Characteristics of [3H](+)-amphetamine binding sites in the rat central nervous system

Recent studies in our laboratory have demonstrated the presence of specific binding sites for [³H](+)-amphetamine in crude membrane preparations derived from rat brain. In this report we have further characterized the specific binding of [³H](+)-amphetamine in various subcellular fractions of rat brain and demonstrate a greater than five-fold enrichment in the crude synaptosomal (P₂) fraction compared to a crude membrane preparation. Specific [³H](+)-amphetamine binding in crude synaptosomal membranes in saturable and stereospecific with an apparent dissociation constant, K_d, of 2.8 ± 0.5 μM and an estimated maximum number of binding sites, B_max, of 60.4 ± 8.4 pmoles/mg protein derived by Scatchard or Klotz analysis of binding data using filtration assays. Centrifugation assays yield a similar K_d though the apparent B_max is higher. In addition specific [³H](+)-amphetamine binding is: rapidly reversible, temperature sensitive, labile to preincubation in Tris buffer, inhibited by sodium ions and unevenly distributed in various brain regions. Specific [³H](+)-amphetamine binding sites are found almost exclusively in the rat central nervous system (the brainstem, hypothalamus, and striatum exhibiting relatively high levels of binding), whereas peripheral tissues such as liver, kidney and heart have very low to undetectable levels of specific binding.     

Lobeline Displaces [3H]Dihydrotetrabenazine Binding and Releases [3H]Dopamine from Rat Striatal Synaptic Vesicles: Comparison with d-Amphetamine

Abstract: Lobeline, an alkaloid from Indian tobacco (Lobelia inflata), is classified as a nicotinic agonist and is currently used as a smoking cessation agent. However, our previous in vitro studies demonstrate that lobeline does not act as a nicotinic agonist but alters presynaptic dopamine (DA) storage by potently inhibiting DA uptake into synaptic vesicles. Recently, d-amphetamine has been reported to act at the level of the synaptic vesicle to alter presynaptic function. The present in vitro studies further elucidate the mechanism of lobeline's action and compare its effects with those of d-amphetamine. [³H]Dihydrotetrabenazine ([³H]DTBZ), used routinely to probe a high-affinity binding site on the vesicular monoamine transporter (VMAT2), bound to vesicle membranes from rat striatum with a K_D of 1.67 nM and B_max of 8.68 pmol/mg of protein. Lobeline inhibited [³H]DTBZ binding with an IC₅₀ of 0.90 µM, consistent with its previously reported IC₅₀ of 0.88 µM for inhibition of [³H]DA uptake into vesicles. These results suggest that lobeline specifically interacts with DTBZ sites on VMAT2 to inhibit DA uptake into synaptic vesicles. Interestingly, d-amphetamine inhibited [³H]DTBZ binding to vesicle membranes with an IC₅₀ of 39.4 µM, a concentration 20 times greater than reported for inhibition of VMAT2 function, suggesting that d-amphetamine interacts with a different site than lobeline on VMAT2 to inhibit monoamine uptake. Kinetic analysis of [³H]DA release from [³H]DA-preloaded synaptic vesicles in the absence of drug revealed a t_1/2 of 2.12 min. Lobeline and d-amphetamine evoked [³H]DA release with EC₅₀ values of 25.3 and 2.22 µM, respectively. At a concentration 10 times the EC₅₀, lobeline and d-amphetamine significantly decreased the t_1/2 of [³H]DA release to 1.58 and 1.48 min, respectively. Thus, in contrast to d-amphetamine, which is equipotent in inhibiting DA uptake and promoting release from the synaptic vesicles, lobeline more potently (28-fold) inhibits DA uptake (via an interaction with the DTBZ site on VMAT2) than it evokes DA release to redistribute presynaptic DA storage.     

