The role of the subependymal plate in avian sarcoma virus brain tumor induction:

Summary F-344 rats were inoculated intracerebrally at 1 and at 133 days of age with the Bratislava-77 strain of avian sarcoma virus. Groups of rats were sequentially sacrificed following inoculation so that early stages of microtumor formation could be evaluated. In neonatally inoculated rats incipient tumors developed in the subependymal region of the lateral ventricles in close juxtaposition to clusters of poorly differentiated germinal cells. Among these animals microtumors were detected as soon as 2 weeks after inoculation; by 4 weeks post-inoculation all rats inoculated at 1 day of age had tumors. In contrast among rats inoculated as adults incipient tumors developed in the cerebral cortex away from the subependymal region but adjacent to the locus of inoculation. Incipient tumors were uncommon in rats inoculated as adults during the first 2 months after inoculation.Supported by USPHS Grants CA-14651 and CA-11898. Dr. Copeland is supported by a National Research Service Award, CA-05431 from NCI. Dr. Bigner is the recipient of TIA fellowship 1F11NS11063 from NINCDS and a JFCF award from the American Cancer Society     

Glial-mesenchymal tropism of in vivo avian sarcoma virus neuro-oncogenesis in rats

Summary Intracerebral inoculation of avian sarcoma virus (ASV) in postnatal animals induceds gliomas and sarcomas but no neuronal tumors. High titer Bratislava-77 strain ASV was inoculated intracerebrally in fetal F-344 rats between 17 and 20 days of gestation: a time of active neuronal proliferation. Following birth inoculated rats developed gliomas and sarcomas but no neuronal tumors. The results are evidence that the glial-mesenchymal tropism of in vivo ASV neuro-oncogenesis is independent of stage of neurocytodifferentiation at inoculation.Supported by USPHS Grants CA-14651 and CA-11898. Dr. Copeland is supported by a National Research Service Award, CA-05431 from NCI. Dr. Bigner is the recipient of TIA fellowship IF11NS11063 from NINCDS and a JFCF award from the American Cancer Society.     

Retinal growth hormone in perinatal and adult rats

Growth hormone (GH) mRNA and protein have recently been localized in the neural retina, of embryonic chicks, in which exogenous GH promotes cell survival. GH is also expressed in the rat CNS, in which it has neuroprotective roles, although its presence in the rat neural retina is unknown and is the focus of the present study. GH immunoreactivity, to a 22-kDa protein, was present in extracts of fetal (embryonic day [ED]17) eyes and in extracts from the neural retinas of newborn pups, comparable to GH immunoreactivity in pituitary extracts. The GH immunoreactivity in the neural retina was widespread but was most intense in large rounded cells in the retinal ganglion cell (RGC) layer and in the optic fiber layer derived from the axons of the RGCs. A 693-bp cDNA was also generated by the RT-PCR of RNA extracted from the eyes of ED17 rats and from the neural retinas and eyes of newborn rats, when amplified in the presence of oligonucleotide primers for the rat GH cDNA. Expression of the GH gene in the neural retina was also shown by specific in situ hybridization of an antisense GH riboprobe to cells in the neural retina, particularly those in the RGC layers of fetal and adult rat eyes. These results demonstrate GH expression in the neural retinas of fetal, newborn, and adult rats, in which retinal GH might have neuroprotective roles.     

The localization of glial fibrillary acidic protein in brain tumors induced in hamsters with avian sarcoma virus

Summary The immunohistochemical localization of glial fibrillary acidic protein (GFAP) was studied by the peroxidase-antiperoxidase (PAP) method in avian sarcoma virus (ASV)-induced brain tumors in hamsters. One hundred twenty-four tumors including 54 astrocytomas, 64 pleomorphic gliomas, five sarcomas, and one unclassified tumor were stained with anti-GFAP serum. A positive immunostaining was seen in astrocytomas and in pleomorphic gliomas. Sarcomas and an unclassified tumor were negative. These results confirmed that a majority of ASV-induced brain tumors contained neoplastic glial cells, and further suggested that the astrocyte is a main target cell of ASV in the experimental neuro-oncogenesis.     

Tenascin-Y in the developing and adult avian nervous system.

