Biomedical subjects
C W Shults
Publications and source records attributed to C W Shults.
Fibroblast growth factor-2-producing fibroblasts protect the nigrostriatal dopaminergic system from 6-hydroxydopamine.
We tested the hypothesis that fibroblasts, which had been genetically engineered to produce fibroblast growth factor-2 (FGF-2), can protect nigrostriatal dopaminergic neurons. Three groups of rats received either a burr hole only (n=5) or implantation of fibroblasts, which had been genetically engineered to produce beta-galactosidase (beta-gal) (n=8) or FGF-2 (n=8), at two sites in the right striatum. Two weeks later, the animals received an injection of 25 microg of 6-hydroxydopamine hydrobromide (6-OHDA) midway between the two implant sites. The group that received FGF-2-fibroblasts had significantly fewer apomorphine-induced rotations than the groups that received a burr hole only or beta-gal-fibroblasts at weeks 2 and 3 following lesioning with 6-OHDA. Testing for amphetamine-induced rotation revealed a mild reduction in rotation in the beta-gal-fibroblast group compared to the burr hole only group, but a striking attenuation of amphetamine-induced rotation in the FGF-2-fibroblast group. There was also preservation of TH-IR neurons on the lesioned side relative to both control groups. The size of the grafts and the gliosis surrounding the injection sites did not differ between the FGF-2-fibroblast and beta-gal-fibroblast groups. To further characterize the production of FGF-2 by the FGF-2-fibroblasts, we implanted FGF-2-fibroblasts and beta-gal-fibroblast into the striatum of rats but did not lesion the animals with 6-OHDA. The animals were then sacrificed at 1, 2 and 5 weeks following implantation. Prior to implantation the FGF-2 fibroblasts contained 148 ng/mg of FGF-2-immunoreactive (FGF-2-IR) material per mg of protein of cell lysate. After implantation FGF-2-IR material was noted in the grafts of FGF-2-fibroblasts, most conspicuously at 1 and 2 weeks following implantation. We also noted FGF-2-IR material in the nuclei of reactive astrocytes adjacent to the implants, and OX-42-immunoreactive (OX-42-IR) cells adjacent and occasionally within the implants. Our work indicates that fibroblasts genetically engineered to produce FGF-2 and implanted in the striatum can protect the nigrostriatal dopaminergic system and may be useful in the treatment of Parkinson's disease.
Calretinin-containing axons and neurons are resistant to an intrastriatal 6-hydroxydopamine lesion.
Relative preservation of dopaminergic axons in patches and a subcallosal layer was observed in the dorsal, lateral and caudal striatum 4 weeks after intrastriatal injection of 6-hydroxydopamine (6-OHDA), a neurotoxin selective for catecholaminergic neurons. Since calcium binding proteins are reported to provide neuroprotective influence in neurons, differences in the distribution of the calcium binding proteins might be related to the different vulnerabilities of dopaminergic neurons and axons to neurotoxins. To address this possibility, we characterized patches of relatively dense tyrosine hydroxylase-immunoreactive (TH-IR) axons in intrastriatal 6-OHDA lesioned rats, focusing on two calcium binding proteins, calbindin (CB) and calretinin (CR). The patches and subcallosal layer of preserved dopaminergic axons in the striatum of rats lesioned with 6-OHDA contained CR, a 31-kDa calcium-binding protein, but interestingly not CB. Dopaminergic neurons containing CR in the substantia nigra pars compacta (SNpc) were relatively spared compared to those that did not contain CR. Taken together, our data indicate that dopaminergic axons and neurons containing CR in the nigrostriatal pathway are more resistant to 6-OHDA lesion than those that do not contain CR.
Image motion and context: a between- and within-subjects comparison.
In two previous experiments, we studied how stimulus motion affects both the self-report of emotion experience and the physiological sequelae of emotion. In both studies, image motion intensified emotional responding, and the effect of motion was relatively specific to the arousal dimension of the emotion; there was little evidence that image motion altered the valence of the image. Moving images also appeared to sustain the attention of the participants for a longer period of time than did the still images. In these two experiments, however, image motion was manipulated within participants. In the present experiment, we used a between-subjects manipulation of image motion and found a nearly identical pattern of results. These data indicate that motion inherently increments the arousal value of an image and that this increment is not dependent on the context in which motion is introduced.
A possible role of coenzyme Q10 in the etiology and treatment of Parkinson's disease.
