Alzheimer's disease: a step closer to understanding type 3 diabetes in African Americans.

Alzheimer's disease (AD) is the fourth leading cause of death in the United States and the most common cause of adult-onset dementia. Recent results suggest an increased prevalence and severity in African Americans compared to Caucasians. Our understanding of the potential mechanism(s) underlying this ethnicity difference is limited. We previously described ethnicity-related differences in levels of neurodegenerative proteins and cytokines/chemokines in the BA21 region of African Americans and Caucasians with AD. Here, similar multiplex assays were used to examine those endpoints in patient postmortem cerebrospinal fluid (CSF). Additionally, we measured levels of C-peptide, ghrelin, gastric inhibitory polypeptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, PAI-1, resistin, and visfatin using a human diabetes 10-plex assay. The cytokine and chemokine assays revealed that levels of 26 chemokines or cytokines differed significantly with ethnicity, and three of those were significantly associated with gender. The neurodegenerative disease panel indicated that levels of soluble RAGE were significantly elevated in African Americans compared to Caucasians. All measures in the diabetes disease panel assay were significantly elevated in African Americans: ghrelin, GIP, GLP-1, glucagon, insulin, and visfatin. Through peripheral sample analysis, these results provide further evidence that ethnicity is critically involved in the manifestation of AD.

Increased inflammation in BA21 brain tissue from African Americans with Alzheimer's disease.

Chronic neuroinflammation is strongly associated with AD and altered peripheral and central levels of chemokines and cytokines have been frequently described in those with AD. Given the increasing evidence of ethnicity-related differences in AD, it was of interest to determine if those altered chemokine and cytokine levels are ethnicity-related. Because African Americans exhibit a higher incidence of AD and increased symptom severity, we explored chemokine and cytokine concentrations in post-mortem brain tissue from the BA21 region of African Americans and Caucasians with AD using multiplex assays. IL-1ß, MIG, TRAIL, and FADD levels were significantly increased in African Americans while levels of IL-3 and IL-8 were significantly decreased. Those effects did not interact with gender; however, overall levels of CCL25, CCL26 and CX3CL1 were significantly decreased in women. The NLRP3 inflammasome is thought to be critically involved in AD. Increased activation of this inflammasome in African Americans is consistent with the current results.

Comparative effect of lurasidone and blonanserin on cortical glutamate, dopamine, and acetylcholine efflux: role of relative serotonin (5-HT)2A and DA D2 antagonism and 5-HT1A partial agonism.

Atypical antipsychotic drugs (AAPDs) have been suggested to be more effective in improving cognitive impairment in schizophrenia than typical APDs, a conclusion supported by differences in receptor affinities and neurotransmitter efflux in the cortex and the hippocampus. More potent serotonin (5-HT)2A than dopamine (DA) D2 receptors antagonism, and direct or indirect 5-HT1A agonism, characterize almost all AAPDs. Blonanserin, an AAPD, has slightly greater affinity for D2 than 5-HT2A receptors. Using microdialysis and ultra performance liquid chromatography-mass spectrometry/mass spectrometry, we compared the abilities of the typical APD, haloperidol, three AAPDs, blonanserin, lurasidone, and olanzapine, and a selective 5-HT1A partial agonist, tandospirone, and all, except haloperidol, were found to ameliorate the cognitive deficits produced by the N-methyl-d-aspartate antagonist, phencyclidine, altering the efflux of neurotransmitters and metabolites in the rat cortex and nucleus accumbens. Blonanserin, lurasidone, olanzapine, and tandospirone, but not haloperidol, increased the efflux of cortical DA and its metabolites, homovanillic acid and 3,4-dihydroxyphenylacetic acid. Olanzapine and lurasidone increased the efflux of acetylcholine; lurasidone increased glutamate as well. None of the compounds significantly altered the efflux of 5-HT or its metabolite, 5-hydroxyindole acetic acid, or GABA, serine, and glycine. The ability to increase cortical DA efflux was the only shared effect of the compounds which ameliorates the deficit in cognition in rodents following phencyclidine.

