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Biomedical subjects

F C Zhou

Publications and source records attributed to F C Zhou.

At least 37 records · Page 2Linked to original sources
PubMed1997

Transplantation of microencapsulated PC12 cells provides long-term improvement of dopaminergic functions.

The purpose of this study is to examine if microencapsulated PC12 cells may provide long term effects to the hemiparkinsonian rats. A modified technique was used to encapsulate PC12 cells into gelled microspheres. We found that the PC12 cells can survive in the modified microcapsules in vitro. Most of the PC12 cells formed cluster 3 weeks after incubation. The PC12 cell-loaded microcapsules were also examined in vitro. Adult Sprague-Dawley rats, anesthetized with chloral hydrate, were injected unilaterally with 6-hydroxydopamine into the medial forebrain bundle. The effectiveness of this lesion was tested by measuring apomorphine or methamphetamine-induced rotation one month after lesioning. The unilaterally lesioned rats were transplanted with microencapsulated PC12 cells. Results showed that apomorphine and methamphetamine-induced rotations were greatly suppressed after transplantation. One year after the grafting, the animals were anesthetized with urethane for the voltammetric study. Low dose of KCl was directly injected into the grafted striatum through pressure microejection. We found that KCl-induced DA release, as measured by voltammetric techniques, was regenerated in the striatum. The animals were later sacrificed for histological examination. We found that capsules were present in the lesioned striatum one year after grafting. Most of the capsules contained no PC12 cell. However, some capsules were filled entirely with PC12 cells. Taken together, our data suggested that PC12 cells can survive in the capsule in vitro and may provide long-term dopaminergic effects to the hemiparkinsonian rats.

Animals↗
PubMed1996

Serotonin transporter antibodies: production, characterization, and localization in the brain.

Serotonin (5-HT) transporter, the mechanism for 5-HT high affinity uptake, is the essential component for the termination of 5-HT transmission. In order to identify transporter sites on 5-HT neurons or on other 5-HT uptaking cells, three rabbit antisera against cocaine sensitive-serotonin transporter (5-HTT) were produced. Antisera 5-HTT55 (against amino acid sequence 55-68 in cytoplasmic N-terminal) and 5-HTT315 (against amino acid sequence 315-325, a 3rd external loop peptide) were produced against synthetic multiple-antigenic peptides (MAP). Antiserum 5-HTTN was produced against a fusion protein of the first 71 amino acids of N-terminal peptide expressed in recombinant DNA transformed bacteria. SDS-PAGE/Western blots indicate that 5-HTT55 and 5-HTT315 recognized bands of 74 and 64 kDa in rat brains with densities in the order of cortex > or = hippocampus > cerebellum, but not in liver, or muscle. The 5-HTTN recognized the fusion protein expressed in the bacteria, and the 64 kDa band with a similar density profile in the rat brain regions, and negative in liver and muscle. The immunocytochemistry of all three antisera revealed 5-HTT-immunostaining (5-HTT-im) in a pattern similar to 5-HT fiber distribution. 5-HTT55 and 5-HTT315 stainings were punctate in appearance, while 5-HTTN outlined the fibers in the 5-HT fiber areas, and neurons in raphe but not in substantia nigra or locus ceruleus. The preimmune serum and immune serum preabsorbed with 5-HTTN showed negative or diminished staining. Specific neurotoxin, 5,7-dihydroxytryptamine lesion removed all of the 5-HTTN fibers from the injection site, indicating, that 5-HTTN-im fibers are 5-HT fibers in nature. Our study indicates that the three antibodies we produced recognize various domains of the 5-HTT. Our 5-HTT antibodies could be used as new markers of 5-HT fibers, and are particularly useful for the study of the plasticity of 5-HT fibers free of the complications involved with 5-HT content.

Amino Acid Sequence↗
PubMed1996

Constructing a new nigrostriatal pathway in the Parkinsonian model with bridged neural transplantation in substantia nigra.