Parkinson's disease (PD) is a degenerative neurological disorder. Recent studies have demonstrated reduced activity of complex I of the electron transport chain in brain and platelets from patients with PD. Platelet mitochondria from parkinsonian patients were found to have lower levels of coenzyme Q10 (CoQ10) than mitochondria from age/sex-matched controls. There was a strong correlation between the levels of CoQ10 and the activities of complexes I and II/III. Oral CoQ10 was found to protect the nigrostriatal dopaminergic system in one-year-old mice treated with MPTP, a toxin injurious to the nigrostriatal dopaminergic system. We further found that oral CoQ10 was well absorbed in parkinsonian patients and caused a trend toward increased complex I activity. These data suggest that CoQ10 may play a role in cellular dysfunction found in PD and may be a potential protective agent for parkinsonian patients.
Coenzyme Q10 attenuates the 1-methyl-4-phenyl-1,2,3,tetrahydropyridine (MPTP) induced loss of striatal dopamine and dopaminergic axons in aged mice.
We investigated whether oral administration of coenzyme Q10 (CoQ10) could attenuate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxicity in one-year-old mice. Four groups of one-year-old, male C57BL/6 mice received a either standard diet or a diet supplemented with CoQ10 (200 mg/kg/day) for five weeks. After four weeks, one group that had received the standard diet and one group that had received the CoQ10 supplemented diet were treated with MPTP. The four groups continued on their assigned diets for an additional week prior to sacrifice. Striatal dopamine concentrations were reduced in both groups treated with MPTP, but they were significantly higher (37%) in the group treated with CoQ10 and MPTP than in the group treated with MPTP alone. The density of tyrosine hydroxylase immunoreactive (TH-IR) fibers in the caudal striatum was reduced in both MPTP-treated groups, but the density of TH-IR fibers was significantly (62%) greater in the group treated with CoQ10 and MPTP than in the group treated with MPTP alone. Our results indicate that CoQ10 can attenuate the MPTP-induced loss of striatal dopamine and dopaminergic axons in aged mice and suggest that CoQ10 may be useful in the treatment of Parkinson's disease.
Absorption, tolerability, and effects on mitochondrial activity of oral coenzyme Q10 in parkinsonian patients.
We report a pilot study of three oral doses of coenzyme Q10 (CoQ10) (200 mg administered two, three, or four times per day for 1 month) in 15 subjects with Parkinson's disease. Oral CoQ10 caused a substantial increase in the plasma CoQ10 level. It was well tolerated, but at the highest dose (200 mg four times per day) mild, transient changes in the urine were noted. CoQ10 did not change the mean score on the motor portion of the Unified Parkinson's Disease Rating Scale. There was a trend toward an increase in complex I activity in the subjects.
Coenzyme Q10 levels correlate with the activities of complexes I and II/III in mitochondria from parkinsonian and nonparkinsonian subjects.
The activities of complex I and complex II/III in platelet mitochondria are reduced in patients with early, untreated Parkinson's disease. Coenzyme Q10 is the electron acceptor for complex I and complex II. We found that the level of coenzyme Q10 was significantly lower in mitochondria from parkinsonian patients than in mitochondria from age- and sex-matched control subjects and that the levels of coenzyme Q10 and the activities of complex I and complex II/III were significantly correlated.
An examination of the nature of attentional deficits in patients with Parkinson's disease: evidence from a spatial orienting task.
Endogenous and exogenous shifts of attention were examined in nondemented patients with Parkinson's disease (PD). In the endogenous condition, an arrow was used to cue participants' attention to the possible location of an impending target, whereas in the exogenous condition, a brightened box was used to cue attention. Cues were either valid (i.e., the target appeared in the cued location) or invalid (i.e., the target appeared in a noncued location). The time between cue onset and target onset (stimulus onset asynchrony or SOA) was varied in each condition. The results indicated that PD patients were not differentially impaired in shifting attention at the shorter SOAs relative to normal controls. However, at longer SOAs, the PD patients demonstrated less of an effect from cueing than did the normal control participants. PD patients' differential effect from cueing was evident in both exogenous and endogenous conditions. These results suggest that PD patients may experience a rapid decay of attentional inhibition and do not support the notion that a decrement in processing resources underlies their attentional deficits. Moreover, these findings further support the notion that the basal ganglia may play an important role in attentional functions.
Intrastriatal injection of GDNF attenuates the effects of 6-hydroxydopamine.
Our study was designed to determine whether intrastriatal administration of glial cell line-derived neurotrophic factor (GDNF) can attenuate the behavioral effects and injury to the mesostriatal dopaminergic system caused by 6-hydroxydopamine (6-OHDA). Four groups of rats received a series of four intrastriatal injections of vehicle or one of three doses of GDNF (0.1, 1 or 10 micrograms per injection) on days 1,3,5 and 8. On day 4 the animals received a single, intrastriatal injection of 25 micrograms 6-OHDA. Treatment with GDNF significantly reduced the development of amphetamine-induced rotation, and the dose of 1 microgram per injection appeared to be the most effective. The group treated with this dose had significantly greater preservation of tyrosine hydroxylase-immunoreactive (TH-IR) fibers adjacent to the injection site in the striatum and significantly greater preservation of Nissl-stained and TH-IR neurons in the substantia nigra pars compacta (SNpc).
