DARPP-32 and regulation of the ethanol sensitivity of NMDA receptors in the nucleus accumbens.

The medium spiny neurons of the nucleus accumbens receive both an excitatory glutamatergic input from forebrain and a dopaminergic input from the ventral tegmental area. This integration point may constitute a locus whereby the N-methyl-D-aspartate (NMDA)-subtype of glutamate receptors promotes drug reinforcement. Here we investigate how dopaminergic inputs alter the ethanol sensitivity of NMDA receptors in rats and mice and report that previous dopamine receptor-1 (D1) activation, culminating in dopamine and cAMP-regulated phosphoprotein-32 kD (DARPP-32) and NMDA receptor subunit-1 (NR1)-NMDA receptor phosphorylation, strongly decreases ethanol inhibition of NMDA responses. The regulation of ethanol sensitivity of NMDA receptors by D1 receptors was absent in DARPP-32 knockout mice. We propose that DARPP-32 mediated blunting of the response to ethanol subsequent to activation of ventral tegmental area dopaminergic neurons initiates molecular alterations that influence synaptic plasticity in this circuit, thereby promoting the development of ethanol reinforcement.

Trauma to the bladder and ureter: a review of diagnosis, management, and prognosis.

BACKGROUND: Injuries to the ureter or bladder are relatively rare. Therefore, a high level of clinical suspicion and knowledge of operative anatomy is of utmost importance for their management. Herein, a review of the literature related to the modern diagnosis, management, and prognosis for bladder and ureteral injuries is presented. METHODS: A literature search was conducted through PubMed. A thorough search of the world's literature published in English was completed. Search terms included "injury, diagnosis, prognosis, and management for ureter and bladder". All years, both genders, as well as penetrating, blunt, and iatrogenic mechanisms were evaluated for inclusion. Following PRISMA guidelines, studies were selected based on relevance and then categorized. RESULTS: 172 potentially relevant studies were identified. Given our focus on modern diagnosis and treatment, we then narrowed the studies in each category to those published within the last 30 years, resulting in a total of 26 studies largely consisting of Level IV retrospective case series. Our review found that bladder ruptures occur from penetrating, blunt, or iatrogenic mechanisms, and most are extraperitoneal (63%). Ureteral injuries are incurred from penetrating mechanisms in 77% of cases. The overall mortality rates for bladder rupture and ureteral injury were 8 and 7%, respectively. LIMITATIONS: Limitations of this article are similar to all PRISMA-guided review articles: the dependence on previously published research and availability of references. CONCLUSION: The bladder is injured far more often than the ureter but ureteral injuries have higher injury severity. Both of these organs can be damaged by penetrating, blunt, or iatrogenic mechanisms and surgical intervention is often required for severe ureter or bladder injuries. Since symptoms of these injuries may not always be apparent, a high level of suspicion is required for appropriate diagnosis and treatment.

Evidence for a plasma membrane calcium pump in bovine adrenal medulla but not adrenal cortex.

Continuous sucrose density gradient subfractions from bovine adrenal medullary microsomes were found to accumulate 45-Ca-2+ in the presence of ATP and ammonium oxalate mainly in subfractions of intermediate density. (Na-++K-+)-ATPase (plasma membrane marker) and Ca-2+-ATPase activities were also concentrated in these intermediate subfractions but thiamine pyrophosphatase (Golgi apparatus marker) was not. NADH oxidase (endoplasmic reticulum marker) activity was distributed throughout all subfractions. 45-Ca-2+ accumulation in adrenal cortical microsomes was found to rise and fall in parallel with thiamine pyrophosphatase but not with (Na-++K-+)-ATPase or NADH oxidase activities. Accumulation of 45-Ca-2+ in membrane vesicles in these experiments suggests the existence of a calcium transfer mechanism in plasma membranes of the adrenal medulla but not adrenal cortex.

N-methyl-D-aspartate mediated responses decrease with age in Fischer 344 rat brain.

