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Chitre AS, Hebda-Bauer EK, Blandino P, Bimschleger H, Nguyen KM, Maras P, Li F, Ozel AB, Pan Y, Polesskaya O, Cheng R, Flagel SB, Watson SJ, Li J, Akil H, Palmer AA. Genome-wide association study in a rat model of temperament identifies multiple loci for exploratory locomotion and anxiety-like traits. Front Genet 2023; 13:1003074. [PMID: 36712851 PMCID: PMC9873817 DOI: 10.3389/fgene.2022.1003074] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/20/2022] [Indexed: 01/12/2023] Open
Abstract
Common genetic factors likely contribute to multiple psychiatric diseases including mood and substance use disorders. Certain stable, heritable traits reflecting temperament, termed externalizing or internalizing, play a large role in modulating vulnerability to these disorders. To model these heritable tendencies, we selectively bred rats for high and low exploration in a novel environment [bred High Responders (bHR) vs. Low Responders (bLR)]. To identify genes underlying the response to selection, we phenotyped and genotyped 538 rats from an F2 cross between bHR and bLR. Several behavioral traits show high heritability, including the selection trait: exploratory locomotion (EL) in a novel environment. There were significant phenotypic and genetic correlations between tests that capture facets of EL and anxiety. There were also correlations with Pavlovian conditioned approach (PavCA) behavior despite the lower heritability of that trait. Ten significant and conditionally independent loci for six behavioral traits were identified. Five of the six traits reflect different facets of EL that were captured by three behavioral tests. Distance traveled measures from the open field and the elevated plus maze map onto different loci, thus may represent different aspects of novelty-induced locomotor activity. The sixth behavioral trait, number of fecal boli, is the only anxiety-related trait mapping to a significant locus on chromosome 18 within which the Pik3c3 gene is located. There were no significant loci for PavCA. We identified a missense variant in the Plekhf1 gene on the chromosome 1:95 Mb QTL and Fancf and Gas2 as potential candidate genes that may drive the chromosome 1:107 Mb QTL for EL traits. The identification of a locomotor activity-related QTL on chromosome 7 encompassing the Pkhd1l1 and Trhr genes is consistent with our previous finding of these genes being differentially expressed in the hippocampus of bHR vs. bLR rats. The strong heritability coupled with identification of several loci associated with exploratory locomotion and emotionality provide compelling support for this selectively bred rat model in discovering relatively large effect causal variants tied to elements of internalizing and externalizing behaviors inherent to psychiatric and substance use disorders.
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Affiliation(s)
- Apurva S. Chitre
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Elaine K. Hebda-Bauer
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - Peter Blandino
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - Hannah Bimschleger
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Khai-Minh Nguyen
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Pamela Maras
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - Fei Li
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - A. Bilge Ozel
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
| | - Yanchao Pan
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
| | - Oksana Polesskaya
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Riyan Cheng
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Shelly B. Flagel
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - Stanley J. Watson
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - Jun Li
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
| | - Huda Akil
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - Abraham A. Palmer
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States,Institute for Genomic Medicine, University of California San Diego, La Jolla, CA, United States,*Correspondence: Abraham A. Palmer,
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Jain N, Smirnovs M, Strojeva S, Murovska M, Skuja S. Chronic Alcoholism and HHV-6 Infection Synergistically Promote Neuroinflammatory Microglial Phenotypes in the Substantia Nigra of the Adult Human Brain. Biomedicines 2021; 9:biomedicines9091216. [PMID: 34572401 PMCID: PMC8472392 DOI: 10.3390/biomedicines9091216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/08/2021] [Accepted: 09/11/2021] [Indexed: 12/25/2022] Open
Abstract
Both chronic alcoholism and human herpesvirus-6 (HHV-6) infection have been identified as promoters of neuroinflammation and known to cause movement-related disorders. Substantia Nigra (SN), the dopaminergic neuron-rich region of the basal ganglia, is involved in regulating motor function and the reward system. Hence, we hypothesize the presence of possible synergism between alcoholism and HHV-6 infection in the SN region and report a comprehensive quantification and characterization of microglial functions and morphology in postmortem brain tissue from 44 healthy, age-matched alcoholics and chronic alcoholics. A decrease in the perivascular CD68+ microglia in alcoholics was noted in both the gray and white matter. Additionally, the CD68+/Iba1− microglial subpopulation was found to be the dominant type in the controls. Conversely, in alcoholics, dystrophic changes in microglia were seen with a significant increase in Iba1 expression and perivascular to diffuse migration. An increase in CD11b expression was noted in alcoholics, with the Iba1+/CD11b− subtype promoting inflammation. All the controls were found to be negative for HHV-6 whilst the alcoholics demonstrated HHV-6 positivity in both gray and white matter. Amongst HHV-6 positive alcoholics, all the above-mentioned changes were found to be heightened when compared with HHV-6 negative alcoholics, thereby highlighting the compounding relationship between alcoholism and HHV-6 infection that promotes microglia-mediated neuroinflammation.
