bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneity of sodium‐dependent excitatory amino uptake mechanisms in rat brain
Authors: Ferkany J. , Coyle J.T.
Published: January 2005

The pharmacologic and kinetic characteristics of sodium‐dependent uptake of [3H] L‐glutamate, [3H] D‐aspartate, and [3H] L‐aspartate into crude synaptosomal preparations of rat corpus striatum and ecrebellum have been examined in vitro. In cerebellum the apparent Kt s and Vmax for the three excitatory amino acids were identical whereas in striatal synaptosomes, the Vmax for [3H] L‐glutamate was 30% greater (P≤.001) than for [3H] D‐aspartate and 50% greater (P ≤.001) than for [3H] L‐aspartate. L‐Amino adipic acid inhibited the uptake of the three amino acids in both regions of brain but was 15‐ to 20‐fold more potent in cerebellum than in striatum. In contrast, dihydrokainic acid inhibited transport processes in the corpus straitum but was without activity in cerebellar preparations. The neurotoxin kainic acid blocked only a portion (60%) of [3H] L‐glutamate and [3H] D‐aspartate uptake in cerebellum while completeley inhibiting amino acid trasport in corpus striatum. Three days post kainic acid lesion, [3H] D‐aspartate uptake was attenuated more than [3H] L‐glutamate uptake in the corpus straitum; destruction of corticostriatal afferents reduced [3H] L‐glutamate to a greater extent than [3H] D‐aspartate. Various lesions of the cerebellum affected excitatory amino acid transport processes to a similar extent. These results suggest that excitatory amino acid transport systems are pharmacologically distinct in different brain regions and may be heterogeneous within a single region.
Effects of hormone therapy on the central cholinergic neurotransmission of the snell dwarf mouse
Authors: Fuhrmann G. , Kempf E. , Ebel A.
Published: January 2005

Effects of growth and thyroid hormone therapy on central cholinergic neurotransmission has been followed in the cholinergic‐deficient Snell dwarf mouse. Growth hormone and thyroxine can reverse the neurotransmission impairment even in adulthood. Furthermore, it appears that in the dw/dw mouse, hormone deficiency becomes determinant only after the critical period of neurogenesis, in a late postnatal developmental stage. At first sight, these observations show that the distrubed cholinergic neurotransmission of the mutant might be linked to the pituitary and thyroxine deficiency that is characteristic of this mouse. Hormone therapy selectively stimulates cholinergic activity in cholinergic‐deficient structures, where it reactivates presynaptic markers. The differential responsiveness of the neuroanatomical and neurochemical targets could be linked to different regulatory hormone effects or to timing in respect to sensitivity to hormones during development.
Double isotopic method using dansyl chloride for the determination of GABA in rat C6 astrocytoma cell cultures
Authors: Kohl R.L. , Quay W.B. , Perez‐Polo J.R.
Published: January 2005

Methods are described for the quantitative measurement of GABA in culture. The method can be adapted to any amino acid or dansyl‐chloride‐reactive species. The sensitivity and selectivity of the procedure result from the double isotopic design in which (14C)‐labeled internal standard was added to the samples before reaction with (3M)‐labeled dansyl chloride. Values obtained by ion‐exchange amino acid analysis of cultures agree closely with the values obtained by the double isotopic method. This method is sensitive enough to measure GABA intracellularly and the condition medium.
Effects of naloxone and morphine on cerebral ischemia in gerbils
Authors: Christie‐Pope B.C. , Palmer G.C. , Palmer S.J.
Published: January 2005

A therapeutic role for naloxone during stroke has been suggested, but a neurochemical site of action remains to be determined. Previous work with the geerbil cerebral cortex has shown that either bilateral secondary ischemia (60‐min occlusion of the carotid arteries followed by 40‐min reflow) or unilateral primary ischemia (permanent ligation of one carotid artery for 6 hr in symptomatic animals) produced deficits in both Na+, K+‐ATPase (EC 3.6.1.3) activity and various parameters of activation of adenylate cyclase (EC 4.6.1.1). Pretreatment of gerbils with either naloxone or morphine failed to ameliorate or exacerbate, respectively, the neurological signs of ischemia; however, morphine did reduce mortality. Infusion of naloxone prior to ischemia afforded varying degrees of protection to forskolin, GTP analogs, and NE (norepinephrine) activation of adenylate cyclase, as well as to Na+, K+‐ATPase (bilateral ischemia only). Similarly, morphine inhibited damage to basal activity of adenylate cyclase and to stimulation by NE, forskolin, and Gpp (NH)p (5′‐guanylyl imidodiphosphate). Under in vitro conditions morphine increased the basal activity of adenylate cyclase but reduced responses to NE and forskolin. Furthermore, morphine injected into control gerbils elevated basal‐ and forskolin‐elicited activities but reduced the activation of adenylate cyclase by NE.
Effects of arginine vasopressin on protein phosphorylation in rat hippocampal synaptic membranes
Authors: Hinko A. , Pearlmutter A. F.
Published: January 2005