Females' participation in psychopharmacology research as authors, editors, and subjects.

This study determined the involvement of women as first authors and other authors for every article published in Experimental and Clinical Psychopharmacology, Pharmacology Biochemistry and Behavior, and Psychopharmacology in 1991, 1996, 2001, and 2006. Their involvement as editors also was determined. Women's participation as authors, but not as editors, slightly increased over time. In 2006, 43% of first authors, 38% of other authors, and 24% of editors were women. The gender of subjects was examined for the same years and journals, but could not be determined for 6% and 9% of articles employing nonhuman and human subjects, respectively. In 2006, when subjects' gender could be determined, 77% of articles involving nonhuman subjects used only males, 9% only females, and 14% both males and females. In articles using human subjects in that same year, 17% involved only males, 6% only females, and 77% both males and females. Women researchers clearly make substantial contributions to the psychopharmacology literature, but are nonetheless underrepresented as editors. Findings regarding subjects indicate that there is growing recognition of the importance of gender as a determinant of drug effects, although the vast majority of nonhuman studies continue to involve only male subjects.

Oligomers of the amyloid-beta protein disrupt working memory: confirmation with two behavioral procedures.

Converging lines of evidence suggest that oligomers of amyloid-beta play a role in the cognitive impairment characteristic of Alzheimer's disease, but only three studies have provided experimental evidence of such impairment. To provide additional information about the effects of these oligomers on memory, the present study examined the memory of groups of rats exposed to ICV injections of the culture media (CM) of Chinese Hamster Ovary cells that were (7PA2) and were not (CHO-) transfected with a human mutation of amyloid precursor protein that appears to cause early-onset Alzheimer's disease. The 7PA2 CM, which contained concentrations of soluble amyloid-beta oligomers physiologically relevant to those found in human brain, significantly disrupted working memory in rats tested in a radial-arm maze. In contrast, CHO- CM, which did not contain such oligomers, had no effect on memory. The disruptive effects of 7PA2-derived amyloid-beta oligomers, evident 2h after exposure, disappeared within a day. These findings are compared to results from 7PA2 CM tested under a complex procedure thought to measure aspects of executive function. The results confirm the disruptive effects of low-n amyloid-beta oligomers and extend them to a well-established rat model of memory.

Neurodegenerative Markers are Increased in Postmortem BA21 Tissue from African Americans with Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) presents with an earlier onset age and increased symptom severity in African Americans and Hispanics. OBJECTIVE: Although the prevalence of plaques and tangles may not exhibit ethnicity-related differences, levels of neurodegenerative proteins have not been described. METHODS: Here, levels of five proteins (i.e., S100B, sRAGE, GDNF, Aß40, and Aß42) and the Aß42/Aß40 ratio were measured in postmortem samples of the middle temporal gyrus (BA21) from age-matched African Americans and Caucasians with AD (n = 6/gender/ethnicity). RESULTS: S100B levels were increased 17% in African Americans (p < 0.003) while sRAGE was mildly decreased (p < 0.09). Aß42 levels were increased 121% in African Americans (p < 0.02), leading to a 493% increase in the Aß42/Aß40 ratio (p < 0.002). Analysis of GDNF levels did not indicate any significant effects. There were no significant effects of gender and no significant ethnicity with gender interactions on any analyte. Effect size calculations indicated "medium" to "very large" effects. CONCLUSION: S100B is typically elevated in AD cases; however, the increased levels in African Americans here may be indicative of increased severity in specific populations. Increased Aß42/Aß40 ratios in the current study are compatible with increased disease severity and might indicate increased AD pathogenesis in African Americans. Overall, these results are compatible with a hypothesis of increased neuroinflammation in African Americans with AD.

Effects of perinatal methylphenidate (MPH) treatment in male and female Sprague-Dawley offspring.

