Beneficial effects of Dendrobium officinale on metabolic hypertensive rats by triggering the enteric-origin SCFA-GPCR43/41 pathway

Given the increasing global trend toward unhealthy lifestyles and dietary decisions, such as "over-consumption of alcohol, and high sugar and fat diets" (ACHSFDs), it is not surprising that metabolic hypertension (MH) is now the most common type of hypertension. There is an urgent, global need for effective measures for the prevention and treatment of MH. Improper diet leads to decreased short-chain fatty acid (SCFA) production in the gut, leading to decreased gastrointestinal function, metabolism, and blood pressure as a result of signaling through G-protein-coupled receptors (GPCRs), ultimately causing MH. Previous studies have suggested that Dendrobium officinale (DO) may improve gastrointestinal function, lower blood pressure, and regulate metabolic abnormalities, but it is not clear whether it acts on MH by increasing SCFA and, if so, how. In this research, it was observed that Dendrobium officinale ultrafine powder (DOFP) could lower blood pressure and improve lipid abnormalities in ACHSFD-induced MH model rats. Moreover, DOFP was found to improve the intestinal flora and increased the SCFA level in feces and serum, as well as increased the expressions of GPCR43/41 and eNOS and the nitric oxide (NO) level. An experiment on isolated aorta rings revealed that DOFP improved the vascular endothelial relaxation function in MH rats, and this effect could be blocked by the eNOS inhibitor l-NAME. These experimental results suggest that DOFP improved the intestinal flora and increased the production, transportation, and utilization of SCFA, activated the intestinal-vascular axis SCFA-GPCR43/41 pathway, improved vascular endothelial function, and finally lowered blood pressure in MH model rats. This research provides a new focus for the mechanism of the effect of DOFP against MH by triggering the enteric-origin SCFA-GPCR43/41 pathway.

Dendrobium officinalis Flower Improves Learning and Reduces Memory Impairment by Mediating Antioxidant Effect and Balancing the Release of Neurotransmitters in Senescent Rats

AIM AND OBJECTIVE

The Dendrobium officinalis flower (DOF) is popular in China due to common belief in its anti-aging properties and positive effects on "nourish yin". However, there have been relatively few confirmatory pharmacological experiments conducted to date. The aim of this work was to evaluate whether DOF has beneficial effects on learning and memory in senescent rats, and, if so, to determine its potential mechanism of effect.

MATERIALS AND METHODS

SD rats were administrated orally DOF at a dose of 1.38, or 0.46 g/kg once a day for 8 weeks. Two other groups included a healthy untreated control group and a senescent control group. During the 7th week, a Morris water maze test was performed to assess learning and memory. At the end of the experiment, serum and brain samples were collected to measure concentrations of antioxidant enzymes, including malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GSH-Px) in serum, and the neurotransmitters, including γ-aminobutyric acid (γ-GABA), Glutamic (Glu), and monoamine oxidase B (MAO-B) in the brain. Histopathology of the hippocampus was assessed using hematoxylin-eosin (H&E) staining.

RESULTS

The results suggested that treatment with DOF improved learning as measured by escape latency, total distance, and target quadrant time, and also increased levels of γ-GABA in the brain. In addition, DOF decreased the levels of MDA, Glu, and MAO-B, and improved SOD and GSHPx. Histopathological analysis showed that DOF also significantly reduced structural lesions and neurodegeneration in the hippocampus relative to untreated senescent rats.

CONCLUSION

DOF alleviated brain aging and improved the spatial learning abilities in senescent rats, potentially by attenuating oxidative stress and thus reducing hippocampal damage and balancing the release of neurotransmitters.

Systematic Understanding of the Mechanisms of Flos Chrysanthemi Indici-mediated Effects on Hypertension via Computational Target Fishing

AIMS AND OBJECTIVE

Hypertension-induced stroke and coronary artery disease are significant causes of global morbidity and mortality. Metabolic hypertension has recently become the leading cause of hypertension. Flos Chrysanthemi Indici (CIF) has a long history as a treatment of hypertension as part of traditional Chinese medicine. However, its mechanisms of activity remain largely unknown. This study was aimed to uncover the potential anti-hypertensive mechanisms of CIF based on network pharmacology.

MATERIALS AND METHODS

In this research, a systems pharmacology approach integrating the measurement of active compounds, target fishing, gene screening, Gene Ontology (GO) pathway analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology Based Annotation System (KOBAS) database analysis, and compound-target network construction were performed to explore the anti-hypertensive mechanisms of CIF.

RESULTS

These studies revealed that 12 bioactive compounds in CIF had good druggability, 5 of which were flavonoids. After screening, 8 of those 12 bioactive compounds interacted with 118 hypertensionrelated target genes, which were mapped to 218 signal pathways. Network analysis showed that these targets were associated with improving insulin resistance, improving vascular function, inhibiting renninangiotensin- aldosterone system (RAAS), inhibiting the sympathetic nervous system (SNS) and regulating other physiological processes.

CONCLUSION

In summary, CIF is predicted to target multiple proteins and pathways to form a network that exerts systematic pharmacological effects in order to regulate blood pressure and metabolic disorder.

Anti-inflammatory effect of Ganluyin, a Chinese classic prescription, in chronic pharyngitis rat model

Background

Ganluyin (GLY) is a famous classical prescription with a long history of use as a treatment for inflammatory conditions such as chronic pharyngitis (CP) in many parts of China. However, it has not been developed as a modern pharmaceutic and its anti-inflammatory mechanisms remain unclear. The aim of this study was to assess the anti-inflammatory efficacy of GLY and potential mechanisms in a rat model of CP.

Methods

The chemical profile of GLY was analyzed by HPLC-UV. We used a mouse model of ear edema and a rat model of paw edema. Specifically, xylene was used to induce edema on the surface of one ear in mice, and carrageenan was injected subcutaneously into the right hind paws of rats to induce paw edema. The paw thickness, ear weight, and ear perfusion were measured and recorded. The CP model in rats was induced by irritating the throat with 5% ammonia and was used to evaluate the therapeutic efficacy of GLY. Levels of interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor (TNF-α), and prostaglandin E2 (PGE2) were measured by ELISA in serum, and protein expression of cyclooxygenase-2 (COX-2) and nuclear factor kappa-B p65 (NF-κB p65) in the throat were detected by immunohistochemistry and Western blot to evaluate the anti-inflammatory mechanism of GLY. Hematological assays were also conducted.

