Binding of 3H-spiperone in the mouse brain after intraperitoneal injection

In experiments on mice 3H-spiperone binding after intraperitoneal injection was studied. The binding of 3H-spiperone was saturable in the frontal cortex and subcortical structures, whereas in the cerebellum, the amount of radioactivity increased in a linear manner and was referred to as nonspecific binding. The neuroleptics haloperidol, chlorpromazine and sulpiride given 0.5 h before 3H-spiperone displaced 3H-spiperone in the subcortical structures in a dose-related manner. Although the level of the specific 3H-spiperone binding after intraperitoneal injection was lower than after intravenous injection, the intraperitoneal method is simpler, well reproduced and given results comparable with the intravenous method.     

Cocaine-induced changes in 3H-naloxone binding in brain membranes isolated from spontaneously hypertensive and Wistar-Kyoto rats

Effects of sub-acute cocaine treatment on 3H-naloxone binding to 6 brain regions were examined in spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Cocaine hydrochloride (3 mg/kg, i.v.) was given by bolus injection daily for five days. Rats were decapitated 24 hr following the final injection and crude membrane fractions prepared from the cortex (CT), hippocampus (HI), striatum (ST), hypothalamus (HY), midbrain (MB) and medulla/pons (MD). Binding of 3H-naloxone was consistent with a single site model in CT, HI, HY, MB and MD from vehicle-treated SHR and WKY. Cocaine treatment of SHR significantly decreased the maximal binding capacity (Bmax) of 3H-naloxone in the HI, ST and HY and the binding affinity was increased in HI. In contrast, a significant increase in Bmax was noted in CT and HI membranes isolated from cocaine-treated WKY. The binding affinity of 3H-naloxone to MB membranes of WKY was significantly decreased by cocaine treatment. The binding characteristics of 3H-naloxone in MD membranes were not different following cocaine treatment or between strains. Scatchard analysis indicated biphasic binding of 3H-naloxone binding to ST membranes from both SHR and WKY. Our results indicate that cocaine produces complex and differential changes in opiate receptors and, presumably, opioid peptide neuronal function in SHR and WKY.     

Binding of 3H-beta-endorphin in rat brain

The binding of 3H-beta-endorphin to rat brain homogenates, reported by several other laboratories, has suggested unique selective beta-endorphin binding sites. We now present additional evidence supporting the concept of distinct beta-endorphin binding (epsilon) sites in rat brain. In competitive displacement studies, 3H-beta-endorphin was inhibited far better by unlabeled beta-endorphin than a variety of opiates and enkephalins. Conversely, beta-endorphin inhibited the binding of a series of 3H-labeled ligands, including dihydromorphine, ethylketocyclazocine, SKF 10,047, naloxone and D-ala2-D-leu5-enkephalin, far less potently than their corresponding unlabeled drug. Other differences were also found. Compared to 3H-dihydromorphine and 3H-D-ala2-D-leu5-enkephalin binding, 3H-beta-endorphin binding was far less sensitive to the reagent N-ethylmaleimide and more sensitive to the proteolytic enzyme trypsin. The regional distribution for 3H-beta-endorphin binding was also distinct from other 3H-ligands tested. This evidence supports the concept of a distinct binding site for beta-endorphin which does not correspond to the previously defined opioid binding sites.     

Glycine protects preimplantation mouse conceptuses from a detrimental effect on development of the inorganic ions in oviductal fluid

Two-cell mouse conceptuses were cultured in media that contained various concentrations of inorganic ions and amino acids. Substrates of the amino acid transport system Gly were detrimental to development at slightly hyposmotic concentrations of other ions. In contrast, these amino acids increased the frequency at which two-cell conceptuses developed into blastocysts at total ion concentrations of 355 to 405 mM. Data reported elsewhere is consistent with the possibility that the total ion concentration in oviductal fluid exceeds 360 mM, whereas the concentration of glycine in this fluid may be on the order of 10 mM. Therefore, a high ion concentration and glycine may counteract the potentially harmful effects of each other in situ. Like some marine organisms, preimplantation mouse conceptuses may use glycine as an intracellular osmolite because accumulation of inorganic ions could perturb the activities of some enzymes.     