The physical repair and restoration of a completely damaged pathway in the brain has not been achieved previously. In a previous study, using excitatory amino acid bridging and fetal neural transplantation, we demonstrated that a bridged mesencephalic transplant in the substantia nigra generated an artificial nerve pathway that reinnervated the striatum of 6-hydroxydopamine (6-OHDA)-lesioned rats. In the current study, we report that a bridged mesencephalic transplant can anatomically, neurochemically, and functionally reinstate the 6-OHDA-eradicated nigro-striatal pathway. An excitatory amino acid, kainic acid, laid down in a track during the transplant generated a trophic environment that effectively guided the robust growth of transplanted neuronal fibers in a bundle to innervate the distal striatum. Growth occurred at the remarkable speed of approximately 200 microm/d. Two separate and distinct types of dopamine (DA) innervation from the transplant have been achieved for the first time: (1) DA innervation of the striatum, and (2) DA innervation of the pars reticularis of the substantia nigra. In addition, neuronal tracing revealed that reciprocal connections were achieved. The grafted DA neurons in the SNr innervated the host's striatum, whereas the host's striatal neurons, in turn, innervated the graft within 3-8 weeks. Electrochemical volt- ammetry recording revealed the restoration of DA release and clearance in a broad striatal area associated with the DA reinnervation. Furthermore, the amphetamine-induced rotation was attenuated, which indicates that the artificial pathways were motor functional. This study provides additional evidences that our bridged transplantation technique is a potential means for the repair of a completely damaged neuronal pathway.

Animals↗
PubMed1996

Increased 5-HT1A receptor immunoreactivity in the rat hippocampus following 5,7-dihydroxytryptamine lesions in the cingulum bundle and fimbria-fornix.

Serotonin (5-HT) projections from the ascending raphe nuclei reach the dorsal hippocampus via the cingulum bundle (CB) and fimbria-fornix (FF). Microinjection of the serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) into the CB and FF produces a significant decrease in the density of 5-HT immunoreactive fibers in the hippocampus as early as 3 days postlesion (Zhou, F.C. and Azmitia, E.C. (1983) Brain Res. Bull., 373, 337-348). In the present study we used an anti-peptide antibody against the second extracellular loop of the 5-HT1A receptor and employed immunocytochemistry to examine changes in the expression and distribution of the 5-HT1A receptor in the hippocampus 14 days following administration of 5,7-DHT into the CB and FF. The density of 5-HT immunoreactive fibers was greatly reduced 14 days following the lesions. 5-HT1A immunoreactivity (IR) was localized to the proximal axon near the axon hillock of cells in the pyramidal cell layer of the cornu Ammonus and in the granule cell layer of the dentate gyrus. The intensity of 5-HT1A-IR was increased in the CA1 and dentate gyrus following 5,7-DHT lesions. Intensity in the CA3 also increased but not to a significant level. These findings demonstrate that 5-HT denervation in the hippocampus is followed by increased expression of the 5-HT1A receptor protein. These changes in receptor expression 14 days postlesion may represent adaptive changes by postsynaptic cells following reduced 5-HT innervation and may be the molecular basis for 5-HT1A receptor supersensitivity.

5,7-Dihydroxytryptamine↗
PubMed1995

Immunohistochemical detection of A1 adenosine receptors in rat brain with emphasis on localization in the hippocampal formation, cerebral cortex, cerebellum, and basal ganglia.

Polyclonal antisera were generated against two identical regions of rat and human A1 adenosine receptors using synthetic multiple-antigenic-peptides as immunogens. Western blotting showed that the antisera recognized a single protein in brain of the expected size for A1 receptors. Immunohistochemistry of CHO cells transfected with the rat or human A1 adenosine receptor cDNAs showed robust labeling of the cell surface. In contrast, labeling was not apparent over non-transfected CHO cells, nor over CHO cells expressing A2a receptors. The pattern of immunoreactivity in rat brain was similar to that expected for A1 adenosine receptors. In contrast to receptor autoradiography or in situ hybridization methods, immunohistochemistry allowed identification of individually labeled cells and processes. Heavy labeling was apparent in many brain regions. In the hippocampal formation, strong labeling was present on granule cell bodies and dendrites, mossy fibers, and pyramidal neurons. In cerebellum, basket cells were the most heavily labeled cell type. Less intense staining was present over granule cells. In cerebral cortex, pyramidal cells were the most heavily labeled cell type, and some interneurons were also labeled. In the basal ganglia, 43% of neurons in the globus pallidus were labeled. In the caudate-putamen region, 38% of neurons were labeled. Heavy labeling was present in most thalamic nuclei, and moderate to heavy labeling was seen in many brainstem nuclei. These data identify specific cellular sites of A1 receptor expression and support the concept of cellular specificity of A1 adenosine receptor action.