Results

There were four flavonoids identified in GLY: naringin, neohesperidin, baicalin, and wogonoside. The oral administration of GLY showed a significant inhibitory effect on xylene-induced ear swelling and ear blood flow in mice and significantly ameliorated rat right hind paw edema at doses of 6.2 and 12.4 g/kg. Mechanistic studies found that the anti-inflammatory activity of GLY was related to the inhibition of pro-inflammatory cytokines such as IL-1β, IL-6, TNF-α, and PGE2 and that GLY reduced the expression of COX-2 and NF-κB p65 proteins in the throat, attenuated throat injury, and reduced inflammatory exudates. Hematological analysis showed that treatment with GLY prevented increases in white blood cell (WBC), neutrophil (NEUT), lymphocyte (LYMPH) and monocyte (MONO) levels.

Conclusions

These studies indicated that GLY has beneficial anti-inflammatory effects on CP and that it acts through reducing pro-inflammatory factors such as IL-1β, IL-6, TNF-α, and PGE2, as well as decreasing WBC, NEUT, LYMPH and MONO levels and decreasing the expression of COX-2 and NF-κB p65 proteins. These findings may lay the groundwork for further studies of GLY as a suitable candidate for the treatment of inflammatory diseases such as CP.

Hypertensive Rats Treated Chronically With Nω-Nitro-L-Arginine Methyl Ester (L-NAME) Induced Disorder of Hepatic Fatty Acid Metabolism and Intestinal Pathophysiology

N^ω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) biosynthesis, results in hypertension and liver injury. This study aimed at investigating the changes of liver lipometabonomics and exploring the underlying mechanisms of liver injury in the L-NAME-treated rats. The male Sprague-Dawley (SD) rats were treated with L-NAME (40 mg/kg, p.o.) for 8 weeks. After that, the liver, aorta, fecal, and serum were collected for analysis. The results showed that L-NAME induced hypertension and disordered the endothelial nitric oxide synthase (eNOS)-NO pathway in the treated rats. L-NAME could also increase the levels of serum total cholesterol (TC), triglyceride (TG), alanine transaminase (ALT), and aspartate transaminase (AST). The multidimensional mass spectrometry-based shotgun lipidomics (MDMS-SL) analysis showed that L-NAME could induce significant changes of the total hepatic lipids and most hepatic triglycerides, as well as fatty acid (FA). A positive correlation was found between the blood pressure and TAG. Immunofluorescence and Western-Blot experiments indicated that the L-NAME treatment significantly influenced some FA β-oxidation, desaturation, and synthesis-related proteins. The increase of intestinal inflammation, decrease of microcirculation and tight junction proteins, as well as alterations of microbial communities were observed in the L-NAME induced hypertensive rats, as well as alterations of microbial communities were notable correlation to TAG and FA species. This study demonstrated that the L-NAME-induced hypertensive rats exhibiting liver injury were the joint action of hepatic abnormal fatty acid metabolism and microcirculation disorder. Furthermore, the gut microflora, as well as the changes of FA β-oxidation (ACOX, CPT1α), desaturation (SCD-1), and synthesis (FAS) may be the potential mechanisms for abnormal fatty acid metabolism.

Excitochemical-Induced Trophic Bridging Directs Axonal Growth of Transplanted Neurons to Distal Target

Brain grafts directly placed in their target regions often lack proper connections and normal regulation. When brain grafts are placed in their ontogenetic normal area, the axonal outgrowth of grafts to distal target regions is a major obstacle. We previously demonstrated that directional axonal growth of grafts can be facilitated by laminin. In this study we demonstrated that excitochemicals induced trophic environment can be strategically used as a bridge to guide transplanted neurons to innervate a distal target of millimeter distance, and has a unique effect on fiber expansion in the target region. To distinguish dopamine (DA) growth from that of transplants, 6-hydroxydopamine was unilaterally injected into medial forebrain bundle to remove dopamine innervation to the striatum. Ibotenic acid (IB), kainic acid (KA), or phosphate buffer (vehicle) were micro-injected through a glass-pipet to make a 7 mm long tract between the substantia nigra and the striatum in Sprague-Dawley rats. Gestational 14-15 days brainstem slurry was transplanted either in the same or a separate tract into nigra at the bottom of the bridge. All transplants survived with abundant serotonin (5-HT) and DA neurons. Traceable DA fibers formed distinct bundles from grafts along the length of IB/KA tracts. Upon arrival at their major target regions, fibers from bundles were capable of leaving the tracts, and reinnervating the DA-vacated striatum. The 5-HT fibers formed bundles similar to DA fibers but left the tract earlier upon arrival at their major target the globus pallidus and when arriving at the striatum and cortex. Fibers from grafts with vehicle tracts grew randomly and not into the tract. These results indicate that the trophic effects of chemical lesioning serves as a remarkably effective axonal guidance for more than one type of fetal neuron to innervate distal brain regions. This method has great potential in directing fibers in many transplant models.

Expression of cellular retinoic acid-binding protein I is specific to neurons in adult transgenic mouse brain

Cellular retinoic acid binding protein I (CRABP-I) plays a role in retinoic acid (RA) metabolism or transport. This report shows specific neuronal expression of CRABP-I in adult transgenic mouse brain using CRABP-I promotor-driven lac-Z and neuron- and astrocyte-markers. Double staining indicates that CRABP-I is expressed in neurons and large cells (>12 microm) but to much lesser degree the astrocytes. CRABP-I-lac-Z(+) neurons were distributed throughout the brain, but in a very discreet pattern in each brain region. CRABP-I expression in specific populations of brain neurons suggests that RA is extensively metabolized in mature brains, mostly in neurons. Additionally, the genetic basis of its specific expression in these brain areas is located in the 5' regulatory region of this gene.