Toxic effect of lithium in mouse brain

The effect of lithium ion on glucose oxidation in the cerebrum and cerebellum of mice was measured in vitro by the conversion of isotopic glucose into 14CO2/mg wet weight. Glucose utilization is unaffected by lowest lithium dosage but is inhibited by high lithium concentrations (197-295 mM). Chronic administration of lithium to adult mice decreased the DNA content of the cerebrum and cerebellum at concentrations of 80 and 108 mM. The DNA content of selected postnatal stages of cerebrum and cerebellum was measured starting on Day 1 or 2. This served as another parameter to evaluate glucose oxidation studies at these ages. On the basis of wet weight, both brain parts of neonates of ages 1 and 10 days were approximately one-half that of the adult counterparts. On the basis of DNA content, the cerebrum enhanced its glucose utilization twofold from Day 1 to Day 10 and tripled its utilization from Day 10 to Day 20. The glucose utilization by cerebrum at Day 20 is similar to adult values. In contrast, glucose oxidation in the cerebellum remained relatively constant throughout the postnatal growth. The relative susceptibility of the two brain parts is discussed.     

Opiate receptor binding of naloxone in the rat brain: effect of sodium ions

The binding levels and opiate receptor binding parameters were determined for 3H-naloxone in rat brain in the presence of NaCl added in vitro. An addition of NaCl at concentrations of 5-35 mM to the reaction medium caused an increase in the level of the antagonist receptor binding. The maximal level of 3H-naloxone reception activation was observed in the presence of 10-20 mM NaCl and was, on the average, 25%. Both the increase in the NaCl dose in vitro and its decrease caused a gradual diminution of the Na+ effect. An analysis of opiate receptor saturation with 3H-naloxone revealed that the label interacted with one type of the binding sites irrespective of NaCl concentration. The affinity of receptor binding sites for 3H-naloxone increased already at NaCl concentration of 2.5 mM. In contrast, the apparent maximal number of binding sites did not change after NaCl addition at concentrations which coincided with the intracellular Na+ level but was decreased with an increase (up to 50-100 mM) in NaCl present in the reaction mixture. The results obtained point to the existence of two different binding sites that are coupled with the 3H-naloxone reactive opiate receptor.     

Pro-Leu-Gly-NH2 and pareptide inhibit development of tolerance to haloperidol catalepsy in the mouse

Single doses of MIF-1 (0.03-2.0 mg/kg, SC) and chronic pretreatments with MIF-1 (0.03-2.0 mg/kg, SC, BID, 3 1/2 days) or pareptide (0.25 mg/kg, SC, BID, 3 1/2 days) did not affect the acute cataleptic response to haloperidol in the mouse. Chronic pretreatment with haloperidol (8.0 mg/kg, IP, BID, 3 days) decreased the duration of catalepsy in mice given smaller challenge dose of haloperidol (2.0 or 3.0 mg/kg, IP) 15 hours after the last pretreatment injections. Administration of either MIF-1 or pareptide to mice also chronically pretreated with haloperidol antagonized the development of tolerance.     

Progressive development of radiation damage in mouse kidneys and the consequences for reirradiation tolerance

The aim of this study was to investigate the influence of protracted overall treatment times on the development and repair of renal irradiation injury in mice. Functional kidney damage was measured, from the proportion of 51CrEDTA remaining in the plasma at 30 min after injection of the tracer. Damage was assessed at monthly intervals for up to 14 months after two equal doses of X-rays given in 1 day, 1 month or 6 months. There was no difference between the time of onset or rate of development of damage after two fractions in 1 day or 1 month, but there was a time lag of 7-15 weeks (depending on dose) before the development of damage after 2F given in 6 months. After this time lag the rate of progression of damage was the same for 2F/6 months as for 2F in the shorter intervals. There was therefore no indication of any increase in total tolerated dose for the kidney when the treatment time was protracted, although the time scales for onset of this damage differed. Tolerance of mouse kidneys to reirradiation at 6 months after single doses of 6-12 Gy was also assessed. All of the previously irradiated animals developed a more severe renal impairment after reirradiation than did the age-matched control mice. The most severe damage occurred in mice which received the highest initial radiation doses, but doses of only 6 Gy were sufficient to markedly reduce the tolerance to reirradiation. It was concluded from these studies that no additional dose-sparing (tissue recovery) took place in the kidneys during a 6-month interval. This was true even when the initial radiation dose alone was insufficient to cause measurable renal dysfunction.     

