1
|
Vorhees CV, Williams MT. Tests for learning and memory in rodent regulatory studies. Curr Res Toxicol 2024; 6:100151. [PMID: 38304257 PMCID: PMC10832385 DOI: 10.1016/j.crtox.2024.100151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 02/03/2024] Open
Abstract
For decades, regulatory guidelines for safety assessment in rodents for drugs, chemicals, pesticides, and food additives with developmental neurotoxic potential have recommended a single test of learning and memory (L&M). In recent years some agencies have requested two such tests. Given the importance of higher cognitive function to health, and the fact that different types of L&M are mediated by different brain regions assessing higher functions represents a step forward in providing better evidence-based protection against adverse brain effects. Given the myriad of tests available for assessing L&M in rodents this leads to the question of which tests best fit regulatory guidelines. To address this question, we begin by describing the central role of two types of L&M essential to all mammalian species and the regions/networks that mediate them. We suggest that the tests recommended possess characteristics that make them well suited to the needs in regulatory safety studies. By brain region, these are (1) the hippocampus and entorhinal cortex for spatial navigation, which assesses explicit L&M for reference and episodic memory and (2) the striatum and related structures for egocentric navigation, which assesses implicit or procedural memory and path integration. Of the tests available, we suggest that in this context, the evidence supports the use of water mazes, specifically, the Morris water maze (MWM) for spatial L&M and the Cincinnati water maze (CWM) for egocentric/procedural L&M. We review the evidentiary basis for these tests, describe their use, and explain procedures that optimize their sensitivity.
Collapse
Affiliation(s)
- Charles V. Vorhees
- Corresponding author at: Div. of Neurology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA.
| | | |
Collapse
|
2
|
Torres DJ, Yorgason JT, Andres MA, Bellinger FP. Methamphetamine Exposure During Development Causes Lasting Changes to Mesolimbic Dopamine Signaling in Mice. Cell Mol Neurobiol 2022; 42:2433-2438. [PMID: 34138411 PMCID: PMC8678368 DOI: 10.1007/s10571-021-01120-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 06/11/2021] [Indexed: 10/21/2022]
Abstract
Methamphetamine (MA) abuse remains a public health issue. Prenatal MA exposure (PME) poses a significant health problem, as we know very little about the drug's long-term physiological impact on the developing human brain. We investigated the long-term consequences of early MA exposure using a mouse model that targets the brain growth spurt, which occurs during human third-trimester. Adult mice previously subjected to acute MA during post-natal days 4-9 exhibited hyperactivity during the Open-Field Test, while exhibiting no motor coordination changes during the Rotarod Test. Neonatal MA exposure reduced basal dopamine (DA) uptake rates in adult nucleus accumbens slices compared with saline-injected controls. Although slices from neonatal MA-exposed mice showed no change in evoked DA signals in the presence of MA, they exhibited potentiated non-evoked DA release through DA efflux in response to MA. These data suggest that developmental MA exposure alters brain development to produce long-lasting physiological changes to the adult mesolimbic DA system, as well as altering responses to acute MA exposure in adulthood. This study provides new insights into an important, under-investigated area in drugs of abuse research.
Collapse
Affiliation(s)
- Daniel J Torres
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, 96813, USA.
- Pacific Biosciences Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI, 96822, USA.
| | - Jordan T Yorgason
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA
| | - Marilou A Andres
- Pacific Biosciences Research Center, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI, 96822, USA
| | - Frederick P Bellinger
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, 96813, USA
| |
Collapse
|
3
|
Vorhees CV, Williams MT. Issues in the design, analysis, and application of rodent developmental neurotoxicology studies. Neurotoxicol Teratol 2021; 87:107018. [PMID: 34256163 PMCID: PMC8440477 DOI: 10.1016/j.ntt.2021.107018] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 07/02/2021] [Accepted: 07/09/2021] [Indexed: 12/16/2022]
Abstract
Developmental neurotoxicity (DNT) studies could benefit from revisions to study design, data analysis, and some behavioral test methods to enhance reproducibility. The Environmental Protection Agency (EPA) reviewed 69 studies submitted to the Office of Pesticide Programs. Two of the behavioral tests identified the lowest observable adverse effect level (LOAEL) 20 and 13 times, respectively, while the other two tests identified the LOAEL only 3 and 4 times, respectively. The EPA review showed that the functional observational battery (FOB) was least effective at detecting the LOAEL, whereas tests of learning and memory (L&M) had methodological shortcomings. Human neurodevelopmental toxicity studies over the past 30 years show that most of the adverse effects are on higher cognitive functions such as L&M. The results of human studies together with structure-function relationships from neuroscience, suggest that tests of working memory, spatial navigation/memory, and egocentric navigation/memory should be added to guideline studies. Collectively, the above suggest that EPA and EU DNT studies would better reflect human findings and be more relevant to children by aligning L&M tests to the same domains that are affected in children, removing less useful methods (FOB), and using newer statistical models to better account for random factors of litter and litter × sex. Common issues in study design and data analyses are discussed: sample size, random group assignment, blinding, elimination of subjective rating methods, avoiding confirmation bias, more complete reporting of species, housing, test protocols, age, test order, and litter effects. Litter in DNT studies should at least be included as a random factor in ANOVA models and may benefit from inclusion of litter × sex as random factors.
