Spontaneous Rotational Behavior Research Articles

Pirouetting pigs: A large non-primate animal model based on unilateral 6-hydroxydopamine lesioning of the nigrostriatal pathway

IntroductionThe rotating 6-hydroxydopamine (6-OHDA) rat model has long been important when developing new treatment strategies for Parkinson’s disease (PD). Similar non-human primate models have been developed for translational research purposes as large animal models are required by regulatory bodies as an intermediate “phase 0” trial step. However, experimental research in non-human primates encounters several economical and regulatory issues, which may be avoided by the alternative use of pigs as a large animal model for experimental brain research. ObjectiveThe primary aim of this study was to examine if unilateral injections of 6-OHDA into the Göttingen minipig nigrostriatal pathway would lead to dopaminergic imbalance and rotational behavior similar to the 6-OHDA unilateral symptomatic model of PD created in other species. The secondary aim was to attempt to verify the rotational behavior as a parkinsonian symptom using subthalamic deep brain stimulation (STN-DBS) to minimize the elicited rotational pattern. Materials and methodsUsing an MRI-based stereotactic procedure, ten female Göttingen minipigs were injected unilaterally with 6-OHDA in the nigrostriatal pathway. Postoperatively, an MRI was performed, and the animals were injected with amphetamine and apomorphine and observed for rotational behavior. After a survival period of three months the brains were removed and immunohistochemically stained for tyrosine hydroxylase (TH). One week before sacrifice two animals had DBS electrodes unilaterally implanted in the subthalamic nucleus and various stimulation protocols were conducted during amphetamine challenge. ResultsAs expected most animals rotated towards the side of the lesion when given amphetamine (3.5–4.0 mg/kg), whereas the predicted opposite response to apomorphine were much harder to reproduce. T1- and T2-weighted postoperative MRI could demonstrate the size and the location of the 6-OHDA injection. Postmortem TH-staining of the final two animals receiving a medial and a lateral injection of 25 μL of 6-OHDA (8 μg/μL, injection rate 5 μL/min) into the diencephalic nigrostriatal pathway showed a prominent unilateral decrease in TH-staining of the substantia nigra pars compacta, the ventral tegmental area and the nigrostriatal pathway on the lesioned side. These two animals displayed spontaneous rotational behavior toward the lesioned side for the first 2–3 days postoperatively, and this behavior could later on be reelicited by amphetamine and attenuated by ipsilateral STN-DBS. ConclusionFemale Göttingen minipigs are susceptible to unilateral dopaminergic degeneration when properly injected unilaterally with sufficient amounts of 6-OHDA in the nigrostriatal pathway. The location of the 6-OHDA injections and thus the accuracy of the employed stereotaxy can be verified in vivo using MRI postoperatively. The injected minipigs display unilateral parkinsonism with a well-defined rotational response to amphetamine that may be ameliated by STN-DBS performed on the lesioned side. The response to apomorphine was, however, not consistent, illustrating that further work on this promising non-primate large animal model is needed, before it is fully similar to the established 6-OHDA models in other species.

Viral Vector-Mediated Overexpression of Estrogen Receptor-α in Striatum Enhances the Estradiol-Induced Motor Activity in Female Rats and Estradiol-Modulated GABA Release

Classical estrogen receptor-signaling mechanisms involve estradiol binding to intracellular nuclear receptors [estrogen receptor-alpha (ERalpha) and estrogen receptor-beta (ERbeta)] to promote changes in protein expression. Estradiol can also exert effects within seconds to minutes, however, a timescale incongruent with genomic signaling. In the brain, estradiol rapidly potentiates stimulated dopamine release in the striatum of female rats and enhances spontaneous rotational behavior. Furthermore, estradiol rapidly attenuates the K(+)-evoked increase of GABA in dialysate. We hypothesize that these rapid effects of estradiol in the striatum are mediated by ERalpha located on the membrane of medium spiny GABAergic neurons. This experiment examined whether overexpression of ERalpha in the striatum would enhance the effect of estradiol on rotational behavior and the K(+)-evoked increase in GABA in dialysate. Ovariectomized female rats were tested for rotational behavior or underwent microdialysis experiments after unilateral intrastriatal injections of a recombinant adeno-associated virus (AAV) containing the human ERalpha cDNA (AAV.ERalpha) into the striatum; controls received either the same vector into areas outside the striatum or an AAV containing the human alkaline phosphatase gene into the striatum (AAV.ALP). Animals that received AAV.ERalpha in the striatum exhibited significantly greater estradiol-induced contralateral rotations compared with controls and exhibited behavioral sensitization of contralateral rotations induced by a low-dose of amphetamine. ERalpha overexpression also enhanced the inhibitory effect of estradiol on K(+)-evoked GABA release suggesting that disinhibition of dopamine release from terminals in the striatum resulted in the enhanced rotational behavior.