DETERMINATION OF SOME MOLECULAR PARAMETERS OF TRYPTOPHAN HYDROXYLASE FROM RAT MIDBRAIN AND MURINE MAST CELL

Amphetamine, a potent sympathomimetic amine, has powerful stimulant actions in the central nervous system. These actions are believed to be related to the influence of amphetamine on release and uptake of catecholamine neurotransmitters. The [¹⁴C]deoxyglucose method makes it possible to study changes in cerebral metabolic rate in different areas of gray and white matter. Because of the close relationship between metabolic rate and functional activity, this method may be used to identify specific structures in the brain in which functional activity is altered. The [¹⁴C]deoxyglucose method was used to explore for changes in metabolic rate produced by d-and l-amphetamine (5 mg/kg) in forty gray and four white matter structures in normal conscious rats. d-Amphetamine produced increases in local cerebral glucose utilization in a number of components of the extrapyramidal motor system, as well as in some other structures known to contain dopamine-producing and/or dopaminoceptive cells. The largest increases after d-amphetamine administration occurred in the subthalamic nucleus and the zona reticulata of the substantia nigra. l-Amphetamine produced increases in some but not all of these same structures, and these were generally smaller than those observed with d-amphetamine. Decreases in local cerebral glucose utilization after either d- or l-amphetamine administration were found in the habenula and the suprachiasmatic nuclei of the hypothalamus. The effects in the suprachiasmatic nuclei may reflect their normal diurnal rhythm in metabolic rate. These results indicate that amphetamines may influence behavior through effects on specific regions of the brain. Only some of these regions have previously been studied as possible sites of action of amphetamine.     

Dopaminergic Regulation of Striatal Acetylcholine Release: The Critical Role of Acetylcholinesterase Inhibition

Abstract: This study examined the effects of different levels of acetylcholinesterase (AChE) inhibition on dopaminergic regulation of striatal acetylcholine (ACh) release as estimated by in vivo brain microdialysis. Systemic administration of d-amphetamine (2 or 10 mg/kg) increased the striatal output of ACh when the AChE inhibitor neostigmine (0.1 µM) was present in the perfusion fluid. In contrast, when the same experiments were conducted at 0.01 µM neostigmine, d-amphetamine failed to affect (2 mg/kg) or significantly decreased (10 mg/kg) striatal ACh output. The inhibitory action of the D₂ receptor agonist quinpirole (0.2 mg/kg) was significantly greater at 0.01 µM than at 0.1 µM neostigmine. Similarly, there was a nonsignificant trend for the D₂ antagonist raclopride (1 mg/kg) to stimulate ACh release to a greater extent at the low neostigmine concentration. In contrast, the stimulant effects of systemic administration of the D₁ agonist A-77636 (1.46 mg/kg) on striatal ACh release were the same at the two neostigmine concentrations. These results demonstrate that the concentration of an AChE inhibitor in the perfusion solution can quantitatively and even qualitatively influence the manner in which dopaminergic agents regulate ACh overflow in the striatum. On comparing the present results with earlier reports concerning the effects of d-amphetamine on tissue concentrations of ACh, it is tentatively concluded that a low neostigmine concentration is the more physiologically relevant condition. Under such conditions, at moderate doses d-amphetamine does not appear to alter striatal ACh release, with this likely being due to the opposing actions of D₁ and D₂ receptors. Nevertheless, until the endogenous interstitial concentrations of striatal ACh can be measured by other methods, the physiological relevance of ACh microdialysis studies in the striatum will remain uncertain.     

