabolism. Here, we investigated the effects of a 24-h MMW exposure at 60.4 GHz, with an incident power density (IPD) of 5 mW/cm², on the dopaminergic turnover of NGF-treated PC12 cells. After MMW exposure, both intracellular and extracellular contents of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were studied using high performance liquid chromatography. Impact of exposure on the dopamine transporter (DAT) expression was also assessed by immunocytochemistry. We analyzed the dopamine turnover by assessing the ratio of DOPAC to DA, and measuring DOPAC accumulation in the medium. Neither dopamine turnover nor DAT protein expression level were impacted by MMW exposure. However, extracellular accumulation of DOPAC was found to be slightly increased, but not significantly. This result was related to the thermal effect, and overall, no evidence of non-thermal effects of MMW exposure were observed on dopamine metabolism.

Early neuromodulation prevents the development of brain and behavioral abnormalities in a rodent model of schizophrenia

The notion that schizophrenia is a neurodevelopmental disorder in which neuropathologies evolve gradually over the developmental course indicates a potential therapeutic window during which pathophysiological processes may be modified to halt disease progression or reduce its severity. Here we used a neurodevelopmental maternal immune stimulation (MIS) rat model of schizophrenia to test whether early targeted modulatory intervention would affect schizophrenia's neurodevelopmental course. We applied deep brain stimulation (DBS) or sham stimulation to the medial prefrontal cortex (mPFC) of adolescent MIS rats and respective controls, and investigated its behavioral, biochemical, brain-structural and -metabolic effects in adulthood. We found that mPFC-DBS successfully prevented the emergence of deficits in sensorimotor gating, attentional selectivity and executive function in adulthood, as well as the enlargement of lateral ventricle volumes and mal-development of dopaminergic and serotonergic transmission. These data suggest that the mPFC may be a valuable target for effective preventive treatments. This may have significant translational value, suggesting that targeting the mPFC before the onset of psychosis via less invasive neuromodulation approaches may be a viable preventive strategy.

Protective effect of aripiprazole against glutamate cytotoxicity in dopaminergic neurons of rat mesencephalic cultures

Aripiprazole, a dopamine D(2) receptor partial agonist, is used to treat schizophrenia. Although aripiprazole has been reported to protect non-dopaminergic neurons, its effect on dopaminergic neurons has yet to be investigated. In the present study, we examined whether aripiprazole protected dopaminergic neurons against glutamate-induced cytotoxicity in rat mesencephalic cultures. Pretreatment with aripiprazole protected dopaminergic neurons in a concentration-dependent manner. The neuroprotective effect was not attenuated by sulpiride, a dopamine D(2) receptor antagonist, suggesting that the effect is independent of dopamine D(2) receptors. Aripiprazole reduced intracellular dopamine content in a concentration-dependent manner. In addition, its neuroprotective effect was partially inhibited when dopamine was added. These results suggest that aripiprazole protects dopaminergic neurons against glutamate cytotoxicity partly by reducing intracellular dopamine content.