BDNF attenuates the effects of intrastriatal injection of 6-hydroxydopamine.
Groups of eight rats received unilateral, intrastriatal injections of 22.5 micrograms brain-derived neurotrophic factor (BDNF) or cytochrome c on 3 consecutive days. Following the injection of BDNF or cytochrome c on the second day, each animal received an intrastriatal injection of 25 micrograms of 6-hydroxydopamine (6-OHDA). During the second week following treatment and thereafter, the animals that received BDNF had significantly fewer apomorphine-induced, contraversive rotations than did the animals that received cytochrome c. The animals that received BDNF but not those that received cytochrome c had a halo of dopaminergic axons around the injection site. Our data indicate that BDNF can attenuate the loss of dopaminergic axons and rotational asymmetry that result from an intrastriatal injection of 6-OHDA.
Brain-derived neurotrophic factor-transduced fibroblasts: production of BDNF and effects of grafting to the adult rat brain.
Local delivery of brain-derived neurotrophic factor (BDNF) by genetically modified cells provides the unique opportunity to examine the effects of BDNF on adult dopaminergic and cholinergic neurons in vivo. Primary rat fibroblasts were genetically engineered to produce BDNF. Conditioned media from BDNF-transduced fibroblasts supported embryonic chick dorsal root ganglion neurons as well as rat fetal mesencephalic neurons. BDNF-transduced fibroblasts grafted to the rat brain survived and showed continued mRNA production for at least 2 weeks. The effects of BDNF-transduced fibroblast grafts on the dopaminergic and cholinergic systems were then assessed. BDNF-transduced fibroblasts grafted into the normal intact substantia nigra induced sprouting of tyrosine hydroxylase- and neurofilament-immunoreactive fibers into the graft. Fibroblast grafts implanted into the normal intact striatum and midbrain as well as the 6-hydroxydopamine-lesioned brain did not induce sprouting of dopaminergic fibers; neither did they affect drug-induced rotational behavior. BDNF-transduced fibroblasts did, however, significantly increase the homovanillic acid/dopamine ratio when grafted into the normal midbrain. Following transection of the fimbriafornix, BDNF-transduced fibroblasts grafted into the septum were unable to rescue the septal cholinergic population, as did nerve growth factor-producing fibroblast grafts. Genetically modified fibroblast grafts may provide an effective, localized method of BDNF delivery in vivo to test biological effects of this factor on the central nervous system.
Low platelet mitochondrial complex I and complex II/III activity in early untreated Parkinson's disease.
Following the discovery of inhibition of electron transport complex 1 by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which produces a parkinsonian syndrome in humans, monkeys, and mice, several laboratories have reported abnormalities of complex I and other electron transport complexes (ETCs) in various tissues from patients with Parkinson's disease (PD). Criticism of the significance of these findings in the etiology of PD has centered on whether drug treatments or the debilitation of the disease process itself produced the low ETC activities. We present results from a blinded study of platelet mitochondrial ETC activities in 18 early untreated PD patients and 18 age- and sex-matched controls and in 13 spousal controls. Lower complex I activity in platelet mitochondria of PD patients was seen in early untreated disease and thus cannot be due to debilitation or drug therapy. Home environmental factors seem an unlikely explanation for the reduced complex I activity in PD patients but have not been excluded. Complex II/III activity was also reduced by 20% in PD compared with age-/sex-matched controls. The low complex I and II/III activities in platelet mitochondria appear to be related to the etiology of PD.
Visual attention and perception in patients with Huntington's disease: comparisons with other subcortical and cortical dementias.
Shifts in attention were examined in patients with Huntington's disease (HD) using a divided attention paradigm that involved the presentation of global-local stimuli. The HD patients' pattern of performance was compared to the previously reported results of groups of patients with Alzheimer's disease (AD; Filoteo et al., 1992) or Parkinson's disease (PD; Filoteo et al., 1994). Across consecutive trials of the divided attention task, a visual target could appear at either the same global-local level or at a different level. When the target changed levels across consecutive trials, the AD patients demonstrated an impairment in disengaging attention from the level at which the last target appeared, whereas the PD patients were impaired in maintaining their attention at the previously attended level. In contrast to these patterns of performances, the HD patients did not demonstrate a significant impairment in shifting attention between hierarchical levels. Both the AD and the PD patients' abnormal shifting ability was significantly related to the number of errors they made in identifying target stimuli; however, the pattern of the relationship was qualitatively distinct. These results suggest that different attentional mechanisms may underlie AD and PD patients' visual-perceptual deficits. The HD patients' shifting ability was not related to the number of errors they made in identifying target stimuli, suggesting that a different mechanism may account for the visual-perceptual impairments exhibited by these patients.