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Affiliation(s)
- Nityanand Jain
- Joint Laboratory of Electron Microscopy, Institute of Anatomy and Anthropology, Rīga Stradiņš University, LV-1010 Riga, Latvia;
- Correspondence: (N.J.); (S.S.); Tel.: +371-673-204-21 (N.J. & S.S.)
| | - Marks Smirnovs
- Joint Laboratory of Electron Microscopy, Institute of Anatomy and Anthropology, Rīga Stradiņš University, LV-1010 Riga, Latvia;
| | - Samanta Strojeva
- Institute of Microbiology and Virology, Rīga Stradiņš University, LV-1067 Riga, Latvia; (S.S.); (M.M.)
| | - Modra Murovska
- Institute of Microbiology and Virology, Rīga Stradiņš University, LV-1067 Riga, Latvia; (S.S.); (M.M.)
| | - Sandra Skuja
- Joint Laboratory of Electron Microscopy, Institute of Anatomy and Anthropology, Rīga Stradiņš University, LV-1010 Riga, Latvia;
- Correspondence: (N.J.); (S.S.); Tel.: +371-673-204-21 (N.J. & S.S.)
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Meyer PJ, Phillips TJ. Sensitivity to ketamine, alone or in combination with ethanol, is altered in mice selectively bred for sensitivity to ethanol's locomotor effects. Alcohol Clin Exp Res 2004; 27:1701-9. [PMID: 14634484 DOI: 10.1097/01.alc.0000093602.00193.39] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Sensitivity to erthanol's locomotor activating and reinforcing effects may be influenced by some common neural mechanisms. Mice selectively bred in replicate for increased (FAST-1 and FAST-2) and decreased (SLOW-1 and SLOW-2) sensitivity to ethanol's locomotor stimulant effects are useful for investigating the neural substrates of ethanol's effects. Previous studies have suggested that differences in N-methyl-d-aspartate (NMDA) receptors may underlie differences in ethanol-induced locomotion in these mice. This study examined the responses of FAST and SLOW mice to ketamine, a fast-acting NMDA antagonist. In addition, reverse-selected lines (r-FAST-1, r-FAST-2, r-SLOW-1, and r-SLOW-2) were tested as a means of verifying correlations detected in the forward-selected lines. Two initial studies characterized ketamine-induced locomotion in DBA/2J (D2) mice, an inbred strain chosen for its high sensitivity to ethanol-induced locomotion. METHODS After a 2- to 3-day period of habituation to test procedures, mice were given intraperitoneal injections of ketamine alone (0, 5, 10, 20, 30, and 60 mg/kg) or in combination with 1 or 2 g/kg ethanol. Locomotor activity was measured for 20 to 30 min in automated activity monitors. RESULTS When administered alone, ketamine dose-dependently stimulated the locomotor activity of D2 mice and also reduced the amount of ethanol-induced stimulation. Ketamine stimulated locomotion more in FAST mice than in SLOW mice. Reverse selection abolished these differences, because r-FAST and r-SLOW mice did not differ in their responses to ketamine. Ketamine potentiated ethanol's locomotor effects within FAST mice and potentiated ethanol's locomotor depressant effect within one replicate of SLOW mice. CONCLUSIONS We propose that sensitivities to ethanol- and ketamine-induced locomotion are genetically correlated and that the combined effects of ethanol and ketamine in FAST mice reflect a leftward shift in ethanol's biphasic dose-response curve.
