Browsing by Author "Mackie, Ken"

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    Altered cerebellar-cortical resting-state functional connectivity in cannabis users
    (Sage, 2021) Schnakenberg Martin, Ashley M.; Kim, Dae-Jin; Newman, Sharlene D.; Cheng, Hu; Hetrick, William P.; Mackie, Ken; O’Donnell, Brian F.; Psychiatry, School of Medicine
    Background: Cannabis use has been associated with abnormalities in cerebellar mediated motor and non-motor (i.e. cognition and personality) phenomena. Since the cerebellum is a region with high cannabinoid type 1 receptor density, these impairments may reflect alterations of signaling between the cerebellum and other brain regions. Aims: We hypothesized that cerebellar-cortical resting-state functional connectivity (rsFC) would be altered in cannabis users, relative to their non-using peers. It was also hypothesized that differences in rsFC would be associated with cannabis use features, such as age of initiation and lifetime use. Methods: Cerebellar-cortical and subcortical rsFCs were computed between 28 cerebellar lobules, defined by a spatially unbiased atlas template of the cerebellum, and individual voxels in the cerebral regions, in 41 regular cannabis users (20 female) and healthy non-using peers (N = 31; 18 female). We also investigated associations between rsFC and cannabis use features (e.g. lifetime cannabis use and age of initiation). Results: Cannabis users demonstrated hyperconnectivity between the anterior cerebellar regions (i.e. lobule I-IV) with the posterior cingulate cortex, and hypoconnectivity between the rest of the cerebellum (i.e. Crus I and II, lobule VIIb, VIIIa, VIIIb, IX, and X) and the cortex. No associations were observed between features of cannabis use and rsFC. Conclusions: Cannabis use was associated with altered patterns of rsFC from the cerebellum to the cerebral cortex which may have a downstream impact on behavior and cognition.
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    Endocannabinoids Regulate Cerebellar Granule Cell Differentiation
    (2017-09) Essex, Amanda; Black, Kylie; Baygani, Shawyon; Mier, Tristan; Martinez, Ricardo; Mackie, Ken; Kalinovsky, Anna
    The cerebellum plays a crucial role in learning and execution of complex automated behaviors, including fine motor skills, language, and emotional regulation. Cerebellar development continues throughout an extended postnatal period. The most numerous neurons in the cerebellum, as well as the entire brain, are the cerebellar granule cells (GCs), which are generated in a dedicated secondary proliferative zone, the external granule cell layer (EGL), during the first three postnatal weeks in mice, and over a year in humans. The robust expansion of granule cells during early development is responsible for the majority of cerebellar expansion. Morphological and molecular changes that drive GC proliferation and differentiation have been extensively characterized, starting from the developmental studies by Santiago Ramón y Cajal. GC progenitors (GCPs) proliferate in the outer EGL (oEGL). As they are pushed into the inner EGL (iEGL) by the newly generated GCPs, they exit the cell cycle and begin differentiation, first extending bipolar neurites, followed by tangential migration, and eventually radial migration to the inner granule cell layer (IGL), their target territory. Deregulation of GCPs expansion, proliferation to differentiation switch, or the rate of migration could contribute to abnormal cerebellar size and compartmentalization and disrupt cerebellar circuits’ wiring and function. Endocannabinoids (eCBs) have been identified as key players regulating neuron proliferation and migration in the fore- and mid-brain development, however their role in cerebellar development has not yet been explored in detail. Our preliminary results show robust expression of cannabinoid receptor 1 (CB1) in iEGL GCs, concomitant with expression diacylglycerol lipase α (DGLα) a major enzyme required for the synthesis of eCB 2-arachidonoylglycerol (2-AG), in PCs. Furthermore, our preliminary results show that cerebellar size is reduced in CB1 KOs. In this study we investigate the mechanisms through which eCB signaling may regulate GC proliferation and differentiation, focusing on the GCPs cycle length, rate of differentiation and migration.