Carbidopa/levodopa and selegiline do not affect platelet mitochondrial function in early parkinsonism.
Previous studies have demonstrated impaired complex I activity in platelets from Parkinson's disease (PD) patients who were receiving levodopa and other medications for their disease. Eleven patients with early PD underwent three sequential plateletphereses: while on no medication, after receiving carbidopa/levodopa for 1 month, and after receiving carbidopa/levodopa plus selegiline for 1 additional month. As expected, carbidopa/levodopa and selegiline significantly improved motor function in these patients. Treatment with carbidopa/levodopa alone and carbidopa/levodopa plus selegiline did not affect the activities of complexes I, II/III, and IV and citrate synthetase. These observations support the hypothesis that impaired complex I activity in PD patients is a characteristic of the disease and not due to medications.
Storage, metabolism, and processing of 125I-fibroblast growth factor-2 after intracerebral injection.
Basic fibroblast growth factor (FGF-2) is a potent trophic agent for both neuronal and non-neuronal cells of the mammalian CNS. It can enhance survival and neurite outgrowth of a variety of neuronal types in vitro and in vivo, and recently has been shown to stimulate neuroblast proliferation in culture. To determine the most effective means of introducing FGF-2 into the brain, and to further our understanding of the behavior of exogenous FGF-2 following intracerebral injection, we examined the diffusion and degradation of 125I-FGF-2 following intraventricular or intraparenchymal injection. SDS-PAGE and autoradiography show that when radiolabelled FGF-2 is injected into the parenchyma of the rat brain, it remains at the site of injection where it is detectable for several days. During this time, it is slowly metabolized to 2 specific heparin-binding metabolic fragments that are virtually identical to the ones described for its metabolism by neurons and astrocytes in vitro. Microscopic examination and autoradiography of these tissue sections show that within these areas, FGF-2 diffuses throughout the site of injection. Initially, it migrates along adjacent fiber tracts, binds to specific cells and to basement membranes of the microvasculature, but later on it remains associated to basement membranes and non-neuronal cells. Based on its slow clearance and slow rate metabolic degradation, this FGF-2 is presumed to be in a sequestered form and to have limited activity. In contrast, the intraventricular injection of 125I-FGF leads to a rapid clearance, with some binding to ependymal cells lining the ventricles and little translocation into the parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)
A single intramesencephalic injection of brain-derived neurotrophic factor induces persistent rotational asymmetry in rats.
Brain-derived neurotrophic factor (BDNF) is expressed in dopaminergic neurons of the substantia nigra pars compacta (SNpc) and the ventral tegmental area and provides trophic support for these neurons in vitro. To study the effects of BDNF on the nigrostrital dopaminergic system in vivo, we administered a single, unilateral injection of BDNF into the medial SNpc of rats and evaluated rotational behavior, striatal levels of dopamine and metabolites, and number of dopaminergic neurons in the SNpc. We found that a single injection of 2 or 3 micrograms of BDNF, but not of vehicle, caused a persistent increase in the net number of amphetamine-induced rotations/min contraversive to the site of injection. The pattern of rotation is consistent with increased activity of the nigrostriatal dopaminergic system on the side of injection. The amphetamine-induced contraversive rotation could be blocked by administration of the dopaminergic antagonist haloperidol. Apomorphine, a direct-acting dopaminergic agonist, did not induce rotation. Levels of dopamine in the striatum and number of dopaminergic neurons in the SNpc were similar in BDNF- and vehicle-treated animals. The increase in contraversive rotations persisted for up to 12 months after a single injection of BDNF.
Thy-1 immunoreactivity distinguishes patches/striosomes from matrix in the early postnatal striatum of the rat.
At P0, P2 and P3, islands of increased density of Thy-1-immunoreactive (Thy-1-IR) material, which coincided with the islands of dense dopaminergic axons, were noted in the striatum. By P5, the distribution of Thy-1-IR material was homogeneous throughout the developing striatum, but islands of dense dopaminergic axons persisted. The pattern of appearance of Thy-1, which is involved in extension of neurites and stabilization of synapses, suggests that it is involved in formation of connections between the substantia nigra and striatum in the developing rat brain.