Norepinephrine Is Lateralized Within the Olfactory Bulbs of Male Mice

Abstract: Concentrations and in vitro release of norepinephrine were determined from left and right olfactory bulbs of adult male CD-1 mice. Norepinephrine concentrations from the left olfactory bulbs were significantly greater than those of the right ( p < 0.01). No statistically significant differences were obtained for dopamine, nor were there differences in tissue weights between the left and right olfactory bulb tissue samples. To verify further this asymmetry, release rates of norepinephrine were measured from superfused left and right olfactory bulbs. Norepinephrine output from the left olfactory bulb was significantly greater than that from the right ( p < 0.05). These results show that norepinephrine is lateralized within the olfactory bulbs of male mice. This asymmetry shows a clear catecholamine specificity with regard to concentrations and may be related to the lateralized olfactory processing that has been reported to occur in humans.     

Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

Opiate Modulation of Striatal Dopamine and Hippocampal Norepinephrine Release Following Morphine Withdrawal

When opiates are abruptly withdrawn after chronic treatment, increases in hippocampal noradre-nergic function are observed which are accompanied by decreases in striatal dopamine release. The latter effects have to shown to persist for several weeks following the onset of opiate withdrawal. We examined the long-term effects of opiate withdrawal on 4-aminopyridine and potassium stimulated release of striatal dopamine and hippocampal norepinephrine. Tissue samples were obtained either from rats that had been exposed to opiate withdrawal following a seven day morphine infusion or sham treated control subjects. At 48 hours after the onset of withdrawal (cessation of morphine infusions), slices were loaded with [³H] neurotransmitter, washed extensively, and exposed to different drug treatments. 4-aminopyridine induced concentration related increases in striatal dopamine release, which was 36% calcium independent. Similar values for fractional release of striatal dopamine were obtained in morphine withdrawn and control subjects, for both potassium and 4-aminopyridine induced release. In addition, thresholds for 4-aminopyridine or potassium induced release of striatal dopamine did not differ between control and morphine withdrawn subjects. Treatment with 1.0 M morphine sulfate potentiated potassium evoked release of norepinephrine to an equal extent in both morphine withdrawn and sham treated hippocampal tissue. Exposure to a threshold concentration of potassium (8.0 mM), stimulated increased release of hippocampal norepinephrine in a significantly greater fraction of tissue samples obtained from morphine withdrawn animals. Although these results do not support changes in striatal dopamine release following opiate withdrawal, opiate mechanisms appear to be important determinants of in vitro hippocampal norepinephrine release.     

Inhibitory effect of norepinephrine on immunoreactive corticotropin-releasing factor release from the rat hypothalamus in vitro

Effects of catecholamines on immunoreactive corticotropin-releasing factor (I-CRF) release from the rat hypothalamus were examined using a rat hypothalamic perifusion system and a rat CRF RIA in vitro. Norepinephrine had a potent inhibitory effect on I-CRF release in a dose-dependent manner at 0.1 nM-1 microM concentrations, but dopamine did not. This inhibitory effect of norepinephrine was completely blocked by propranolol, but only partially blocked by phentolamine. Isoproterenol also had a potent inhibitory effect at 0.01-100 nM concentrations, and a high dose of phenylephrine (10 nM) inhibited I-CRF release. Clonidine did not influence I-CRF release. These results suggest that norepinephrine inhibits I-CRF release mainly through the beta-adrenergic receptor and partially through the alpha 1-receptor.     