Animals↗
PubMed1995

Rapid serotonergic fiber sprouting in response to ibotenic acid lesion in the striatum and hippocampus.

Serotonergic (5-HT) sprouting occurs after damage of neighboring 5-HT or non-5-HT fibers. The sprouting signals appear to originate from the target tissue where neural trophic factors are secreted. In order to determine the cellular source of the trophic signal we currently report that removal of local neurons with a neurotoxin, ibotenic acid (IB), triggered a vigorous sprouting of 5-HT fibers in the striatum as early as 3 days after the lesion, which lasted throughout the entire length (21 days) of our study. The 5-HT fiber density in the injection site increased 10-fold in the striatum compared to the contralateral side, and the density of 5-HT varicosities increased 4-fold of normal. The 5-HT level in the striatum correspondingly increased on the lesion side. Three clear morphological concentric zones were formed by the lesion: acellular, aneuronal and outer zones. These zones represent the characteristic reorganization of astrocytes and neurons following an injection of IB. Devoid of any cells, the small acellular zone in the center of the injection site contained few 5-HT fibers. Devoid of neurons, the aneuronal zone contained reactive astrocytes and an abnormally high density of 5-HT fibers with increased staining of S-100. Containing neurons and astrocytes, the outer zone had a normal 5-HT fiber density. The induced 5-HT sprouting in the aneuronal zone strongly suggests that local neurons could provide a trophic factor, but that astrocytes would be the most plausible candidate. This is not an isolated case, IB injections in the hippocampus also induce a similar phenomenon.

Animals↗
PubMed1995

Suitability of fetal tissues from spontaneous abortions and from ectopic pregnancies for transplantation. Human Fetal Tissue Working Group.

OBJECTIVE: To assess the potential availability and utility of fetal tissues obtained from spontaneous abortions and from ectopic pregnancies for human transplantation therapy. DESIGN: Tissue collection and analysis by personnel skilled in tissue banking. SETTING: Procurement programs in five tissue banks located in diverse geographical areas that are funded by the National Institutes of Health. PATIENTS: All women entering obstetric clinics during 1993 who consented to participate in the study. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Evaluation of the products of conception by standard developmental, histological, microbiological, and cytogenetic criteria. RESULTS: From 22,235 obstetric admissions, 1250 spontaneously aborted embryos and 247 products of ectopic pregnancies were obtained. Of these, seven embryos (0.5%) were potentially useful for human transplantation therapy. CONCLUSION: Fetal tissues from spontaneous abortions and from ectopic pregnancies are quite limited as feasible sources for human transplantation therapy.

Aborted Fetus↗
PubMed1995

Human ventromesencephalic grafts restore dopamine release and clearance in hemiparkinsonian rats.

We and others reported previously that transplantation of fetal ventromesencephalic homograft restores the apomorphine-induced rotational behavior and electrochemical indices of dopamine (DA) depletion in the 6-hydroxydopamine (6-OHDA)-lesioned rat. We found that regeneration of KCl-evoked DA release and tyrosine hydroxylase (TH) immunoreactivity was limited to the graft area even 4 months after transplantation. In the present experiments, we transplanted human fetal ventromesencephalic tissue to the 6-OHDA-lesioned rats. After transplantation, rats received chronic cyclosporin and vibramycin treatment. We found that human fetal grafts from the substantia nigra can restore the effects of DA depletion in 6-OHDA-lesioned rats; these fetal grafts were found to reduce the apomorphine-induced rotational behavior and restore K(+)-evoked DA release as well as DA clearance in the striatum. The area with active DA release is far beyond the transplantation site, unlike that seen in the homografted rats. These electrochemical responses correspond to the extended outgrowth of TH-positive neuronal fibers distal to the graft area. Taken together, our data suggest that rats that received human mesencephalic graft had much greater DA innervation and more complete restoration of function than those that received homografts.

Animals↗
PubMed1995

Fetal tissue derived from spontaneous pregnancy losses is insufficient for human transplantation.

