Behavioral assessment of the ability of intracerebral embryonic neural tissue grafts to ameliorate the effects of brain damage in marmosets.

The transplantation of neuronal tissue into the brains of patients with Parkinson's disease is already being assessed as an experimental treatment for the symptoms of this disease, and the possibility of using similar graft tissue to ameliorate the symptoms of other neurodegenerative diseases is being considered. In this context, a small number of transplant experiments have been carried out in monkeys with lesions of the central dopamine and cholinergic systems. These experiments make it possible to determine the optimum methods of transplantation in an animal whose brain is structurally more closely related to the human than that of the rat and to assess the behavioral consequences of transplantation on symptoms that either resemble very closely the symptoms seen in patients, or are of a complex cognitive nature and are therefore more difficult to measure in the rat. It is intended that these experiments will contribute to the development of better treatments for the neurodegenerative diseases, either by the use of transplantation as a clinical treatment, or by contributing to a better understanding of the mechanisms that normally maintain neuronal function and that fail in these diseases.

Social withdrawal following amphetamine administration to marmosets.

Approaches and leaves from social encounters by marmosets which had received amphetamine injected either intramuscularly or into the nucleus accumbens or caudate nucleus were recorded and used to determine whether social behaviour was disrupted as a result of behavioural competition or more active social withdrawal. The social isolation observed after the marmosets had received an IM injection of amphetamine (2 mg/kg) was not due to drug-induced increases in alternative behaviours. Drugged animals immediately withdrew from social encounters, interrupting their stereotypies in order to do so, whenever they were approached by an undrugged animal. In contrast, the reduced time spent in social encounters following amphetamine injections into the nucleus accumbens (10, 20 or 40 micrograms) appeared to be a direct consequence of the concurrent increase in locomotion. Animals continued to initiate social encounters despite being hyperactive. Amphetamine injections into the caudate nucleus were without effect on any of the social or individual behavioural measures.

Survival of nigral grafts within the striatum of marmosets with 6-OHDA lesions depends critically on donor embryo age.

The study examined the importance of embryonic donor age for the survival of nigral grafts in 6-OHDA-lesioned marmosets. The issue as to whether donor age is critical for the survival of nigral grafts in primates is controversial, because several early reports suggested that relatively old tissue could survive transplantation and produce functional benefits in monkeys, in contrast to the restrictive time dependence observed in rodents. Embryonic marmoset donors embryos of three different ages were employed: 1) E74 (Carnegie stage 18-19); 2) E83-84 (Carnegie stage 23+); 3) E92-93 (foetal period). The nigral neurons derived from the ventral mesencephalon in the two older donor age groups did not survive well when grafted to the striatum of adult marmosets with unilateral 6-OHDA lesions. Although a few tyrosine hydroxylase (TH+) neurons could be identified by immunohistochemistry at graft sites in all recipients in older donor age groups, the numbers of surviving neurons in these were small, on average typically less than 100 TH+ cells. These small grafts were not sufficient to affect amphetamine-induced rotation. In contrast, many more TH+ cells typically survived transplantation in the recipients of graft tissue derived from the youngest donors and amphetamine-induced rotation was significantly reduced in this group alone. The time course and extent of the reduction in rotation was remarkably similar to that observed in previous marmoset nigral graft studies, confirming the utility of amphetamine-induced rotation as a sensitive and reliable indicator of nigral graft function in this species. Considering these results and other recent evidence from monkey to monkey, human to rat, and human to human graft studies, the survival of embryonic nigral tissues derived from primate donors transplanted into the striatum does appear to be critically dependent on the age of the donor tissue.

The effects of ibotenic acid lesions of the nucleus accumbens on spatial learning and extinction in the rat.

Rats with ibotenic acid lesions of the nucleus accumbens (N. Acc) were studied in two spatial learning paradigms: a T-maze and a Morris water maze. Learning of a spatial discrimination task and its reversal in the T-maze were disrupted by the N. Acc lesions. As both original and reversal learning were impaired, there was no evidence of a specific lesion effect on reversal learning. The lesioned rats did not perseverate excessively in their choice of the previously reinforced arm. There was evidence of behavioural inflexibility during extinction when the lesioned rats failed to slow the pace at which they ran the maze in the absence of reward. Spontaneous alternation was not significantly affected by the lesion. Acquisition of the second spatial task, locating the hidden platform in the Morris water maze, was also impaired. The lesioned rats did eventually learn the task and successfully reached the platform with similar latencies and heading errors to controls. Thus, the N. Acc lesion impaired but did not abolish spatial learning in the T-maze and the water maze. The deficits observed in this study may reflect a role for the N. Acc in the reorganisation of behaviour in response to external change.