Effect of pH on lipolysis, cAMP and cAMP-dependent protein kinase activity in isolated rat fat cells

The effect of acidosis and alkalosis on lipolysis, cAMP production and cAMP-dependent protein kinase activity in isolated rat fat cells incubated in the presence of norepinephrine and norepinephrine plus theophylline has been investigated. The pH of the incubation medium was adjusted to 6.8, 7.4 and 7.8 respectively. Acidosis inhibited both norepinephrine- and norepinephrine plus theophylline-induced release of glycerol whereas alkalosis led to slight stimulation. Norepinephrine produced an increase in cAMP and cAMP-dependent protein kinase activity. However, comparison of both parameters in acidosis and alkalosis with those at pH 7.4 indicates that they were higher at pH 7.8 and lower at pH 6.8. Addition of theophylline in combination with norepinephrine increases cAMP production within 5 min, under acidosis to values similar to those obtained at pH 7.4 with norepinephrine. The same effect on protein kinase activity was obtained. In spite of this increment in cAMP and protein kinase activity produced by addition of norepinephrine plus theophylline, lipolysis remains inhibited by acidosis. Addition of theophylline at pH 7.4 and 7.8 induced a much higher cAMP production and cAMP-dependent protein kinase activity although at pH 7.8 there was a statistically significant increase in protein kinase activity at 10 min it did not induce a significant increase in lipolysis. This is discussed and possible mechanisms are suggested to explain the effect of acidosis and alkalosis on the lipolysis induced by norepinephrine in rat fat cells.     

Regulation of (Na+, K+) adenosinetriphosphatase of nerve ending membranes

Norepinephrine added in vitro to nerve ending membranes from rat cerebral cortex stimulates the activity of (Na⁺, K⁺) adenosinetriphosphatase (ATPase) only in the presence of the soluble brain fraction. In its absence norepinephrine inhibits the enzyme. (Mg²⁺)ATPase also showed stimulation by norepinephrine in the presence of the soluble fraction, but of lesser magnitude. The activation of (Na⁺, K⁺)ATPase by norepinephrine is not reproduced by cyclic AMP and is not antagonized by either - or -adrenergic blocking agents. These results suggest that the stimulation caused by norepinephrine is a direct effect on the enzyme and is not mediated by cyclic AMP or adrenergic receptors.     

Alkaline phosphatase in HeLa cells. Stimulation by phospholipase A2 and lysophosphatidylcholine.

Treatment of homogenates and plasma membrane preparations from HeLa cells with phospholipase A2 (EC 3.1.1.4) caused a 50% increase in activity of membrane-associated alkaline phosphatase. Lysophosphatidylcholine, dispersed in 0.15 M KCl, affected alkaline phosphatase in a similar fashion by releasing the enzyme from particulate fractions into the incubation medium and by elevating its specific activity. Higher concentrations of lysophosphatidylcholine solubilized additional protein from particulate fractions but did not further increase the specific activity of the released alkaline phosphatase. Particulate fractions from HeLa cells were exposed to the effects of liposomes prepared from lysophosphatidylcholine and cholesterol. The ratio of particulate protein/lysophosphatidylcholine (by weight) required for optimal activation of alkaline phosphatase was one. Kinetic studies indicated that phospholipase A2 and lysophosphatidylcholine enhanced the apparent V of the enzyme but did not significantly alter its apparent Km. The increased release of alkaline phosphatase from the particulate matrix by lysophosphatidylcholine was confirmed by disc electrophoresis. The release of the enzyme by either phospholipase A2 or by lysophosphatidylcholine appeared to be followed by the formation of micelles that contained lysophosphatidylcholine. The new complexes had relatively less cholesterol and more lysophosphatidylcholine than the native membranes. The possibility that lysophosphatidylcholine formed a lipoprotein complex with the solubilized alkaline phosphatase was indicated by a break point in the Arrhenius plot which was evident only in the lysophosphatidylcholine-solubilized enzyme but could not be demonstrated in alkaline phosphatase that had been released with 0.15 M KCl alone.     

Vasopressors for the Treatment of Septic Shock: Systematic Review and Meta-Analysis

Objective

International guidelines recommend dopamine or norepinephrine as first-line vasopressor agents in septic shock. Phenylephrine, epinephrine, vasopressin and terlipressin are considered second-line agents. Our objective was to assess the evidence for the efficiency and safety of all vasopressors in septic shock.