Our laboratory has reported previously the characteristics of specific AVP binding to rat hippocampal synaptic membranes (SPM) in the presence of Ni2+ [Costantini MG, Pearlmutter AF: J Biol Chem 259:11739–11745, 1984]. We extended our investigation to determine the effects of Ni2+, (AVP), and AVP analogs on SPM protein phosphorylation. Ni2+ (5 mM) caused a dramatic reduction in phosphorylation of most SPM phosphoproteins. The most prominent protein which is phosphorylated in SPM has a molecular weight of 48 kilodaltons (KDa) and has been named B50 or F1; this protein shows altered phosphorylation in vitro in response to long‐term potentiation in vivo as well as changes induced by exposure of SPM to ACTH (1–24), dopamine, and somatostatin. AVP and related peptides reduced phosphorylation of this presynaptic phosphoprotein in the following order of potency: AVP = oxytocin >DG‐AVP>dDAVP> d(CH2)5Tyr(Me) AVP = [pGlu4, Cyt6]AVP‐(4–9). Except for the pressor antagonist d(CH2)5Tyr(Me)AVP, this corresponds to their relative efficacy in displacing 3H‐AVP from high‐affinity specific binding sites on rat hippocampal synaptic membranes. Ni2+ did not alter the degree of inhibition caused by the peptides. When SPM were treated with AVP after the attainment of maximum 32P incorporation, AVP inhibited dephosphorylation over a 30‐min period. Our results show that AVP can alter both phosphorylation and dephosphorylation of hippocampal SPM phosphoproteins in vitro; the direction of these effects depends upon experimental conditions. Since B50/F1 is known to be a substrate for protein kinase C, AVP may act by inhibition of protein kinase C activity, either directly or indirectly.
Intracellular acetylcholinesterase of adult rat myofibers is more concentrated in endplate than non‐endplate regions
Authors: Donoso J. A. , Stiles J. R. , Fernandez H. L.
Published: January 2005

The intracellular distribution of acetylcholinesterase (AChE) was determined in adult rat anterior gracilis muscles. Echothiophate iodide (ECHO), a water‐soluble cholinesterase inhibitor, was applied to muscles in situ to eliminate extracellular and/or extracellularly oriented enzyme. Control and ECHO‐treated muscles were either cut into 1‐mm segments and assayed for AChE activity or cytochemically stained for AChE. Subsequent analysis by light and electron microscopy showed that the AChE stain inside myofibers was highly localized and clearly visible only in the zone immediately underlying the point of nerve‐muscle contact. Biochemical assay of muscle segments showed intracellular AChE to be most highly concentrated in regions containing large numbers of endplates (approximately twice the activity of endplate‐free areas). Since such “endplate‐rich” segments are in fact mostly extra‐synaptic tissue, we conclude that intracellular AChE of adult rat gracilis myofibers, although present along the length of the cell, is more than two times as concentrated in sub‐synaptic areas as compared to extra‐synaptic areas. This result must be carefully considered when attempting to identify “endplate‐specific” AChE activity of mammalian muscle, and further points to the importance of neural influences on AChE metabolism/regulation.
Acidic phospholipids, diacylglycerols, and free fatty acids in gerbil brain: A comparison of ischemic changes resulting from carotid ligation and decapitation
Authors: Huang S. F.‐L. , Sun G. Y.
Published: January 2005

The levels of brain acidic phospholipids (poly‐PI, PI, PA, and PS), DG, and FFA and their acyl group profiles were determined after induction of ischemia in gerbils by ligation of the common carotid arteries and decapitation. Ischemia induced by both procedures resulted in a significant decrease in poly‐PI (20% for 1‐min decapitation and 1‐min ligation). Except for a 16% increase in PI in the 5‐min decapitation group, no apparent change was found in other phospholipids after either ischemic condition. The level of DG was increased one‐ and threefold after 1 and 5 min, respectively, of decapitative ischemic treatment. Ligation of the carotid arteries for 1 min resulted also in a onefold increase in the DG level. The decapitative model resulted in a one‐ and fivefold increase in FFA level (with respect to 1 and 5 min, respectively), whereas ligation for 1 min resulted in an increase of 42% of the FFA. The acyl groups of poly‐PI and PI in the control gerbil brain are enriched in 18:0 and 20:4, but those of DG, FFA, and PA have a higher proportion of 16:0 besides 18:0 and 20:4. However, a preferential increase in the proportion of 18:0 and 20:4 was shown for the DG and FFA in both types of ischemic treatments. It is concluded from the results that both models of ischemic treatment elicit a similar decrease in poly‐PI and increase in DG, but differ in the amount of FFA release. The higher level of FFA release in the decapitative model suggests that other biochemical mechanisms may be activated to cause the additional release.
Cerebellum plus locus coeruleus in tissue culture II: Development and metabolism of catecholamines
Authors: Woodward W. R. , Seil F. J. , Hammerstad J. P.
Published: January 2005

In contrast to locus coeruleus neurons in vivo, dopamine was the predominant catecholamine synthesized, stored, and released by neonatal mouse locus coeruleus cultures which included target cerebellar tissue, and norepinephrine was present in these cultures only at very low levels. Developmentally, norepinephrine increased slightly in the explants during the first 4 days in vitro and declined thereafter to barely detectable levels, whereas dopamine began to rise after 4 days and reached maximal levels by 7 days. Dopamine β‐hydroxylase was present in these cultures throughout maturation. These results suggest that the high ratio of dopamine to norepinephrine in locus coeruleus cultures cannot be attributed to the absence of appropriate target tissue or to a lack of the enzyme, dopamine β‐hydroxylase.
Glycosaminoglycan composition of electric organ basement membranes
Authors: Inestrosa N. C. , Nader H. B. , Garrido J. , Sampaio L. O. , Brandan E. , Dietrich C. P.
Published: January 2005

