bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regional changes in phenylethanolamine‐N‐Methyltransferase of rat brain during development
Authors: Díaz Borges J. M. , Rodríguez L. , Urbina M. 
Published: January 2005

AbstractThe changes of phenylethanolamine‐N‐methyltransferase (PNMT, EC 2.1.1.28), the enzyme that catalyzes the final step in the biosynthesis of adrenaline, were studied during the development of several regions of rat brain. PNMT is present in medulla oblongata‐pons, hypothalamus, cerebellum, and midbrain five days before birth, and a progressive increase in the enzyme activity is observed during development. The adult levels are attained between 15 and 20 days, depending on the region. The increases in PNMT activity in the rostral regions are higher than in the caudal regions. PNMT attains adult levels earlier than tyrosine hydroxylase and dopamine‐β‐hydroxylase. The apparatus for adrenaline synthesis seems to be mature at three weeks after birth in the medulla oblongata‐pons, which contains the cell bodies of adrenaline‐containing neurons. In the other regions the adult levels of enzyme activity are attained at 15 days after birth.
Adrenal and hypothalamic dopamine‐beta‐hydroxylase activity in the hamster: Evidence for species‐distinctive day‐night and post‐pinealectomy differences in activity
Authors: Banerji Tapan K. , Kachi T. , Quay W. B. 
Published: January 2005

AbstractDopamine‐beta‐hydroxylase (DBH) activities were measured in the adrenal gland and hypothalamus of the golden hamster (Mesocricetus auratus) by means of a sensitive radioenzymatic method. Groups of unoperated control (C), sham pinealectomized (SPX), and pinealectomized (PX) adult males were sacrificed shortly before (09:00 h) and after (11:00 h) the onset of darkness of the daily photoperiod of LD 12:12 (lights on 22:00 h to 10:00 h). In neither adrenal gland nor the hypothalamus were there any day‐night changes in the C groups. Pinealectomy led to no significant differences in hypothalamic DBH activity either in light or in dark. However, intracranial surgery resulted in increased DBH activity in the adrenal gland, evident in both light and dark. Although this increase was greatest in the PX groups, intracranial surgery in SPX groups also showed a trend of increase in adrenal DBH, evident even one month after surgery. Such an increase, however, was not found in hypothalamic DBH in the same SPX groups. In both the adrenal gland and the hypothalamus, copper‐sensitive endogenous inhibitors of DBH did not show any notable change in concentration, either in relation to the daily light‐to‐dark change or as a consequence of intracranial surgery. These and related results suggest that important interspecies variations exist in DBH activities in relation to diurnal changes, and also in control or modulation by pineal and other factors.
Effects of morphine on sensory‐evoked responses recorded from central gray, reticular formation, thalamus, hypothalamus, limbic system, basal ganglia, dorsal raphe, locus ceruleus, and pineal body
Authors: Dafny N. , Marchand J. , McClung R. , Salamy J. , Sands S. , Wachtendorf H. , Burks T. F. 
Published: January 2005

AbstractField potential recordings of acoustic and photic‐evoked responses were obtained from 15 brain sites of freely behaving unanesthetized rats previously implanted stereotaxically with permanent electrodes. Several dosages of morphine (1, 5, 10, 30, and 50 mg/kg) were examined. The activities recorded from all the structures in this study, except the cochlear nucleus (CoN), were affected by morphine. Different sensitivities to morphine threshold were observed between structures, and several structures exhibited dose‐related patterns (ventromedial hypothalamus (VMH), caudate nucleus (CN), central gray (CG), hippocampus (Hipp), and lateral septum (Spt)). Several brain sites, after the initial dose of morphine, did not recruit more responses to subsequent doses of the drug, ie, exhibited all‐or‐none responses (pineal body (PB), medial thalamus (MTh), anterior hypothalamus (AH), mesencephalic reticular formation (MRF), and the dorsal raphe (DR)). In some structures, morphine induced increases in the response amplitudes, while in other sites decreases in response amplitudes were elicited. Biphasic responses, ie, increases in response amplitude after low doses of the drug and decreases in response amplitude after higher dosages, were also observed (VMH, CN, DR, CG, and MRF). The acoustic‐evoked responses were affected by morphine more than the photic responses. The present observations indicated that (1) morphine exerts effects in many parts of the central nervous system (CNS); (2) some structures are more sensitive to morphine than others; (3) only a few structures exhibit dose‐related patterns and, thus, may represent sites of direct morphine action; (4) some structures exhibit all‐or‐none responses; and (5) morphine depressed activity in some structures and increased activity in others, ie, morphine elicited different effects in different structures.
Tay‐sachs disease brain cells in culture: Mobilization of stored GM2 after concanavalin A‐mediated uptake of hexosaminidase A
Authors: Hoffman Linda M. , Brooks Steven E. , Amsterdam Daniel , Oropello John , Schneck Larry 
Published: January 2005