The glycoproteins tenascin-C and tenascin-R are abundant in the developing and adult nervous system, respectively. We have used a polyclonal antiserum to determine if tenascin-Y, a novel member of the tenascin family previously identified in the extracellular matrix of muscle, is also expressed in the avian nervous system. Beginning at embryonic day 3 tenascin-Y immunoreactivity is associated with bottle-shaped ependymal cells in the roof plate and floor plate of the spinal cord and brain. These cells resemble the secretory cells that synthesize the ventricular extracellular matrix, including Reissner's fiber. Tenascin-Y immunoreactivity is also seen in pia mater and blood vessels in the developing and adult central nervous system. Anti-tenascin-Y stains the connective tissue sheath of peripheral nerves and the dorsal roots beginning around embryonic day 20. In vitro, sensory neurites fail to form lamellipodia when cultured in the presence of recombinant tenascin-Y, suggesting that tenascin-Y may play a role in inhibiting sensory neurite regeneration into the spinal cord. There is little overlap in the expression patterns of tenascin-Y and tenascin-C during development and between tenascin-Y and tenascin-R in the adult central nervous system, which is further evidence of distinctive mechanisms of gene regulation by the different members of the tenascin family.     

'Glioblastoma'. Induction of a reproducible autochonous tumor in rats with murine sarcoma virus.

Inoculation of 0.02 ml of high-titer Kirsten strain Murine Sarcoma Virus into the brains of 10-day-old Wistar/Furth rats yields, with 100 percent incidence, a uniform glioblastoma-like tumor within 16 days. Light and electronmicroscopy confirmed the neuroectodermal origin of the parenchymal cells. The remarkable vascular component was studied with extracellular tracers. The permeability of the abnormal endothelium to constituents of the blood vascular compartment was confirmed. Accessory vascular channels, and blood channels devoid of endothelium entirely, were observed. This reporducible system should provide a useful model for further studies of the biology of brain tumors.     

Regional blood flow in avian sarcoma virus (ASV)-induced brain tumors

Regional blood flow (F) was measured in avian sarcoma virus (ASV)-induced brain tumors in rats. Blood flow was variable in individual as well as different tumors; tumor F did not correlate with histologic classification, tumor size, central versus peripheral tumor regions, intraparenchymal location, cell density, or specific cytologic characteristics. Low values of F did correlate with tumor necrosis and hydrocephalus; high values of F correlated with tumorous invasion or association with choroid plexus. Mean tumor F was not significantly different from that of the same anatomic, tumor-free brain region of the contralateral hemisphere, but F in brain tissue adjacent to the tumor was depressed significantly. Depression of F was observed in tumor-free cortex and corpus callosum, especially in the hemisphere ipsilateral to the main tumor mass and in those animals with hydrocephalus.     

Brain tumor types induced by the Schmidt-Ruppin strain of Rous sarcoma virus in inbred fischer rats

Summary The Schmidt-Ruppin strain of Rous sarcoma virus has been shown to induce neuroectodermal and mesenchymal tumors of the brain of inbred CDF Fischer rats. The inoculation of 10⁵ FFU of virus into the cerebrum of 2 day old rats was followed by 96% incidence of tumor growth after a latency period of 3 months. Twenty-four of twenty-five inoculated animals developed tumors, all of which were primary intracerebral neoplasms. They fell into three main groups: gliomas 60%, sarcomas 31%, gliosarcomas 9%. Of the 34 gliomas induced, 28 (84%) were astrocytic, and there was one oligodendroglioma, 2 mixed gliomas, and 3 ependymoma-like tumors. The advantages of this brain tumor model are a high glioma incidence, and a short induction time in a commercially available strain of inbred Fischer rats previously shown to be susceptible to the neuro-oncogenic action of resorptive chemical carcinogens.Supported by fellowships of the Max-Planck-GesellschaftUSPHS Grant CA-11898     

The production of focal herpes encephalitis in mice by stereotaxic inoculation of virus. Anatomical and behavioral effects

A low virulence strain of herpes simplex type 1 was microinjected into the hippocampus of BALB/c mice. Intense replication of virus at the inoculum site was followed by spread of viral antigen to the afferent connections of the hippocampus. Surviving animals showed focal damage of limbic structures and specific behavioral abnormalities generally consistent with hippocampal damage. This procedure thus produces an animal model which more closely resembles human herpes encephalitis than those previously reported.     

Moderate and severe perinatal asphyxia induces differential effects on cocaine sensitization in adult rats