The basement membranes of the innervated surface of the electric organ of Discopyge tschudii present a high concentration of mucopolysaccharides as revealed by intense ruthenium red‐positive reaction. Glycosaminoglycans (GAGs) were isolated and characterized from these pure basement membranes by using a combination of agarose gel electrophoresis and enzymatic degradation with specific enzymes. The isolated basement membrane showed a high concentration of GAGs (130 mg/g of dry tissue); of this amount 49% was hyaluronic acid, 24% was chondroitin‐6‐sulfate, 12% was heparan sulfate, and 14% was dermatan sulfate. Controlled digestion with heparinase and heparitinases I and II was used to study the structural features of the heparan sulfate. Four unsaturated disaccharide units were found in the heparan sulfate: disulfated, N‐sulfated, N‐acetylated, and N‐acetylated O‐sulfated disaccharides. The disaccharide units of the cholinergic heparan sulfate present a high amount of disulfated disaccharides and a low amount of N‐acetylated O‐sulfated disaccharides. The N‐sulfated disaccharides, in contrast to the N‐acetylated ones, were found through all the structure of the cholinergic heparan sulfate. Finally our work shows for the first time the presence of dermatan sulfate in the basal lamina of the electric organ.
Regulation of dihydropyridine calcium antagonist binding sites in the rat hippocampus following neurochemical lesions
Authors: Bolger G. T. , Basile A. S. , Janowsky A. J. , Paul S. M. , Skolnick P.
Published: January 2005

The effects of catecholaminergic, cholinergic, serotonergic, and glutaminergic terminal destruction and neurotransmitter depletion on [3H]nitrendipine binding to rat brain membranes were determined using the neurotoxins 6‐hydroxydopamine, 5,7‐dihydroxytryptamine, and kainic acid and the neurotransmitter‐depleting agent reserpine. Following intracisternal injection of 6‐hydroxydopamine there were time‐dependent increases (14–23%) in the density but not change in the affinity of hippocampal [3H]nitrendipine binding sites. 6‐Hydroxydopamine significantly increased [3H]nitrendipine binding in the hippocampus 4 and 10 days following injection. However, no significant change in binding was observed at 16 and 26 days. [3H]Nitrendipine binding in the cerebral cortex, striatum, cerebellum, and brain stem was unaffected by 6‐hydroxydopamine. Neither 5,7‐dihydroxytryptamine nor kainic acid affected [3H]nitrendipine binding in the hippocampus and cerebral cortex. Acute and chronic reserpinization also did not affect [3H]nitrendipine binding in the hippocampus and cerebral cortex. These results indicate that dihydropyridine calcium antagonist bindings sites in rat brain are subject to brain region‐specific regulation following neurochemical lesions and may be present in their largest densities on postsynaptic membranes.
Cation effects on taurine release from brain slices: Comparison to GABA
Authors: Oja S. S. , Kontro P.
Published: January 2005

The effects of cations on the spontaneous and potassium‐stimulated taurine release from mouse cerebral cortex slices were assessed with an emphasis on the as yet unestablished calcium dependence of the stimulated release. Spontaneous and stimulated GABA release was analyzed for comparison. A depolarizing concentration (50 mM) of potassium ions caused an approximately 3.5‐fold increase in taurine release and the omission of sodium a 6‐fold enhancement. GABA release was increased by the same stimuli about 20‐ and 34‐fold, respectively. Omission of calcium ions greatly enhanced basal taurine and GABA release when the medium was supplemented with the calcium chelator ethylenediaminetetraacetate. The potassium stimulation was then abolished, however, with taurine even more readily than with GABA. Magnesium and calcium ions had antagonistic effects on the stimulated release, more clearly with taurine than with GABA. Verapamil abolished the potassium stimulation of both taurine and GABA release, the latter being more sensitive. Although the stimulated taurine release was less in magnitude and had a slower time course than the GABA release, the results are not at variance with the possible neurotransmitter role of taurine.
The influence of muscle‐conditioned media on chick embryo brainstem neurons in culture
Authors: Heaton M. B. , Kemperman H.
Published: January 2005

Brainstem pieces from the trigeminal region of the metencephalic basal plate of 10‐day chick embryos were dissociated and cultured in control conditions or in the presence of muscle‐conditioned medium (MCM). The MCM was derived from age‐matched target tissue relevant to this neuronal region (jaw musculature), from relevant target tissue of an age at which innervation would initially be taking place (4 days), and from nonrelevant target tissue also of an early stage (4‐day limb bud). Neuronal survival and differentiation was assessed daily, for 7 days. Survival and differentiation were significantly enhanced by the 4‐day jaw MCM compared to both the controls and the cultures grown with 10‐day jaw MCM and 4‐day limb MCM. These measures in the presence of 10‐day jaw MCM and 4‐day limb MCM did not differ, but surpassed that seen in control cultures. The results are compared to the more specific responsiveness seen in earlier (2‐day) neural tube cultures, and their relationship to in vivo regenerative nerve fiber outgrowth is considered.
Experiential factors in the expression of hypermotility produced by intradentate colchicine: Lack of effect of GM1 ganglioside on colchicine‐induced loss of granule cells and mossy fibers
Authors: Tilson H. A. , Harry G. J. , Nanry K. , Rogers B. , Peterson J. , Jensen K. , Dyer R.
Published: January 2005

Adult male Fischer‐344 rats were given bilateral injections of 2.5 μg colchicine or artificial cerebrospinal fluid into caudal and rostra1 sites of the dentate gyrus of the hippocampus. One group of rats received 21 consecutive daily injections of 20 mg/kg GM1 gangliosides, i.p., beginning the day prior to surgery. Another group received saline. Colchicine‐induced hypermotility was not seen in animals repeatedly handled 21 d after surgery, in spite of significant decreases in granule cell number and decreases in the volume of hippocampal mossy fibers. Pretreatment with GM1 had no effect on behavior and it did not protect against the hippocampal damage produced by colchicine. Rats given colchicine, but not handled for 21 d, showed significant hypermotility, which was associated with decreases in hippocampal granule cells. These data underscore the importance of handling in postlesion functional recovery.
Effects of intraocular tetrodotoxin on the postnatal development of the dorsal lateral geniculate nucleus of the rat: A golgi analysis
Authors: Riccio R. V. , Matthews M. A.
Published: January 2005

The postnatal development of the rat dorsal lateral geniculate nucleus (dLGn) during tetrodotoxin (TTX)‐induced monocular impulse blockade was investigated by quantitative Golgi techniques

Intraocular injections of 1 × 10‐4M TTX were repeated every 2 days in rats aged 5–21 days postnatal dpn.