Changes in the serotonergic system in the main olfactory bulb of rats unilaterally deprived from birth to adulthood

The serotonergic system plays a key role in the modulation of olfactory processing. The present study examined the plastic response of this centrifugal system after unilateral naris occlusion, analysing both serotonergic afferents and receptors in the main olfactory bulb. After 60 days of sensory deprivation, the serotonergic system exhibited adaptive changes. Olfactory deprivation caused a general increase in the number of fibres immunopositive for serotonin but not of those immunopositive for the serotonin transporter. HPLC data revealed an increase in serotonin levels but not in those of its major metabolite, 5-hydroxyindole acetic acid, resulting in a decrease in the 5-hydroxyindole acetic acid/serotonin ratio. These changes were observed not only in the deprived but also in the contralateral olfactory bulb. Double serotonin-tyrosine hydroxylase immunolabelling revealed that the glomerular regions of the deprived olfactory bulb with a high serotonergic fibre density showed a strong reduction in tyrosine hydroxylase. Finally, the serotonin(2A) receptor distribution density and the number of juxtaglomerular cells immunopositive for serotonin(2A) receptor remained unaltered after olfactory deprivation. Environmental stimulation modulated the serotonergic afferents to the olfactory bulb. Our results indicate the presence of a bilateral accumulation of serotonin in the serotonergic axon network, with no changes in serotonin(2A) receptor density after unilateral olfactory deprivation.

Neurotransmitters and substances of abuse: effects on adult neurogenesis

Neurogenesis in the adult brain is now a well-recognized phenomenon. The compelling subject of interest now is that besides the intrinsic, what are the environmental factors which affect neural stem cells ability to maintain themselves and enter the pool of the adult brain. While the molecular and cellular mechanisms that regulate this process remain to be elucidated, substantial data implicate common pathways involving action of neurotransmitters through neurotrophic factors to regulate the neural stem cells. This transmitter-mediated neurotrophic factor pathway could be altered by extrinsic environmental factors including enriched environment, exercise, stress, and drug abuse (i.e. alcohol, opioid, methamphetamine). Our special attention focuses on the role of neurotransmitters; among them are serotonin (5-HT), glutamate and gamma-amino-butyric acid (GABA). Substances of abuse including alcohol, which may interact through these neurotransmitters and neurotrophic factors to affect neurogenesis, are also reviewed.

First human ventral mesencephalon and striatum cografting in a Parkinson patient

Fetal ventral mesencephalon (VM) transplantation has been reported to improve parkinsonian symptoms. Animal studies show that cografting of striatal tissue increases the survival of dopamine neurons. Whether or not VM and striatum cografting could ameliorate motor dysfunction in a Parkinson's disease (PD) patient was explored in this study. The patient was a 53-year-old male who had presented with symptoms of tremor, rigidity and bradykinesia for 11 years. He had been treated with L-dopa and had progressive deterioration of symptoms even with the daily dosage of L-dopa increased to 900 mg per day. Before transplantation, his PD symptoms were scored with Unified Parkinson's Disease Rating Scale (UPDRS) and video recordings. The influx constant (ki) of the [18F] 6-fluoro-L-dopa uptake in the striatum was measured by positron emission tomography (PET) imaging. The fetal VM and the lateral part of the lateral ganglionic eminence (LGE) were cografted into the right putamen and, one week later, fetal VM alone was transplanted into the left putamen. After the transplantation, the patient's UPDRS score improved from 128 to 62 at 6 months and to 24 at 22 months during the "off" phase. The score of daily living disability improved from 35 to 18 at 6 months and to 10 at 22 months post transplantation. Twenty-two months after grafting, "off" phases were almost absent, and the freezing had totally disappeared. The [18F] 6-fluoro-L-dopa PET studies were performed 1 month before and 21 months after transplantation. The ki for [18F] 6-fluoro-L-dopa was decreased by 15% in the right caudate and 5% in the left caudate, both of which did not have any ventral mesencephalic grafts. However, the ki was increased by 35%, in the left non-cografted putamen, and by 58% in the right cografted putamen. In conclusion, cografting the fetal VM and the LGE in the putamen may improve the motor function of PD patients.

DNA microarray analysis of differential gene expression of 6-year-old rat neural striatal progenitor cells during early differentiation

EGF-responsive striatal progenitor cells from rat brain have been maintained in culture in the form of neurospheres for six years without exhausting their renewal capacity. The events surrounding differentiation of stem cells in the brain after a long progenitorship remain a mystery. Using DNA microarray analysis we investigated differential gene expression, comparing progenitor cells in their neurosphere state with the cells 24 hours after induction of differentiation. Eighty-one genes showed increased expression in the differentiated condition. Genes associated with cellular growth, neurite outgrowth, and synaptogenesis were activated, including both anti-apoptotic and pro-apoptotic genes. Two transmitter- related genes, acetylcholine receptor-beta and glutamate receptor-beta-unit were also elevated-, these genes not only fit the profile of early neural development, but also reflect the characteristics of striatal neurons. In addition, there are approximately 30 expressed sequence tags (ES7) increased during neural differentiation. Forty-seven genes showed decreased expression; half of them are known genes related to the cell cycle, cell adhesion, transcription, and signaling. Tbe signaling and cell cycle genes may be responsible for the life-long self-renewal. These data demonstrate for the first time that life-long quiescent stem cells retain the potential to become activated and develop into specific types of brain cells. The six-year long-term neural stem cells are an excellent model for studying developmental neurobiological processes and aging.

Upregulation of cellular retinoic acid-binding protein I expression by ethanol

Acute and chronic ethanol ingestion cause embryopathy similar to that of hyper- or hypovitaminosis A. Experimental data have suggested interaction between vitamin A and alcohol signaling pathways at the level of metabolic interference, which ultimately affects the concentration of retinoic acid (RA) in animals. The present study was set up to examine the possible effects of alcohol on cellular RA binding protein I (CRABP-I) expression during embryonic development by using transgenic mouse embryos and P19 embryonal carcinoma cells as experimental models. It was found that expression of the mouse CRABP-I gene was elevated in developing embryos at mid-gestation stages as a result of ethanol consumption by the mothers. Specific elevation of this gene was detected in the limb bud and the gut. In the P19 model, the CRABP-I gene was directly upregulated by ethanol, which was not blocked by a protein synthesis inhibitor. Furthermore, the regulation of the CRABP-I gene by ethanol was mediated by the 5' upstream regulatory region of the CRABP-I gene promoter. A potential interaction of vitamin A and ethanol at the level of CRABP-I gene expression is discussed.