Demonstration of reduced levels of zinc in rat brain after treatment with d-amphetamine,but not after treatment with reserpine

Summary Histochemical and atomic absorption spectrophotometric methods were used to study the effects of reserpine and d-amphetamine on the neuronal trace metal distribution in various regions of the central nervous system (hippocampus, parietal cortex, cerebellum). Six hours after single d-amphetamine treatment (15 mg/kg i.p.), the neuronal zinc level was significantly decreased in the hippocampus and in the parietal cortex. The intensity of sulphide silver staining was similarly greatly decreased in all layers of the hippocampus and the parietal cortex. Such a change was not observed when d-amphetamine was administered in a lower dose (5 or 10 mg/kg i.p.).Twenty hours after single reserpine treatment (10 mg/kg i.p.), there were no changes in the tissue levels and distribution of zinc, copper, iron and manganese. In animals treated with reserpine on five consecutive days, in a dose of 10 mg/kg/day i.p., the trace metal distribution twenty hours following the final treatment was essentially the same as in the control.The results strongly suggest that zinc does not play a direct role in vivo in the storage and mobilization processes of the catecholamines. A high dose of d-amphetamine, however, has a non-specific, toxic effect that is not interrelated with the catecholaminergic neuronal function; this effect is manifested in a diminished intensity of sulphide silver staining and in a reduction of the tissue zinc level.     

Na+-independentl-aspartate binding sites in chick brain

1. One binding component with aK _d value of 200×10^–9 M and half-life of the ligand binding component of 30 min was found. 2. Chloride ions produced a significant increase ofl-[³H]aspartate andl-[³H]glutamate binding. 3.l-Glutamate,l-ibotenate,l-quisqualate, anddl-homocysteic acid were potent inhibitors ofl-[³H]aspartate binding. 4. In all brain regions major increases of binding were observed during the third week of the in ovo period of life.     

Influence of prenatal d-amphetamine administration on development and behavior of rats.

Beginning on the fifth day of gestation, rats were administered 1 or 3 mg/kg of $\text{d}$-amphetamine sulfate s.c. twice daily until term. The administration of $\text{d}$-amphetamine caused a dose-related increase in pup mortality. However, the increase in pup death could not be correlated with any gross pathological signs. The surviving 3 mg/kg amphetamine pups were analyzed for changes in motor behavior and brain biogenic amine levels. It was found that the amphetamine offspring showed a marked reduction in the ability to habituate to new surroundings, and this effect persisted for at least three months after birth. On day 35, brain levels of norepinephrine in the “amphetamine” offspring were decreased 21 percent. On day 84, in the “amphetamine offspring,” norepinephrine levels were reduced 18 percent in both the diencephalon and brainstem; dopamine levels were reduced 21 percent in the brainstem compared to control offspring.     

l-[3H]lysine binding to rat retinal membrane: II. effect of kainic acid,d,l-α-aminoadipic acid,iodoacetic acid,and modification by dark-exposure

The rat retina and the different brain regions contain membranes sites that bindl-lysine in the nanomolar range. These binding sites undergo changes in different experimental conditions, thus: I) intraocular injection of kainic acid induces a reduction of the density ofl-lysine binding sites, II)d,l--aminoadipic acid injected into the eye enhances both kinetic parameters (B _max andK _d) ofl-[³H]lysine binding sites, III) the intraperitoneal injection of iodoacetic acid decreases the sensitivity for its ligand binding sites, and IV) the exposure to darkness of the rats reducesl-[³H]lysine binding in the retina, thalamus, hypothalamus and superior colliculus, but not in the occipital cortex; such a decrease appears to be characterized, at least in the retina, by a lower sensitivity of the binding sites forl-lysine after the exposure to darkness. The results show thatl-lysine binding sites are located on kainic acid-sensitive cells and can be involved in the physiological mechanism of vision.     

Comparison of the binding properties of A1 adenosine receptors in brain membranes of two congeneric marine fishes living at different depths