N-Methyl-D-aspartate (NMDA) receptor-mediated responses were studied in hippocampus, cortex, and striatum of Fischer 344 rats of various ages (3-5, 12-14, or 24-28 months old; young, middle-aged, and senescent or old, respectively) to determine whether aging alters the function of NMDA receptors. NMDA-induced inhibition of muscarinic-stimulated phosphoinositide hydrolysis in hippocampus, and NMDA-stimulated release of [3H]norepinephrine (NE) or [3H]dopamine (DA) were used as indices of NMDA receptor function. The muscarinic agonist carbachol (1 mM) stimulated PI hydrolysis in hippocampi from all three age groups with no significant differences between the groups. NMDA inhibited the carbachol-evoked PI response in a concentration-dependent manner (10-100 microM) in all age groups. However, the NMDA-induced (100 microM) inhibition of the carbachol-stimulated response was markedly reduced in an age-dependent manner with losses of 25% and 53% in middle-aged and senescent rats compared to young. Concentration-effect curves for NMDA-stimulated [3H]NE release were determined using hippocampal and cortical slices from rats of the three age groups. In the hippocampus the maximal response for NMDA was significantly decreased from 6.55 fractional [3H]NE release in young to 4.51 and 4.18 in middle-aged and old rats, respectively, with no age-related changes in the potency of NMDA or slope of the curves. In cortical slices the maximal response was significantly reduced in an age-dependent manner by 23% in the senescent rats compared to the young rats. NMDA-stimulated [3H]DA release from striatal slices was significantly lower in the senescent rats at concentrations of NMDA from 500-2000 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell surface expression of NR1 splice variants and NR2 subunits is modified by prenatal ethanol exposure.

N-methyl-D-aspartate receptor dysfunction has been strongly suggested to link with the abnormalities seen in fetal alcohol syndrome. Thus, the effects of prenatal ethanol exposure on the total expression of NR1 splice variants and the cell surface expression of both NR1 and NR2 subunits in brain were investigated in rats. Western blot studies of membrane homogenates from cerebral cortices at postnatal days 1 through 21 indicate that prenatal ethanol treatment does not alter total NR1 expression or differential expression of NR1 splice variants during development. However, immunoprecipitation studies using PSD95 suggest that both C2'-terminal variants and NR2A subunits at the cortical postsynaptic membrane of postnatal day 21 were significantly reduced after prenatal ethanol treatment. Moreover, C1-terminal variants were decreased in both pair-fed and ethanol-treated groups, while no significant differences in the levels of total NR1 subunits, NR1 splice variants containing the N- or C2-terminal cassettes, or NR2B subunits were observed. Thus, these results suggest that prenatal exposure to ethanol may influence neuronal function by selective regulation of expression of C2'-terminal variants and NR2A subunits at the cell surface.

[3H]adenosine uptake and release from synaptosomes. Alterations by barbiturates.

The effects of barbiturates on adenosine movements across the synaptic plasma membrane have been investigated using rodent whole brain synaptosomes. The hypothesis tested was that some of the depressant actions of these drugs may be mediated through interference with an endogenous adenosine system. Adenosine uptake was studied using synaptosomes prepared from Swiss-Webster mice. After preincubation at 37 degrees, [3H]adenosine was added to the synaptosomes in the presence or absence of pentobarbital, methohexital, phenobarbital, or 5-(2-cyclohexylideneethyl)-5-ethyl barbituric acid (CHEB) at various concentrations and times. All four compounds significantly inhibited [3H]adenosine uptake at concentrations of 100-300 microM. Pentobarbital did not affect the distribution of synaptosomal adenosine metabolites. Release of [3H]adenosine was studied using the P2 pellet from male CD-1 mice. Addition of 50 mM KCl caused an enhancement of 3H-efflux mainly due to increased release of adenosine and inosine. This effect was abolished in the presence of 250 microM ethylene glycol bis(beta-aminoethyl-ether)-N,N2-tetraacetic acid (EGTA). Pentobarbital, 0.3 mM, caused a significant increase in the net potassium-induced release of [3H]adenosine. These results suggest that some of the depressant effects of barbiturates may be due to inhibition of adenosine reuptake and enhancement of release resulting in elevated synaptic adenosine levels.