OBJECTIVE: To determine if sufficient fetal tissue with desirable transplant characteristics can be obtained from spontaneous abortions. METHODS: A survey of fetal tissues collected from newly diagnosed spontaneous pregnancy losses from three Indianapolis hospitals was conducted from December 1992 to September 1993. Forty-nine of 356 mothers (13.8%) with spontaneous abortions or ectopic pregnancies consented to the evaluation of their products of conception by gross and microscopic pathologic examination, bacterial culture, cytogenetic analysis, cell culture, and maternal serologic tests. RESULTS: Forty-nine pregnancies (gestational age range 5-30 weeks) provided four identifiable embryos, 12 second-trimester fetuses, and one third-trimester fetus. Nine samples (18.4%) were of excellent or good quality on pathologic grading. Twenty-five of 38 samples tested (66%) grew pathogenic bacteria. Maternal serologic tests were negative for antibodies to human immunodeficiency virus, human T-cell lymphotropic virus, syphilis, and hepatitis B in all cases. One of 43 sera was reactive for hepatitis C, and 33 (77%) were positive for cytomegalovirus. Cytogenetic abnormalities were found in 25% of cultured samples. Five fetal brain samples had cell viabilities of 50% or more. Few viable fetal hepatocytes were found. Only two fetal brain samples (4.1%) were potential candidates for human transplantation. CONCLUSION: Spontaneous pregnancy losses yield minimal usable tissue for human transplantation because of a lack of embryonic or fetal tissues, delayed collection, decomposition, genetic abnormality, and bacterial contamination.

Abortion, Spontaneous↗
PubMed1995

Operant response suppression induced with systemic administration of 5-hydroxytryptophan is centrally mediated.

Intracerebroventricular (ICV) administration of selective serotonergic agents was used to examine the extent of central mediation of 5-HTP-induced operant response suppression in rats. ICV administration of LY53857 (1.0, 3.75, or 7.5 micrograms/5 microliters/5 min) dose dependently blocked response suppression induced with systemically administered 5-HTP (25 mg/kg, IP), whereas ICV 0.9% saline (5 microliters over 5 min) had no significant effect on 5-HTP-induced response suppression. ICV ketanserin (7.5 micrograms/5 microliters/5 min) also blocked response suppression induced with systemically administered 5-HTP. ICV administration of the 5-HT2A/2C receptor agonist DOI (80 micrograms/5 microliters/5 min) induced significant periods of response suppression in this model, which was blocked with LY53857 (1.0 mg/kg, IP) pretreatment. These data demonstrate that central administration of 5-HT2A/2C antagonists potently attenuate operant response suppression induced with systemically administered 5-HTP or DOI and are in agreement with previous findings suggesting central mediation of 5-HTP-induced operant response suppression.

5-Hydroxytryptophan↗
PubMed1995

Quantitative immunocytochemical evaluation of serotonergic innervation in alcoholic rat brain.

Neurotoxicity can be divided into three levels: depletion, degeneration and denervation. The first level is determined by the transmitter content, and the second and third levels, which require anatomical evaluation, can be analyzed by quantitative immunocytochemistry on a specific neurotransmitter system. An antibody specific to serotonin (5-HT) can reveal detailed normal as well as degenerative morphology of 5-HT neurons. Quantitative alterations of 5-HT fibers in a particular brain region indicate degenerative or plastic changes. This study demonstrates quantitative immunocytochemistry by using image analysis of immunostained 5-HT fibers in selectively-bred, alcohol-preferring and nonpreferring rats, which are known to have divergent drinking behaviors, and 5-HT contents in specific brain regions. The method of the image analysis is described in detail and the advantages and disadvantages of using this method to detect the degeneration of a particular fiber system are discussed. The 'area density' traditionally measured in image analysis was converted (with Zhou-Tam formula) into 'volume density' to correct the mismeasurement of fibers through the optical depth. Quantitative immunostaining shows that the difference in 5-HT fiber density in particular brain regions between the two rat lines is consistent with changes in content of the 5-HT/5-HIAA and hypersensitivity of 5-HT1 a receptor. This result indicates either (a) the 5-HT content is too low to be detected in the nerve terminals; (b) degeneration of 5-HT fibers occurs in P rats sometime during development; or (c) a smaller number of 5-HT fibers was preprogrammed in the brain regions of P than NP rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1994

NGF-response of EGF-dependent progenitor cells obtained from human sympathetic ganglia.