. Beyond 14 days postnatal (dpn), the effectiveness of TTX was monitored by loss of the pupillary light reflex. By 21 dpn, Golgi analysis indicated that TTX had no effect on the pattern of dendritic branching of class A or class B neurons, although the number of dendritic spinous protrusions was reduced. No evidence of any TTX‐induced loss of optic axons or neuronal degeneration in the dLGn was found, despite a 16% decrease in the size of the nucleus, suggesting a reduction in the growth of neuropil. These data indicate that optic impulses are important in mediating the proper growth of postsynaptic specializations in the dLGn during ontogenesis, but that the postnatal development of the dendritic arbor of neurons in the dLGn appears to be independent of retinal impulse activity.
Neural pathways that mediate the effects of afferent stimuli on paraventricular nucleus multiunit activity in freely moving rats
Authors: Mor G. , Saphier D. , Feldman S.
Published: January 2005

The direct involvement of the hypothalamic paraventricular nucleus (PVN) in the control of adrenocortical secretion is now generally accepted. In order to contribute to our understanding of the electrical activity of cells in this region during adrenocortical activation, we have recorded multiunit electrical activity (MUA) in response to acute neural stimuli in freely moving male rats and have examined the pathways involved. Photic, acoustic, olfactory, and sciatic nerve stimulation all increased PVN MUA by between 130% and 250%. These responses were selectively blocked, according to the stimulus modality tested, by radiofrequency lesions of central neural structures. Thus PVN responses to photic stimulation were blocked by lesions of the suprachiasmatic nuclei and reduced by mammillary peduncle lesions but were unaffected by lesions of the bed nuclei of the stria terminalis. Responses to acoustic stimulation were blocked by lesions of the mammillary peduncles but not by those placed in the suprachiasmatic nuclei, the septum, or the bed nuclei of the stria terminalis. Lesions of the septum blocked the response to sciatic nerve stimulation but did not affect the response to olfactory stimulation with amyl acetate fumes, which was blocked by lesions of the bed nuclei of the stria terminalis. The data confirm those obtained in endocrine studies concerning the neural pathways involved in the transmission of neural stimuli that produce adrenocortical activation.
Noradrenergic sympathetic innervation of the spleen: V. Acute drug‐induced depletion of lymphocytes in the target fields of innervation results in redistribution of noradrenergic fibers but maintenance of compartmentation
Authors: Carlson S. L. , Felten D. L. , Livnat S. , Felten S. Y.
Published: January 2005

Sympathetic noradrenergic fibers follow the vasculature into the white pulp of the spleen and branch from the periarteriolar plexuses into T lymphocyte zones. These lymphocytes, reported to express adrenergic receptors, are contacted directly by norepinephrine (NE) terminals and are putative targets of the locally released NE. Although this splenic innervation has been studied extensively, the functional interdependence of the lymphocytes and the sympathetic innervation is not well understood. To assess the effect of acute lymphocyte loss on the splenic innervation, T and B lymphocytes were depleted through treatment with cyclophosphamide (CY) or hydrocortisone acetate (HC). Despite reductions in spleen weight and cellularity, the total NE content (pmol) per spleen did not change. However, the NE concentration increased in the treated spleens. Although the general compartmental organization of the noradrenergic fibers in the treated spleens was similar to that of controls, the NE fibers redistributed and increased in density around the smaller central arteries in lymphocyte depleted spleens. The accommodation of these NE fibers to the changing environment of the white pulp suggests that the innervation to the spleen remains chemically stable despite a large disruption to the normal splenic milieu, but is capable of plasticity in the face of a shrinking white pulp.
Enkephalins and autoimmunity: Differential effect of methionine‐enkephalin on experimental allergic encephalomyelitis in wistar and lewis rats
Authors: Janković B. D. , Marić D.
Published: January 2005

To evaluate the immunomodulating activity of methionine‐enkephalin (Met‐Enk) and leucine‐enkephalin (Leu‐Enk) in the development of experimental allergic encephalomyelitis (EAE), two strains of rats, one highly susceptible to EAE (Lewis rats) and the other relatively resistant to the disease (Wistar rats) were used. The animals were given daily injections of either a high dose (5 mg/kg b.w.) or a low dose (0.2 mg/kg b.w.) of these opioid peptides, after receiving guinea pig spinal cord in combination with immunological adjuvants. A major conclusion from this study is that Met‐Enk is a potent immunomodulator/regulator of the autoimmune disease, whereas Leu‐Enk does not affect EAE.