Summary The binding properties of A₁ adenosine receptors in brain membranes were compared in two congeneric marine teleost fishes which differ in their depths of distribution. Adenosine receptors were labeled using the A₁ selective radioligand [³H]cyclohexyladenosine ([³H]CHA). The A₁ receptor agonist [³H]CHA bound saturably, reversibly and with high affinity to brain membranes prepared fromSebastolobus altivelis andS. alascanus; however, the meanK _d values differed significantly (Figs. 1–3, Table 1). Saturation data fit to a one site model indicated that the A₁ receptor inS. alascanus exhibited a higher affinity (K _d=1.49 nM) for [³H]CHA whereas A₁ receptors inS. altivelis exhibited a significantly lower affinity (K _d=3.1 nM). Moreover,S. altivelis, but notS. alascanus, parameter estimates for [³H]CHA binding to two sites of receptor were obtained (Fig. 3, Table 1). The mean dissociation constant values for the high and low affinity sites for [³H]CHA inS. altivelis were 0.43 nM and 16.3 nM, respectively. In equilibrium competition experiments the adenosine analogs R-phenylisopropyladenosine (R-PIA), N-ethylcarboxamidoadenosine (NECA) and S-phenylisopropyladenosine (S-PIA) all displayed higher affinities for A₁ receptors inS. alascanus as compared toS. altivelis brain membranes (Table 2, Fig. 6). The specific binding of [³H]CHA was significantly increased by 0.1 and 1.0 mM MgCl₂ in both fishes; however, the sensitivity (95–131% increase) ofS. altivelis to this effect was significantly greater than that ofS. alascanus (48–91% increase) (Fig. 5). The results of kinetic, equilibrium saturation and equilibrium competition experiments all suggest that A₁ adenosine receptors ofS. altivelis andS. alascanus brain membranes differ with respect to their affinities for selected adenosine agonists.Abbreviations CHA cyclohexyladenosine - R-PIA R-phenylisopropyladenosine - S-PIA S-phenylisopropyladenosine - NECA N-ethylcarboxamidoadenosine - NEM N-ethylmaleimide - 2-ClAdo 2-chloroadenosine - GTP guanosine triphosphate - N protein guanine nucleotide binding protein - _{n H} Hill slope     

Transepithelial transport in cell culture: Stoichiometry of Na/phlorizin binding and Na/d-glucose cotransport. A two-step,two-sodium model of binding and translocation

Summary The renal cell line LLC-PK₁ cultured on a membrane filter forms a functional epithelial tissue. This homogeneous cell population exhibits rheogenic Na-dependentd-glucose coupled transport. The short-circuit current (I _sc) was acccounted for by net apical-to-basolaterald-glucose coupled Na flux, which was 0.53±0.09(8) eq cm^–2hr^–1, andI _sc, 0.50±0.50(8) eq cm^–2hr^–1. A linear plot of concurrent net Na vs. netd-glucose apical-to-basolateral fluxes gave a regression coefficient of 2.08. As support for a 21 transepithelial stoichiometry, sodium was added in the presence ofd-glucose and the response ofI _sc analyzed by a Hill plot. A slope of 2.08±0.06(5) was obtained confirming a requirement of 2 Na for 1d-glucose coupled transport. A Hill plot ofI _sc increase to addedd-glucose in the presence of Na gave a slope of 1.02±0.02(5). A direct determination of the initial rates of Na andd-glucose translocation across the apical membrane using phlorizin, a nontransported glycoside competitive inhibitor to identify the specific coupled uptake, gave a stoichiometry of 2.2 A coupling ratio of 2 for Na,d-glucose uptake, doubles the potential energy available for Na-gradient coupledd-glucose transport. In contrast to coupled uptake, the stoichiometry for Na-dependentphlorizin binding was 1.1±0.1(8) from Hill plot analyses of Na-dependent-phlorizin binding as a function of [Na]. Although occurring at the same site the process of Na-dependent binding of phlorizin differs from the binding and translocation ofd-glucose. Our results support a two-step, two-sodium model for Na-dependentd-glucose cotransport; the initial binding to the cotransporter requires a single Na andd-glucose, a second Na then binds to the ternary complex resulting in translocation.     

Production ofd-mannitol fromd-aldopentoses by the yeastRhodotorula minuta

Rhodotorula minuta produced 16% ofd-mannitol and 3% ofd-arabinitol when cultivated ond-ribose, 4% of mannitol and 11% of arabinitol when grown ond-xylose, 5% ofd-mannitol and 5% ofd-arabinitol when grown ond-arabinose, and 5% ofd-mannitol and 6% ofd-arabinitol when cultivated ond-lyxose.     