Signalling molecules are thought to play a significant role in determining the fate of neural crest progenitor cells. The human sympathetic chain was identified at 6.5, 7.5, 8.2, 10.2 and 11.4 postconception (PC) weeks demonstrating low affinity nerve growth factor (NGF) receptors, and was processed for tissue culture. In the presence of epidermal growth factor (EGF), floating spheres of proliferating progenitor cells were developed in vitro. In the absence of EGF progenitor cells differentiated into tyrosine hydroxylase (TH)-immunoreactive neuronal and TH-negative flat cells. NGF treatment significantly increased neurite outgrowth and survival of TH-immunoreactive cells. The multipotent cells we isolated differ from previously reported sympathoadrenal progenitors in that they give rise to TH immunoreactive neurones precociously sensitive to NGF.

Cell Survival↗
PubMed1994

Reduced serotonergic immunoreactive fibers in the forebrain of alcohol-preferring rats.

Our previous study indicated that 5-hydroxytryptamine (5-HT) immunoreactive fiber densities were decreased in specific areas of the brain in alcohol-preferring rats (P) when compared with alcohol-nonpreferring rats (NP). The results of our current study show that there are quantitative and qualitative differences in 5-HT innervation in other selected regions of the forebrains of P rats. The 5-HT fiber density in the brains of young adult P and NP rats was measured by immunocytochemistry and quantitative image analysis. A routine error of two-dimensional quantitation of nerve fiber was addressed and an adjustment was made. The amount of 5-HT fibers was significantly lower in CA4 and fasciola cinereum of the dorsal hippocampus, caudate-putamen, and hypothalamus of the P as compared with NP rats (unpaired Student's t tests). In examining the fiber types, we found that, in the frontal cortical and hippocampal regions, where normally fine 5-HT fibers with small varicosities and thick 5-HT fibers with large varicosities coexist, fewer fine 5-HT fibers were seen in P rats as compared with NP rats. The fine fibers are known to be vulnerable to abusive drugs. These observations indicate that (a) there are quantitative differences in 5-HT innervation or that the 5-HT in some 5-HT fibers is reduced to a level undetectable by immunocytochemistry, and (b) the fine 5-HT fibers are specifically reduced to a greater degree in the selected brain regions of P rats when compared with that of NP rats. The involvement of the 5-HT system in the alcohol abuse is discussed.

Alcohol Drinking↗
PubMed1993

Zonal distribution of protein-acetaldehyde adducts in the liver of rats fed alcohol for long periods.

Acetaldehyde, a highly reactive intermediate of alcohol metabolism, has been shown to form adducts with liver proteins in rats fed alcohol for long periods. In this report, the zonal distribution of liver protein-acetaldehyde adducts that formed in vivo was studied by means of histoimmunostaining. Rats were pair-fed alcohol-containing and alcohol-free AIN'76 liquid diets for 2 or 11 wk before they were killed and subjected to whole body perfusion with paraformaldehyde. Each liver was cut into 60-microns-thick slices. Slices were first treated with 10% hydrogen peroxide to eliminate endogenous peroxidase activity. They were then incubated sequentially with rabbit antihemocyanin-acetaldehyde adduct, goat antirabbit serum IgG and rabbit peroxidase-antiperoxidase complex. The liver slices were stained with diaminobenzidine and counterstained with methylgreen. In the livers of rats fed alcohol for 2 wk, peroxidase activity was evident in the perivenous zone but not the periportal zone. No staining was obtained when the primary antibody had been preabsorbed with immobilized hemocyanin-acetaldehyde adduct or if the liver slices were incubated with the unimmunized rabbit IgG. Slight staining of the perivenous zone was seen in the livers of control rats, presumably because of minimal protein-acetaldehyde adduct formation emanating from endogenous acetaldehyde. When rats were fed alcohol for longer periods (e.g., 11 wk), protein-acetaldehyde adducts were still seen predominantly in the perivenous zone, but the distribution pattern was more diffuse than that observed in the livers of rats fed alcohol for only 2 wk. More liver cells produced protein-acetaldehyde adducts when rats were fed the alcohol-containing diet supplemented with cyanamide.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde↗
PubMed1992

Response suppression induced with selective 5-HT agonists can be differentially blocked with LY53857 in an animal model of depression.