The high dose of 5 mg/kg b.w. of Met‐Enk completely or significantly inhibited neurological signs and markedly diminished occurrence and intensity of histological lesions in the brain, and cervical, thoracic, and lumbar spinal cord. The loss of body weight, which accompanies EAE, was also prevented by a high dose of Met‐Enk. In contrast, the low dose of 0.2 mg/kg b.w. Met‐Enk potentiated neurological and histopathological features of the disease. Nonimmunized rats injected with enkephalins for a period of 17 consecutive days showed neither neurological nor histological signs of EAE, nor signs of intoxication due to the application of enkephalins. Thus, these data establish a link between methionine‐enkephalin and EAE, and suggest that this opioid pentapeptide might be important in the pathogenesis and prevention of the inflammatory autoimmune disease.
Thymosin fraction 5 stimulates secretion of immunoreactive β‐endorphin in mouse corticotropic tumor cells
Authors: Farah J. M. , Hall N. R. , Bishop J. F. , Goldstein A. L. , O'Donohue T. L.
Published: January 2005

In addition to reconstituting immune competence, the thymus gland preparation, thymosin fraction 5 (TSN‐5), has recently been shown to stimulate secretion of hormones from the hypothalamic‐pituitary adrenal axis in vivo and from pituitary corticotropes in vitro. The purpose of the present study was to investigate the effects of TSN‐5 on secretion of immunoreactive β‐endorphin (iβ‐E) by mouse corticotropic tumor cells. The release of iβ‐E by AtP‐20 pituitary tumor cells was increased in a dose‐dependent manner by concentrations trations of 30–600 pg/ml of TSN‐5, whereas concenconcentrations greater than 1,000 μg/ml were increasingly less effective in stimulating secretion. TSN‐5 (600 μg/ml) significantly stimulated iβ‐E release within 7 min; maximal secretory responses (up to 275% of control release) occurred by 4 hr. The secretory response of AtP‐20 cells to 600 μg/ml TSN‐5 (37.9 ± 2.0 vs. 16.1 ± 1.0 ng iβ‐E/ml/4 hr, mean ± SE) was similar in magnitude to release evoked by 0.1 μM corticotropin‐releasing factor (CRF). Combining TSN‐5 and CRF treatment increased secretion of iβ‐E to nearly 600% of control levels, an effect greater than an additive influence of the two independent treatments. Whereas CRF treatment reduced the levels of iβ‐E in AtP‐20 cell extracts after 24‐hr treatment by 45% (231.8 ± 24.7 vs. 417.2 ± 17.8 ng iβ‐E/mg protein, CRF vs. vehicle treatments, respectively), TSN‐5 did not significantly alter cellular hormone content. Neither TSN‐α1 nor TSN‐β4, two of the component peptides of TSN‐5, affected basal or CRF‐stimulated releast of iβ‐E, indicating that an unidentified constituent(s) is corticotropic. This study demonstrates that TSN‐5 directly stimulates hormone release from AtT‐20 cells and potentiates the secretory actions of CRF. These findings support the concept of interactions between neuroendocrine and immune regulators of the hypothalamic‐pituitary adrenal axis. Additionally, corticotropic tumor cells appear to be a useful model in which to differentiate a hormonally active constitutent(s) of TSN‐5 and evaluate the cellular mechanisms of action of TSN‐5 on corticotropic cells.
Ameboid microglia as effectors of inflammation in the central nervous system
Authors: Giulian D.
Published: January 2005

Techniques for selective isolation, labeling, stimulation, and destruction of ameboid microglia allow study of some fundamental questions in neuroimmunology. Examination of surface morphology, proliferative capacity, and cytochemistry suggests that microglia are a class of brain mononuclear phagocytes distinct from blood monocytes, spleen macrophages, or resident peritoneal macrophages. Morover, cultured ameboid microglia isolated from newborn brain can be induced to grow thin cytoplasmic projectios several hundred microns in length; these process‐bearing cells resemble a differentiated form of microglia found in adult brain.

Ameboid microglia may contribute to brain inflammation by engulfing debris, by releasing cytotoxins, by killing neighboring cells, and by secreting astroglial growth factors. Importantly, ameboid microglia are closely tied to a network of immunomodulators that include colony‐stimulating factors and Interluekin‐1. The presence of activated microglia during normal embryogenesis and at sites of penetrating brain injury suggests that these cells serve as important effectors linking the immune system with growth and repqir of the CNS.
Interleukin‐3 modulation of mouse bone marrow derived mast cell receptors for somatostatin
Authors: Renold F. K. , Dazin P. , Goetzl E. J. , Payan D. G.
Published: January 2005

Receptors for somatostatin (SOM) were identified on mouse bone marrow derived mast cells (MBMMC) and shown to vary in expression with the state of proliferation and differentiation of the MBMMC. Flow cytometric studies of the binding of fluorescein‐labeled SOM and concurrent analyses of the binding of [125I]SOM demonstrated that the population of MBMMC capable of recognizing SOM specifically is that exhibiting a proliferative response to interleukin‐3. The MBMMC that bound SOM reached a maximal number at 72 hr following the addition of interleukin‐3, and were distributed principally in the G2/M phase of the cell cycle. SOM did not influence directly the proliferative responses of MBMMC to interleukin‐3. The level of expression of SOM receptors thus may reflect the state of differentiation of mast cells, as well as determining the funcitonal sensitivity to the inhibitory effects of SOM.
Effects of entorhinal lesions on trophic activities present in rat entorhinal cortex and hippocampus as studied using primary cultures of entorhinal and septal tissues
Authors: Gibbs R. B. , Needels D. L. , Yu J. , Cotman C. W.
Published: January 2005

The present study examined trophic activities in normal and injured brain which affect the survival and growth of central neurons in culture. Adult rats received bilateral lesions through the angular bundle, severing projections between the entorhinal cortex and the hippocampus. Ten days later, extracts were prepared from the entorhinal or hippocampal regions of the injured brains and compared with extract prepared from analogous regions of normal brains for trophic activities in cultures of either entorhinal or septal tissues.