Perinatal asphyxia (PA) increases the likelihood of suffering from dopamine‐related disorders, such as ADHD and schizophrenia. Since dopaminergic transmission plays a major role in cocaine sensitization, the purpose of this study was to determine whether PA could be associated with altered behavioral sensitization to cocaine. To this end, adult rats born vaginally (CTL), by caesarean section (C+), or by C+ with 15 min (PA15, moderate PA) or 19 min (PA19, severe PA) of global anoxia were repeatedly administered with cocaine (i.p., 15 mg/kg) and then challenged with cocaine (i.p., 15 mg/kg) after a 5‐day withdrawal period. In addition, c‐Fos, FosB/ΔFosB, DAT, and TH expression were assessed in dorsal (CPu) and ventral (NAcc) striatum. Results indicated that PA15 rats exhibited an increased locomotor sensitization to cocaine, while PA19 rats displayed an abnormal acquisition of locomotor sensitization and did not express a sensitized response to cocaine. c‐Fos expression in NAcc, but not in CPu, was associated with these alterations in cocaine sensitization. FosB/ΔFosB expression was increased in all groups and regions after repeated cocaine administration, although it reached lower expression levels in PA19 rats. In CTL, C+, and PA15, but not in PA19 rats, the expression of TH in NAcc was reduced in groups repeatedly treated with cocaine, independently of the challenge test. Furthermore, this reduction was more pronounced in PA15 rats. DAT expression remained unaltered in all groups and regions studied. These results suggest that moderate PA may increase the vulnerability to drug abuse and in particular to cocaine addiction. Synapse 67:553–567, 2013. © 2013 Wiley Periodicals, Inc.     

ICP47 mediates viral neuroinvasiveness by induction of TAP protein following intravenous inoculation of herpes simplex virus type 1 in mice

Herpes simplex virus type 1 (HSV-1) expresses an immediate-early protein, ICP47, that blocks the major histocompatibility complex class I antigen presentation pathway by binding to the transporter associated with antigen presentation (TAP). The result is the virus' evasion of the immune system. Although the interaction between ICP47 and TAP has been examined in vitro, this paper is the first to report their interaction in vivo. In C57BL/6 adult female mice, ICP47-defective virus (Delta ICP47, F strain) was less able to invade the organs studied than was wild-type HSV-1 F strain, showing that ICP47 influences general invasiveness. However, the neuroinvasiveness of the Delta ICP47 virus was recovered in TAP-deficient mice, indicating that the TAP-ICP47 interaction is specific to neural tissues. HSV-1 F strain showed no significant differences in their invasiveness in TAP-deficient and wild-type mice. Therefore, although ICP47 appears to be essential for invasion, the presence of TAP appears not to be crucial. Western blotting showed TAP1 expression to increase by at least fourfold in the brains and adrenal glands of infected mice. This suggests that TAP plays an important role in the host defense system. This increased expression may be particularly important in the encephalon since the baseline protein levels of this organ are low (ratio adrenal protein level/encephalon protein level > 100). However, Delta ICP47 virus provoked no significant increase in the brain TAP1 levels of wild-type mice because it could not invade this organ. These results suggest that ICP47 plays a role in infection, and that TAP1 production is regulated during viral challenge.     

Rapid prolactin induction in adult male rats after treatment with diethylstilbestrol

Diethylstilbestrol (DES) is a synthetic oestrogen known to disrupt the endocrine system and to cause reproductive toxicity mediated via the hypothalamic‐pituitary‐adrenal axis; however, its molecular mechanism of action is poorly understood. In the present study, we found that, after only 1 week of exposure to DES, blood testosterone dramatically decreased and that this decrease was associated with a strong induction of prolactin (PRL). Even with the increase in PRL, the luteinising hormone and follicle‐stimulating hormone mRNAs slightly decreased. Our results show that, after 48 hours of a single dose of DES, there was a six‐fold increase in PRL expression. After exploring the upstream mechanisms, we determined that dopamine, which inhibits PRL secretion in male rats, did not decrease in the pituitary gland of DES‐treated rats, whereas vasoactive intestinal peptide (VIP), which mediates the acute release of PRL, was elevated. Serotonin (5‐HT) increased in the brain of male rats 24 hours after a single DES treatment; however, PRL, VIP or 5‐HT was not induced by DES in female rats. Our results indicate that DES induces the expression of pituitary PRL in male rats by stimulating VIP in the hypothalamus and 5‐HT in the central nervous system.     

Increased Fos induction in adult rats that experienced neonatal peripheral inflammation

The response to noxious stimulation was compared in adult rats that had peripheral inflammation as neonates and untreated rats. On postnatal day 1, rat pups experienced complete Freund's adjuvant (CFA)-induced inflammation of the left hind paw. At 8 weeks of age, these rats and neonatal untreated rats received a bilateral injection of CFA into their hind paws. Fos-like immunoreactivity (Fos-LI) was used as a measure of neuronal activity in dorsal horn nociceptive pathways. A significant increase in Fos-LI was found on the left side of the lumbar spinal cord of neonatal treated rats as compared to neonatal untreated rats. These results suggest that the experience of neonatal peripheral inflammation may result in an increase in the response of spinal cord neurons to peripheral inflammation as adults.     

Oligodendroglia in the avian retina: immunocytochemical demonstration in the adult bird.