Methods

Systematic review and meta-analysis. We searched electronic database of MEDLINE, CENTRAL, LILACS and conference proceedings up to June 2014. We included randomized controlled trials comparing different vasopressors for the treatment of adult patients with septic shock. Primary outcome was all-cause mortality. Other clinical and hemodynamic measurements were extracted as secondary outcomes. Risk ratios (RR) and mean differences with 95% confidence intervals (CI) were pooled.

Results

Thirty-two trials (3,544 patients) were included. Compared to dopamine (866 patients, 450 events), norepinephrine (832 patients, 376 events) was associated with decreased all-cause mortality, RR 0.89 (95% CI 0.81-0.98), corresponding to an absolute risk reduction of 11% and number needed to treat of 9. Norepinephrine was associated with lower risk for major adverse events and cardiac arrhythmias compared to dopamine. No other mortality benefit was demonstrated for the comparisons of norepinephrine to epinephrine, phenylephrine and vasopressin / terlipressin. Hemodynamic data were similar between the different vasopressors, with some advantage for norepinephrine in central venous pressure, urinary output and blood lactate levels.

Conclusions

Evidence suggests a survival benefit, better hemodynamic profile and reduced adverse events rate for norepinephrine over dopamine. Norepinephrine should be regarded as the first line vasopressor in the treatment of septic shock.     

Release and exchange of neurotransmitters in synaptosomes: Effects of the ionophore A23187 and of ouabain

The effects of the ionophore A23187 and of ouabain on the release of [³H]GABA and [³H]norepinephrine were studied in superfused rat brain synaptosomes. Each of the two drugs moderately stimulated the spontaneous release of [³H]GABA, but greatly potentiated the release of [³H]GABA induced by unlabeled GABA. In contrast, the ionophore and norepinephrine showed an additive, but not a supraadditive, releasing effect on synaptosomal [³H]norepinephrine. Ouabain modestly and transiently potentiated the norepinephrine-induced [³H]norepinephrine release, which, however, was inhibited by the drug after a few minutes. It is suggested that in the new intrasynaptosomal ionic conditions determined by the two drugs, the stoichiometry of the basal homoexchange of GABA is changed in a direction favoring net outward transport.     

The role of catecholamines in the prolactin release induced by salsolinol

Salsolinol (1,2,3,4-tetrahydro-6,7-dihydroxy-1-methylisoquinoline) is an endogenous prolactin releasing agent. Its action can be inhibited by another isoquinoline, 1-methyl-3,4-dihydroisoquinoline (1MeDIQ), which has a strong norepinephrine releasing activity. Salsolinol does not alter the dopamine release in median eminence in vitro, providing evidence for the lack of interaction with presynaptic D2 dopamine receptors. At the same time, lack of norepinephrine transporter abolishes salsolinol's action. Salsolinol decreases tissue level of dopamine and increases norepinephrine to dopamine ratio in organs innervated by the sympathetic nervous system indicating a possible decrease of norepinephrine release. Enzymes of catecholamine synthesis and metabolism are probably also not the site of action of salsolinol. In summary, based upon all of these observations a physiologically relevant interplay might exist between the sympatho-neuronal system and the regulation of prolactin release.     

Effect of dietary proteins and carbohydrates on urinary and sympathoadrenal catecholamines