At least three activities were observed: (1) a trophic activity which bound to polylysine‐treated wells, which was >10,000 Da in size, heat labile, and sensitive to trypsin, and which supported the survival of both septal and entorhinal neurons in culture; (2) a trophic activity which did not bind to polylysine‐treated wells, which was >10,000 Da in size, heat labile, and sensitive to trypsin, and which, in the presence of polylysine‐bindable material, facilitated the survival and growth of entorhinal cells in culture, and (3) an inhibitory activity which significantly reduced survival in entorhinal cultures when cells were plated in the presence of high concentrations of extract prepared from normal brain. These effects were not due to nonspecific effects of plating the cells in, or treating the wells with, large amounts of protein.

A significant injury‐related increase in nonpolylysine‐bindable trophic activity was also observed. Extracts prepared from either the hippocampus or the entorhinal area of the injured brains contained more non‐polylusine‐bindable trophic activity than extract prepared from normal brains. Injury‐related changes in trophic activities were more prominent in entorhinal than in septal cultures. This increase in activity may account for the injury‐related effects on the survival of entorhinal transplants reported previously [Gibbs and Cotman: Neuroscience (in press) 1987], and may represent an endogenous mechanism by which the brain attempts to selectively support the survival of injured cells following injury.
Isolation of intact capillaries and capillary plasma membranes from frozen human brain
Authors: Pardridge W. M. , Yang J. , Eisenberg J. , Tourtellotte W. W.
Published: January 2005

The development of methods for the isolation of brain capillaries and brain capillary plasma membranes makes possible biochemical studies of the blood‐brain barrier (BBB), which is made up of brain capillaries. Studies aimed at assessing the role of the BBB in the pathogenesis of specific neurologic diseases, e.g., Alzheimer's disease or multiple sclerosis, will necessitate the isolataion of capillaries from brain involved with specific pathology. Such tissue is most readily available from banks containing frozen human brain. The present studies show that intact capillaries and capillary plasma membranes can be isolated from frozen human brain, including as little as five g of multiple sclerosis plaque tissue. Capillaries from frozen human brain are enriched in gamma‐glutamyl transpeptidase, factor VIII antigen, and a 46K protein which has recently been shown to be a BBB‐specific protein. These studies provide the basis for future biochemical studies of human brain microvessels in neurologic disease.
Effect of phenytoin on cytoskeletal protein phosphorylation and neuronal structure in the rat sensory cortex
Authors: Ruiz G. , Flores O. G. , González‐Plaza R. , Inestrosa N. C.
Published: January 2005

Phenytoin (PH) is commonly used as an anticonvulsant drug, and it causes several collateral effects including morphological changes in brain cortex neurons and teratogenic lesions in infants of epileptic mothers. Several lines of evidence indicate that PH may exert its action through the modification of phosphorylation patterns of neuronal polypeptides. We have studied the effects of PH on the phosphorylation of cytoskeletal proteins, because this could be relted to the structural modifications induced by PH administration. The dendritic pattern of deep layers of the somatosensory cortex is clearly modified by PH but not the cell number, indicating that the drug disturbs the architecture of the neurons examined. In fact, the pattern of phosphorylation in cytoskeletal extracts of brains of 30‐day‐old rats is changed by PH. In vitro labeling experiments show decrease in the [32P] level of a 43‐kDa polypeptide, whereas 38‐ and 120‐kDa polypeptides show increases in their [32P] contents. The 43‐kDa polypeptide has been identified as actin by in vitro experiments using a novel approach to determine cytoskeletal poypeptide behvior. We conclude that PH affects the posttranslational phosphorylation of actin and other related cytoskeletal proteins and in this manner may alter the normal morphological layout of dendritic patterns in the somatosensory cortex.
Sodium‐dependent high‐affinity uptake of taurine in cultured cerebellar granule cells and astrocytes
Authors: Holopainen I. , Malminen O. , Kontro P.
Published: January 2005

Taurine uptake in cultured cerebellar granule cells and astrocytes consisted of a saturable high‐affinity component and nonsaturable diffusion. The transport constant (Km) was significantly lower and the maximal velocity (V) higher in granule cells than in astrocytes. The uptakes were strictly sodium dependent and also moderately decreased in potassium‐free medium. The specificity profile of taurine uptake was similar in both cell types, hypotaurine β‐alanine, and guanidinoethanesulphonic acid being the most potent inhibitors, followed by GABA and homotaurine. Glutamate inhibited taurine uptake more in astrocytes than in granule cells. In principle, the uptake systems were similar in granule cells and astrocytes, exhibiting features characteristic of uptake of a neurotransmitter or ‐modulator.
Nerve growth factor protein level increases in the adult rat hippocampus aftera specific cholinergic lesion
Authors: Lärkfors L. , Strömberg I. , Ebendal T. , Olson L.
Published: January 2005

Nerve growth factor (NGF) is the best‐characterized neurotrophic substance and has recently been shown to influence cholinergic neurons in the basal forebrain. Hippocampus and neocortex, the primary targets for these central neurons, have further been found to contain high levels of NGF. Using enzyme immunoassay and acetylcholine esterase (AChE) histochemistry we have now studied the levels of NGF and AChE after a specific cholinergic lesion, transection of the fimbria fornix comprising the major cholinergic input to hippocampus. Fimbriectomy in adult rats led to a marked decrease in AChE‐positive nerve terminals in both hippocampus and neocortex 10 days later, and to an increase (40%) of NGF protein concentration in hippocampus. Thirty days after surgery, NGF had returned to control levels and remained there after 90 days. Removal of superior cervical ganglion did not after the results. The density of cholinergic terminals in both hippocampus and neocortex increased with time (90 days) after fimbrial transection. The results support the idea that cholinergic neurons in the basal forebrain take up and retrogradely transport NGF from their target areas and suggest that transection of the pathway interrupts the transport thereby increasing NGF distal to the lesion. The return of NGF to control levels probably reflects reestablished cholinergic contacts in the hippocampus.
Effect of injury on nerve growth factor uptake by sensory ganglia
Authors: Khan T. , Green B. , Perez‐Polo R. J.
Published: January 2005