AbstractA human Tay‐Sachs disease (TSD) fetal‐brain‐cell line is a useful model for the disease since the cells lack hexosaminidase A and accumulate the ganglioside, GM2. This brain‐cell line was used to assess the effect of hexosaminidase A treatment on GM2 storage material. Entry of placental hexosaminidase A into the cells was obtained by pretreatment of the cultures with concanavalin A. Cells were analyzed periodically during six days. During the course of the experiment, GM2 in the cells decreased by approximately 50%. A substantial amount of hexosaminidase A was maintained in the cultures throughout the experiment. This strategy was successful in mobilizing stored GM2 in TSD brain‐cell cultures. Therefore, the activating factor needed for hexosaminidase A activity must be present in TSD‐cultured brain cells.
Reactions of lateral geniculate cells to chemical and electrical excitation of the visual cortex in rabbits
Authors: Molotchnikoff S. , Richard D. 
Published: January 2005

AbstractIn anesthetized and paralyzed rabbits unitary discharges of lateral geniculate nucleus (LGN) were studied after cortical excitation by strychnine and following electrical stimulation of the visual cortex (VC). Results showed that local application of strychnine produced a general increase of the spontaneous and evoked activity of geniculate cells. By contrast, cortical depression with KCl led to a differential decrement of one of the evoked responses (on or off). Electrical cortical stimulation paired with on or off stimuli led to a differential increment of on or off responses. The results support the notion that, in rabbits, the corticogeniculate system is center‐surround organized. A diagrammatic model is proposed to account for the relationship between the VC and the LGN in rabbits.
Studies on choline and ethanolamine phosphoglyceride biosynthesis in developing rabbit brain
Authors: Fimbres E. , Saenz R. , Smith N. , Percy A. K. 
Published: January 2005

AbstractActivities of cholinephosphotransferase (EC 2.7.8.2) and ethanolaminephosphotransferase (EC 2.7.8.1) were evaluated in microsomal preparations derived from rabbit cerebrum. Animals ranged in age from nineteen day's gestation through two months of postnatal development. Under optimal conditions the properties of these transferases in rabbit brain were remarkably similar relative to pH, divalent cation requirements, and apparent‐Km values for the CDP‐intermediates and the lipid acceptor, respectively. Cholinephosphotransferase‐specific activity exhibited a dramatic rise during the last 15%–20% of fetal life and a second rise to a maximum near the 15th postnatal day. Ethanolaminephosphotransferase‐specific activity exhibited a similar, but less striking age‐related increase during the same period. Growth of rabbit cerebrum, as determined by weight, increased 30‐fold during this same period (24 days gestation to the 19th postnatal day). Specific activities of these transferases were similar in brain preparations from mid‐fetal and early adult rabbits. The maximum specific activity of cholinephosphotransferase exceeded that of ethanolaminephosphotransferase by 3–4‐fold.Age‐related changes in the specific activities of these transferases appear to correlate with the developmental pattern of morphological and compositional events occurring in rabbit cerebrum during the last third of gestation and the first three weeks of postnatal life.
Regional changes in adrenaline of rat brain during development
Authors: Borges J. M. Díaz , Chávez M. 
Published: January 2005

AbstractThe changes of adrenaline during development were studied in several regions of rat brain. Adrenaline is present in hypothalamus, medulla oblongata‐pons, midbrain, and cerebellum. Adult levels are attained between 15 and 30 days, depending on the region. These adult levels are attained earlier in the caudal regions than in the rostral regions. In cerebellum and medulla oblongata‐pons, the adrenaline content reaches a maximum at 15 days which is close to the time in which the levels of phenylethanolamine‐N‐methyltransferase (PNMT) reach their maximum. In midbrain and hypothalamus, there is a lag between the adult levels of adrenaline and the activity of PNMT. Adrenaline reaches adult levels at 25 days in midbrain and at 30 days in hypothalamus, while PNMT activity adult levels are attained at 15 days.
High‐affinity uptake system for cysteine in crude synaptosomal fractions of rat cerebral cortex
Authors: Misra Chandra H. 
Published: January 2005