Effects of sodium on cell surface and intracellular 3H-naloxone binding sites

The binding of the opiate antagonist 3H-naloxone was examined in rat whole brain homogenates and in crude subcellular fractions of these homogenates (nuclear, synaptosomal, and mitochondrial fractions) using buffers that approximated intra- (low sodium concentration) and extracellular (high sodium concentration) fluids. Saturation studies showed a two-fold decrease in the dissociation constant (Kd) in all subcellular fractions examined in extracellular buffer compared to intracellular buffer. In contrast, there was no significant effect of the buffers on the Bmax. Thus, 3H-naloxone did not distinguish between binding sites present on cell surface and intracellular tissues in these two buffers. These results show that the "sodium effect" of opiate antagonist binding is probably not a function of altered selection of intra- and extracellular binding sites.     

The effect of temporary hypoxia on prostaglandin synthesis in mouse brain cell cultures during development

Cultures of dissociated brain cells of new born mice represent a model for the study of brain development. One and two weeks old, they correspond in regard to oligodendrocyte differentiation to about the developmental stage of a human newborn and a six months old infant respectively. Such cultures were used to establish the developmental prostaglandin pattern and to study early and late recovery of prostaglandin synthesis from temporary hypoxia. Basal and bradykinin stimulated prostaglandin release were examined. Most prominently in stimulated release, the developmental prostaglandin pattern at one week showed a prevalence of PGE2 (33 +/- 4%) over PGD2 (12 +/- 5%), which in two weeks old cultures changes to an opposite distribution (PGE2 10 +/- 4%; PGD2 25 +/- 6%). This change goes parallel with the number and differentiation of oligodendrocytes. During the first day post hypoxia, imposed at the end of one week, the production of 6 oxo PGF1 alpha, PGE2, PGD2 and TXB2 was significantly decreased in two study series and increased compared to control in another. Since the arachidonic acid uptake was the same in all three series, this differential observation indicates differential early recovery. 8 days post hypoxia (late recovery), PG release was not different from control, indicating complete recovery at that time. During early recovery from hypoxia on 14 days old cultures, basal PG release was not significantly different from control, however bradykinin stimulated release was significantly inhibited in all three series. This may indicate that mainly regulatory influences on PG release in older cultures are compromised by hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changing iron content of the mouse brain during development

Iron is crucial to many processes in the brain yet the percentages of the major iron-containing species contained therein, and how these percentages change during development, have not been reliably determined. To do this, C57BL/6 mice were enriched in (57)Fe and their brains were examined by M?ssbauer, EPR, and electronic absorption spectroscopy; Fe concentrations were evaluated using ICP-MS. Excluding the contribution of residual blood hemoglobin, the three major categories of brain Fe included ferritin (an iron storage protein), mitochondrial iron (consisting primarily of Fe/S clusters and hemes), and mononuclear nonheme high-spin (NHHS) Fe(II) and Fe(III) species. Brains from prenatal and one-week old mice were dominated by ferritin and were deficient in mitochondrial Fe. During the next few weeks of life, the brain grew and experienced a burst of mitochondriogenesis. Overall brain Fe concentration and the concentration of ferritin declined during this burst phase, suggesting that the rate of Fe incorporation was insufficient to accommodate these changes. The slow rate of Fe import and export to/from the brain, relative to other organs, was verified by an isotopic labeling study. Iron levels and ferritin stores replenished in young adult mice. NHHS Fe(II) species were observed in substantial levels in brains of several ages. A stable free-radical species that increased with age was observed by EPR spectroscopy. Brains from mice raised on an Fe-deficient diet showed depleted ferritin iron but normal mitochondrial iron levels.     

