Magda Giordano

The catalepsy test: Its ups and downs.

The typical catalepsy test consists of placing an animal into an unusual posture and recording the time taken to correct this posture. This time is regarded as an index of the intensity of catalepsy. Catalepsy is a robust behavior, and the lack of standardization does not usually hinder its actual detection. However, the intensity of the cataleptic effect is influenced by minor methodological differences, and thus interpretation and comparison of results across laboratories are difficult. The behavioral catalepsy test can use any of several different apparatus, including wire grids, parallel bars, platforms, or pegs, to situate the animals in unusual positions. The most common, however, is the bar test, and despite its wide use in psychopharmacological research, even parameters of this test are not standardized. The present article reviews the wide variety of parameters chosen by investigators that measure catalepsy. The methodological issues of repeated testing, scaling of scores, apparatus, animal weight, maximal test duration, behavioral criteria, and other influences are discussed. In addition, a brief review of the neuropharmacological basis of catalepsy is also included. Finally, it is argued that a universal, standardized bar test be adopted by researchers. New data on a novel automated bar test in the Digiscan Activity Monitoring System is presented.

The quinolinic acid model of Huntington's disease: Locomotor abnormalities

In contrast to other excitotoxins, such as kainic acid, quinolinic acid (QA) may spare a specific population of striatal neurons that is also spared in Huntingtons disease (HD). Although several histological and biochemical experiments support the use of QA as a model for HD, to date no behavioral experiments have been performed to examine the suitability of this model. The present study explored the behavioral effects of bilateral intrastriatal microinjections of four doses (75, 150, 225, 300 nmol) of QA in the male rat. Using a multidimensional analysis of spontaneous locomotion (Digiscan activity) and a record of metabolic indicators, such as weight loss, a dose-dependent effect was found. The 75-nmol dose had no significant effect on locomotion or feeding behavior. In contrast, the 150- and 225-nmol doses induced hyperactivity and weight loss, whereas the 300-nmol dose was lethal. The results obtained suggest that striatal injections of 150-225 nmol of QA induce behavioral deficits qualitatively similar though quantitatively less than those which are seen after similar injection of 3 nmol of kainic acid and which have been reported to be comparable to the symptomatology of HD. Together with QAs possible greater histological selectivity, the present results support the use of QA-induced striatal lesions as a behavioral model of Huntingtons disease.

Immortalized GABAergic Cell Lines Derived from Rat Striatum Using a Temperature-Sensitive Allele of the SV40 Large T Antigen

Embryonic striatal cells were immortalized using the A58 temperature-sensitive allele of the SV40 large T antigen. Two cell lines, M213-2O and M26-1F, with gamma-aminobutyric acid (GABA)ergic properties were selected from 85 clones thus developed. M213-2O is a multipolar, polygonal cell line which expresses SV40 large T antigen and glutamate decarboxylase (GAD) at the permissive temperature (33 degrees C) and GAD and MAP-2 immunoreactivity at the nonpermissive temperature (39.3 degrees C). M26-1F has a fibroblast-like morphology and expresses SV40 large T antigen and GAD both at the permissive and nonpermissive temperatures and MAP-2 immunoreactivity at the nonpermissive temperature. Both lines contain GABA as measured by reversed-phase HPLC and M213-2O expresses nipecotic-sensitive [14C]GABA uptake.

Striatal tissue transplants attenuate apomorphine-induced rotational behavior in rats with unilateral kainic acid lesions

Four to six weeks following unilateral striatal kainic acid (KA) lesions, challenge with apomorphine (0.5-0.75 mg/kg s.c.) elicited rotational behavior. Gestational day 17-19 rat fetal striatal tissue was implanted into the lesioned striatum, and rats were rechallenged with apomorphine 10 weeks post-transplant. There was a significant reduction in the maximal rate of rotations and an alteration in the topography of locomotor activity in response to apomorphine. These data indicate that the transplanted material may possess similar pharmacological properties as the original host tissue and is capable of functionally repairing damage to a complex neurochemical system.

Intraparenchymal fetal striatal transplants and recovery in kainic acid lesioned rats

Striatal kainic acid (KA) lesions induce behavioral and biochemical deficits which resemble symptoms encountered in patients suffering from Huntingtons disease. In rats with KA lesions, fetal striatal transplants have shown to reverse the pervasive nocturnal hyperactivity induced by the lesion. In the present study 4.6 mm3 of fetal striatal tissue were delivered bilaterally into the anterodorsal portion of the lesioned caudate nucleus. Care was taken to deliver the transplant within the host parenchyma and away from the lateral ventricles. Locomotor behavior analyzed using the Digiscan animal activity monitors before and after the transplants demonstrated a reversal of the hyperactivity following transplants in 70% of lesioned animals. Microinjections of horseradish peroxidase delivered into the globus pallidus and substantia nigra of a small group of functionally recovered transplanted animals, did not reveal evidence for reinnervation between host nigra or pallidum and the transplant at 10 weeks post-transplantation. Other laboratories have reported anatomical connections by 6 months post-transplantation. Ventricular/brain ratios demonstrated that intraparenchymal transplants significantly reduced the ventricular dilation following KA lesion. These results suggest that functional recovery can be obtained when the transplant is immersed into the hosts striatal parenchyma regardless of the existence of long-range anatomical connections.