Collapse
Affiliation(s)
- Charles V Vorhees
- Department of Pediatrics, College of Medicine, University of Cincinnati and Division of Pediatric Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, United States of America.
| | - Michael T Williams
- Department of Pediatrics, College of Medicine, University of Cincinnati and Division of Pediatric Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, United States of America
| |
Collapse
|
4
|
Vorhees CV, Williams MT, Hawkey AB, Levin ED. Translating Neurobehavioral Toxicity Across Species From Zebrafish to Rats to Humans: Implications for Risk Assessment. FRONTIERS IN TOXICOLOGY 2021; 3:629229. [PMID: 35295117 PMCID: PMC8915800 DOI: 10.3389/ftox.2021.629229] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/27/2021] [Indexed: 12/12/2022] Open
Abstract
There is a spectrum of approaches to neurotoxicological science from high-throughput in vitro cell-based assays, through a variety of experimental animal models to human epidemiological and clinical studies. Each level of analysis has its own advantages and limitations. Experimental animal models give essential information for neurobehavioral toxicology, providing cause-and-effect information regarding risks of neurobehavioral dysfunction caused by toxicant exposure. Human epidemiological and clinical studies give the closest information to characterizing human risk, but without randomized treatment of subjects to different toxicant doses can only give information about association between toxicant exposure and neurobehavioral impairment. In vitro methods give much needed high throughput for many chemicals and mixtures but cannot provide information about toxicant impacts on behavioral function. Crucial to the utility of experimental animal model studies is cross-species translation. This is vital for both risk assessment and mechanistic determination. Interspecies extrapolation is important to characterize from experimental animal models to humans and between different experimental animal models. This article reviews the literature concerning extrapolation of neurobehavioral toxicology from established rat models to humans and from zebrafish a newer experimental model to rats. The functions covered include locomotor activity, emotion, and cognition and the neurotoxicants covered include pesticides, metals, drugs of abuse, flame retardants and polycyclic aromatic hydrocarbons. With more complete understanding of the strengths and limitations of interspecies translation, we can better use animal models to protect humans from neurobehavioral toxicity.
Collapse
Affiliation(s)
- Charles V. Vorhees
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, OH, United States
| | - Michael T. Williams
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, OH, United States
| | - Andrew B. Hawkey
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, United States
| | - Edward D. Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, United States
| |
Collapse
|
5
|
Williams MT, Amos-Kroohs RM, Vorhees CV. Prolonged methamphetamine exposure during a critical period in neonatal Sprague Dawley rats does not exacerbate egocentric and allocentric learning deficits but increases reference memory impairments. Int J Dev Neurosci 2020; 80:163-174. [PMID: 32043612 DOI: 10.1002/jdn.10014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 01/24/2020] [Accepted: 02/04/2020] [Indexed: 01/05/2023] Open
Abstract
Children exposed to methamphetamine (MA) in utero have cognitive deficits. MA administration in rats for 5-10 days between postnatal days (P)6 and 20 produces cognitive deficits. The purpose of this study was to determine if extending MA administration by 5 days within P6-20 would exacerbate allocentric (Morris water maze) and egocentric (Cincinnati water maze) learning deficits. Sprague Dawley female and male offspring (split-litter design) were administered saline (SAL) or MA (10 mg/kg) four times daily from P6 to 20 to create four groups: (a) SAL from P6 to 20, (b) MA from P6 to 20 (MA6-20), (c) MA from P6 to 15 (MA6-15), or (d) MA from P11 to 20 (MA11-20); the latter groups received saline on days they did not receive MA. Egocentric, allocentric, and conditioned freezing tests began on P60. The MA6-15 and MA6-20 groups showed egocentric deficits, all MA groups had allocentric deficits but no differences in conditioned freezing compared with SAL controls. The MA6-15 and MA6-20 groups had similar deficits in learning and memory that were larger than in the MA11-20 group. Learning in both mazes was sex dependent, but no interactions with MA were found. The data demonstrate that extending the exposure period of MA beyond the sensitive periods (P6-15 and P11-20) did not exacerbate the cognitive deficits.