Involvement of GDNF in neuronal protection against 6-OHDA-induced parkinsonism following intracerebral transplantation of fetal kidney tissues in adult rats

Exogenous application of transforming growth factors-beta (TGF beta) family proteins, including glial cell line-derived neurotrophic factor (GDNF), neurturin, activin, and bone morphogenetic proteins, has been shown to protect neurons in many models of neurological disorders. Finding a tissue source containing a variety of these proteins may promote optimal beneficial effects for treatment of neurodegenerative diseases. Because fetal kidneys express many TGF beta trophic factors, we transplanted these tissues directly into the substantia nigra after a unilateral 6-hydroxydopamine lesion. We found that animals that received fetal kidney tissue grafts exhibited (1) significantly reduced hemiparkinsonian asymmetrical behaviors, (2) a near normal tyrosine hydroxylase immunoreactivity in the lesioned nigra and striatum, (3) a preservation of K(+)-induced dopamine release in the lesioned striatum, and (4) high levels of GDNF protein within the grafts. In contrast, lesioned animals that received grafts of adult kidney tissues displayed significant behavioral deficits, dopaminergic depletion, reduced K(+)-mediated striatal dopamine release, and low levels of GDNF protein within the grafts. The present study suggests that fetal kidney tissue grafts can protect the nigrostriatal dopaminergic system against a neurotoxin-induced parkinsonism, possibly through the synergistic release of GDNF and several other neurotrophic factors.

Prenatal alcohol exposure retards the migration and development of serotonin neurons in fetal C57BL mice

Incomplete neural tube fusion (iNTF), induced by alcohol, in midline floor and roof plates was found in our recent study. In this study, serotonin (5-HT) neurons, known to be born entirely in the midline raphe at brainstem, were examined during their development with fetal alcohol exposure. Weight-matched C57BL mice pregnant dams were divided into three groups on E8: one received ethanol via a chocolate Sustacal liquid diet providing 20% ethanol-derived calories as the sole source of nutrients (ALC); the second received an isocaloric Sustacal liquid diet and was pair-fed to individual dams in the ethanol-fed group (PF); the third was fed ad lib rat chow (Chow). Fetal brains were obtained on E15 and were processed for immunostaining of 5-HT and its trophic factor, S100 beta. The ascending 5-HT neurons, in normal development, appear bilaterally near midline on E12, and by E15, as seen in chow and PF groups, migrate from the midline germinal zone laterally and dorsally to their final position with rich fibers. In contrast, in the E15 ALC group, many 5-HT-im neurons were found remaining in the midline germinal region or had migrated, but with under-differentiated, sparse fibers. There were 20--30% fewer 5-HT-im neurons in ALC as compared to PF and Chow. In addition, the number of S100 beta cells was less in ALC as compared with PF and Chow groups. No difference was found between PF and Chow in number of 5-HT-im or S100 beta-im cells. The 5-HT neurons found compromised in migration and differentiation may, in part, stem from failure of access to floor plate or midline tissue induction and the insufficient support by S100 beta. As 5-HT neurons have been implicated for signaling brain maturation, fewer 5-HT neurons may have lasting effects on the development of brain or, if persistent in the adult, profoundly affect adult brain function.

Characterization of the promoter region of the viral interferon regulatory factor encoded by Kaposi's sarcoma-associated herpesvirus

Viral interferon regulatory factor (vIRF) encoded by Kaposi's sarcoma-associated herpesvirus (KSHV) inhibits the expression of interferon-responsive genes, causes cellular transformation and transactivates KSHV genes. In the present study, we characterized the mRNA expression pattern of the vIRF gene and its promoter. A vIRF transcript of 1.7 kb in size was detected in low level in uninduced KSHV-infected cells and its expression was inducible by 12-O-tetradecanoylphorbol-13-acetate (TPA), sensitive to cycloheximide and resistant to phosphonoacetic acid. The transcription start site was mapped to 79 nt upstream of the ATG initiation site by 5'-RACE. Mutagenesis analysis identified a region between -56 and the transcription start site (+1) as the minimal promoter region that contains a functional TATA box at -27. A region between -337 and -125 contains a repressor domain negated by sequence from -991 to -499 in BCBL-1 cells, a region which was also identified to be responsive to TPA induction. These results demonstrate vIRF as a KSHV early gene, identify its promoter and define the promoter regions that contain regulatory elements controlling vIRF transcription.

Fetal intra-nigral ventral mesencephalon and kidney tissue bridge transplantation restores the nigrostriatal dopamine pathway in hemi-parkinsonian rats

We have previously demonstrated that intranigral transplantation of fetal ventral mesencephalic (VM) tissue and nigrostriatal administration of glial cell line-derived neurotrophic factor (GDNF) restores striatal dopamine input in hemiparkinsonian rats. Since it has been found that GDNF is highly expressed in fetal kidney, we examined the possibility that fetal kidney tissue may provide trophic support, similar to GDNF, to an intranigral dopamine (DA) transplant and restore the nigrostriatal pathway. Adult Sprague-Dawley rats were anesthetized and unilaterally injected with 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. Completeness of the lesion was evaluated by measuring amphetamine-induced rotation. One month after 6-OHDA lesioning, fetal VM cells were grafted into the lesioned nigral area followed by transplantation of fetal kidney tissue or vehicle along a pathway from nigra to striatum. Animals receiving these transplants showed a significant decrease both in amphetamine-induced rotation and in postural asymmetry 1 to 3 months after grafting. Immunocytochemical studies demonstrated tyrosine hydroxylase (TH) positive fiber tracts in the lesioned striatum. Control animals that received vehicle injection after the intranigral graft or no transplantation showed no alterations in amphetamine-induced turning and no TH-positive fibers in the lesioned striatum. These results indicate that combinations of fetal nigral and kidney transplants may restore the nigrostriatal DA pathway in Parkinsonian rats. As fetal kidney contains a variety of trophic proteins, it may provide a synergistic admixture to optimally promote DA fiber outgrowth.

Alcohol deters the outgrowth of serotonergic neurons at midgestation

We have previously demonstrated that treatment of pregnant C57BL mice from gestation days 8 to 14 with alcohol with 20% ethanol-derived calories (EDC) reduced the number of serotonin (5-HT) neurons and retarded their migration in the fetal brains. In the present study, we obtained similar results with the use of 25% EDC and extended our previous findings by demonstrating that besides the alteration of the number of 5-HT neurons, prenatal alcohol exposure also affects their projecting fibers in their early development. Pregnant C57BL mice were divided into an alcohol-exposed (ALC) group given 25% EDC (4.49%, v/v), a pair-fed group to the ethanol-fed group (PF) and a chow-fed group (Chow). The PF and Chow groups served as controls. Our results showed that in the ALC group, when compared with the control groups, prenatal alcohol exposure with 25% EDC reduced the number of 5-HT-immunoreactive neurons in both the median and dorsal raphe, and the amount of 5-HT-immunoreactive fibers in the medial forebrain bundle (MFB). The diameter of the 5-HT-immunoreactive MFB was also reduced as a result of treatment. No significant differences of the above parameters were found between the PF and Chow groups. The previous and present work confirmed that alcohol reduces the normal formation and growth of 5-HT neurons in the midbrain. Furthermore, the projection of 5-HT fibers, in density as well as in distribution, is reduced in the major trajectory bundle. This may affect the amount of 5-HT fibers available to the forebrain. In light of the importance of the 5-HT system in brain development, alcohol may affect the growth of the forebrain through its effect on 5-HT signaling.