We previously observed that administration of tyrosine to rats or humans elevated urinary dopamine, norepinephrine and epinephrine levels. The present studies examine the effects on these urinary catecholamines of varying the ratio of protein to carbohydrate in the diets.Rats consumed diets containing 0, 18 or 40% protein (76, 58 and 36% carbohydrate respectively) for 8 days. The stress of consuming the protein-free food was associated with a 16% weight reduction, and with significantly lower serum, heart and brain tyrosine levels than those noted in rats eating the 18 or 40% protein diets. Absence of protein from the diet also decreased urinary levels of dopamine and DOPA but increased urinary norepinephrine and epinephrine, probably by increasing sympathoadrenal discharge; it also increased the excretion of DOPA in animals pretreated with carbidopa, a DOPA decarboxylase inhibitor. Carbidopa administration decreased urinary dopamine, norepinephrine and epinephrine as expected; however, among carbidopa-treated rats urinary norepinephrine and epinephrine concentrations were highest for animals consuming the protein-free diet, again suggesting enhanced release of stored catecholamines from sympathoadrenal cells. The changes in urinary catecholamines observed in animals eating the protein-free diet were similar to those seen in rats fasted for 5 days: dopamine levels fell sharply while norepinephrine and epinephrine increased.These data indicate that the effects of varying dietary protein and carbohydrate contents on dopamine secretion from peripheral structures differ from its effects on structures secreting the other two catecholamines. Protein consumption increases dopamine synthesis and release probably by making more of its precursor, tyrosine, available to peripheral dopamine-producing cells; it decreases urinary norepinephrine and epinephrine compared with that seen in protein-deprived animals, probably by diminishing the firing of sympathetic neurons and adrenal chromaffin cells.     

Characterization of calcium-dependent forms of protein kinase C in adult rat ventricular myocytes

The presence and subcellular localization of the Ca2+-dependent protein kinase C (PKC) isoforms and were investigated in freshly isolated adult rat cardiac ventricular myocytes. PKC activity was measured in cytosolic and particulate fractions prepared from control myocytes and those treated with either phorbol ester (phorbol 12-myristate 13-acetate, PMA) or a permeant synthetic diacylglycerol analog (1-oleoyl-2-acetylglycerol, OAG) in the absence or presence of an inhibitor of diacylglycerol kinase activity, compound R59022. Preliminary studies detected no Ca2+-/phospholipid-dependent histone kinase activity in either subcellular fraction. To reproducibly observe Ca2+-/phospholipid-dependent protein kinase activity, partial purification using a MonoQ HR 5/5 column and the presence of the peptide inhibitor of the cAMP-dependent protein kinase were essential. MonoQ chromatography of cytosolic and particulate fractions resulted in three peaks of Ca2+/phospholipid-dependent protein kinase activity. In the cytosolic fraction a large peak of activity eluted at 230-300 mM NaCl. Isoform-specific antisera indicated both PKC and PKC were present. In the particulate fraction two peak of Ca2+-/phospholipid-dependent protein kinase activity, both containing PKCa immunoreactivity, were observed. The larger peak eluted at 230-300 mM NaCl. In addition, a peak eluting at lower salt concentrations contained a Ca2+-/phospholipid-independent histone kinase activity. This peak of kinase activity contained PKC immunoreactive bands of 80- and 50-kDa. The 80-kDa band was the holoenzyme of PKC whereas the band of lower molecular mass was likely a proteolytic fragment. In both cytosolic and particulate fractions, the peak of kinase activity eluting at 230-300 mM NaCl contained PKC in the form of an 80-kDa doublet; this suggested the presence of autophosphorylated PKC. Incubation of the myocytes with PMA, but not OAG, resulted in translocation of PKC from the cytosolic to the particulate fraction. Curiously, a transient decrease in PKC activity was observed in both subcellular fractions following treatment with either OAG or ethanol (1%). Results from this study show that freshly isolated adult rat cardiac ventricular myocytes contain both PKC and PKC, and that these isoforms translocate to the particulate fraction in response to treatment with PMA, but not OAG. (Mol Cell Biochem 166: 11-23, 1997)     

The specific activity of retained and released norepinephrine in dog saphenous vein prelabeled with radiolabeled norepinephrine

The specific activities of released and retained norepinephrine (NE) in the isolated superfused dog saphenous vein preparation, prelabeled with [³H]NE, have been determined. Norepinephrine was isolated from extracts of vein superfusate and its concentrations were measured by high pressure liquid chromatography with electrochemical detection. The specific activity of NE in superfusate collected under basal conditions was lower than that of NE in veins after electrical stimulation or in parallel unstimulated veins. However, NE released during electrical stimulation had a specific activity 1.5 to 3 times higher than the NE in the veins. Thus, NE taken up by neuronal uptake in the prelabeling procedure enters a pool from which is preferentially released by electric stimulation. In addition, NE is released from different compartments during basal conditions and during electric stimulation.     

