Nicholas Waters

Analysis of two measures of paw preference in a large population of inbred mice

Two measures of lateralized forelimb usage, the Collins paw preference test and the Lateral Paw Preference test (LPP), were tested in 693 mice of 29 inbred strains and F1 crosses, and 2 embryo transfer groups. These strains included NZB, SM, and the NXSM recombinant inbred (RI) strains; RF and the NXRF RI strains; BXSB and the Y-consomic BXSB-Yaa+; DBA/2 and F1s of DBA/2 and BXSB and BXSB-Yaa; and NZB x NZW F1s. The findings indicated that (1) the Collins and LPP tests were independent in terms of direction of lateralization, (2) there were significant population biases of 60.96% rightward on the LPP test, and 54.39% leftward on the Collins test, (3) there were significant strain differences on measures of absolute asymmetry on both tests, (4) there were strain differences for direction of asymmetry on the Collins test, but not on LPP, (5) on the basis of the NXSM RI strains, 3 genetic loci contribute to strength of laterality on the LPP test, and (6) there was a strong correlation among strain means for strength of lateralization on the two tests. These results extend previous findings on the strength and direction of laterality, showing that two independent systems for direction of laterality may depend on the same mechanism for magnitude, and establish that multiple factors of handedness, previously identified in humans and other primates, also exist in mice.

Effects of the autoimmune uterine/maternal environment upon cortical ectopias, behavior and autoimmunity

NZB and BXSB mice develop autoimmune disease and learn poorly on avoidance tasks. In addition, many of these mice have ectopic collections of neurons, which occur prenatally, in layer I of the cerebral neocortex. The purpose of these experiments was to evaluate the contribution of the uterine/maternal environment upon these variables by transferring fertilized ova to an autoimmune or a non-autoimmune maternal host. In Experiment 1 fertilized DBA ova were transferred into the uteri of BXSB maternal recipients. Later, these animals and conventionally reared DBAs were tested for paw preference, swimming rotation, water escape learning, and shuttlebox avoidance learning. Blood was taken for measurement of immune parameters, and their brains were examined for cortical ectopias. As compared to conventional DBAs, the ova transfer mice had greater amounts of anti-dsDNA autoantibodies, poorer avoidance learning, and poorer water escape learning; in addition, the females had greater paw asymmetry. There was only 1 ectopia in the 81 ova transfer animals, and none in the 78 control mice. In Experiment 2 fertilized NZB ova were transferred into the uteri of non-autoimmune hybrid females and the same procedures were followed as in Experiment 1. Ova transfer mice had lesser amounts of anti-dsDNA autoantibodies, better avoidance learning scores, and females had less paw asymmetry; in addition, within the ova transfer group males were clockwise swimmers whereas females swam counterclockwise. There were 4 ectopics out of 17 ova transfer mice (23.5%), which did not differ from the 40.5% of the control group. In both experiments the uterine environment did not affect the occurrence of ectopias.(ABSTRACT TRUNCATED AT 250 WORDS)

Learning and memory in the autoimmune BXSB mouse: effects of neocortical ectopias and environmental enrichment

Approximately 40-60% of BXSB mice have ectopic cell clusters in layer 1 of neocortex. Prior studies have shown distinct behavioral differences between those with ectopias and their non-ectopic littermates. In this study, female BXSB mice were reared after weaning in either enriched environments or standard cages. Following an initial round of behavioral testing, all mice were housed in standard cages and retested. Enriched cage mice (both ectopic and non-ectopic) showed increased activity, greater speed, and enhanced learning scores across a variety of tests. Additionally, prior test experience itself had significant positive effects on Hebb-Williams maze learning. The presence of ectopias resulted in better Morris maze learning for standard cage reared mice. Further, ectopic mice, regardless of their housing condition, showed better long-term retention in the Morris maze than did their non-ectopic counterparts. These findings show that abnormalities in corticogenesis need not always result in functional deficit.