Three to four-year-old nonpassaged EGF-responsive neural progenitor cells: proliferation, apoptosis, and DNA repair

Epidermal growth factor responsive (EGFr) neural progenitor (NP) cells have been shown to be a potential alternative tissue source for neural transplantation and for developmental study. We have shown that nonpassaged EGFr NP cells can self-renew for 2 years in neurospheres and can robustly differentiate into glia and a number of neuronal cell types. We are now attempting to investigate if the EGFr NP cells will die or continue to live beyond the life span of the donor. In addition, we and other investigators have also found that EGFr NP cells, after transplant, retain only a small number of cells in the transplant site. In this study, we investigate the plasticity and fate of the EGFr NP cells. Using the nonpassaged method, we found EGFr NP cells live in the EGF supplement medium for over 4 years-the longest-lived EGFr NP cells ever reported. The 4-year-old striatal or cortical EGFr neurospheres, when subplated with substrate coating, migrate out of neurospheres and have robust growth with many processes. Furthermore, when nucleotide marker bromodeoxyuridine (BrdU) was added 3 days prior to the subplating, the EGFr NP cells were labeled positively with BrdU in the nucleus, indicating active proliferation activity. Meanwhile two other events were also found in the long-term EGFr NP cells. In the midst of the proliferation, apoptosis occurred. A subpopulation of EGFr NP cells are undergoing programmed cell death as indicated by the cell morphology and the TUNEL staining for DNA strand breaks. The TUNEL fluorescein-staining indicates that over 50% of EGFr NP cells are positive in the nuclei. On the other hand, we have also found that the major base excision repair enzyme, APE/ref-1, which is responsible for recognizing and repairing baseless sites in DNA, was present in the progenitor cells. However, in those cells undergoing apoptosis, APE/ref-1 levels were dramatically reduced or missing, and only a small percentage of cells were TUNEL and APE/ref-1 positive. These observations indicate that EGFr neural progenitor cells can live beyond the life span of the donor animal. The longevity of these cells in culture may be enhanced due to decreased apoptosis and the retention of normal DNA repair capacity.

Expression of serotonin transporter protein in developing rat brain

Serotonin transporter (5-HTT), a transmembrane protein, has been shown in adult brain to be distributed not only on synaptic terminals but to a great extent on axons as well. Here we report the ontogeny of 5-HTT and its relationship with serotonin (5-HT) neurons using established 5-HTT and 5-HT antibodies. Both 5-HTT- and 5-HT-immunostaining (-im) appear in 5-HT neurons at embryonic day 12 (E12) in rostral raphe nuclei (RRN). Soon after appearing, 5-HTT-im is highly expressed on axons, similar to adult expression. However, in contrast to adult, 5-HTT-im also outlines the soma-dendrites. Rich 5-HTT-im appears along the entire length of projecting axons, extending to the growth tip. In the next 2 days, intensive 5-HTT-im axons from RRN travel a course preferentially in the floor plate and later, the medial forebrain bundle trajectory. A group of new 5-HT-im neurons and 5-HTT-im axons appear at E13 in caudal raphe nuclei. At E16-18, taking the exact trajectory course of 5-HT axons, 5-HTT-im axons reach ganglionic eminence, olfactory bulb, and cortex and disperse into many brain regions in E18-20. No 5-HTT-im cell bodies were seen in nigral, locus ceruleus, or hypothalamus. However, the transient expression of 5-HTT on non-serotonergic system was seen in cortical and striatal neuroepithelia at E12 and sensory thalamic pathways at P0-P10. Prominent 5-HTT-im fibers in thalamocortical bundles project from sensory thalamic nuclei through reticular nucleus, internal capsule bundle and form barrels in somatosensory cortices. No 5-HTT-im was seen in glia-like cells using currently available antibody. These observations indicate that 5-HTT is: (a) associated preferentially with 5-HT neurons in brainstem, (b) temporally co-expressed with 5-HT in 5-HT neurons, (c) expressed on axons prior to synaptical sites at target neurons, which strongly indicates a volumic (extrasynaptic) transmission, (d) expressed in non-5-HT neurons within a specific window, which may affect the development of the systems "borrowing" the 5-HT. The early appearance of 5-HTT may also endow functionality as well as vulnerabilities of 5-HT, sensory thalamic, and cortical neurons to 5-HTT targeting drugs during pregnancy and after birth.

Differential polarization of serotonin transporters in axons versus soma-dendrites: an immunogold electron microscopy study

In spite of the conventional belief that neurotransmitter uptake occurs at the synapses, we demonstrated previously that serotonin transporters and the high-affinity uptake of serotonin were not confined to the terminals but rather occurred throughout the axons [Zhou F. C. et al. (1998) Brain Res. 805, 241-254]. In the present study, the detailed distribution of serotonin transporters over various parts of the neuron was illustrated and analysed morphometrically using a pre-embedding immunogold method with a characterized serotonin transporter antibody at the electron microscopic level. Our findings reveal a highly polarized distribution of serotonin transporters between axons and soma-dendrites in two aspects. (1) On the plasma membrane, serotonin transporter-immunogold is extremely low on soma-dendrites and synaptic junctions, but consistently dense along the axons and perisynaptic area. (2) In contrast, serotonin transporter labeling in the cytoplasm is concentrated in soma and dendrites, particularly on the membranes of rough endoplasmic reticulum, Golgi complexes and tubulovesicular structures, but low in the axoplasm. The extensive distribution of serotonin transporter along the axolemma suggests a broad range of uptake sites beyond synaptic junctions, and is consistent with the notion that the major mode of transmission for serotonin neurons is through volume (extrasynaptic) transmission. The highly polarized distribution also indicates that the major serotonin uptake sites are on axons and not on soma-dendrites.