Immunohistochemical techniques were used in conjunction with an avian-specific probe for oligodendrocyte (OLG) marker, the antibody for transferrin binding protein (TfBP), to study the characteristics and distribution of OLGs in the retina of chickens and quails. For comparison, other antibodies such as myelin basic protein, Rip, and those for labeling Müller cells and microglia were used. A large population of OLGs was found to be distributed throughout the retina, with the distinct pattern of a central-to-peripheral gradient. It was possible to detect a spectrum of OLG morphology that bore a resemblance to the subtype of the mammalian central nervous system. In addition to these mature OLGs, limited numbers of TfBP-positive (TfBP(+)) cells with the morphology of immature OLGs were found in the immediate vicinity of the optic head. The majority of OLGs appeared in the ganglion cell layer throughout the retina, whereas OLGs in the nerve fiber layer were seen mainly in the central zone of the retina, near the optic nerve head. Double-labeling experiments showed that OLGs were associated with myelin only in the central region, where the majority of retinal OLGs occurred, but not toward the periphery of the retina. The present study is the first comprehensive analysis of the morphological features and spatial distribution of OLGs in the adult avian retina and provides in vivo evidence for the existence of a substantial population of both mature and immature OLGs in the retina of adult birds. The putative functions of TfBP(+) OLGs including myelination and the tropic role of the ganglion cells are discussed in conjunction with the physical properties of TfBP and structural characteristics of the avascular retina of birds.     

Attention-deficit and hyperactive neurobehavioural characteristics induced by perinatal hypothyroidism in rats

Thyroid hormone is essential for the proper development of the mammalian central nervous system (CNS). In the present study, we examined behavioural alterations caused by transient perinatal hypothyroidism induced by an anti-thyroid drug, propylthiouracil (PTU). This drug produces perinatal disruption of the thyroid system and subsequent behavioural changes, which we investigated using a series of behavioural tests and focusing particularly on attention-deficit/hyperactivity disorder (ADHD)-like behaviours. In the open field test, both male and female rats that had experienced perinatal hypothyroidism (HT rats) showed an increased percent of locomotion behaviour and reduced grooming behaviour, suggesting that HT rats may be hyperactive and show fewer anxiety characteristics. Neither male nor female HT rats showed retention in the passive avoidance test. Male HT rats showed a significantly lower rate of correct avoidance responses than control rats in earlier sessions in the active avoidance test. In addition, we observed significant increases in the number of times that rats crossed the partition during inter-trial intervals and the percent of failure of avoidance during 5 s electrical stimuli in HT rats, suggesting that HT rats are restless, have a shortened attention span and panic easily. In measuring spontaneous motor activity during a period of darkness, male HT rats appeared to plunge into active phase with short, quick steps, while male control rats showed only long active phases during a stress-free period of darkness. These abnormal behavioural characteristics in HT rats might coincide with those found in some cases of ADHD.     

Neuronal apoptosis in immunodeficient mice infected with the challenge virus standard strain of rabies virus by intracerebral inoculation

The challenge virus standard-11 strain (CVS) of fixed rabies virus produces neuronal apoptosis in widespread areas of the brain of mice after intracerebral inoculation. The role of the adaptive immune response in producing neuronal apoptosis in this model was evaluated by comparing the infections in adult C57BL/6J mice with nude mice (T cell deficient) and Rag1 mice (T and B cell deficient). Both strains of immunodeficient mice showed very similar clinical disease and neuropathological findings, including marked neuronal apoptosis. The adaptive immune response is unlikely of fundamental importance in producing neuronal apoptosis in the brains of mice in this model.     

Productive infection in the murine central nervous system with avian influenza virus A (H5N1) after intranasal inoculation

The H5N1 type of influenza A virus isolated from human patients in 1997 has a characteristic hemagglutinin and was considered to be directly transmitted from birds. Although neuropathogenicity of this virus was not demonstrated in human autopsy cases, some experimental studies using mice have disclosed that this virus infects the central nervous system (CNS) after intranasal inoculation. In this study we focused on the topographical localization of virus-infected cells in the murine CNS after intranasal inoculation. We immunohistochemically examined virus-infected cells in mouse tissues using a rabbit antiserum recognizing the nucleoprotein of influenza A virus. The virus-infected cells appeared initially in the respiratory tract. Thereafter, the virus antigen-positive cells appeared in the olfactory system and the cranial nerve nuclei innervating the facial region. This suggests that this virus is principally transmitted from the nasal cavity to CNS through the cranial nerves. Neurons were frequently infected and glial and ependymal cells were also infected. Transneuronal transmission of the virus might play the important role of viral spread within the CNS.