Effects of rotational side preferences on immobile behavior of normal mice in the forced swimming test

It has been suggested that side preferences in spontaneous rotational behavior are determinant of differences in vulnerability to the effects of the learned helplessness paradigm. The purpose of the present study was to investigate the effects of side preferences of rotational behavior in another animal model of depression, the forced swimming test. Immobility was also investigated upon repeated testing sessions and in interaction with sex. Swiss mice (69 males and 73 females) were submitted to three sessions (test time=5 min) of forced swimming. Immobile and turning behaviors were measured for each session and within each testing session. Consistency of laterality was defined considering the persistence of the same side turning preference in the three sessions. In general, there was an increase in immobility as test progressed and upon repeated testing sessions. Marked interindividual differences in mice immobile behavior were observed when consistency of laterality was considered. Consistent-right-turners presented greater immobility in the first session and better test–retest reliability, indicating that for this group, the adoption of immobile behavior was faster and more reliable over time. Immobility was higher for side-consistent males than for side-consistent females in the first session. This difference became even greater when consistent-right-turner males were compared to consistent-left-turner females. These results reinforce the idea that side preferences of spontaneous rotational behavior may account for interindividual differences in animal models of depression.

Immunohistochemical and neurochemical studies on nigral and striatal functions in the circling (ci) rat, a genetic animal model with spontaneous rotational behavior

Asymmetrical spontaneous turning behavior or circling phenomena are often related to components of the dopaminergic system, particularly to an imbalance of nigrostriatal function. When a rotational preference is observed, it is typically in a direction away from the brain hemisphere with higher striatal dopaminergic transmission. We have recently described a rat mutant ( ci) with spontaneous circling behavior and other signs of functional brain asymmetry. Neurochemical determinations showed that mutants of both genders have significantly lower concentrations of dopamine and dopamine metabolites in the striatum ipsilateral to the preferred direction of rotation. In the present study, we used immunohistochemical, neurochemical, and autoradiographic techniques to characterize the dopaminergic abnormalities of the ci rat mutant in more detail. Age-matched non-affected controls of the same strain were used for comparison. Immunohistochemical labeling of dopaminergic neurons and fibers in substantia nigra pars compacta, ventral tegmental area, and striatum did not indicate any significant neurodegeneration or asymmetry that could explain the lateralization in dopamine levels in striatum of ci rats. Neurochemical determinations substantiated that ci rats of both genders have a significant imbalance in striatal dopamine metabolism, but a similar significant lateralization was also seen in non-affected female controls. Comparison of dopamine, serotonin, noradrenaline and several monoamine metabolite levels in substantia nigra, striatum, nucleus accumbens and frontal cortex of ci rats and controls did not disclose any marked difference between affected and non-affected animals which was consistently found in both genders. Quantitative autoradiographic determination of binding densities of dopamine transporter and D 1 and D 2 receptors in several parts of the striatum and substantia nigra indicated that ci rats have a significantly higher binding density of dopamine transporter and receptors than controls. Taken together, ci mutant rats of both genders exhibit an asymmetry in striatal dopamine and metabolite levels and an enhanced dopamine transporter and receptor binding, but the link of these differences in dopaminergic parameters with the rotational behavior of the animals is not clear yet. The lack of any significant dopaminergic cell loss in the substantia nigra and the locomotor hyperactivity observed in the mutants clearly suggest that the ci rat is not suited as a model of Parkinsonism but rather constitutes a model of a hyperkinetic motor syndrome.

Differential immune responses in mice with left- and right-turning preference

Humoral and cell-mediated immune responses of inbred BALB/c male mice were assayed for differential reactivities associated with behavioral sidedness, which was evaluated by spontaneous rotational behavior in a circular cage model system. Mice with left-turning preference had lower in vivo primary IgM and IgG anti-Keyhole Limpet Hemocyanin (KLH) antibody responses, delayed-type hypersensitivity (DTH) responses, and host-resistance against the intracellular bacteria, Listeria monocytogenes, than mice with right-turning preference. The only immune parameter not shown to be associated with turning preference was the secondary humoral immune response to KLH. The weak innate immune response of left-turners for clearance of Listeria showed close intercorrelation with elevated serum IL-6 levels. Serum corticosterone and splenic norepinephrine levels were differentially increased and decreased by infection, respectively. We suggest that the observed differential immune reactivities of individual animals with same age, gender, and genetic background are associated with functional asymmetries within the brain, that the hypothalamic–pituitary–adrenal (HPA) axis and sympathetic innervation are involved in the regulatory brain: immune interconnection after infection, and that the HPA axis and sympathetic nervous system are involved in the brain laterality effects on immune responses.