Different affinities of the α- and β-anomers ofD-glucose,D-mannose andD-xylose for the glucose uptake system of baker’s yeast

A recording technique for measuring the sugar uptake by cell suspensions using a polarimeter is described. The method makes it possible to calculate the uptake rates of the α-and β-anomers. The constitutive monosaccharide transport system ofSaccharomyces cerevisiae andSaccharomyces fragilis exhibits a higher affinity for the α-anomers ofd-glucose,d-manose andd-xylose than for the corresponding β-anomers, this resulting in a preferential uptake of the α-anomers from a mixture. The α-anomer ofd-xylose is preferred both during influx and efflux. The membrane transport ofd-xylose inSaccharomyces cerevisiae is not associated with a change of the anomer configuration. The facilitated diffusion system appears to possess a regulatory role for the utilization ofd-glucose andd-mannose in both yeast species investigated.     

Biological nitrogen and organic matter removal from tannery wastewater in pilot plant operations in Ethiopia

A whole-cell biotransformation system for the conversion of d-fructose to d-mannitol was developed in Escherichia coli by constructing a recombinant oxidation/reduction cycle. First, the mdh gene, encoding mannitol dehydrogenase of Leuconostoc pseudomesenteroides ATCC 12291 (MDH), was expressed, effecting strong catalytic activity of an NADH-dependent reduction of d-fructose to d-mannitol in cell extracts of the recombinant E. coli strain. By contrast whole cells of the strain were unable to produce d-mannitol from d-fructose. To provide a source of reduction equivalents needed for d-fructose reduction, the fdh gene from Mycobacterium vaccae N10 (FDH), encoding formate dehydrogenase, was functionally co-expressed. FDH generates the NADH used for d-fructose reduction by dehydrogenation of formate to carbon dioxide. These recombinant E. coli cells were able to form d-mannitol from d-fructose in a low but significant quantity (15 mM). The introduction of a further gene, encoding the glucose facilitator protein of Zymomonas mobilis (GLF), allowed the cells to efficiently take up d-fructose, without simultaneous phosphorylation. Resting cells of this E. coli strain (3 g cell dry weight/l) produced 216 mM d-mannitol in 17 h. Due to equimolar formation of sodium hydroxide during NAD⁺-dependent oxidation of sodium formate to carbon dioxide, the pH value of the buffered biotransformation system increased by one pH unit within 2 h. Biotransformations conducted under pH control by formic-acid addition yielded d-mannitol at a concentration of 362 mM within 8 h. The yield Y _{D-mannitol/D-fructose}was 84 mol%. These results show that the recombinant strain of E. coli can be utilized as an efficient biocatalyst for d-mannitol formation.     

d-Pentose metabolism byBacteroides vulgatus strain 8482

Bacteroides vulgatus strain 8482 metabolizedd-arabinose by a mechanism involving a 32 (top to bottom) cleavage of the arabinose carbon skeleton. During growth in the presence of 1-¹⁴C-d-arabinose, acetate, propionate, and succinate were labeled, but during growth in the presence of 5-labeledd-arabinose, only labeled acetate and succinate were formed. The metabolism ofd-ribose by strain 8482 differed from that ford-arabinose. Strain 8482 converted glycolic acid and glycine to acetate and succinate, but not propionate, by a mechanism involving cleavage of the glycine and glycolic acid carbon skeletons and equilibration of carbons 1 and 2 of glycolic acid and glycine with nonequivalent metabolic pools. The metabolism ofd-arabinose,d-ribose,d-glycine, andd-glycolic acid by strain 8482 was similar, in some respects, to that ofBacteroides fragilis strain 2044, but differed substantially from the metabolism of the same substances byBacteroides ruminicola strain B₁4.     