The level of the nerve growth factor protein, NGF, in vivo has a profound influence on axonal sprouting by sensory neurons of vertebrate dorsal root ganglia. There is evidence also that NGF may play similar roles in cholinergic central structures in brain. In both instances, retrograde transport of NGF has been demonstrated. Here we examined uptake of NGF by DRG neurons in response to contusion injury of the spinal cord. Under these conditions there was uptake and tranport of NGF into large DRG neurons via central processes but no uptake by non‐DRG central neurons. Thus, any effects of NGF on spinal neurons or their processes would be secondary to the direct effects of NGF on DRG Neurons.
Perinatal, not adult, hypothyroidism suppresses dopaminergic axon sprouting in the deafferented olfactory tubercle of adult rat
Authors: Gottesfeld Z. , Garcia C. J. , Chronister R. B.
Published: January 2005

We reported recently that chronic thyroid deficiency in rat, beginning in utero and terminating after maturity, suppresses lesion‐induced central catecholaminergic axon sprouting in the adult brain [Gottesfeld et al, 1985]. The present work was undertaken to define the critical period of hypothroidism on subsequent neuronal sprouting.

Thyroid hormones deficiency was induced in rats by methimazole during (a) gestational days 8–21 (20 mg/kg/day in the drinking water); (b)postnatal days 1–15 (0.2 or 0.4 mg/pup/day; i.p.), or (c) in the mature animal for 4 weeks (20 mg/kg/day in the drinking water). The olfactory tubercles (ITs) were used as a model to study sprouting of dopaminergic (DA) nerve terminals, elicited by olfactory bulbectomy. Animals in each group received lesions or sham operations as adults, and sacrificed 3 weeks after the operation. Thus, for each of the above treatments four subgroups were formed: (c) hypothyroid/sham‐operation, and (d)hypothyroid/lesion.

Sprouting of DA axon ternminals in the OTs was identified by biochemical assays and quantitative immunofluorescent microscopy, using throxine levels served as an index of the thyroid status.

The results demonstrate that lesion‐induced sprouting of DA axon terminals in OTs of adult rats is suppressed by hypothyroidism induced prenatally of during the early postnatal period, but not after maturity. Thus, there is a perinatal critical period during which altered thyroid funciton exerts long‐term effects on neuronal plasticity.
Visual acuity loss ion rhesus monkey infants fed a taurine‐free human infant formula
Authors: Neuringer M. , Sturman J.
Published: January 2005

This study examinedthe effects of dietary taurine deprivation on visual development in rhesus monkeys. From birth to 3 months of age, rhesus monkeys were fed a taurine‐free, soy protein‐based infant formula, or the same formula supplemented with taurine. The early postnatal development of visual function was assessed with behavioral measurements of visual acuity.

Plasma taurine levels in the taurine‐deprived group fell to 35–50% of control values, as in human infants fed similar formulas. The visual acuity of the taurine‐deprived infants was significantly impaired: acuity thresholds differed from control values by nearly a factor of 2 at 4, 8, and 12 weeks of age. The loss of acuity is associated with morphological changes in photoreceptors, particularly cones in the foveal region.

These results provide direct evidence that taurine is essential for normal visual development in primates, and they support the nutritional importance of taurine for human infants.
Retinal degeneration in 3‐month‐old rhesus monkey infants fed a taurine‐free human infant formula
Authors: Imaki H. , Moretz R. , Wisniewski H. , Neuringer M. , Sturman J.
Published: January 2005

Rhesus monkey infants were raised from birth on a taurine‐free soy protein‐based human infant formula or on the same formula supplemented with taurine. The monkeys were killed 3 months after birth and the retinas examined by light and electron microscopy. All of the monkeys raised on formula alone showed degenerative ultrastructural changes in photoreceptor outer segments that ranged froom swelling and disorientation to fragmentation and disorganiozation. Cones were more severely affected than rods, and changes were most pronounced in the foveal region. Changes were also noted ion the fine structure of the retinal pigment epithelium. These changes were prevented in all but one monkey fed the same formula supplemented with taurine. These results provide further support for the addition of taurine to commercial human infant formulas.
Damaged rat peripheral nerves do not contain detectable amounts of α‐MSH
Authors: Verhaagen J. , Edwards P. M. , Gispen W. H.
Published: January 2005

Peptides related to α‐MSH (collectively termed melanocortins) stimulate nerve growth following injury and may play a physiological role in the repair process. Melannocortins are not normally present in mature peripheral nerves but MSH‐like bioactivity has been observed in extracts of injured nerves. α‐MSH could derive from reexpression of the POMC prohormone in injured nerves or from proteolysis of the intermediate‐size neurofilament protein that bears antigenic similarities to melanocortins. Using a radioimmunoassay that will distinguish between α‐MSH and neurofilament‐derived fragments, we have shown that α‐MSH is not present (detection limit 74 pg α‐MSH/mg protein) in damaged rat sciatic nerves.
Purification and partial amino acid sequence of bvino adernal phenylethanolamine N‐methyltransfersase: A comparision of nucleic acid and protein sequence data
Authors: Weisberg E. P. , Batter D. K. , Brown W. E. , Kaplan B. B.
Published: January 2005