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    Examining Simultaneous Alcohol and ∆9-Tetrahydrocannabinol Self-Administration on Behavioral Flexibility and Dorsal Striatal CB1 Expression in cHAP Mice
    (2020-08) Millie, Lauren A.; Grahame, Nicholas; Boehm, Stephen; Logrip, Marian; Mackie, Ken
    Although marijuana and alcohol are two of the most commonly used drugs in the United States, relatively little is understood about how these drugs interact to effect drug use, cognitive behaviors, and neurophysiological changes. Specific drug use patterns such as simultaneous use may produce differential effects for consumption and other behaviors in addition to unique neurobiological changes compared to singular drug use. In order to better understand the effects of simultaneous alcohol and marijuana (SAM) use, we used the selectively bred crossed High Alcohol Preferring mice to examine consummatory, cognitive, and neurobiological changes following chronic alcohol and THC self-administration. We hypothesized that SAM mice would consume more drug than animals exposed to either substance alone. We used an operant behavioral flexibility paradigm to assess cognitive impairments believing that drug-exposed animals would show deficits relative to Control animals, with SAM mice being the most impaired of all drug conditions. Finally, we assessed CB1 receptor changes in the dorsal striatum, as this region is critical for behavioral flexibility (Bissonette & Powell, 2012; Ragozzino, 2007), CB1 receptors are the primary target of THC and these receptors are involved in numerous alcohol related behaviors (Maldonado et al., 2006; Pava & Woodward, 2012). Contrary to our hypothesis, SAM animals did not consume higher levels of drug compared to mice exposed to only THC or alcohol. Interestingly, female THC consumption was robust when THC was consumed alone but was reduced when simultaneous access to alcohol was available. Surprisingly, although we speculated that drug-exposed mice would be impaired compared to Control animals, and that SAM animals would likely be more compromised than THC and alcohol for Reversal Learning and Attentional Set-Shifting respectively, behavioral flexibility deficits were absent in our paradigm. Finally, alterations to dorsal striatal CB1 receptor expression were observed following a Short Abstinence period. Despite an absence of cognitive behavioral effects, this research contributes to furthering our understanding of co-drug use for consummatory and neurobiological changes, both of which are critically necessary given the evolving landscape surrounding simultaneous alcohol and recreational marijuana use.
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    Long-Term Aberrations To Cerebellar Endocannabinoids Induced By Early-Life Stress
    (Nature Research, 2020-04-29) Moussa-Tooks, Alexandra B.; Larson, Eric R.; Gimeno, Alex F.; Leishman, Emma; Bartolomeo, Lisa A.; Bradshaw, Heather B.; Green, John T.; O’Donnell, Brian F.; Mackie, Ken; Hetrick, William P.; Psychiatry, School of Medicine
    Emerging evidence points to the role of the endocannabinoid system in long-term stress-induced neural remodeling with studies on stress-induced endocannabinoid dysregulation focusing on cerebral changes that are temporally proximal to stressors. Little is known about temporally distal and sex-specific effects, especially in cerebellum, which is vulnerable to early developmental stress and is dense with cannabinoid receptors. Following limited bedding at postnatal days 2-9, adult (postnatal day 70) cerebellar and hippocampal endocannabinoids, related lipids, and mRNA were assessed, and behavioral performance evaluated. Regional and sex-specific effects were present at baseline and following early-life stress. Limited bedding impaired peripherally-measured basal corticosterone in adult males only. In the CNS, early-life stress (1) decreased 2-arachidonoyl glycerol and arachidonic acid in the cerebellar interpositus nucleus in males only; (2) decreased 2-arachidonoyl glycerol in females only in cerebellar Crus I; and (3) increased dorsal hippocampus prostaglandins in males only. Cerebellar interpositus transcriptomics revealed substantial sex effects, with minimal stress effects. Stress did impair novel object recognition in both sexes and social preference in females. Accordingly, the cerebellar endocannabinoid system exhibits robust sex-specific differences, malleable through early-life stress, suggesting the role of endocannabinoids and stress to sexual differentiation of the brain and cerebellar-related dysfunctions.