Ca2+ channel activating function of maitotoxin, the most potent marine toxin known, in clonal rat pheochromocytoma cells

Actions of maitotoxin, the most potent marine toxin known obtained from toxic dinoflagellate, Gambier-discus toxicus, were studied using clonal rat pheochromocytoma cells (PC12), rat liver mitochondria and liposomes. Maitotoxin induced a profound release of norepinephrine and dopamine from PC12 cells and the molar ratio of norepinephrine to dopamine was almost the same as that stored in the cells. This releasing action was apparent at a concentration of 5 X 10(-10) g/ml or more, the releasing rate increased with an increase in the concentration of applied maitotoxin and attained maximum at about 10(-6) g/ml. The [3H]norepinephrine release induced by maitotoxin was abolished in the absence of external Ca2+ and increased with increasing concentration of external Ca2+ up to 10 mM. The release gradually decreased as the external Na+ concentrations were reduced from 130 to 20 mM, but maitotoxin is still able to induce a profound release in the absence of external Na+. The releasing action of maitotoxin was markedly suppressed by various Ca2+ channel blockers, such as Mn2+, verapamil, and nicardipine, and by a local anesthetic, tetracaine. The inhibitory actions of Ca2+ channel blockers were antagonized by external Ca2+ and became less obvious in the higher Ca2+ concentration range. Maitotoxin did not exhibit any ionophoretic activities on rat mitochondrial and liposomal membranes. These results suggest that maitotoxin has the ability to activate voltage-dependent Ca2+ channels of PC12 cells.     

Dopamine and norepinephrine in the alimentary tract changes after chemical sympathectomy and surgical vagotomy

The aim of this study was to examine the distribution of dopamine and norepinephrine in the proximal alimentary tract of the rat and to assess the contributions of sympathetic and vagal fibers to the tissue concentrations of both catecholamines. Tissues were extracted in perchloric acid and the catecholamines were separated by high pressure liquid chromatography and detected electrochemically. In untreated rats (controls) both catecholamines were concentrated in the gastric muscle but norepinephrine levels were 6-8 times higher (corpus, dopamine 35 +/- 7 ng . g-1, norepinephrine 265 +/- 50 ng . g-1, mean +/- SE, n = 6). In the mucosa norepinephrine concentrations were 10-12 times higher (corpus, dopamine 12 +/- 3 ng . g-1, norepinephrine 140 +/- 26 ng . g-1). Chemical sympathectomy (6 hydroxydopamine, 100 mg . kg-1 ip 3 days) significantly reduced dopamine concentrations in muscle and norepinephrine in muscle, mucosa, pylorus and duodenum. In all tissues the effects on norepinephrine were greater. Surgical vagotomy significantly reduced dopamine concentrations in the gastric muscle, but not the mucosa. Norepinephrine concentrations in the stomach of vagotomized rats were significantly reduced only in the pylorus. Differences in the relative concentrations of dopamine and norepinephrine in gastric tissues of the normal rat and differences in the effects of sympathectomy and vagotomy suggest that dopamine and norepinephrine exist, to an extent, in separate populations of cells and that dopamine is not merely a precursor of norepinephrine. Gastric mucosal dopamine, which was mainly unaffected by either treatment, may exist in APUD cells.     

Release of norepinephrine from the rat ovary: local modulation of gonadotropins.