Further observations on the effect of air ions on influenza in the mouse

In earlier papers we reported that the course of respiratory infections in mice produced by intranasal instillation of measured amounts of: (1) a fungus, COCCIDIOIDES IMMITIS, (2) a bacterium, KLEBSIELLA PNEUMONIAE and (3) a virus, PR8 strain of influenza virus was materially affected by the air ion environment. When the challenge dose of influenza virus was administered as an aerosol, as described here, the cumulative mortality rate was completely uninfluenced by shifts in the concentration of positive and negative air ions in the ambient atmosphere and by the accompanying electrical fields. A hypothetical mechanism accounting for the different results obtained with intranasal and aerosol challenge is presented.

---

Zusammenfassung In früheren Arbeiten wurde über den Verlauf von Infektionen der Atemwege von Mäusen nach intranasaler Instillation bekannter Mengen (1) des Fungus COCCIDIOIDES IMMITIS, (2) KLEBSIELLA PNEUMONIAE und (3) PR8 Influenzavirus berichtet, die durch Luftionen beeinflusst waren. Hier wurde die Dosis von Influenzavirus als Aerosol verabreicht. Die kumulative Mortalitätsrate wurde durch den Wechsel der Konzentrationen von positiven und negativen Luftionen in der Umgebungsatmosphäre und begleitenden elektrischen Feldern nicht beeinflusst. Eine Erklärung für die unterschiedlichen Ergebnisse bei intranasaler und Aerosol-Virusapplikation wird diskutiert.

---

Resume Dans des travaux précédents, on a montré que l'évolution de maladies du système respiratoire provoquées chez des souris par l'instillation intranasale de doses déterminées d'agents pathogènes était affectée de façon significative par le taux d'ionisation de l'air ambiant. Il s'agissait d'agents cryptogamiques (COCCIDIOIDES IMMITIS), bactériens (KLEBSIELLA PNEUMONIAE) et de virus (lignée PR8 du virus de la grippe). Lorsque la dose minimum de virus grippal est appliquée sous forme d'aérosole — selon la méthode décrite ici — le taux cumulatif de mortalité n'est aucunement influencé par les variations de concentration d'ions positifs ou négatifs de l'air ambiant ni par les champs électriques qui les accompagnent. On développe une hypothèse pour expliquer la diversité des résultats obtenus au moyen des infectations intranasales ou par aérosoles.

     

Fluctuations of acetylcholinesterase in the mouse spinal cord and in vivo sodium effect during the development of morphine tolerance,dependence, and withdrawal

Tolerance to and physical dependence on morphine were produced and assessed in Swiss inbred albino mice by giving morphine sulphate (s.c.) three times a day for a period of 15 days in an increasing dose of 10 mg/kg every 24 hours. Physical dependence was assessed taking naloxone induced jumping as well as weight loss during normal withdrawal into consideration. The effect of sodium ions in the potency of naloxone in antagonizing morphine's effect was also analyzed. The spinal cord was assayed for acetylcholinesterase employing both biochemical and histochemical parameters. It was found that the amount of the enzyme increased with the development of tolerance but the amount decreased as the animals became physically dependent. However, the values were significantly above the control. Administration of naloxone brought about a sudden and significant fall in the level of the enzyme. Normal withdrawal too was characterized by a weak activity of the enzyme. It has been found that sodium ions can influence naloxone antagonism in an in vivo system.     

Binding properties of testosterone receptors in the hypothalamic-preoptic area of the adult male mouse brain.