Environmental enrichment, neocortical ectopias, and behavior in the autoimmune NZB mouse

New Zealand Black (NZB) mice have severe autoimmune disease and approximately 40% have cortical ectopias in layer I of sensorimotor cortex. Because the ectopias are similar to those found in dyslexics, NZB mice have been used as an animal model for developmental learning disorders. In addition, these mice have been used as a model of learning deficits associated with autoimmune disease. To determine whether early intervention would affect learning processes in NZB mice, they were reared after weaning in standard cages or enriched environments. They were given a battery of behavioral tests to measure learning, laterality, and activity, after which they were sacrificed and their brains examined for cortical ectopias. The tests sorted into two behavioral sets. Ectopia-associated behaviors included black-white discrimination learning and the Morris spatial maze. As a group, the mice performed well on these tasks. Ectopic mice had poorer performance than non-ectopics on these measures, and environmental enrichment countered the effects of the ectopias. Autoimmune-associated behavior involved two-way avoidance learning in a shuttlebox. Mice were uniformely poor on this task, ectopias did not affect behavior, and environmental enrichment was without benefit. Evidence from this and other studies shows that poor shuttlebox performance is related to the presence of autoimmune disease. Thus, autoimmune disease and cortical ectopias each appear to affect a separate set of behavioral processes. Environmental enrichment is most effective for behavioral impairments mediated via cortical ectopias, but is much less effective, if at all, if autoimmunity is the primary mediator of the impairments.

In vivo pharmacology of the dopaminergic stabilizer pridopidine

Pridopidine (ACR16) belongs to a new pharmacological class of agents affecting the central nervous system called dopaminergic stabilizers. Dopaminergic stabilizers act primarily at dopamine type 2 (D(2)) receptors and display state-dependent behavioural effects. This article aims to give an overview of the preclinical neurochemical and behavioural in vivo pharmacological properties of pridopidine. Pridopidine was given s.c. to male Sprague-Dawley rats (locomotor, microdialysis and tissue neurochemistry) and i.p. to Swiss male mice (tail suspension test). Pridopidine dose-dependently increased striatal tissue levels of the dopamine metabolite 3,4-dihydroxyphenylalanin (ED(50)=81 micromol/kg), and prefrontal cortex dialysate levels of dopamine and noradrenaline as measured by high performance liquid chromatography. The agent reduced hyperlocomotion (d-amphetamine: ED(50)=54 micromol/kg; MK-801: ED(50)=40 micromol/kg), but preserved spontaneous locomotor activity, confirming state-dependent behavioural effects. In addition, pridopidine significantly reduced immobility time in the tail suspension test. We conclude that pridopidine state-dependently stabilizes psychomotor activity by the dual actions of functional dopamine D(2) receptor antagonism and strengthening of cortical glutamate functions in various settings of perturbed neurotransmission. The putative restoration of function in cortico-subcortical circuitry by pridopidine is likely to make it useful for ameliorating several neurological and psychiatric disorders, including Huntingtons disease.

Behavioral consequences of neonatal injury of the neocortex

Several strains of autoimmune mice spontaneously develop molecular layer ectopias that are similar in appearance to those seen in humans and are caused by disturbances in neocortical neuronal migration. These mice also exhibit behavioral anomalies, some of which correlate with ectopias, others with the immunological disorder. In this study, we induced neocortical ectopias (via puncture wounds) and microgyria (via freezing lesions) in the neocortex of 1-day-old (newborn) mice without immune disorders in an attempt to further disentangle the effects of autoimmunity and of cortical malformation on behavior. In addition, we wished to compare the behavioral effects of small ectopias to larger microgyric lesions. DBA mice were assigned at birth to receive either a puncture wound or freezing lesion of either the left or right hemisphere. An independent group was subjected to sham surgery. In adulthood, these mice were given a battery of tests designed to measure lateralization and learning capacity. Lesioned mice (irrespective of hemisphere or type of damage) performed poorly when compared to sham-operated animals in discrimination learning, in a spatial Morris Maze Match-to-Sample task, and in a Lashley Type III maze. In shuttlebox avoidance conditioning, where immunological disorder has been shown to compromise behavioral performance in autoimmune mice, there was no difference between lesioned and sham animals. These results (1) support the dissociation between the effects of developmental neocortical anomalies and autoimmune disease on behavior (2) reveal similarities between spontaneous and induced neocortical malformations and (3) fail to support a difference in behavioral effects between ectopias and microgyria.