MPH is a common treatment for adult Attention Deficit Hyperactivity Disorder (ADHD). However, little information exists regarding its safety during pregnancy and thus, women with ADHD face difficult decisions regarding continued use during pregnancy. Here, Sprague-Dawley rats were orally treated 3 ×/day with 0 (control), 6 (low), 18 (mid), or 42 (high) mg MPH/kg/day (i.e., 0, 2, 6, or 14 mg/kg at each treatment time) on gestational days 6-21. On postnatal days (PNDs) 1-21, all offspring/litter were orally treated 2 ×/day with the same dose. Righting reflex (PNDs 3-6) and slant board performance (PNDs 8-11) were assessed. T3, T4, E2, testosterone, LH and corticosterone were measured at PND 22. Separate pregnant dams and resulting litters were used for serum MPH measurements. MPH treatment had mild, but significant, effects on gestational body weight and food intake. Birth weight of high MPH offspring was 5% more than controls (p<0.0500). Relative to same-sex controls on PNDs 1-22, low and mid MPH males weighed more (p<0.0094), low MPH females weighed more (p<0.0001), while high MPH females weighed less (p<0.0397). PND 22 serum E2 levels were significantly decreased (20-25%) in high MPH males and females (p<0.0500). Behavioral performance was unaffected by treatment. Serum MPH levels of the low MPH pregnant dams were within the range produced by therapeutic MPH doses in adults; however, offspring levels in all groups were substantially higher. These results indicate that developmental MPH treatment has mild effects on gestational body weight and food intake and offspring preweaning body weight. Potential functional consequences of decreased serum E2 levels are not clear, but may impact later behavior or physiology.

Effects of developmental methylphenidate (MPH) treatment on monoamine neurochemistry of male and female rats.

Attention Deficit Hyperactivity Disorder (ADHD) is estimated to affect 4-5% of the adult human population (Kessler et al., 2006; Willcutt, 2012). Often prescribed to attenuate ADHD symptoms (Nair and Moss, 2009), methylphenidate hydrochloride (MPH) can have substantial positive effects. However, there is a paucity of literature regarding its use during pregnancy. Thus, adult women with ADHD face a difficult decision when contemplating pregnancy. In this study, pregnant Sprague-Dawley rats were orally treated a total of 0 (water), 6 (low), 18 (medium), or 42 (high) mg MPH/kg body weight/day (divided into three doses) on gestational days 6-21 (i.e., the low dose received 2 mg MPH/kg body weight 3×/day). Offspring were orally treated with the same daily dose as their dam (divided into two doses) on postnatal days (PNDs) 1-21. One offspring/sex/litter was sacrificed at PND 22 or PND 104 (n=6-7/age/sex/treatment group) and the striatum was quickly dissected and frozen. High Performance Liquid Chromatography (HPLC) coupled to a Photo Diode Array detector (PDA) was used to analyze monoamine content in the striatum of one side while a sandwich ELISA was used to analyze tyrosine hydroxylase (TH) from the other side. Age significantly affected monoamine and metabolite content as well as turnover ratios (i.e., DA, DOPAC, HVA, DOPAC/DA, HVA/DA, 5-HT and 5-HIAA); however, there were no significant effects of sex. Adult rats of the low MPH group had higher DA levels than control adults (p<0.05). At both ages, subjects of the low MPH group had higher TH levels than controls (p<0.05), although neither effect (i.e., higher DA or TH levels) exhibited an apparent dose-response. PND 22 subjects of the high MPH treatment group had higher ratios of HVA/DA and DOPAC/DA than same-age control subjects (p<0.05). The increased TH levels of the low MPH group may be related to the increased DA levels of adult rats. While developmental MPH treatment appears to have some effects on monoamine system development, further studies are required to determine if these alterations manifest as functional changes in behavior.

Modulatory effects of low-dose MDMA on cocaine-induced locomotor activity and place conditioning in rats.