Experiments were undertaken to define the role of gonadotropins in the release of norepinephrine and the relationship with beta-receptors of the ovary. Rat ovaries were removed at different stages of the estrous cycle and incubated in [3H]norepinephrine. Subsequently, ovaries were electrically stimulated and the release of [3H]norepinephrine was recorded. There were no changes in the norepinephrine content during the estrous cycle. The ovary exhibited cyclical variation in norepinephrine-induced release during the estrous cycle. The lowest release of norepinephrine was found during diestrus; there was an increase during proestrus and estrus followed by a decline during metestrus. The release of norepinephrine changed in the opposite way to the beta-receptor number, suggesting a process involving down-regulation between norepinephrine release and beta-receptors of the ovary. Norepinephrine released from the ovary was locally regulated by gonadotropins. The presence of FSH in the superfusion medium stimulated the norepinephrine-induced release from the ovaries of rats in diestrus (by 20%) and estrus (by 40%), but no effect was found during proestrus. In addition, the presence of hCG stimulated (by 40%) norepinephrine-induced release during proestrus, but no changes were apparent during the other stages of the estrous cycle. These results suggest that the local action of gonadotropins on nerve terminals of the ovary might be one of the factors governing the changes in norepinephrine release through the estrous cycle. The changes in the norepinephrine released to the synaptic cleft might exert down-regulation on the beta-adrenergic receptor content of the ovary and in this way control the ovarian steroid secretory activity.     

Protein Kinase C of Sympathetic Neuronal Membrane Is Activated by Phorbol Ester-Correlation Between Transmitter Release, 45Ca2+ Uptake, and the Enzyme Activity

The effects of phorbol esters [phorbol 12,13-dibutyrate (PDB), 12-O-tetradecanoylphorbol 13-acetate (TPA), and phorbol 13-acetate] were investigated on the release of [3H]norepinephrine, 45Ca2+ accumulation, and protein kinase C activity in cultured sympathetic neurons of the chick embryo. Sympathetic neurons derived from 10-day-old chick embryo were cultured in serum-free medium supplemented with insulin, transferrin, and nerve growth factor. After 3 days, neurons were loaded with [3H]-norepinephrine and the release of [3H]norepinephrine was determined before and after electrical stimulation. Stimulation at 1 Hz for 15 s increased the release of [3H]-norepinephrine over the nonstimulation period. Stimulation-evoked release gradually declined with time during subsequent stimulation periods. Incubation of neurons in Ca2+-free Krebs solution containing 1 mM EGTA completely blocked stimulation-evoked release of [3H]-norepinephrine. Stimulation-evoked release of [3H]-norepinephrine was markedly facilitated by 3 and 10 nM PDB or TPA. The spontaneous release was also enhanced by PDB and TPA. The net accumulation of 45Ca2+ during stimulation of sympathetic neurons was increased by two- to fourfold in the presence of PDB or TPA. PDB at 1-100 nM produced a concentration-dependent increase in the activation of protein kinase C. PDB at 30 nM increased the activity of protein kinase C of the particulate fraction from 0.09 to 0.58 pmol/min/mg protein. There was no significant change in protein kinase C activity of the cytosolic fraction (0.14 pmol/min/mg versus 0.13 pmol/min/mg protein). The ratio of the particulate to cytosolic protein kinase C increased from a control value of 0.62 to 4.39 after treatment with 30 nM PDB. TPA (10 and 30 nM) also increased protein kinase C activity of the particulate fraction by six- to eightfold. Phorbol 13-acetate had no effect on protein kinase C activity, [3H]norepinephrine release, and 45Ca2+ accumulation. These results provide direct evidence that activation of protein kinase C enhances Ca2+ accumulation, which in turn leads to the facilitation of transmitter release in sympathetic neurons.     