A lateralised grip strength test to evaluate unilateral nigrostriatal lesions in rats.

A modified grip strength meter was designed to enable the separate measurement of lateralised grip strength in the two forelimbs of rats, in order to allow assessment of deficits in animals with unilateral lesions and grafts within the basal ganglia. Unilateral 6-hydroxydopamine lesions of the dopaminergic nigrostriatal bundle induced a significant asymmetry, marked by an increased grip strength on the side contralateral to the lesion. Lesioned animals with additional implants of embryonic nigral cell suspensions into the dopamine-denervated neostriatum showed a reduced (but not significant) deficit and did not differ from control performance. The lateralised nature of the deficit excludes explanation based on global activational changes; rather the unilateral deficit may provide a simple test of unilateral 'rigidity' in a widely used rodent model of Parkinson's disease.

A novel population of tyrosine hydroxylase immunoreactive neurones in the basal forebrain of the common marmoset (Callithrix jacchus).

We have observed in the basal forebrain of the common marmoset a group of neurones which display tyrosine hydroxylase immunoreactivity (THir) with three different polyclonal antibodies and one monoclonal antibody, and which express TH mRNA as shown by in situ hybridization histochemistry. The population of cells is composed of large multipolar neurones and is located predominantly in the substantia innominata and at the ventral, medial and lateral margins of the external segment of the globus pallidus. The cell morphology and the distribution of THir cells corresponds closely to the caudal portion of the nucleus basalis of Meynert. Adjacent sections demonstrate both THir and choline acetyltransferase immunoreactivity in the cells in this group, as well as strong acetylcholinesterase activity but not dopamine immunoreactivity. These observations indicate that many cholinergic neurones in the posterior nucleus basalis of Meynert of the marmoset contain tyrosine hydroxylase, and suggest that both acetylcholine and catecholamine may be synthesised as co-localised neurotransmitters within the same magnocellular neurones. We observe no THir cells in similar areas of the basal forebrain of either rhesus or talapoin monkeys.

The placement of a striatal ibotenic acid lesion affects skilled forelimb use and the direction of drug-induced rotation.

The motor consequences of excitotoxic striatal damage have been evaluated extensively in the rat, using tests of whole body motor asymmetry and of deficits in skilled paw and limb movements. However conflicting results of both the type and extent of behavioural deficits have been reported, particularly in the direction of rotation observed in response to the dopamine receptor agonist, apomorphine. The present study investigated the effect of unilateral ibotenic acid lesions in the dorsal striatum of the adult rat, placed at either anterior, posterior, medial, or lateral loci, on rotation in response to both amphetamine and apomorphine, and in the "staircase test" of skilled forelimb use. In a 2 x 2 matrix design experiment, adult female albino rats received a double unilateral lesion of 0.5 microliter 0.06 M ibotenic acid injected at each of two sites either anterior (medial and lateral), posterior (medial and lateral), medial (anterior and posterior), or lateral (anterior and posterior). Rats that received posterior lesions showed a marked ipsilateral rotation in response to both amphetamine and apomorphine, while animals receiving anterior lesions showed little ipsilateral or a slight contralateral bias. Rats receiving lateral lesions showed a marked impairment of contralateral paw use on the "staircase test," while animals with medial lesions showed no significant difference to control unoperated animals. These results confirm the somatotopic organisation of the dorsal striatum in its control of motor functions, and indicate the need to take into account the locus of an excitotoxic lesion in the design of lesion and transplantation studies if we are to achieve reliable tests of the behavioural deficits and recovery.

Influence of health and environmental information on hedonic evaluation of organic and conventional bread.

Grain from paired samples of the hard red spring wheat cultivar "Park" grown on both conventionally and organically managed land was milled and baked into 60% whole wheat bread. Consumers (n= 384) rated their liking of the bread samples on a 9-point hedonic scale before (blind) and after (labeled) receiving information about organic production. Consumers liked organic bread more (P < 0.05) than conventional bread under blind and labeled conditions. Environmental information about organic production did not impact consumer preference changes for organic bread, but health information coupled with sensory evaluation increased liking of organic bread. Ordinary least squares (OLS) and binary response (probit) regression models identified that postsecondary education, income level, frequency of bread consumption, and proenvironmental attitudes played a significant role in preference changes for organic bread. The techniques used in this study demonstrate that a combination of sensory and econometric techniques strengthens the evaluation of consumer food choice.