Corpus callosum : interactive effects of infantile handling and testosterone in the rat

Previous research found that the corpus callosum of male rats is larger than that of females; handling rats in infancy enhances this sex difference; and female rat pups, when handled in infancy and given 1 injection of testosterone propionate (TP) on Day 4 of life, will have callosa as large as those of males. In 2 experiments, male pups were castrated on Day 1 or received sham surgery; female pups were injected with TP on Day 4 or received an oil injection. Litters were handled or nonhandled. The previous finding that females, when handled and given TP in infancy, have a larger callosum was confirmed; however, a TP effect when administered to nonhandled females was not found. Because handling is known to cause a corticosterone release, these findings were interpreted as evidence of a developmental interaction between adrenal and gonadal hormones at the cortical level.

A measure of lateral paw preference in the mouse

A lateral paw preference testing unit is described. Mice are allowed access to preferred food with either their left or right forepaw, and the amount eaten with each paw is measured. The unit allows easy measurement and quantification of this behavior, without requiring food deprivation or continuous monitoring of the subjects, and may be performed in the subjects home cage. Its reliability under a number of conditions is reported. The results do not correlate with those obtained using the Collins paw preference test.

Behavior, ectopias and immunity in BD/DB reciprocal crosses

In a previous study, in which fertilized DBA ova were transferred into an autoimmune female, and NZB ova were transferred into a non-autoimmune female, we found that (1) the maternal environment affected the degree of autoimmunity, (2) the incidence of cortical ectopias was not affected by the maternal environment (3) DBA and NZB females had greater paw asymmetry if reared in an autoimmune uterus, and (4) avoidance learning scores were inversely related to degree of autoimmunity. In the present experiment, reciprocal crosses of DBA and BXSB mice were studied to confirm and extend the original findings. DB mice (DBA female x BXSB male) had greater immune activity than the BD animals, had poorer avoidance learning, but were better on black-white discrimination learning and the Lashley III maze. The BD mice had greater paw asymmetry. Only one of 38 animals had a cortical ectopia. The results lead to the following conclusions: (1) there is an inverse relationship between amount of immune activity and active avoidance learning; (2) some uterine factor in autoimmune mice causes females to have greater paw asymmetry; (3) cortical ectopias are under genetic control; and (4) the lesser immune activity of the BD mice suggests that they developed a suppressor system following early exposure to autoimmunity in the uterine/maternal environment.

Effects of embryo transfer and cortical ectopias upon the behavior of BXSB-Yaa and BXSB-Yaa + mice.

The BXSB-Yaa and BXSB-Yaa + inbred strains of mice differ primarily with respect to the Y chromosome, although there is evidence that they differ on several autosomal genes as well. Each strain has ectopic collections of neurons in neocortical layer I (ectopias), with a higher occurrence in males (58%) than females (42%). Conventionally reared mice from these strains were compared to mice that were transferred, as 8-cell embryos, into the uteri of non-autoimmune recipients, who gave birth to and reared the offspring. The transfer procedure did not change the incidence of ectopias in either sex. There were, however, major differences in behavior. Compared to conventionally reared controls, embryo transfer mice had greater behavioral asymmetry, poorer performance in a black-white discrimination, poorer Morris maze learning, better Lashley maze learning, and better performance in a two-way shuttlebox. Within the transfer groups, females differed as much as males, confirming our prior findings and supporting our thesis that the two strains differ on several autosomal genes in addition to the Y chromosome. These findings show that the intra-uterine environment can powerfully and selectively affect later behavior. When ectopic and non-ectopic mice were compared, BXSB-Yaa mice with neocortical ectopias were better able to learn the Morris spatial maze than non-ectopic controls; this was true whether the mice were conventionally reared or embryo transferred. In contrast, BXSB-Yaa + ectopic mice did not differ from their controls if conventionally reared, but were much worse than controls if embryo transferred.