Griffonia simplicifolia lectins bind specifically to endothelial cells and some epithelial cells in mouse tissues

Summary The binding ofGriffonia simplicifolia agglutinin-I (GSA—I) and the isolectins GSA-I-AB₃ and GSA-I-B₄, having affinity for some -d-galactosyl andN-acetyl galactosaminyl residues was studied in different mouse tissues. In brain, cardiac muscle and skeletal muscle, the GSA-I-lectin conjugates showed prominent binding only to blood vessel endothelia. Similarly, in the liver and kidney cortex the GSA-I-conjugates selectively reacted with endothelial cells of the sinusoids and with intertubular and glomerular capillaries, respectively. However, a strong reactivity with the GSA-I-conjugates was additionally seen in the acinar cells of the pancreas, in the stratified squamous epithelia of skin and tongue, and in transitional epithelium. SDS—PAGE electrophoresis combined with the lectin-blotting technique indicated that a similar set of glycoproteins are responsible for the GSA-I binding, even in different tissues. Another lectin with specificity for -d-galactose, theMaclura pomifera agglutinin, displayed a distinctly different distribution of binding sites, mainly in the basement membranes, of all mouse tissues studied. The results suggest that some -d-galactosyl residues, recognized by the binding of GSA-I lectins, are preferentially expressed in endothelial cells of mouse tissues, and also provide further evidence that endothelial cells can present a highly specific surface glycosylation pattern.     

Heterogeneity in oligosaccharides from theO-polysaccharide chain of the lipopolysaccharide fromSalmonella typhi 253Ty determined by fast atom bombardment mass spectrometry

Oligosaccharides from theO-polysaccharide chain of theSalmonella typhi 253Ty lipopolysaccharide (LPS) were prepared from delipidated LPS by digestion with bacteriophage P22. The oligosaccharides were separated by gel chromatography into fractions representing monomers to polymers of the basic tetrasaccharide repeating unit. Fractions containing the dimer and the trimer were analysed by fast atom bombardment-mass spectrometry as methylated alditols. The mass spectra clearly showed heterogeneity in terms ofd-glucose substitution of thed-galactose residue in the tetrasaccharide repeating unit: dimers with none, one, or twod-glucosyl branches and trimers with none, one, two, or threed-glucosyl branches were found. This suggests a randomd-glucosylation of theO-polysaccharide chain ofS. typhi 253Ty.     

Performance deficits of NK1 receptor knockout mice in the 5-choice serial reaction-time task: effects of d-amphetamine, stress and time of day

Background

The neurochemical status and hyperactivity of mice lacking functional substance P-preferring NK1 receptors (NK1R-/-) resemble abnormalities in Attention Deficit Hyperactivity Disorder (ADHD). Here we tested whether NK1R-/- mice express other core features of ADHD (impulsivity and inattentiveness) and, if so, whether they are diminished by d-amphetamine, as in ADHD. Prompted by evidence that circadian rhythms are disrupted in ADHD, we also compared the performance of mice that were trained and tested in the morning or afternoon.

Methods and Results

The 5-Choice Serial Reaction-Time Task (5-CSRTT) was used to evaluate the cognitive performance of NK1R-/- mice and their wildtypes. After training, animals were tested using a long (LITI) and a variable (VITI) inter-trial interval: these tests were carried out with, and without, d-amphetamine pretreatment (0.3 or 1 mg/kg i.p.). NK1R-/- mice expressed greater omissions (inattentiveness), perseveration and premature responses (impulsivity) in the 5-CSRTT. In NK1R-/- mice, perseveration in the LITI was increased by injection-stress but reduced by d-amphetamine. Omissions by NK1R-/- mice in the VITI were unaffected by d-amphetamine, but premature responses were exacerbated by this psychostimulant. Omissions in the VITI were higher, overall, in the morning than the afternoon but, in the LITI, premature responses of NK1R-/- mice were higher in the afternoon than the morning.