Sensory profiles of bread made from paired samples of organic and conventionally grown wheat grain.

The Canadian hard red spring wheat cultivar "Park" was grown in 2005 in Edmonton, AB, Canada on both conventionally and organically managed land, situated less than 1 km apart. Grains from the paired wheat samples were compared for cereal-grain-quality attributes. For sensory analysis, organically and conventionally produced wheat grains were milled into flour and baked into 60% whole wheat bread. Color, texture, taste, and aroma attributes of bread were compared using the sensory technique of descriptive analysis. Organic grain contained more wholemeal protein than conventional grain (P < or = 0.05), but both were greater than 14% protein, indicating excellent grain quality for yeast-leavened bread. Mixograph analysis revealed that conventional flour produced stronger bread dough than organic flour (P < or = 0.05). Visual observation confirmed these findings as conventional flour produced larger bread loaf volume. Fourteen sensory attributes were generated by the descriptive analysis panel. No differences were observed for flavor, aroma, or color attributes (P > 0.05), but the panel perceived the organic bread to be more "dense" in texture (P < or = 0.05) with smaller air cells in the appearance of the crumb (P < or = 0.05) than conventional bread.

Behavioural analysis of unilateral monoamine depletion in the marmoset.

Unilateral stereotaxic injections of 6-hydroxydopamine (6-OHDA) into the nigrostriatal bundle of marmosets (Callithrix jacchus) produced substantial losses of tyrosine hydroxylase immunoreactive neurons from the substantia nigra, and mean dopamine (DA) depletions of 98-99% in the caudate nucleus, putamen and nucleus accumbens, and of 91-97% in frontal cortex, on the side of the lesion. Noradrenaline (NA) and 5-hydroxytryptamine (5-HT) levels were also affected. Behavioural tests conducted pre-operatively and at regular intervals during the 6 mths following surgery revealed persistent deficits in the lesioned marmosets as a group compared with sham-lesioned controls, although individual marmosets sometimes recovered or showed no initial deficit on some tests. The main behavioural effects of the lesion were as follows: (i) an increase in the time spent with the head positioned ipsilaterally with respect to the rest of the body; (ii) ipsilateral spontaneous and amphetamine-induced rotation, although occasional intermittent periods of contralateral rotation and head biases were also recorded; (iii) contralateral apomorphine-induced rotation; (iv) reduced spontaneous activity; (v) ipsilateral hand preference on a conveyor belt task, although hand skill (measured as percentage errors when the speed of the belt was increased) was not affected; (vi) neglect of contralateral stimuli, both at the conveyor belt where lesioned monkeys often failed to respond on trials on which apple pieces arrived from the contralateral side, and on a test of sensorimotor neglect in which adhesive labels were placed around both feet. Comparisons of biochemical measures of the lesion with behavioural scores in individual monkeys suggest that DA depletions in excess of 95% are essential for long-term behavioural deficits.

Behavioural effects of subthalamic nucleus lesions in the hemiparkinsonian marmoset (Callithrix jacchus).

Recent studies in non-human primates support a role for the subthalamic nucleus in the expression of parkinsonian symptomatology, and it has been proposed that subthalamic lesions may provide a surgical treatment for the symptoms of Parkinson's disease in humans. We have applied a broad range of behavioural tests to characterize the effects of lesions of the subthalamic nucleus on parkinsonian symptoms in the unilateral 6-hydroxydopamine (6-OHDA) lesioned marmoset (Callithrix jacchus). Thirteen marmosets were trained on a battery of behavioural tasks that were conducted at regular intervals before and after surgery. All received unilateral 6-OHDA lesions to the medial forebrain bundle. Seven animals were then given an additional N-methyl-D-aspartate lesion of the ipsilateral subthalamic nucleus, whereas the remaining six animals received a variety of control or sham lesions to the nucleus. The 6-OHDA lesions induced a strong ipsilateral bias in head position; mild-moderate ipsilateral rotation spontaneously and after injection of saline or amphetamine; and contralateral rotation after injection of apomorphine. Hemineglect was evident as delayed initiation of reaches on the contralateral side on the staircase reaching task. Additional subthalamic lesions significantly reversed the bias in head position from ipsilateral to contralateral and decreased neglect as evidenced by improved latencies to initiate reaching on the contralateral side at the staircase. However, deficits in skilled movements persisted in the subthalamic nucleus lesion group in that they did not complete the staircase task any faster than the control group and remained impaired on another task which required reaching into tubes. These behavioural effects demonstrate that excitotoxic lesioning of the subthalamic nucleus can ameliorate some, but not all, parkinsonian-like deficits in the unilateral 6-OHDA lesioned marmoset.