AbstractThe in vitro uptake of [35S] cysteine was studied in crude synaptosomal preparation of the cerebral cortex of rat. The accumulation of cysteine was found to be temperature‐ and time‐dependent. It was linear at least for four minutes at 37 C with characteristics of saturable kinetics. Uptake of cysteine was Na+‐ and K+‐dependent. Increasing the Na+ ion concentration increased the accumulation of cysteine in synaptosomal preparations; unlike the Na+ ion, an increase in the K+ ion, an increase in the K+ ion inhibited cysteine uptake. Cysteine was accumulated against concentration gradients by a saturable mechanism. Double reciprocal plot of the cysteine uptake suggests two types of affinity systems, with Km values for the high‐affinity uptake of about 12.2 μM and for the low‐affinity uptake of about 4 mM. The high‐affinity uptake was also significantly inhibited by ouabain, a potent inhibitor of the Na+‐K+‐dependent ATPase, and other metabolic inhibitors. The results of the effects of cysteine analogues on uptake also suggested that it is a substrate‐specific high‐affinity uptake system for cysteine.
In vitro evidence of photoreception in the chick pineal gland and its interaction with the circadian clock controlling N‐acetyltransferase (NAT)
Authors: Kasal Charles A. , Perez‐Polo J. Regino 
Published: January 2005

AbstractThe response of the circadian rhythm in N‐acetyltransferase (NAT) activity to phase‐shifted light cycles was examined in vitro in explant cultures of chick (Gallus domesticus) pineal glands. Bisected portions of glands, obtained from birds housed in a light—dark cycle (LD 12:12), were explanted into culture and maintained under one of three light cycles (LD 12:12), the phase of which was either (1) similar to that of the birds' previous cycle, (2) seven hours phase‐delayed, or (3) six hours phase‐advanced. Following two to three days of exposure to the respective light cycles, cultures were placed into continuous darkness (DD). Sampling from cultures during exposure to DD revealed a circadian rhythm of NAT activity. In each case, the phase of the subsequent rhythm of enzyme activity in DD reflected that of the preceding in vitro light cycle. A distinct phase difference of approximately 180° was observed between cultures exposed to opposite lighting regimes. These results indicate entrainment of the circadian rhythm of NAT activity to the prevailing in vitro light cycle and suggest a direct interaction between pineal photoreception and the circadian “clock” controlling NAT.
Effects of low ammonia levels on NAD(P)H levels and glutamate secretion during calcium‐dependent depolarization of CNS slices
Authors: Cummins J. T. , Hamberger A. , NystróOum B. 
Published: January 2005

AbstractSimultaneously with an evoked release of endogenous glutamate, redox changes in NAD(P)H levels occur as a response to electrical or chemical stimulation of the isolated CNS tissue. While electrical‐field stimulation induces a transient increase in tissue NAD(P)H, KCl stimulation produces a decrease in NAD(P)H. One possible interpretation for this difference is that elevated KCl induces glutamate release from larger cell populations, including glia, while electrical stimulation might have a more neuro‐specific action. In the present report, it is shown that the electrically or biochemically evoked release of endogenous glutamate is strongly inhibited by ammonium ions at 3–5 mM in the hippocampus and frontal cortex. At the same time, ammonium ions inverted the NAD(P)H response of the tissue during electrical stimulation, making both electrical and KCl depolarization induce a decrease in NAD(P)H. There was no effect of ammonium ions per se on the NAD(P)H levels, and to obtain the effects on both NAD(P)H and glutamate release, the tissue had to be exposed for 40–60 minutes to ammonium ions. The results are interpreted to indicate that ammonium ions influence regulatory control mechanisms in cell populations in the tissue slice that secretes glutamate in response to depolarization.
Effects of partial and complete vagal denervation on spontaneous ingestion and drinking induced with volemic and osmotic regulatory challenges
Authors: Martin James R. 
Published: January 2005