Production and characterization of an anti-serotonin 1A receptor antibody which detects functional 5-HT1A binding sites

We describe the production and characterization of a specific anti-5-HT1A receptor antibody made against a fusion protein consisting of glutathione-S-transferase (GST) coupled to a 75-amino acid sequence from the middle portion of the third intracellular loop (5-HT1A-m3i, serine253-arginine327) of the rat 5-HT1A receptor protein. This region was chosen to avoid putative phosphorylation and glycosylation sites and regions of known homology with other 5-HT receptors. Western blot analysis indicated that the polyclonal anti-5-HT1A-m3i antibody accurately recognized the fusion protein expressed in bacteria and labeled a prominent 67 kDa protein band in the hippocampus, cortex, brainstem, cerebellum and kidney with a density profile corresponding to the relative abundance of the 5-HT1A receptor in these tissues. No protein was detected in liver or muscle tissue preparations, and no protein bands were labeled in any of the above tissues following preabsorption of the antibody with the 5-HT1A-m3i fusion protein. Immunohistochemistry revealed prominent labeling in limbic structures including the hippocampus, amygdala, entorhinal cortex, and septum as well as in raphe nuclei. In the hippocampus, 5-HT1A-m3i labeling revealed a characteristic laminar pattern that coincided with that seen by autoradiographic binding of the 5-HT1A agonist [3H]-8-OH-DPAT in all strata of the hippocampal formation. In the dorsal and medial raphe nuclei, anti-5-HT1A-m3i antibodies labeled the somatodendritic membranes of 5-HT neurons, consistent with its role as an autoreceptor. The detailed matching of the anti-5-HT1A-m3i antibody with [3H]-8-OH-DPAT binding suggests that the antibody recognizes a functionally active form of the 5-HT1A receptor protein capable of binding 5-HT1A agonist ligands. These anti-5-HT1A antibodies may therefore be useful tools in localizing functional 5-HT1A receptors in specific regions of the brain as well as in studying the plasticity and ontogeny of the 5-HT1A receptor at the cellular and subcellular level.

Relationship between [125I]RTI-55-labeled cocaine binding sites and the serotonin transporter in rat placenta

We investigated the characteristics of cocainelike binding sites in rat placenta using [125I]RTI-55. [3H]paroxetine binding and immunocytochemical staining for serotonin [5-hydroxytryptamine (5-HT)] and for the 5-HT transporter were also used to obtain evidence for rat placental 5-HT uptake. [125I]RTI-55 saturation analyses with membranes from normal gestational day 20 placentas yielded curvilinear Scatchard plots that were resolved into high- and low-affinity components (mean dissociation constants of 0.29 and 7.9 nM, respectively). Drug competition studies with various monoamine uptake inhibitors gave rise to complex multiphasic displacement curves, although the results obtained with the selective 5-HT uptake inhibitor citalopram suggest that the 5-HT transporter is an important component of placental high-affinity [125I]RTI-55 binding. The presence of a rat placental 5-HT uptake system was additionally supported by the [3H]paroxetine binding experiments and by the presence throughout the placenta of immunoreactivity for 5-HT and the 5-HT transporter. Immunostaining with both antibodies was most intense in the junctional zone, whereas the density of [125I]RTI-55 binding sites was greater in the placental labyrinth. This discrepancy may be due to the fact that [125I]RTI-55 appears to be labeling additional cellular components besides the 5-HT transporter. The presence of cocaine- and antidepressant-sensitive 5-HT transporters in the placenta has important implications for the possible effects of these compounds on pregnancy and fetal development.

Serotonin transporters are located on the axons beyond the synaptic junctions: anatomical and functional evidence

The serotonin (5-HT) transporter (5-HTT) is known to play a role in depression and many 5-HT related diseases, and is the target site for drugs of abuse, such as cocaine, MDMA, and methamphetamine. The major role of the 5-HTT has long been considered to be to inactivate serotonin transmission through the elimination of serotonin at release sites. However, immunocytochemistry using an antibody against the N-terminal of the 5-HTT at the light microscopic (LM) level indicates that the 5-HTT is associated not only with 5-HT varicosities but also with axons. Electron microscopy (EM) reveals that the majority of the 5-HTTs exist on the axolemma outside the synaptic junctions. In studying whether axonal 5-HTTs are involved in the uptake of 5-HT, we found with autoradiography that [3H]citalopram bound to all major 5-HT fibers, not only in the terminal regions, but also in 5-HT axonal bundles such as the cingulum bundle and medial forebrain bundle. Furthermore, voltammetry recordings indicated that serotonin axonal bundles were actively engaged in high affinity serotonin uptake. The evidence indicates that 5-HTTs on 5-HT axons away from the synapse are likely to be functional in a manner similar to the terminal 5-HTT for serotonin uptake. It also suggests that the role of the 5-HTT may not only be for the termination of synaptic transmission, but also for the regulation of 5-HT through extrasynaptic (volume) transmission. Our findings may also impact the understanding of the sites of action of selective serotonin reuptake inhibitors and drug entry into serotonin neurons via the numerous axonal sites.

Long-term nonpassaged EGF-responsive neural precursor cells are stem cells

We have screened lines of nonpassaged epidermal growth factor-responsive neurospheres from embryonic striatum and brainstem. They have been maintained in defined medium with epidermal growth factor over a period of 2 years and remained in an undifferentiated state to this date. Since isolation from the brain 2 years ago, these nonpassaged epidermal growth factor responsive neurospheres have shown active proliferation and self-renewal capacity. When subplated on a poly-D-lysine coated surface, they resumed differentiation within 24 hours. The differentiation process of the nonpassaged epidermal growth factor responsive neurosphere appeared to recapitulate the neural development in the brain. Many cells migrated, extending radial processes while expressing nestin and S100 in the early 7-day subplating culture. They continued to differentiate into major neural types in 14-day subplating culture, including fibrous and cytoplasmic astrocytes, oligodendrocytes, and serotonin, gamma-aminobutyric acid, and a small number of tyrosine hydroxylase-positive neurons. The nonpassaged epidermal growth factor-responsive neurospheres in many ways resemble hemopoietic cells. Both are proliferative, possess the potential of indefinite self-renewal, yet multipotent, and are capable of resuming the differential pathway. The nonpassaged epidermal growth factor responsive neurospheres meet the criteria of stem cells and have been found to be a useful model to study the development in vitro.