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    Self-administration of edible Δ9-tetrahydrocannabinol and associated behavioral effects in mice
    (Elsevier, 2019) Smoker, Michael P.; Mackie, Ken; Lapish, Christopher C.; Boehm, Stephen L., II; Psychology, School of Science
    Background With increasing access to legal cannabis across the globe, it is imperative to more closely study its behavioral and physiological effects. Furthermore, with the proliferation of cannabis use, modes of consumption are changing, with edible formulations becoming increasingly popular. Nevertheless, there are relatively few animal models of self-administration of the primary psychoactive component of cannabis, Δ9-tetrahydrocannabinol (THC), and almost all incorporate routes of administration other than those used by humans. The aim of the current study was to develop a model of edible THC self-administration and assess its impact on CB1 receptor-mediated behaviors in female and male mice. Methods Mice were given limited access to a palatable dough which occasionally contained THC in doses ranging from 1 to 10 mg/kg. Following dough consumption, mice were assessed for home cage locomotor activity, body temperature, or analgesia. Locomotor activity was also assessed in conjunction with the CB1 receptor antagonist SR141716A. Results Dough was well-consumed, but consumption decreased at the highest THC concentrations. Edible THC produced dose-dependent decreases in locomotor activity and body temperature in both sexes, and these effects were more pronounced in male mice. Hypolocomotion induced by edible THC was attenuated by SR141716A, indicating mediation by CB1 receptor activation. Conclusions In contrast to other cannabinoid self-administration models, edible THC is relatively low in stress and uses a route of administration analogous to one used by humans. Potential applications include chronic THC self-administration, determining THC reward/reinforcement, and investigating consequences of oral THC use.
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    Short-Term Genetic Selection for Adolescent Locomotor Sensitivity to Delta9-Tetrahydrocannabinol (THC)
    (Springer Nature, 2018-05) Kasten, Chelsea R.; Zhang, Yanping; Mackie, Ken; Boehm, Stephen L., II; Psychology, School of Science
    Cannabis use is linked to positive and negative outcomes. Identifying genetic targets of susceptibility to the negative effects of cannabinoid use is of growing importance. The current study sought to complete short-term selective breeding for adolescent sensitivity and resistance to the locomotor effects of a single 10 mg/kg THC dose in the open field. Selection for THC-locomotor sensitivity was moderately heritable, with the greatest estimates of heritability seen in females from the F2 to S3 generations. Selection for locomotor sensitivity also resulted in increased anxiety-like activity in the open field. These results are the first to indicate that adolescent THC-locomotor sensitivity can be influenced via selective breeding. Development of lines with a genetic predisposition for THC-sensitivity or resistance to locomotor effects allow for investigation of risk factors, differences in consequences of THC use, identification of correlated behavioral responses, and detection of genetic targets that may contribute to heightened cannabinoid sensitivity.
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    Tubular Human Brain Organoids to Model Microglia-Mediated Neuroinflammation
    (Royal Society of Chemistry, 2021) Ao, Zheng; Cai, Hongwei; Wu, Zhuhao; Song, Sunghwa; Karahan, Hande; Kim, Byungwook; Lu, Hui-Chen; Kim, Jungsu; Mackie, Ken; Guo, Feng; Medical and Molecular Genetics, School of Medicine
    Human brain organoids, 3D brain tissue cultures derived from human pluripotent stem cells, hold promising potential in modeling neuroinflammation for a variety of neurological diseases. However, challenges remain in generating standardized human brain organoids that can recapitulate key physiological features of a human brain. Here, we present a tubular organoids-on-a-chip device to generate better organoids and model neuroinflammation. By employing 3D printed hollow mesh scaffolds, our device can be easily incorporated into multiwell-plates for reliable, scalable, and reproducible generation of tubular organoids. By introducing rocking flows through the tubular device channel, our device can perfuse nutrients and oxygen to minimize organoid necrosis and hypoxia, and incorporate immune cells into organoids to model neuro-immune interactions. Compared with conventional protocols, our method increased neural progenitor proliferation and reduced heterogeneity of human brain organoids. As a proof-of-concept application, we applied this method to model the microglia-mediated neuroinflammation after exposure to an opioid. We found isogenic microglia were activated after exposure to an opioid receptor agonist (DAMGO) and transformed back to the homeostatic status with further treatment by a cannabinoid receptor 2 agonist (LY2828360). Importantly, the activated microglia in tubular organoids had a stronger cytokine response compared to those in 2D microglial cultures. Our tubular organoid device is simple, versatile, inexpensive, easy-to-use, and compatible with multiwell-plates, so it can be widely used in common research and clinical laboratory settings. This technology can be broadly used for basic and translational applications in inflammatory diseases including substance use disorders, neural diseases, autoimmune disorders, and infectious diseases.