AbstractThe present study investigated the effects of unilateral right or left cervical vagotomy, selective subdiaphragmatic transection of the anterior vagal trunk, the posterior vagal trunk or the hepatic branch of the vagus, and the effects of total abdominal vagotomy with concomitant pyloroplasty on the regulation of spontaneous ingestive behavior and responsiveness to osmotic and volemic challenges. Total abdominal vagotomy with pyloroplasty somewhat reduced food intake, water consumption, and body weight measured ten weeks postsurgery. The other denervation procedures did not affect these parameters of spontaneous ingestive behavior. In additional tests given approximately two and four months postsurgery, rats that had undergone total abdominal vagotomy exhibited a significantly longer latency to drink and consumed less water than controls during the initial 0.5 hours after injection of hypertonic saline. These total abdominally vagotomized rats also exhibited significantly lower cumulative physiological saline intake in comparison to controls for 4, 8, and 16 hours after subcutaneous injection with polyethylene glycol, but not 2 or 24 hours postinjection. However, total abdominal vagotomy did not impair water drinking one, two, or four hours after injection with D,L‐isoproterenol (0.04–0.32 mg/kg body weight). The other denervation procedures did not alter drinking in response to isoproterenol or polyethylene glycol injections, and most of these groups exhibited normal latency and intake following injection of hypertonic saline. The hepatic vagotomy group, however, exhibited a shorter latency to drink in response to hypertonic saline injection than controls. The present results demonstrate that spontaneous food and water intake, body weight, and responsiveness to various volemic and osmotic regulatory challenges are clearly impaired only by the total abdominal vagotomy procedure.
Regional circadian variation of acetylcholine muscarinic receptors in the rat brain
Authors: Por Suzanne B. , Bondy Stephen C. 
Published: January 2005

AbstractThe level of binding of a labeled acetylcholine muscarinic antagonist (quinuclidinyl benzilate) to different cerebral membranes has been measured. Of the regions examined, circadian rhythmicity of binding could only be detected significantly in the hippocampus and the hypothalamus and not in the cerebral cortex, striatum, or cerebellum.
Noncoordinate regulation of myelinogenic parameters in primary cultures of dissociated fetal rat brain
Authors: Pfeiffer S. E. , Barbarese E. , Bhat S. 
Published: January 2005

AbstractThe developmental regulation of sulfogalactosylceramide (sulfatide) synthesis, 2′,3′‐cyclic nucleotide‐3′‐phosphohydrolase activity (CNP), and myelin basic protein (MBP) accumulation, three markers characteristic of myelinogenesis, were observed in dispersed cultures of fetal rat brain in spite of the absence of the formation of compact, multilamellar myelin. Sulfatide synthetic rate and CNP activity began to increase by 8 days in vitro (DIV) (approximately comparable to days post‐natal) and reached their maxima by 20 DIV. MBP began to accumulate after 14 DIV and reached a maximum by 38 DIV. Thus, the temporal regulation of the onset of expression of these parameters, which is coordinate in vivo, has been dissociated into two sequential periods in vitro. Similarly, the regulatory mechanisms controlling the subsequent decline of the net expression of these three parameters were dissociated. Whereas, the increase in the net CNP activity ceased on schedule, the decline of sulfatide synthetic rate was delayed 20 days, and the accumulation of MBP underwent a net loss. These data suggest that there are multiple parallel but separate mechanisms of temporal regulation controlling myelinogenic gene expression, and that, among them, those factors that control MBP accumulation are more sensitive to disruption by the rigors of dissociated culture.
Alteration of metabolism of retinal taurine following prolonged light and dark adaptation: A quantitative comparison with gamma‐aminobutyric acid (GABA)
Authors: Ida Shuji , Nishimura Chihiro , Ueno Eiko , Kuriyama Kinya 
Published: January 2005

AbstractAlteration of metabolism of taurine in prolonged light‐ and dark‐adapted frog retinae were studied in comparison with that of gamma‐aminobutyric acid (GABA) and the following results were obtained. (1) Statistically significant alterations in retinal taurine, an increase in dark‐adapted, and a decrease in light‐adapted states, respectively, occurred when frogs were adapted continuously to light or dark for more than 3 weeks. Under the same experimental conditions, no alteration in retinal GABA was noted. (2) At 3 weeks and thereafter, a significant increase of retinal cysteine sulfinic acid decarboxylase (CSD; EC 4.1.1.12) activity, an enzyme involved in the biosynthetic pathway of taurine, also occurred in the dark, whereas the activity in the light‐adapted retina was reduced. On the other hand, the retinal activity of L‐glutamate decarboxylase (GAD; EC 4.1.1.15), the rate‐limiting enzyme of GABA biosynthesis, was not altered in dark‐ as well as light‐adapted state. Similarly, retinal GABA‐transaminase (GABA‐T; EC 2.6.1.19)‐succinic semialdehyde dehydrogenase (SSADH; EC 1.2.1.16) was unaltered. (3) These alterations in retinal taurine were, however, unaccompanied by any changes in factors related to transmitter actions such as evoked release, high affinity uptake, and specific binding to synaptic membranes. The above results suggest that, different from GABA as a potent candidate for inhibitory neurotransmitter, retinal taurine may act as neuromodulator and/or may play an important role as a basic factor for maintaining cellular integrity under certain pathophysiological conditions.
Endogenous activation of guanylate cyclase in synaptosomal soluble fraction from rat brain
Authors: Yoshikawa Kazuaki , Kuriyama Kinya 
Published: January 2005