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Affiliation(s)
- Paul J Meyer
- Department of Behavioral Neuroscience and Portland Alcohol Research Center, Oregon Health & Science University, USA
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Bergstrom HC, Palmer AA, Wood RD, Burkhart-Kasch S, McKinnon CS, Phillips TJ. Reverse Selection for Differential Response to the Locomotor Stimulant Effects of Ethanol Provides Evidence for Pleiotropic Genetic Influence on Locomotor Response to Other Drugs of Abuse. Alcohol Clin Exp Res 2003; 27:1535-47. [PMID: 14574223 DOI: 10.1097/01.alc.0000091226.18969.b9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Addictive drugs share the ability to induce euphoria, which may be associated with their potential for abuse. Replicate mouse lines with high (FAST-1, FAST-2) and low (SLOW-1, SLOW-2) sensitivity to ethanol-induced psychomotor stimulation (a possible animal model for the euphoria experienced by humans) have provided evidence for common genetic influences (pleiotropy) on sensitivity to the effects of ethanol and of GABA-A receptor acting compounds on locomotor activity. Differences between FAST and SLOW mice in locomotor response to certain other drugs were found later in selection. Reverse selection produced lines (r-FAST-1, r-FAST-2, r-SLOW-1, r-SLOW-2) with similar locomotor responses to ethanol. These lines are well suited for asking whether the same alleles that influence sensitivity to ethanol are also responsible for these later arising differences in drug sensitivity. METHODS Two replicate sets of forward- and reverse-selected FAST and SLOW lines were tested for the effects of multiple doses of morphine, cocaine, methamphetamine, nicotine, and scopolamine on their locomotor behavior. We predicted that differences in drug sensitivity between the FAST and SLOW lines would be reduced or eliminated in the reverse-selected lines. RESULTS Differences in sensitivity to morphine, cocaine, methamphetamine, and nicotine that arose in earlier generations of the FAST-1 and SLOW-1 lines ultimately also appeared in the FAST-2 and SLOW-2 lines. However, some differences between the FAST-2 and SLOW-2 lines (those in response to cocaine and methamphetamine) were not seen until several generations after selection had been relaxed. In lines reverse-selected for sensitivity to ethanol, differences in sensitivity to the other drugs were decreased, eliminated, or even reversed. No differences in scopolamine response were found in the replicate 1 forward- or reverse-selected lines. However, a small difference in scopolamine response in the replicate 2 lines was reversed. CONCLUSIONS Genes that influence the locomotor response to ethanol also influence locomotor response to other drugs with stimulant effects in the FAST and SLOW mice. The current data most strongly support this conclusion for sensitivity to morphine and nicotine.
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Affiliation(s)
- Hadley C Bergstrom
- Department of Veterans Affairs Medical Center, Research Service, Portland, Oregon 97239, USA
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Palmer AA, McKinnon CS, Bergstrom HC, Phillips TJ. Locomotor activity responses to ethanol, other alcohols, and GABA-A acting compounds in forward- and reverse-selected FAST and SLOW mouse lines. Behav Neurosci 2002; 116:958-67. [PMID: 12492294 DOI: 10.1037/0735-7044.116.6.958] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mice selectively bred for high (FAST) or low (SLOW) locomotor stimulant response to ethanol have been found to differ in response to drugs with gamma-aminobutyric acid (GABA)-ergic actions. Reverse selection produced lines that are similar in sensitivity to ethanol stimulation (r-FAST and r-SLOW) and provided a unique model for testing hypotheses about shared genetic influence on sensitivity to ethanol and GABAergic drugs. FAST mice were more stimulated than SLOW mice by all drugs tested: ethanol, methanol, n-propanol, t-butanol, pentobarbital, diazepam, and allopregnanolone. In contrast, r-FAST and r-SLOW mice differed in sensitivity to only a few isolated drug doses. Locomotor responses of each reverse-selected line were significantly different from the responses of their respective forward-selected line for all drugs. Results support an effect of selection for ethanol sensitivity on allosteric modulation of the GABA-A receptor.
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