Immunomagnetic isolation of human developing motor neurons

Human motor neuron (MN) isolation provides a critical tool to study neurophysiological properties and the effects of molecules of clinical relevance on isolated neurons. We developed an immunomagnetic separation technique based on specific MN antigen recognition for nerve growth factor receptor (p75-NGFR). We cultured an average of 250,000 cells from the anterior horns of a single cord (four specimens at postconception Weeks 6.0, 7.2, 8.0, and 8.3). At day 7 in vitro (DIV), choline acetyltransferase (ChAT) and/or p75-NGFR-expressing cells (MNs) represented 72 +/- 2% of the total growing cells. MNs survived for at least 4 weeks in biochemically defined medium. The immunomagnetic separation method has been demonstrated to be effective, reproducible, and quantitative for separation of MNs.

Intranigral ventral mesencephalic grafts and nigrostriatal injections of glial cell line-derived neurotrophic factor restore dopamine release in the striatum of 6-hydroxydopamine-lesioned rats

We have previously reported that grafting of fetal ventral mesencephalic (VM) tissue to the nigral region of unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats, in conjunction with glial cell line-derived neurotrophic factor (GDNF) injection between nigra and striatum, restores nigrostriatal tyrosine hydroxylase (TH) immunoreactivity. In this study, we investigated the electrochemical indices of dopamine (DA) release in these grafted animals in the striatum and nigra. Adult Sprague-Dawley rats were anesthetized and unilaterally injected with 6-OHDA into the medial forebrain bundle. The completeness of lesions was tested by measuring methamphetamine-induced rotations. One to two months after 6-OHDA administration, fetal VM tissues were grafted in the lesioned nigral area followed by injection of GDNF, brain-derived neurotrophic factor (BDNF), or phosphate-buffered saline (PBS), along a tract from nigra to striatum. Animals receiving transplantation and GDNF, but not BDNF or PBS, injection showed a significant decrease in rotation 1-3 months after grafting. High-speed chronoamperometric recording techniques, using Nafion-coated carbon fiber electrodes, were used to evaluate DA overflow in the striatum. We found that 6-OHDA lesions resulted in a loss of KCl-induced DA overflow in the urethane-anesthetized rats. Three months after GDNF-bridged grafting, application of KCl elicited DA release both in nigra and striatum. The KCl-evoked DA release area was limited to the GDNF-bridging tract in the striatum. On the other hand, KCl did not induce DA release in the BDNF- or PBS-bridged grafts. Immunocytochemical studies indicated that TH-positive neurons and fibers were found in the nigra and striatum after GDNF-bridged grafting. Taken together, our data suggest that fetal nigral transplantation and GDNF injection may restore the nigrostriatal DA pathway and DA release in these hemiparkinsonian animals and support the hypothesis of trophic activity of GDNF on fiber outgrowth from midbrain DA neurons.

Additive reduction of alcohol drinking by 5-HT1A antagonist WAY 100635 and serotonin uptake blocker fluoxetine in alcohol-preferring P rats

We found previously that alcohol-preferring (P) rats have fewer serotonin (5-HT) neurons and fibers in key brain regions than alcohol-nonpreferring (NP) rats. Because 5-HT uptake blockers increase synaptic 5-HT content and 5-HT1A receptor antagonists increase 5-HT release by disinhibiting 5-HT autoinnervation, in the present study, our intent was to determine whether increased synaptic 5-HT content and/or 5-HT release in P rats would effectively reduce alcohol consumption. In experiment 1, the 5-HT antagonist WAY 100635 (WAY) was tested on adult female P rats maintained on 24-hr free-choice access to ethanol (10% v/v) and water. Twice daily doses of WAY (0.05, 0.1, 0.5, and 1.0 mg/kg, subcutaneously) were administered to each rat in a counterbalanced order. Baseline ethanol intake, derived from the mean ethanol intakes of the three previous non-drug days, was approximately 8 g/kg/day. Results indicated that 0.05, 0.1, and 0.5 mg/kg doses of WAY reduced 24-hr ethanol drinking by 25-30% (p < 0.01) without affecting 24-hr water intake or body weight. In the second experiment, the effects of WAY (0.5 mg/kg), fluoxetine (1.0 mg/kg), or a combination of both were tested in another group of female P rats. WAY and fluoxetine, each alone, reduced ethanol drinking by around 20% and, when combined, decreased ethanol intake by 50%, whereas the body weight and the total fluid intake were not significantly affected. Taken together, these results indicate that both fluoxetine and WAY preferentially reduce ethanol drinking in the P line of rats and, when administered together, reduce ethanol intake in an additive manner. It is proposed that coadministration of these two compounds with distinct mechanisms of action may be a new strategy for reducing alcohol intake.

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.

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.

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.

Morphological Differentiation of Astroglial Progenitor Cells from Egf-Responsive Neurospheres in Response to Fetal Calf Serum, Basic Fibroblast Growth Factor, and Retinol

Procurement of multipotential neuroglial stem cells is possible with the addition of epidermal growth factor (EGF). Stem cells will differentiate into neurons and glia upon the removal of EGF from the culture medium. We have previously characterized the neuronal differentiation of stem cells derived from long-term cultured nonpassage neurospheres. In the current study, we (1) characterize the morphological differentiation of the astroglial progenitor cell from 3-mo-old neurospheres, (2) examine whether the astroglial progenitor cells from neurospheres of different brain areas exhibit different differentiation responses to the same exogenous signals, and (3) test the effects of basic fibroblast growth factor (bFGF) and retinol on differentiation. Cerebral cortex, striatum, and mesencephalon cells were obtained from Embryonic Day 14 (E-14) rat fetuses and were dissociated for the procurement of neurospheres in chemically defined medium supplemented with EGF. After 3 mo in culture, the neurospheres, derived from each of the three brain areas, were subcultured into three groups on chamber slides: (1) basal medium, (2) the basal medium plus 20 ng/mL bFGF, and (3) the basal medium plus 10 μM retinol. Phenotypic expression of astroglial cells was examined after 14 days subculture. Our findings indicate that the 3-mo-old cultured nonpassage neurospheres contained numerous multipotential stem cells that stained positive with nestin, and that environmental factors played an important role in influencing the differentiation of astroglial progenitor cells. As detected by glial fibrillary acid protein (GFAP), astroglial progenitor cells turned into protoplasmic astrocytes in the FCS-containing basal medium, fibrous astrocytes in the presence of bFGF, and spindle-shaped astrocytes in the presence of retinol. There were no noticeable differences in differentiation among astroglial progenitor cells of the various brain region-derived neurospheres in any of the three medium conditions. Peculiar varicosity-and growth cone-like structures on the long slender GFAP-positive processes suggest that neuroblasts and glioblast may share common morphologies, features, or common progenitor cells during initial differentiation in vitro.