Acute ethanol affects phosphorylation state of the NMDA receptor complex: implication of tyrosine phosphatases and protein kinase A.

Phosphorylation has been shown to regulate N-methyl-D-aspartic acid receptor (NMDAR) function. The inhibitory effect of ethanol on NMDAR function could be due, at least in part, to a change in NMDAR phosphorylation states. In order to investigate the effect of ethanol on phosphorylation of NR1 and NR2 subunits, NMDAR complexes were immunoprecipitated from cortical slices pre-exposed to ethanol. Acute ethanol, 100 and 200 mM, significantly decreased the tyrosine phosphorylation of NR2 subunits (Tyr-NR2). Treatment with a tyrosine phosphatase inhibitor reduced the inhibition of Tyr-NR2 phosphorylation caused by 100 mM ethanol. This suggests an involvement of tyrosine phosphatases in ethanol-induced inhibition of Tyr-NR2 phosphorylation. Slices pre-exposed to 100 and 200 mM ethanol exhibited a significant increase in the phosphorylation of NR1 by PKA at serine 897 (Ser897-NR1), which was blocked by a PKA inhibitor. Moreover, at 200 mM, ethanol produced a significant increase in PKA activity. Together, these results indicate that ethanol may increase Ser897-NR1 phosphorylation by activating PKA. However, ethanol did not affect phosphorylation of NR1 subunits by PKC at serine 896. We conclude that ethanol has the ability to modulate phosphorylation of both NR2 and NR1 subunits and these effects appear to implicate tyrosine phosphatases and PKA, respectively.

Penetration of clindamycin into the human appendix.

Clindamycin penetrated extremely well into inflamed (19) and normal (one) appendices. Average levels in appendiceal tissue taken 26 to 300 minutes after a single intravenous dose were 154% of the simultaneous serum concentration.

Impact of body weight on urinary electrolytes in urinary stone formers.

OBJECTIVES: Obesity increases the risk of developing chronic medical conditions such as diabetes mellitus, hypertension, and coronary artery disease. We performed a retrospective review of a large data base on urinary stones to determine if differences are found in urine and serum chemistries among obese and nonobese stone-forming patients. The effect of body weight on stone recurrence among urinary stone formers was also determined. METHODS: A national data base containing serum biochemical profiles, 24-hour urine specimens, and standardized questionnaires was retrospectively evaluated from 5942 consecutive patients with urinary stone disease. Stone-forming patients were classified by body weight: nonobese men, less than 100 kg and nonobese women, less than 85 kg; intermediate men, 100 to 120 kg and intermediate women, 85 to 100 kg; and obese men, more than 120 kg and obese women, more than 100 kg. RESULTS: Obese stone formers comprised 6.8% (n = 404) of the patient population. The mean weight in the nonobese and obese groups was 81 kg versus 134 kg, respectively, for men and 64 kg versus 112 kg, respectively, for women. Obese patients represented 3.8% of the male and 12.6% of the female population. Obese patients had increased urinary excretion of sodium, calcium, magnesium, citrate, sulfate, phosphate, oxalate, uric acid, and cystine; obesity was associated with increased urinary volumes and urine osmolality compared with the nonobese patients. Obese men had increased concentration of urinary sodium, oxalate, uric acid, sulfate, and phosphate when corrected for urinary volume. Obese women had increased concentrations of sodium, uric acid, sulfate, phosphate, and cystine. The mean number of stone episodes in nonobese versus obese men was similar (3.55 and 3.56), whereas mean stone episodes were 2.93 and 3.38 (P = 0.045) for nonobese versus obese women. CONCLUSIONS: Among known stone formers, obesity is associated with unique changes in both serum and urinary chemistries. These changes are associated with an increased incidence of urinary stone episodes in obese women but not in obese men.

Inhibition of fast phase calcium uptake and endogenous norepinephrine release in rat brain region synaptosomes by ethanol.