RAT BRAIN SYNAPTIC VESICLES: UPTAKE SPECIFICITIES OF [3H]NOREPINEPHRINE AND [3H]SEROTONIN IN PREPARATIONS FROM WHOLE BRAIN AND BRAIN REGIONS1

A fraction containing neurotransmitter storage vesicles was isolated from rat whole brain and brain regions, and the uptakes of [³H]norepinephrine and [³H]serotonin were determined in vitro. Norepinephrine uptake in vesicle preparations from corpus striatum was higher than in prep arations from cerebral cortex, and uptake in vesicles from the remainder (midbrain + brainstem + cerebellum) was intermediate. The K_m for norepinephrine uptake was the same in the three brain regions, but the regions differed in maximal uptake capacity by factors which paralleled total catecholamine concentration rather than content of norepinephrine alone. Intracisternal administration of 6-hydroxydopamine, but not of 5,6-dihydroxytryptamine, reduced vesicular norepinephrine uptake, and pretreat-ment with desmethylimipramine (which protects specifically norepinephrine neurons but not dopamine neurons from the 6-hydroxydopamine) only partially prevented the loss of vesicular norepinephrine uptake. These studies indicate that uptake of norepinephrine by rat brain vesicle preparations occurs in vesicles from norepinephrine and dopamine neurons, but probably not in vesicles from serotonin neurons. Uptake of serotonin by brain vesicle preparations exhibited time, temperature and ATP-Mg²⁺ requirements nearly identical to those of norepinephrine uptake. The affinity of serotonin uptake matched that of serotonin for inhibition of norepinephrine uptake, and the maximal capacity was the same for serotonin as for norepinephrine. Norepinephrine, dopamine and reserpine inhibited serotonin uptake in a purely competitive fashion, with K_is similar to those for inhibition of norepinephrine uptake. Whereas 5,6-dihydroxytryptamine treatment reduced synaptosomal serotonin uptake but not vesicular serotonin uptake, 6-hydroxydopamine reduced vesicular serotonin uptake in the absence of reductions in synaptosomal serotonin uptake. Thus, in this preparation, serotonin appears to be taken up in vitro into catecholamine vesicles, rather than into serotonin vesicles.     

Norepinephrine Depletion in the Spinal Cord Gray Matter of Rats with Experimental Allergic Encephalomyelitis

Norepinephrine and dopamine concentrations were determined by radioenzymatic assay in discrete gray matter regions of the spinal cords of rats with experimental allergic encephalomyelitis (EAE). Norepinephrine was depleted in most spinal cord regions of EAE rats compared with controls, whereas dopamine depletion in EAE rats was restricted to the cervical dorsal horn. There was a rostrocaudal gradient of norepinephrine reduction in the spinal cords of the EAE rats with most severe depletion in the lumbar region. The results of this experiment confirmed recent anatomical observations that suggested that catecholamine-fluorescent axons and terminals were damaged in spinal cords of rats with EAE.     

Individual differences in the motivation to communicate relate to levels of midbrain and striatal catecholamine markers in male European starlings

Individuals display dramatic differences in social communication even within similar social contexts. Across vertebrates dopaminergic projections from the ventral tegmental area (VTA) and midbrain central gray (GCt) strongly influence motivated, reward-directed behaviors. Norepinephrine is also rich in these areas and may alter dopamine neuronal activity. The present study was designed to provide insight into the roles of dopamine and norepinephrine in VTA and GCt and their efferent striatal target, song control region area X, in the regulation of individual differences in the motivation to sing. We used high pressure liquid chromatography with electrochemical detection to measure dopamine, norepinephrine and their metabolites in micropunched samples from VTA, GCt, and area X in male European starlings (Sturnus vulgaris). We categorized males as sexually motivated or non-sexually motivated based on individual differences in song produced in response to a female. Dopamine markers and norepinephrine in VTA and dopamine in area X correlated positively with sexually-motivated song. Norepinephrine in area X correlated negatively with non-sexually-motivated song. Dopamine in GCt correlated negatively with sexually-motivated song, and the metabolite DOPAC correlated positively with non-sexually-motivated song. Results highlight a role for evolutionarily conserved dopaminergic projections from VTA to striatum in the motivation to communicate and highlight novel patterns of catecholamine activity in area X, VTA, and GCt associated with individual differences in sexually-motivated and non-sexually-motivated communication. Correlations between dopamine and norepinephrine markers also suggest that norepinephrine may contribute to individual differences in communication by modifying dopamine neuronal activity in VTA and GCt.