Conclusion

In addition to locomotor hyperactivity, NK1R-/- mice express inattentiveness, perseveration and impulsivity in the 5-CSRTT, thereby matching core criteria for a model of ADHD. Because d-amphetamine reduced perseveration in NK1R-/- mice, this action does not require functional NK1R. However, the lack of any improvement of omissions and premature responses in NK1R-/- mice given d-amphetamine suggests that beneficial effects of this psychostimulant in other rodent models, and ADHD patients, need functional NK1R. Finally, our results reveal experimental variables (stimulus parameters, stress and time of day) that could influence translational studies.     

Binding of concanavalin A to intact cells and spheroplasts ofAnacystis nidulans

Native cells of the cyanobacterium (blue-green alga)Anacystis nidulans did not bind fluorescein isothiocyanate-conjugated concanavalin A (FITC-ConA) as measured by fluorescent spectrophotometry. By contrast, spheroplasts ofA. nidulans underwent rapid and specific agglutination in the presence of ConA thus showing appreciable affinity towards the lectin. After treatment with 0.01–0.05% (wt/vol) cetyltrimethylammonium bromide (CTAB) intact cells also became liable to ConA binding, which was not accompanied by significant agglutination. Detergents, other than CTAB, were far less effective. Specific and nonspecific binding was discriminated, as usual, with the aid of methyl -d-mannoside. Conditions are described that allow specific binding of up to 7×10⁴ molecules of FITC-ConA per cell. The binding of ConA to pretreated cells ofA. nidulans was verified by freeze-etching electron microscopy using ferritin-ConA conjugate. Our results appear to be first to demonstrate lectin binding to a cyanobacterium.     

Pentose metabolism byBacteroides ruminicola subsp.brevis strain B14

The fermentation ofd-arabinose byBacteroides ruminicola strain B₁4 occurs in a manner similar to or identical with that shown previously forl-arabinose metabolism by the organism, a combination of hexose resynthesis and the Embden-Meyerhof sequence. The use ofd-arabinose by strain B₁4 was repressed by prior growth in medium containingd-glucose and induced by prior growth in the presence ofl-arabinose ord-xylose. The use ofd-ribose andd-xylose by strain B₁4 is different from that ford-arabinose. During growth in the presence of 1-14C-d-arabinose, labeled acetate, propionate, and succinate were formed, whereas during 1-14C-d-ribose growth only labeled acetate and propionate were obtained. Under the conditions used,d-xylose growth failed to allow formation of acetate, propionate, or succinate. Strain B₁4 incorporates label from 1- or 2-labeled glycine into acetate, propionate, and succinate by a mechanism involving the cleavage of glycine and equilibration of glycine carbons 1 and 2 with different metabolic pools.     

Neurochemical Consequences of Dysphoric State During Amphetamine Withdrawal in Animal Models: A Review

Chronic abuse of amphetamines, such as d-amphetamine (AMPH) and d-methamphetamine, results in psychological dependence, a condition in which the drug produces a feeling of satisfaction and a drive that requires periodic or continuous administration of the drug to produce overwhelming pleasure or to avoid discomfort such as dysphoria. The dysphoric state of AMPH withdrawal has been recognized as depressive syndromes, such as anhedonia, depression, anxiety, and social inhibition, in early drug abstinence. Medication for treatment of the dysphoric state is important for AMPH abusers to avoid impulsive self-injurious behavior or acts that are committed with unconscious or uncontrolled suicidal ideation. However, successful treatments for AMPH withdrawal remain elusive, since the exact molecular basis of the expression of dysphoria has not been fully elucidated. This review focuses on the molecular aspects of AMPH withdrawal as indexed by neurochemical parameters under a variety of injection regimens (for example, levels of brain monoamines and their metabolites, and γ-aminobutyric acid, expression of genes and proteins involved in neuronal activity, and monoamine metabolism and availability) in rodent models which exhibit significant phenotypic features relevant to the syndromes of AMPH withdrawal in humans.