Fetal striatal tissue grafts into excitotoxin-lesioned striatum: Pharmacological and behavioral aspects

In an excitotoxin animal model of Huntingtons disease (HD), fetal striatal tissue transplants survive and grow in the host brain and reverse the behavioral, and, hence, functional deficits produced by the lesion. In the present study we found recovery of apomorphine-induced rotation behavior in unilateral excitotoxin-lesioned rats indicating that the transplant reverses this functional pharmacologic deficit induced by the lesion. It might, therefore, by expected that the transplanted fetal striatal tissue would possess similar pharmacological characteristics as the host striatum. However, autoradiographic localization of D1 and D2 dopamine receptors demonstrated that the transplanted tissue expressed relatively small numbers of these receptor subtypes. Furthermore, there was a relative deficit of [3H]forskolin binding to the stimulatory guanine nucleotide regulatory subunit/adenylate cyclase complex in the fetal striatal tissue transplants. Therefore, transplanted tissue which is neurochemically dissimilar to the host striatum is capable of reversing deficits in both drug-induced and spontaneous locomotor activity.

Neural grafts and pharmacological intervention in a model of Huntington's disease

Using the excitotoxic animal model of Huntingtons disease, two experimental treatments were evaluated. The first experiment explored the effect of MK801 (a systemically active anticonvulsant, and noncompetitive NMDA antagonist) pretreatment on quinolinic acid (QA)-induced striatal degeneration and behavioral deficits. MK801 prevented QA-induced neuropathological changes in the striatum and the anatomical protection was correlated with the absence of deficits in the cataleptic response to haloperidol. The second experiment tested the ability of three types of fetal grafts to reverse behavioral deficits induced by kainic acid (KA) lesion. Fetal (E15-16) striatal, cortical and tectal grafts were delivered into the KA-lesioned striatum one week or one month after lesion. Animals in this experiment were evaluated on a motor coordination task, haloperidol-induced catalepsy and amphetamine-induced locomotor activity. Striatal grafts attenuated the deficits induced by KA in all of the tasks observed, and no effect of time of grafting was detected. Tectal grafts had a partial beneficial effect, attenuating the decrease in the cataleptic response to haloperidol observed after KA lesions. No effect of time of grafting was detected for these grafts. In contrast, a clear effect of time of grafting was detected for the cortical grafts. Early cortical grafts reversed the exaggerated response to amphetamine observed after KA lesions whereas late cortical grafts resulted in sham-like scores on the catalepsy test. Histochemical analysis showed that most of the grafts survived, had acetylcholinesterase (AChE) positive fibers and cell bodies, and were metabolically active as indicated by cytochrome oxidase (CO) positive staining. It is suggested that striatal grafts may have restored to some extent the striatal GABAergic control over output structures, and that trophic factors play a role in behavioral recovery as is evident from the beneficial effects of the tectal grafts. Although the mechanisms underlying the differential effects observed after early or late cortical grafts are unknown, the interaction between the cellular components and trophic factors present in the cortical grafts and the condition of the lesioned host at the time of grafting may yield a host-graft complex with a unique profile.

Neural transplants disrupt the blood-brain barrier and allow peripherally acting drugs to exert a centrally mediated behavioral effect

The disruption of the blood-brain barrier (BBB) following neural transplantation has been demonstrated with horseradish peroxidase histochemistry. It appears that the BBB becomes at least temporarily permeable to large macromolecules. In this study, two drugs (N-methylscopolamine and domperidone) that do not normally cross the BBB were shown to exert a centrally mediated behavioral effect when systematically administered in transplanted rats. This demonstrates that N-methylscopolamine, domperidone, and perhaps other peripherally acting drugs can enter the brain via transplants and directly modify CNS function.

Intraparenchymal Striatal Transplants Required for Maintenance of Behavioral Recovery in an Animal Model of Huntington's Disease

Rats which receive injections of kainic acid (KA) into the striatum show many of the anatomical, biochemical and behavioral abnormalities seen in patients with Huntingtons disease. Recently, it has been reported that fetal striatal transplants into the lesioned striatum could normalize the neurological and behavioral abnormalities produced by the KA lesion. The present study examined the issue of transplant integration in producing behavioral recovery. In one experiment, lesioned animals with transplants located within the lateral ventricle were compared against parenchymally transplanted rats. It was found that unless the ventricular transplant grew into the lesioned striatum there was no recovery. The second experiment demonstrated that electrolytic destruction of a successful fetal striatal transplant could reverse the transplant-induced behavioral recovery. These results suggest that the integrity of the transplant is important in maintaining behavioral recovery. A continuing functional interaction between the host brain and transplanted tissue may be a vital element in the success of the fetal striatal transplant.

Constitutive expression of glutamic acid decarboxylase (GAD) by striatal cell lines immortalized using the tsA58 allele of the SV40 large T antigen.

Rodent striatal cells were immortalized using the A58 temperature-sensitive allele of the SV40 large T antigen. Seventy-eight clones and 10 mixed cultures were characterized at the nonpermissive and permissive temperatures. Based on morphology and expression of proteins, cells were classified into three primary types, with types b and c expressing some neuronal characteristics. Type a cells have an epithelial-like morphology with coarse cytoplasmic extensions and occasional fine processes. These cells express vimentin, do not grow well under serum-free conditions and, when confluent, form a uniform monolayer. Type b cells have a polygonal shape and usually extend multiple thin processes. These cells possess large nuclei with multiple nucleoli and do not express vimentin. Type c cells have a fibroblast-like appearance, are unipolar or multipolar, and their soma is smaller than that of type b cells. Type c cells do not express vimentin, and when confluent form a uniform monolayer. Some type b and c clones express N-CAM and MAP-2. Several type b and c cell lines were found to consistently express glutamic acid decarboxylase (GAD) immunoreactivity under several tissue culture conditions. Selected cell lines were transplanted into the intact adult rat brain in several locations. Cells survived well for 15 wk and did not form tumors. The proteins expressed in vivo were similar to those expressed in vitro.