Intrastriatal dopamine-rich grafts induce a hyperexpression of Fos protein when challenged with amphetamine.

The aim of the present experiment was to characterize the effect of intrastriatal grafts of embryonic dopaminergic neurones on the expression of Fos protein in the striatum when challenged with amphetamine. Unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway were made in adult rats and grafting was performed 3 weeks later. The numbers of Fos-positive nuclei in the ipsi- and contralateral striata were counted on coronal sections following immunohistochemical staining 5 months after grafting. Administration of d-amphetamine induced an increase in the density of Fos-positive nuclei in the intact striatum. This stimulatory effect of amphetamine on c-fos expression was blocked by 6-hydroxydopamine hydrobromide lesions and was restored in the striata bearing transplants. However, an overshoot was observed as the density of Fos-positive cells within the grafted striatum was larger than that observed within the intact striatum. This hyperexpression of Fos-positive nuclei was correlated with the exaggerated compensation of amphetamine-induced rotation in the same animals.

A comparison of the behavioural effects of embryonic nigral grafts in the caudate nucleus and in the putamen of marmosets with unilateral 6-OHDA lesions.

The behaviour of marmosets with unilateral 6-hydroxydopamine lesions of the nigrostriatal bundle and grafts of embryonic mesencephalon in either the caudate nucleus or the putamen was compared with that of lesion-alone and unoperated controls. The grafts comprised injections of cell suspensions prepared from marmoset ventral mesencephalon (i.e. allografts) targeted at four sites either entirely within the caudate nucleus or entirely within the putamen. Behavioural tests, including measures of amphetamine-induced rotation, neglect and use of each arm to retrieve food from inside tubes, were given before and after the 6-hydroxydopamine lesion and at regular intervals for 6 months after transplantation surgery. Grafts in the caudate nucleus reduced the ipsilateral rotation induced by amphetamine, whereas grafts in the putamen did not. Despite the absence of an effect on rotation, the putamen grafts were effective in reducing lesion-induced deficits on the task in which the marmosets were required to reach into tubes. In this latter task, the caudate grafts were also effective when the monkeys were given a free choice of which hand to use. However, when constrained to use the hand contralateral to the lesion and graft, the performance of the marmosets with caudate grafts was not significantly improved compared with that of lesion-alone controls. Neither the grafts in the caudate nucleus nor the grafts in the putamen abolished the contralateral somatosensory neglect induced by the lesion, although there was a trend for the marmosets with putamen grafts to contact the label on the contralateral side more quickly than those with caudate grafts or the lesion-alone controls. These results demonstrate that the location of embryonic nigral grafts within the primate striatum influences the profile of functional recovery.

Behavioral assessment of the effects of embryonic nigral grafts in marmosets with unilateral 6-OHDA lesions of the nigrostriatal pathway.

Grafts of embryonic nigral tissue were made into the striatum of marmosets (Callithrix jacchus) which had previously received a unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal bundle. The grafts comprised injections of cell suspensions prepared from embryonic (74 day) marmoset ventral mesencephalic tissue targeted at multiple striatal sites in the caudate nucleus, the putamen, and the nucleus accumbens on the same side as the initial lesion. A series of behavioral tests was used to assess the monkeys prior to surgery, following the 6-OHDA lesion, and at regular intervals for 6 months after transplantation surgery. Lesioned and grafted (n = 6) or lesion alone (n = 4) monkeys were matched as far as possible with respect to their scores prior to transplantation so that explicit graft-derived recovery could be distinguished from any spontaneous recovery that might occur. Sham-lesioned or unoperated monkeys served as further controls (n = 5). The grafts were functionally effective as measured by a reduction, and in some cases a reversal, of spontaneous, amphetamine- and apomorphine-induced rotation. The reversal of amphetamine-induced rotation correlated with the number of dopaminergic neurons in the grafts visualized by tyrosine hydroxylase immunohistochemistry. Successful use of the hands was restored by the grafts on tasks in which the monkeys reached into tubes to retrieve food. However, functional recovery was not seen on some other behavioral tests. In particular, grafts did not influence ipsilateral biases induced by the lesion, including the position of the head with respect to the rest of the body, hand preference while reaching for food at a conveyor belt, and neglect of contralateral stimuli either at the conveyor belt or of adhesive labels placed around the feet. Indeed, the graft group was impaired compared with the lesion group in the accuracy of reaches at the conveyor belt. Overall, these results indicate that embryonic nigral grafts can yield a partial recovery from the symptoms induced by unilateral nigrostriatal lesions in a primate model of hemiparkinsonism.