Sex differences in spontaneous locomotor activity and rotational behavior in meadow voles

MARCZINSKI, C., T. S. PERROT-SINAL, M. KAVALIERS AND K.-P. OSSENKOPP. Sex differences in spontaneous locomotor activity and rotational behavior in meadow voles. PHYSIOL BEHAV 65(2) 387–391, 1998.—Sex differences in rotational behavior have been most clearly established in laboratory rats with females exhibiting a turning bias. Here, using an automated open-field apparatus, locomotor activity and spontaneous rotational behavior were examined in diurnally crepuscularly active reproductive male and female meadow voles ( Microtus pennsylvanicus). Meadow voles, being induced ovulators, permitted analysis of females in constant behavioral estrous. Males displayed significantly greater levels of activity and also significantly greater levels of clockwise but not counterclockwise rotational behavior relative to the females. Rotational behavior was less strongly related to activity levels in female as compared to male voles. In addition, females displayed an overall turning bias. These results contrast with findings from laboratory rats in which females are reported to display greater levels of both locomotor activity and rotational behavior. They are, however, consistent with the rotational bias evident in female rats. The present findings confirm the presence of sex differences in rotational behavior and indicate that factors other than activity levels are involved in the generation and/or expression of these sex differences. Sex differences in anxiety and routine-like behavior (i.e., asymmetry in movement) are discussed as possible factors contributing to these male-female differences in rotational behavior.

Ontogenesis of lateralized rotational behavior in hamsters: a time series study

This is a longitudinal study of the postnatal development of lateralized rotational behavior. Hamsters ( n=75) were tested for spontaneous rotational behavior in cylindrical arenas, from P2 (P1=day of birth) to P60. A daily laterality index was calculated for each animal, of which the averages and standard deviations were used to follow the animals' lateralized behavior. A strong variability between and within animals appeared throughout development, with a tendency to the right side in most animals, which declined after the first postnatal week. No oscillatory cycles were identified. To study patterns of development, the series were divided into four periods and the animals were separated into five groups. The laterality indexes of all four periods were significantly different between the groups. A total of 79% of the animals showed consistent behavior along development: either a preference to one side (20% left, 26% right), or no preference at all (33%). The remaining animals changed preference during development. Only a few animals remained strongly lateralized throughout the 60 days, most of them showing a slight, non-significant preference after P10. Results suggest an ontogenetic decrease in lateralization of this behavior that could in part be explained by the maturation of an interhemispheric regulatory system.

Evaluation of a 200 mm long vacuum aspiration tube for measurement of erythrocyte sedimentation rate.

The ESrT-system 200 comprises a 215 mm long vacuum aspiration venepuncture tube which contains anticoagulant diluent for the measurement of the erythrocyte sedimentation rate (ESR) without direct handling of the blood sample. This combines the advantage of a tube of "Westergren" length with a reduction in biohazard risk. Blood from 160 patients (ESR range 2-135 mm/first hour) was tested in parallel with the selected Westergren ESR method of the International Committee for Standardization in Haematology (ICSH) and a close correlation (r = 0.967) between the two methods was obtained. A second Westergren ESR, using anticoagulated but undiluted blood, was measured on 58 specimens to give an ICSH "expected" ESR. The ESrT-system 200 result was within 12 mm/first hour of the "expected" result for 91% of the specimens. This new ESR system is simple to use, does not require mathematical correction of the ESR reading for tube length, and gives results that are comparable with those obtained with the ICSH Westergren method.

Circadian studies of the spontaneous rotational behavior of the gerbil

Normal unoperated gerbils rotate or turn in circles spontaneously (i.e., without lesions or drugs). Two experiments were conducted to determine possible circadian patterns of spontaneous rotation. In Experiment 1, one hour testing indicated that rotational behavior during the light and dark portions of the diurnal cycle are not different. In Experiment 2, continuous monitoring of rotation for 6-day sessions revealed that gerbils maintain a steady baseline level of rotation throughout the diurnal cycle, unlike rats which spontaneously rotate only at night. Two-thirds of gerbils tested rotated in one direction during an initial phase of testing and then switched the direction of preferred rotation for the remainder of the test session. These shifts in direction of rotation by some gerbils may reflect the influence of arousal on lateralized behavior. Thus, the spontaneous rotational behavior of gerbils is characterized both by a distinct lack of circadian fluctuation and directional variability.

Spontaneous and drug-induced rotation (Circling behavior) in the mongolian gerbil ( Meriones unguiculatus)

Eight normal gerbils were tested for spontaneous and drug-induced rotation in an automated rotometer. When tested without any drug every other day for five test sessions, each gerbil displayed significant rotation that was consistent in direction and magnitude from session to session. Apomorphine and d-amphetamine potentiated whereas haloperidol antagonized the animals' spontaneous rotational behavior. In previous work with rats and mice, drug-induced rotation has been attributed to an asymmetry in nigro-striatal function. The occurrence of spontaneous rotation in gerbils suggests that gerbils have normally a much larger asymmetry.