Glucagon-Like Peptide 1 (GLP-1) has insulin-like effects on myocardial glucose uptake which may contribute to its beneficial effects in the setting of myocardial ischemia. Whether these effects are different in the setting of obesity or type 2 diabetes (T2DM) requires investigation. We examined the cardiometabolic actions of GLP-1 (7–36) in lean and obese/T2DM humans, and in lean and obese Ossabaw swine. GLP-1 significantly augmented myocardial glucose uptake under resting conditions in lean humans, but this effect was impaired in T2DM. This observation was confirmed and extended in swine, where GLP-1 effects to augment myocardial glucose uptake during exercise were seen in lean but not in obese swine. GLP-1 did not increase myocardial oxygen consumption or blood flow in humans or in swine. Impaired myocardial responsiveness to GLP-1 in obesity was not associated with any apparent alterations in myocardial or coronary GLP1-R expression. No evidence for GLP-1 mediated activation of cAMP/PKA or AMPK signaling in lean or obese hearts was observed. GLP-1 treatment augmented p38-MAPK activity in lean, but not obese cardiac tissue. Taken together, these data provide novel evidence indicating that the cardiometabolic effects of GLP-1 are attenuated in obesity and T2DM, via mechanisms that may involve impaired p38-MAPK signaling.
BACKGROUND Although the incidence of cannabis abuse/dependence in Americans is rising, the neurobiology of cannabis addiction is not well understood. Imaging studies have demonstrated deficits in striatal D2/D3 receptor availability in several substance-dependent populations. However, this has not been studied in currently-using chronic cannabis users. OBJECTIVE The purpose of this study was to compare striatal D2/D3 receptor availability between currently-using chronic cannabis users and healthy controls. METHODS Eighteen right-handed males age 18–34 were studied. Ten subjects were chronic cannabis users; eight were demographically matched controls. Subjects underwent a [11C] raclopride (RAC) PET scan. Striatal RAC binding potential (BPND) was calculated on a voxel-wise basis. Prior to scanning, urine samples were obtained from cannabis users for quantification of urine Δ-9-tetrahydrocannabinol (THC) and THC metabolites (11-nor-Δ-9-THC-9-carboxylic acid; THC-COOH and 11-hydroxy-THC;OH-THC). Results There were no differences in D2/D3 receptor availability between cannabis users and controls. Voxel-wise analyses revealed that RAC BPND values were negatively associated with both urine levels of cannabis metabolites and self-report of recent cannabis consumption. CONCLUSIONS In this sample, current cannabis use was not associated with deficits in striatal D2/D3 receptor availability. There was an inverse relationship between chronic cannabis use and striatal RAC BPND. Additional studies are needed to identify the neurochemical consequences of chronic cannabis use on the dopamine system.
-Altered myocardial fuel selection likely underlies cardiac disease risk in diabetes, affecting oxygen demand and myocardial metabolic flexibility. We investigated myocardial fuel selection and metabolic flexibility in human type 2 diabetes mellitus (T2DM), using positron emission tomography to measure rates of myocardial fatty acid oxidation {16-[ 18 F]fluoro-4-thia-palmitate (FTP)} and myocardial perfusion and total oxidation ([ 11 C]acetate). Participants underwent paired studies under fasting conditions, comparing 3-h insulin ϩ glucose euglycemic clamp conditions (120 mU·m Ϫ2 ·min Ϫ1 ) to 3-h saline infusion. Lean controls (n ϭ 10) were compared with glycemically controlled volunteers with T2DM (n ϭ 8). Insulin augmented heart rate, blood pressure, and stroke index in both groups (all P Ͻ 0.01) and significantly increased myocardial oxygen consumption (P ϭ 0.04) and perfusion (P ϭ 0.01) in both groups. Insulin suppressed available nonesterified fatty acids (P Ͻ 0.0001), but fatty acid concentrations were higher in T2DM under both conditions (P Ͻ 0.001). Insulin-induced suppression of fatty acid oxidation was seen in both groups (P Ͻ 0.0001). However, fatty acid oxidation rates were higher under both conditions in T2DM (P ϭ 0.003). Myocardial work efficiency was lower in T2DM (P ϭ 0.006) and decreased in both groups with the insulin-induced increase in work and shift in fuel utilization (P ϭ 0.01). Augmented fatty acid oxidation is present under baseline and insulin-treated conditions in T2DM, with impaired insulin-induced shifts away from fatty acid oxidation. This is accompanied by reduced work efficiency, possibly due to greater oxygen consumption with fatty acid metabolism. These observations suggest that improved fatty acid suppression, or reductions in myocardial fatty acid uptake and retention, could be therapeutic targets to improve myocardial ischemia tolerance in T2DM. myocardial; heart; diabetes; metabolism; metabolic flexibility; positron emission tomography ALTERATIONS IN METABOLIC SUBSTRATE uptake and metabolism are part of the phenotype that defines type 2 diabetes mellitus (T2DM) (3,4,33,39,74). The phenomenon of "metabolic flexibility" is the capacity of an organism, a tissue bed, or a cell system to switch readily among fuel types. Impaired metabolic flexibility is another phenotypic feature of T2DM (33, 66).Impaired metabolic flexibility has been demonstrated in skeletal muscle in human diabetes (32,66). This whole body effect likely arises due to effects of impaired insulin-stimulated glucose uptake, together with abnormalities in availability, uptake, and metabolism of fatty acid fuels (33,66,75).The myocardium is also affected by T2DM. The fuel needs of the heart are dramatically different than those of skeletal muscle, supporting continuous work even under resting conditions. Abnormalities in myocardial fuel selection in animal models of diabetes have been described (42,54,75), including impairments in insulin-stimulated glucose uptake and impaired suppression of myocardial fatty acid u...
The current study examined the websites of the 231 clinical psychology doctoral programs accredited by the American Psychological Association (APA) in 2007 and found that more than half described themselves as offering a track, emphasis, certificate, or degree in a specialized training area. About 18% of programs required students to enroll in a specialized training stream. The most common areas of specialized training were clinical child, clinical health, forensic, family, and clinical neuropsychology. The most common format for specialized training was a track within a general clinical training program. A greater percentage of PsyD programs than PhD programs offered specialized training,and PsyD programs offered more areas of specialization than PhD programs. Overall, results indicate that specialized training is common among APA-accredited clinical psychology doctoral programs.
Knowledge of the reproducibility of striatal [11C]raclopride (RAC) binding is important for studies that use RAC PET paradigms to estimate changes in striatal dopamine during pharmacological and cognitive challenges. To our knowledge, no baseline test-retest data exist for nontreatment-seeking alcoholics (NTS). We determined the test-retest reproducibility of baseline RAC binding potential (BPND) in twelve male NTS subjects. Subjects were scanned twice with single-bolus RAC PET on separate days. Striatal RAC binding potential (BPND) for left and right dorsal caudate, dorsal putamen, and ventral striatum was estimated using the Multilinear Reference Tissue Method (MRTM) and Logan Graphical Analysis with a reference region (LGA). Test-retest variability (TRV), % change in BPND between scan days, and the intraclass correlation coefficient (ICC) were used as metrics of reproducibility. For MRTM, TRV for striatal RAC binding in NTS subjects was ± 6.5%, and ± 7.1% for LGA. Average striatal ICCs were 0.94 for both methods (p < 0.0001). Striatal BPND values were similar to those reported previously for detoxified alcoholics. The results demonstrate that baseline striatal RAC binding is highly reproducible in NTS subjects, with a low variance similar to that reported for healthy control subjects.
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