The influence of excitotoxic basal ganglia lesions on motor performance in the common marmoset.

Huntington's disease is a genetically inherited neurodegenerative disorder for which currently there is no effective treatment or cure. In order to gauge the potential therapeutic benefits of neuroprotective or restorative treatments, it is necessary to create an animal model that is associated with readily measurable and long-lasting functional impairments. The undifferentiated neostriatum and limited behavioural repertoire of rodents have led to the extension of our investigations into the common marmoset. We have used quinolinic acid to create unilateral excitotoxic lesions of the caudate nucleus or the putamen in this small non-human primate. Following rigorous investigation of each monkey on a battery of behavioural tests, we found that the unilateral putamen lesion was associated with a contralateral motor impairment that persisted for at least 9 months and withstood repeated testing. However, the unilateral caudate nucleus lesion did not appear to be associated with any detectable motor deficit. The stability and the reproducibility of the unilateral putamen lesion in the marmoset provide a suitable tool for the investigation of potential treatments for neurodegenerative disorders that attack this region of the brain.

Conditioning versus priming of dopaminergic grafts by amphetamine.

Previous treatment with amphetamine can influence the rotational response induced by amphetamine in rats with dopaminergic grafts. In order to distinguish whether this is due to graft "priming" or conditioning effects of the drug, groups of adult rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra, or with the lesion plus grafts of embryonic mesencephalic tissue in the striatum, were exposed to either: (1) amphetamine in the test environment and saline in the home cage; (2) saline in the test environment and amphetamine in the home cage; or (3) saline in the test environment and saline in the home cage. During this conditioning stage of the experiment, rats with the lesion alone rotated ipsilaterally and rats with the lesion plus grafts contralaterally when tested after administration of amphetamine. The rotation sensitized, i.e. the rats with lesions made more ipsilateral and the rats with grafts more contralateral turns, with repeated injections of the drug. On a subsequent no-drug test, only the rats with grafts which had previously experienced amphetamine in the test environment (1) showed conditioned contralateral rotation. Rats with grafts which had received the same number of amphetamine injections, but experienced the effects of the drug in the home cage (2), rotated ipsilaterally on the no-drug test to the same extent as rats with grafts which had received only saline (3). Thus, amphetamine treatment per se did not "prime" grafts. Rather, the response of the rats with grafts was the result of formation of a conditioned association between the amphetamine and the environment with which it had been paired.(ABSTRACT TRUNCATED AT 250 WORDS)

Subthalamic nucleus lesions induce deficits as well as benefits in the hemiparkinsonian rat.

Lesions of the subthalamic nucleus can restore some imbalances in motor output of the basal ganglia induced by nigrostriatal dopamine depletion, and have been proposed as a potential therapy for Parkinson's disease. Although there is substantial supporting evidence from experimental studies in both rats and primates, there is less information on the effects of subthalamic lesions alone. In order to characterize potential side effects, the present study evaluates the behavioural effects of unilateral excitotoxic lesions of the subthalamic nucleus in rats that have previously received either unilateral saline or 6-hydroxydopamine injections into the nigrostriatal bundle on the same side. The 6-hydroxydopamine lesions induced ipsilateral orientation asymmetries in head position and body axis bias, rotational asymmetries following injections of direct or indirect dopamine agonists, neglect of contralateral stimuli, and a reduction in the numbers of pellets retrieved with the contralateral paw in a skilled reaching task. Subsequent excitotoxic lesions of the subthalamic nucleus reduced (but did not abolish) rotational asymmetries, had no effects on the measures of neglect and skilled paw-reaching, and produced contralateral orientation biases in head turning and body axis curling. Rats that received subthalamic lesions alone exhibited de novo impairments comprising contralateral biases in the orientation tests. These results support a neuromodulatory role of the subthalamic nucleus in regulating motor outputs of the basal ganglia, and caution that there may be distinct side effects of the lesion by itself. Whereas some impairments attributable to dopamine depletion may be alleviated by subthalamic manipulations, other symptoms are not, or may even be aggravated.