This study reports the specificity, kinetics and thermodynamics of the binding of tritiated testosterone to specific receptors in the cytosol of the hypothalamic-preoptic area of the adult male mouse brain. Values for the kinetic is parametrs KA, KD, ka, kd and the apparent free energy (delta GOoc) are reported. The specificity of these receptors was investigated by LH-20 chromatography and sucrose-gradient centrifugation. Differences inreceptor specificity between the mouse and that reported for the rat are described. The effects of the antiandrogens, cyproterone acetate and BOMT, and the anti-estrogens MER-25 and clomiphene citrate on the binding of tritiated testosterone to specific 8S receptors are also reported. The effect of these steroid receptor antagonists on testosterone binding is discussed in relation to the current theory on the mechanism by which androgens influence brain function.     

Binding of 5-hydroxytryptamine to brain hydrophobic proteins. Inhibition by structural analogues and ions

Binding studies with hydrophobic proteins extracted from cerebral cortex homogenates by mixtures of n-butanol-water and separated by chromatography on LH-20 Sephadex, have been done. 5-HT-(14C) binds to this fraction with high affinity. This binding saturates with 5 X 10(-6) M 5-HT, with K1/2 value of 1 X 10(-7) M. Binding is partially inhibited by a mixture of alkaloids ergocornine, ergocrystine and ergocryptine, as well as by tryptamine. A light inhibition has been observed in presence of tryptophan or lysine, but none in presence of methysergide or hypoxanthine. Binding is strongly inhibited by monovalent ions (Li+, Na+ and NH4+). The influence of pH in the incubation medium has also been studied; maximal rates of binding were obtained at neutral pH.     

Oxidative-damage effect of Fe3O4 nanoparticles on mouse hepatic and brain cells in vivo

To assess the biological safety of Fe3O4 nanoparticles （NPs）, the oxidative-damage effect of these NPs was studied. Twenty-five Kunming mice were exposed to Fe3O4 NPs by intraperitoneai injection daily for 1 week at doses of 0, 10, 20, and 40 mg.kg1. Five Kunming mice were also injected with 40 mg.kg 1 ordinary Fe3O4 particles under the same physiological conditions. Biomarkers of reactive oxygen species （ROS）, glutathione （GSH）, and malondialdehyde （MDA） in the hepatic and brain tissues were detected. Results showed that no significant difference in oxidative damage existed at concentrations lower than 10 mg.kg i for NPs compared with the control group. Fe3O4 NP concentration had obvious dose-effect relationships （P〈 0.05 or P 〈 0.01） with ROS level, GSH content, and MDA content in mouse hepatic and brain tissues at〉20 mg.kg 1 concentrations. To some extent, ordinary Fe3O4 particles with 40mg.kg -1 concentration also affected hepatic and brain tissues in mice. The biological effect was similar to Fe3O4 NPs at 10 mg. kg-1 concentration. Thus, Fe3O4 NPs had significant damage effects on the antioxidant defense system in the hepatic and brain tissues of mice, whereas ordinary Fe3O4 had less influence than Fe3O4 NPs at the same concentration.     

The effects of phencyclidine on operant behavior in the rat: biphasic effect and tolerance development

Rats were trained to respond on a variable interval 60 sec (VI-60) schedule of water reinforcement. Phencyclidine (PCD) in doses of 0.25, 0.5, and 1.0 mg/kg i.p. increased response rates, respectively, to 118%, 140%, and 143% of the control rates. In contrast, doses of 2.0 and 4.0 mg/kg decreased response rates to 73% and 6% of the control rates. In the tolerance study, one group of rats received daily treatments of 4.0 mg/kg PCD immediately prior to the operant session, while a second group received the same daily dose of PCD after the operant session. When both groups of animals were treated prior to the operant session on a test day, they both displayed complete tolerance to the rate depressant effect of PCD. These results indicate that the observed tolerance to PCD was not dependent on behavioral compensatory mechanisms.     

Ischemic tolerance in the brain

Endogenous tolerance to cerebral ischemia is nature's strategy for neuroprotection. Exploring the physiologic and molecular mechanism of this phenomenon may give us new means of protection against ischemia and other degenerative disorders. This article reviews the currently available experimental methods to induce ischemic tolerance in the brain and gives a brief summary of the potential mode of action.