Methylenedioxymethamphetamine (MDMA; "Ecstasy") is commonly abused by humans in environments such as nightclubs and rave parties where other drugs of abuse are readily available. Despite the popularity of polysubstance abuse among recreational MDMA users, relatively few controlled experimental studies have documented the neurobehavioral effects of MDMA in combination with other abused substances. This study employed conditioned place preference procedures (CPP) to assess the locomotor activating and place conditioning effects of acute concurrent administration of MDMA (1.5 or 3.0 mg/kg) and cocaine (10 or 20 mg/kg) in rats. Results indicate that low dose MDMA can enhance the locomotor and conditioned rewarding effects of cocaine. These findings may have important implications for understanding the contribution of serotonergic-dopaminergic interactions in the abuse liability of MDMA when used in combination with cocaine or other psychostimulant drugs.

An in vivo microdialysis assessment of concurrent MDMA and cocaine administration in Sprague-Dawley rats.

BACKGROUND AND RATIONALE: Despite the popularity of polysubstance abuse among recreational methylendioxymethamphetamine (MDMA) users, relatively few controlled experimental studies have documented the neurobehavioral effects of MDMA in combination with other abused substances. OBJECTIVE: In this study, the combined acute effects of MDMA and cocaine were examined by conducting in vivo microdialysis in the rat nucleus accumbens while simultaneously monitoring locomotor activity. METHODS: Male Sprague-Dawley rats were administered cocaine (10 or 20 mg/kg, i.p.), MDMA (1.5 or 3.0 mg/kg, i.p.), or one of four combinations of cocaine and MDMA during microdialysis experiments. Locomotor activity was monitored, and dialysis samples were collected every 30 min for 3 h prior to injections, for one 30-min period following saline injections, and for an additional 3-h period following drug injections. Samples were analyzed for dopamine content by high-performance liquid chromatography with electrochemical detection. RESULTS: Significant differences in locomotor activity and dopamine efflux were found among treatment groups, with some MDMA/cocaine combinations producing significantly greater increases compared to single doses of cocaine or MDMA within the first 30 min after injection. CONCLUSION: Considering the popularity of polysubstance use among recreational MDMA users, the clinical implications of the current findings warrant further investigation.

Comparison of the discriminative stimulus effects of salvinorin A and its derivatives to U69,593 and U50,488 in rats.

BACKGROUND AND RATIONALE: Research interests regarding the psychopharmacology of salvinorin A have been motivated by the recreational use and widespread media focus on the hallucinogenic plant, Salvia divinorum. Additionally, kappa opioid (KOP) receptor ligands may have therapeutic potential in the treatment of some neuropsychiatric conditions, including drug dependence and mood disorders. Salvinorin A is a selective KOP agonist, but only a few studies have explored the discriminative stimulus effects of this compound. OBJECTIVE: This study compared the discriminative stimulus effects of salvinorin A and two synthetic derivatives of salvinorin B to the KOP agonists, U69,593 and U50,488. MATERIALS AND METHODS: Sixteen male Sprague-Dawley rats trained to discriminate U69,593 (0.13 mg/kg, s.c., N = 8) or U50,488 (3.0 mg/kg, i.p., N = 8) under a fixed-ratio 20 schedule of food reinforcement were administered substitution tests with salvinorin A (0.125-3.0 mg/kg, i.p.). The animals trained to discriminate U69,593 were also administered substitution tests with salvinorin B ethoxymethyl ether (0.005-0.10 mg/kg, i.p.) and salvinorin B methoxymethyl ether (0.03-0.10 mg/kg, i.p.). Another eight rats were trained to discriminate 2.0 mg/kg salvinorin A and tested with U69,593 (0.04-0.32 mg/kg) and U50,488 (0.4-3.2 mg/kg). RESULTS: Salvinorin A and both synthetic derivatives of salvinorin B substituted completely for U69,593. Additionally, cross-generalization was observed between salvinorin A and both KOP agonists. CONCLUSION: These findings support previous reports indicating that the discriminative stimulus effects of salvinorin A are mediated by kappa receptors. Future studies may assist in the development and screening of salvinorin A analogs for potential pharmacotherapy.