Collapse
Affiliation(s)
- Michael T Williams
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,Division of Neurology (MLC 7044), Cincinnati Children's Research Foundation, Cincinnati, OH, USA
| | - Robyn M Amos-Kroohs
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,Division of Neurology (MLC 7044), Cincinnati Children's Research Foundation, Cincinnati, OH, USA
| | - Charles V Vorhees
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.,Division of Neurology (MLC 7044), Cincinnati Children's Research Foundation, Cincinnati, OH, USA
| |
Collapse
|
6
|
Neuroprotective effect of ghrelin in methamphetamine-treated male rats. Neurosci Lett 2019; 707:134304. [DOI: 10.1016/j.neulet.2019.134304] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/26/2019] [Accepted: 05/28/2019] [Indexed: 11/23/2022]
|
7
|
Jablonski SA, Williams MT, Vorhees CV. Learning and Memory Effects of Neonatal Methamphetamine Exposure in Sprague-Dawley Rats: Test of the Role of Dopamine Receptors D1 in Mediating the Long-Term Effects. Dev Neurosci 2019; 41:44-55. [PMID: 31212274 DOI: 10.1159/000498884] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 02/12/2019] [Indexed: 11/19/2022] Open
Abstract
Methamphetamine (MA) abuse is a worldwide issue that produces health and cognitive effects in the user. MA is abused by some women who then become pregnant and expose their developing child to the drug. Preclinical rodent models demonstrate cognitive deficits following developmental MA exposure, an effect observed in children exposed to MA in utero. To determine if the dopamine receptor D1 (DRD1) is involved in the learning and memory deficits following MA exposure, male Sprague-Dawley rats were treated 4 times daily at 2 h intervals with 0 (saline) or 10 mg/kg of MA from postnatal day (P)6-15, 30 min after 0.5, 1.0, or 2.0 mg/kg SCH23390. Cincinnati water maze testing began on P30, and the high dose of SCH23390 blocked the learning deficits induced by MA with no effect from the lower doses. Morris water maze (MWM) learning deficits following MA were not protected by SCH23390, although there was a non-dose dependent effect in the acquisition phase. Locomotor deficits induced by MA were reversed by all doses of SCH23390. There were no effects of MA on criterion to trial passive avoidance. Taken together, these data show that behaviors that are dependent on the striatum are better protected with the DRD1 antagonist during MA treatment than the hippocampally mediated spatial learning in the MWM. This suggests that multiple mechanisms exist for the deficits induced by neonatal MA administration.
Collapse
Affiliation(s)
- Sarah A Jablonski
- Department of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, Ohio, USA
| | - Michael T Williams
- Department of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, Ohio, USA
| | - Charles V Vorhees
- Department of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, Ohio, USA,
| |
Collapse
|
8
|
Loss of Intercalated Cells (ITCs) in the Mouse Amygdala of Tshz1 Mutants Correlates with Fear, Depression, and Social Interaction Phenotypes. J Neurosci 2017; 38:1160-1177. [PMID: 29255003 DOI: 10.1523/jneurosci.1412-17.2017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 11/10/2017] [Accepted: 12/10/2017] [Indexed: 01/17/2023] Open
Abstract
The intercalated cells (ITCs) of the amygdala have been shown to be critical regulatory components of amygdalar circuits, which control appropriate fear responses. Despite this, the molecular processes guiding ITC development remain poorly understood. Here we establish the zinc finger transcription factor Tshz1 as a marker of ITCs during their migration from the dorsal lateral ganglionic eminence through maturity. Using germline and conditional knock-out (cKO) mouse models, we show that Tshz1 is required for the proper migration and differentiation of ITCs. In the absence of Tshz1, migrating ITC precursors fail to settle in their stereotypical locations encapsulating the lateral amygdala and BLA. Furthermore, they display reductions in the ITC marker Foxp2 and ectopic persistence of the dorsal lateral ganglionic eminence marker Sp8. Tshz1 mutant ITCs show increased cell death at postnatal time points, leading to a dramatic reduction by 3 weeks of age. In line with this, Foxp2-null mutants also show a loss of ITCs at postnatal time points, suggesting that Foxp2 may function downstream of Tshz1 in the maintenance of ITCs. Behavioral analysis of male Tshz1 cKOs revealed defects in fear extinction as well as an increase in floating during the forced swim test, indicative of a depression-like phenotype. Moreover, Tshz1 cKOs display significantly impaired social interaction (i.e., increased passivity) regardless of partner genetics. Together, these results suggest that Tshz1 plays a critical role in the development of ITCs and that fear, depression-like and social behavioral deficits arise in their absence.SIGNIFICANCE STATEMENT We show here that the zinc finger transcription factor Tshz1 is expressed during development of the intercalated cells (ITCs) within the mouse amygdala. These neurons have previously been shown to play a crucial role in fear extinction. Tshz1 mouse mutants exhibit severely reduced numbers of ITCs as a result of abnormal migration, differentiation, and survival of these neurons. Furthermore, the loss of ITCs in mouse Tshz1 mutants correlates well with defects in fear extinction as well as the appearance of depression-like and abnormal social interaction behaviors reminiscent of depressive disorders observed in human patients with distal 18q deletions, including the Tshz1 locus.
Collapse
|