AbstractGuanylate cyclase in crude mitochrondrial (P2) soluble fraction prepared from rat brain, obtained by a hypo‐osmotic treatment of P2, showed extremely higher activity than that in the same fraction from other organs. In addition the soluble fraction obtained from synaptosomes (P2‐B) contained the highest enzyme activity among other subfractions of the cerebral P2 examined. Guanylate cylase activity in the synaptosomal soluble fraction was, however, markedly suppressed by various compounds reacting with free radicals.These results suggest that guanylate cyclase in the synaptosomal soluble fraction may be activated endogenously by a free radical and involved in the regulatory mechanisms for cyclic guanosine monophosphate (cyclic GMP) at presynaptic terminals.
Modification in messenger RNA population synthesized in rabbit cerebral cortex in the recovery period following convulsions
Authors: Cupello A. , Ferrillo F. , Rosadini G. 
Published: January 2005

AbstractThe labeling pattern of microsomal poly(A)‐associated messenger RNA was studied in rabbit cerebral cortex during the postconvulsive period. Labeled uridine was injected into the brain 2 hr after a single electroconvulsive shock and the animals sacrificed 1 hr later. Poly(A) RNA was then extracted from cerebral cortex microsomes, and fractionated by gel electrophoresis. The results indicate that the messenger RNA population synthesized in the cortex in the postconvulsive recovery period is clearly different from that synthesized in the normal controls.
Studies in neuronal ceroid lipofuscinosis: Enzymes of liver and brain tissues involved in the defense against oxidative damage
Authors: Garg Hari S. , Awasthi Yogesh C. , Neff William A. , Ansari Naseem H. , Srivastava Satish K. 
Published: January 2005

AbstractThe levels and the nature of peroxidase isozymes in the liver and brain tissues of a patient with Batten‐Spielmeyer‐Vogts (BSV) syndrome were found to be comparable to those of normal controls, indicating that peroxidase deficiency is probably not the basic genetic defect in Battens disease. The isoelectric focusing profile (four isozymes at pI 4.0, 4.5, 5.3, and 7.2) of liver peroxidases in the BSV patient was similar to that of normal control. Ion exchange chromatography revealed no noticeable difference in the liver peroxidase isozymes of the normal control and the BSV syndrome patient. The quantitative difference often observed in total peroxidase activity in normals and BSV syndrome patients can be attributed to different amounts of hemoglobin, which is known to express peroxidase activity. The levels of other enzymes known to be involved in the defense of tissues against oxidative damage, such as superoxide dismutase and glutathione peroxidase, and catalatic and peroxidatic activities of catalalase in the liver and brain tissues of the Battens patient, were comparable to the levels in the control subject. The brain peroxidase from both normal subjects and the Battens patient was completely inhibited by 5 mM sodium azide, whereas it did not affect the liver peroxidase activity.
Synaptosomes and mitochondria from rat brain cerebral cortex: In vivo interference on some enzymatic activities by SAMe and CDP‐choline
Authors: Villa R. F. , Curti D. , Polgatti M. , Benzi Gianni 
Published: January 2005

AbstractThe interference of cytidine diphosphate choline (CDP‐choline) and of S‐adenosyl‐L‐methionine (SAMe) on several enzymatic activities related to energy transduction (citrate synthase, malate dehydrogenase, total NADH‐cytochrome c reductase, cytochrome oxidase) and cholinergic metabolism (acetylcholine esterase) was studied. These enzymatic activities were evaluated in the purified mitochondrial fraction and in the crude synaptosomal fraction of rat cerebral cortex, 30 or 60 minutes after the in vivo administration of a single dose of 40 and/or 80 and 320 mg.kg−1 by intraperitoneal injection. SAMe left the enzymatic pattern studied totally unmodified, while CDP‐choline increased the cytochrome oxidase, evaluated in the synaptosomal fraction. These findings are discussed with regard to SAMe compartmentation and CDP‐choline action.