Studies from this laboratory have demonstrated that administration of the selective 5-HT2/1C antagonist LY53857 can block 5-HTP-induced response suppression. To further investigate the serotonergic mechanisms involved in this effect, we decided to test the capacity of LY53857 to block response suppression induced with two selective 5-HT agonists. After a 15 minute baseline period, rats trained to press a lever for milk reinforcement on a VI 1' schedule were given IP injections of 1.0 mg/kg DOI, or 1.0 mg/kg 8-OH-DPAT to induce response suppression. Subsequently, rats were injected with 1.0 mg/kg LY53857 1 hour prior to DOI- or 8-OH-DPAT-induced response suppression. Preinjections with LY53857 resulted in a 100% blockade of DOI-induced response suppression whereas the same dose did not block response suppression induced with 8-OH-DPAT. These results indicate that the 5-HTP-induced response suppression shows some pharmacological similarity to DOI-induced response suppression and may be mediated through 5-HT2 and/or 5-HT1C receptors.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1991

Serotonergic sprouting is induced by dopamine-lesion in substantia nigra of adult rat brain.

We have previously extracted a serotonin (5-HT) neurotrophic supernatant from the 5,7-DHT lesioned hippocampus. The current study shows that a new 5-HT neurotrophic signal was monitored in the striatum and nigra after DA-denervation. Such a signal may be involved in the heterotypic sprouting. Dopaminergic neurotoxin, 6-hydroxydopamine (6-OHDA), was injected directly into the substantia nigra of adult rats. Two months after surgery, immunocytochemical staining showed that tyrosine hydroxylase (TH)-positive cell bodies had mostly disappeared in the substantia nigra, and TH-positive terminals in the striatum were almost completely depleted. Meanwhile, the 5-HT fibers, which exist in the same areas with low density, sprouted in the nigra as well as in the striatum and became dense. Normally 5-HT fibers innervate the striatum sparsely and the globus pallidus densely with sharp delineation (in the control side), and become dense across both areas with no appreciable delineation (in the lesion side). The increase of 5-HT fibers was more prominent in the posterior than in the anterior striatum. A significant increase in 5-HT and 5-HIAA levels was also evident in the posterior striatum when the decrease in DA level exceeded 90% in the nigra and striatum. In addition, we found that induction of 5-HT sprouting requires a greater than 90% decrease of DA level. Current data support that 6-OHDA injection in the substantia nigra of adult rats triggered a trophic signal or removed an inhibition for the growth of 5-HT neurons which responded with sprouting in the nigra as well as in the striatum.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Activity of hippocampal extract on development of [3H]5-HT high-affinity uptake in dissociated microcultures.

Specific and localized lesions of the 5-HT fibers in the hippocampus induce homotypic collateral sprouting and enhance serotonergic fiber outgrowth from adult neurons and transplanted fetal tissue. In this study, hippocampal extracts were prepared and applied to primary cultures of fetal serotonergic neurons. The effects of plating density and serum additives were examined. The growth of the serotonergic neurons in the rostral brainstem dissociated cultures were estimated by measuring the specific uptake of [3H]5-HT. The results indicate the presence of a trypsin-sensitive factor which is active when prepared fresh at dilutions up to 1/10,000. The factor is higher in hippocampus than cerebellum. Young male tissue contained more activity than either female or aged hippocampus. Although both positive and negative effects are described, higher dilutions of factor (1/1,000) were generally stimulatory in high density cultures while lower dilutions (1/10) were inhibitory in low density cultures. Specific removal of 5-HT hippocampal afferents with fornix-fimbria microinjections of 5,7-dihydroxytryptamine resulted in an initial loss of activity (2 days and 2 weeks) followed by an enhanced activity (2 months) compared to normal hippocampal extract. Several possibilities are discussed as to the identity of the serotonergic growth factor from hippocampal supernatant.

5,7-Dihydroxytryptamine↗