Recently, We have reported the isolation and characterization of a putative genomic DNA clone encoding bovine adernal phenylethanolamine N‐methyltrasferase (PNMT) (Batter et al., 1988). However, the lack of primary amino‐acid sequence data for this enzyme precluded a definitive proof of the authenticity of this clone. To establish identity, the amino acid sequence of several peptides generated by chemical and enzymatic hydrolysis of purifide PNMT was compared to that predicted from the nucleotid sequence of the exons of the putative PNMT gene. Bovine adrenomedullary PNMT was purified by ammonium sulfate precipitation, gel filtration, and ion exchange chromatography. Treatment with 70% formic acid cleaved the protein at a single Asp‐Pro bond near the N‐terminus. The purified protein was also cleaved at a single methionine residue near the C‐terminus by treatment with cyanogen bromide. N‐terminal amino acid sequence analysis identified 8 and 10 amino acid residues, respectively, following each of the scissile peptide bonds. Four tryptic peptides, generated by complete enzymatic digestion, were isolated by reverse‐phase HPLC and subjected to sequence analysis. Combined, the amino acid sequence of these six peptides represent 20% of the PNMT protein. These amino acid sequence matched exactly the sequences predicted from the exons of the putative PNMT genomic clone.
The induction of the major heat‐stress protein in purified rat glial cells
Authors: Nishimura R. N. , Dwyer B. E. , Welch W. , Cole R. , de Vellis J. , Liotta K.
Published: January 2005

Cultured purified oligodendroglia and astroglia exposed to heat stress (45 °C, 10 or 20 min) synthesized a 68‐kDa heat‐stress protein, which migrates on twodimensional gel electrophoresis and reacts with a specific monoclonal antibody suggesting it is similar to a major 72‐kDa heat‐shock protein previously reported in other cell types. This protein was not detected in control glial cultures. Actinomycin D prevented synthesis of this protein demonstrating an absolute requirement for newly synthesized mRNA. The response was prolonged by increasing the period of heat stress from 10 to 20 min. In addition to the 68‐kDa HSP protein, the incorporation of radioactivity into 70‐, 89‐, and 97‐kDa proteins was also increased after heating, but in contrast to the 68 kDa protein these proteins appeared to be made in control glial cultures.
Influence of monensin on ganglioside anabolism and neurite stability in cultured chick neurons
Authors: Hogan M. V. , Saito M. , Rosenberg A.
Published: January 2005

We have examined the effects of monensin, a monovalent cationophore that disrupts exo‐ and endocytosis of membrane vesicles and diminishes Golgi anabolic function, on the incorporation of [3H]‐galactose into glycosphingolipids in neurited primary cultures of chick embryo central nervous system neurons. A linear rate of incorporation into all ganglioside species from extracellular‐‐labeled galactose was observed. Specific activity of anabolic labeling was markedly lower in GT1b and GQ1b than in the other major gangliosides of the embryonic neuron (GM3, GD3; GM2, GD2; GM1, GD1a, GD1b). With 100 nM monensin in the extracellular medium, the rate of labeling of GT1b diminished markedly to 20% of control; GD1a, GD1b, and GD2, to 35%; GQ1B to 48%; GD3 to 60%. Vigorous incorporation of label into GM3 was entirely undiminished by monesin. From these findings, it is suggested that ganglioside biosynthesis is compartmentalized in the cytodifferentiating embryonic neuron, with GM3 entirely, and GD3 and GQ1b partially, an extra‐Golgi product. Extensive loss of neurites that occurred after several hours of exposure of the neurons to monensin could not be correleated directly with decreased ganglioside anabolism.
Phosphofructokinase in the rat nervous system: Regional differences in activity and characteristics of axonal transport
Authors: Oblinger M. M. , Foe L. G. , Kwiatkowska D. , Kemp R. G.
Published: January 2005

The distribution of phosphofructokinase (PFK) in gray and white matter regions of the rat nervous system was evaluated. Determinations of PFK activity revealed that cell body enriched regions (sensorimotor cortex) had a significantly higher level of activity than axonal regions (sciatic nerve, dorsal roots, and optic nerve). The level of PFK activity was also significantly higher in central axons (optic nerve) than in peripheral axons (sciatic nerve). Differences in PFK activity could be largely attributed to differences in tissue content of the enzyme rather than to differences in the types of PFK isozymes present. Cortex contained significantly larger amounts of PFK relative to total protein than did peripheral nerve. However, purification of PFK revealed that all three of the PFK isozymes, C (86 kd), A (84 kd), and B (80 kd), were present in both cortex and sciatic nerve. Both SDS/PAGE and immunoblotting studies using PFK isozyme‐specific antibodies demonstrated that the relative proportions of the three PFK isozymes were similar in cell body and axonal regions of the nervous system. The PFK‐C and PFK‐A isozymes each comprised about half the total and only small amounts of the PFK‐B isozyme were present in both regions. However, immunoprecipitation experiments suggested that quantitatively different proportions of the possible PFK hybrids (tetramers) may be distributed between axonal and cell body regions. The transport of PFK was examined in this study and PFK was identified in slow component b (SCb) of axonal transport. SCb moves at a rate of 2–4 mm/day in rat axons and is known to contain several other enzymes of intermediary metabolism as well as actin. The finding that PFK, the rate limiting enzyme in glycolysis, is present in SCb lends support to the hypothesis that glycolytic enzymes are not freely diffusing proteins in axons but, instead, are present as organized assemblies that have long‐term, yet flexible, associations with structural elements of the cytoplasm.