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.

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.

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.

Mesolimbic dopamine system in alcohol-preferring rats

The mesolimbic dopamine system of the brain, in particular the nucleus accumbens (Acb), is long known to be involved in reward behavior. When compared with the alcohol-nonpreferring NP rats, the alcohol-preferring P rats exhibit lower dopamine (DA) levels in the Acb as well as in other forebrain areas (20). In the present study, the DA innervation density, as determined by tyrosine hydroxylase (TH) immunostaining, was found lower in the selective cingulum cortex and the shell of the Acb of the P compared with that of NP rats. These structures cluster in the medial aspect of the mesolimbic system. There were no differences in other major DA mesolimbic brain regions. The subpopulation of DA neurons in the ventral tegmental area (VTA) projecting to the Acb was found to be smaller in the P than in the NP rats, as shown by horseradish peroxidase tracing and TH immunocytochemistry double staining. However, the total number of the DA neurons in the VTA, the major mesolimbic DA center, was found to be similar in the P and NP rats. These results indicate a selective reduction of catecholaminergic innervation in the dopaminergic medial mesolimbic system in the P rats and suggest that the P and NP rat lines should be a useful model for the investigation of DA involvement in alcohol drinking as well as other reinforced behaviors.

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.

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.

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)

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.

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.

Excitochemical-induced trophic bridging directs axonal growth of transplanted neurons to distal target

Brain grafts directly placed in their target regions often lack proper connections and normal regulation. When brain grafts are placed in their ontogenetic normal area, the axonal outgrowth of grafts to distal target regions is a major obstacle. We previously demonstrated that directional axonal growth of grafts can be facilitated by laminin. In this study we demonstrated that excitochemicals induced trophic environment can be strategically used as a bridge to guide transplanted neurons to innervate a distal target of millimeter distance, and has a unique effect on fiber expansion in the target region. To distinguish dopamine (DA) growth from that of transplants, 6-hydroxydopamine was unilaterally injected into medial forebrain bundle to remove dopamine innervation to the striatum. Ibotenic acid (IB), kainic acid (KA), or phosphate buffer (vehicle) were microinjected through a glass-pipet to make a 7 mm long tract between the substantia nigra and the striatum in Sprague-Dawley rats. Gestational 14-15 days brainstem slurry was transplanted either in the same or a separate tract into nigra at the bottom of the bridge. All transplants survived with abundant serotonin (5-HT) and DA neurons. Traceable DA fibers formed distinct bundles from grafts along the length of IB/KA tracts. Upon arrival at their major target regions, fibers from bundles were capable of leaving the tracts, and reinnervating the DA-vacated striatum. The 5-HT fibers formed bundles similar to DA fibers but left the tract earlier upon arrival at their major target the globus pallidus and when arriving at the striatum and cortex. Fibers from grafts with vehicle tracts grew randomly and not into the tract. These results indicate that the trophic effects of chemical lesioning serves as a remarkably effective axonal guidance for more than one type of fetal neuron to innervate distal brain regions. This method has great potential in directing fibers in many transplant models.

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.

Serotonergic neurons in the alcohol preferring rats

Previously, we have shown that the serotonin (5-HT) content and fiber density in a number of terminal brain regions have been found to be decreased in the selectively bred, alcohol preferring (P) rats than in the alcohol nonpreferring (NP) rats. In this study, we further report that, compared with NP rats, there were fewer 5-HT-immunostained (5-HT-IM) neurons in the major ascending raphe nuclei of the P rats. Among the three major groups of 5-HT neurons responsible for the majority of ascending projections to forebrain, dorsal raphe (B7), median raphe (B8), and B9, there were fewer 5-HT-IM neurons in the median and dorsal raphe (not including nucleus oralis) of P rats, compared with NP rats (unpaired Student's test). No difference was observed in the B9 group. When the animals were treated with pargyline and L-tryptophan to enhance the 5-HT in the neurons, the number of 5-HT-IM neurons increased in both lines of rats. However, the difference in the number of 5-HT neurons between the rat lines remained. The intensity of 5-HT-IM was also found to be lower in the dorsal raphe neurons of the untreated P than in the untreated NP rats. The decreased 5-HT-IM was supported by high performance liquid chromatography measurement of 5-HT content, which also indicated that 5-HT content of the dorsal raphe was lower in the P than in the NP rats.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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)

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.

Immunostained serotonergic fibers are decreased in selected brain regions of alcohol-preferring rats

The levels of serotonin (5-HT) and 5-hydroxyindole-acetic acid (5-HIAA) are decreased in the hippocampus, nucleus accumbens, and cortex of selectively bred alcohol-preferring (P) rats, compared with the alcohol-nonpreferring (NP) rats. In this study, we have confirmed these findings by immunocytochemistry and quantitative image analysis which indicates that there is a reduction of 5-HT immunostained fibers in several brain areas of alcohol-naive P rats. Three major areas possibly related to alcohol drinking, hippocampus, accumbens, and cortex, were examined. Pathways to these areas were also examined. The 5-HT fiber bundles had the same pattern in P and NP rats. However, in the terminal regions of the ventral hippocampus, the amount of 5-HT fibers was reduced in P rats as compared with NP rats. The 5-HT fibers in the hilus and CA4 of the dentate gyrus were also significantly decreased in the P rats. No differences in fiber density were seen in the anterior nucleus accumbens, but a significant decrease was seen in the middle medial and posterior accumbens of P rats. In the cortical regions examined, decreases in 5-HT fibers were observed in the posterior cingulum and anterior frontal cortex, but not in the insular frontal cortex of P rats. These observations indicate that there are quantitative decreases in 5-HT innervations or that the 5-HT in some 5-HT fibers is reduced to a level undetectable by immunocytochemistry in the brains of P rats when compared with that of NP rats.

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.

Nimodipine-enhanced survival of suboptimal neural grafts

The present experiment was conducted to see whether nimodipine, a calcium channel blocker with the potential to protect vulnerable neurons, could improve the survival rate of striatal grafts under suboptimal conditions. The drug markedly improved graft viability of rats with near-term (E21) striatal implants. Untreated rats showed no surviving neurons while all treated rats showed surviving grafts rich in neuron. It did not affect the survival of striatal grafts from E14/15 donors into the striatum, in which the high rates of survival are normally obtained.