The effects of ethanol on fast phase calcium (Ca2+) uptake and endogenous norepinephrine release were assessed simultaneously in KCl-depolarized synaptosomes isolated from rat hypothalamus, brainstem and cerebellum. Incubation of brain regional synaptosomes with ethanol resulted in a concentration-dependent inhibition of Ca2+ uptake after 1 s of depolarization. Hypothalamic synaptosomes were most sensitive to the inhibitory effect of ethanol on voltage-dependent Ca2+ uptake and brainstem synaptosomes were least sensitive. Endogenous norepinephrine release from synaptosomes was not altered by addition of ethanol in vitro at any of the concentrations examined (25-200 mM). Chronic ethanol administration resulted in an adaptation to the inhibitory effect of ethanol on Ca2+ uptake into hypothalamic synaptosomes but did not alter the inhibitory effect of ethanol on Ca2+ uptake into brainstem or cerebellar synaptosomes. Fast phase, voltage-dependent norepinephrine release was inhibited by ethanol added in vitro but only in synaptosomes isolated from hypothalami and cerebella of chronically treated animals. Brain regional norepinephrine concentrations were unaltered by chronic ethanol administration. These results suggest that chronic ethanol treatment may alter the coupling of Ca2+ entry with norepinephrine release in some noradrenergic neurons. Effects of ethanol on synaptosomal Ca2+ entry and norepinephrine release differ depending on the brain region.

Bay K 8644 stimulation of calcium entry and endogenous dopamine release in rat striatal synaptosomes antagonized by nimodipine.

The calcium channel agonist Bay K 8644 (0.1-100 nM) significantly increased the fast-phase entry of calcium and release of endogenous dopamine from rat striatal synaptosomes partially depolarized with 15 mM KCl. This increase was completely blocked by 10 nM nimodipine which had no inhibitory effect on calcium influx and dopamine release in the absence of Bay K 8644. Bay K 8644's agonist effect was attenuated with higher KCl concentrations. These findings suggest that Bay K 8644, in combination with partial KCl depolarization, may expose brain synaptosomal calcium channels which are sensitive to nanomolar concentrations of dihydropyridine calcium channel blockers.

Opioid peptides increase calcium uptake by synaptosomes from brain regions.

The fast-phase calcium uptake by depolarized hippocampal synaptosomes was increased significantly following treatment with 10 nM or 10 microM D-Ala2,D-Leu5-enkephalin (DADLE). No significant changes of calcium uptake by depolarized cortical or striatal synaptosomes were observed for 10 nM or 10 microM treatment with this enkephalin analog. Dynorphin 1-17 analog at 10 nM produces a significant increase in calcium uptake by depolarized striatal synaptosomes. beta-Endorphin and the dynorphin 1-13 fragment analog (10 nM) caused no significant change in the calcium uptake by depolarized synaptosomes from any of the three brain regions. However, calcium uptake by non-depolarized striatal and cortical synaptosomes was increased significantly in the presence of 10 nM beta-endorphin and DADLE. Opioid peptide action on neural calcium uptake is complex and appears to vary somewhat from one brain region to another.

Ethanol inhibits NMDA-induced increases in free intracellular Ca2+ in dissociated brain cells.

The effect of N-methyl-D-aspartate (NMDA) on free intracellular Ca2+ concentrations [( Ca2+]i) and the interaction of ethanol on the NMDA-mediated response was examined in freshly dissociated brain cells isolated from newborn rats. NMDA (25 microM) increased [Ca2+]i by approximately 70 nM, measured by fura-2 fluorometry, and this increase could be prevented or reversed by the NMDA antagonists Mg2+ (1.0 mM) and 2-amino-5-phosphonovalerate (AP5, 100 microM). Ethanol (25, 50, 100 mM) added 50 s before NMDA (25 microM) reduced the rise in [Ca2+]i when compared to the 25 microM NMDA response in the absence of ethanol. Thus, ethanol may have direct actions on NMDA-receptor activated increases in [Ca2+]i.

The effects of chronic ethanol exposure on N-methyl-D-aspartate-stimulated overflow of [3H]catecholamines from rat brain.

The effects of acute and chronic ethanol administration on N-methyl-D-aspartate-stimulated catecholamine overflow were examined. Three groups of male Sprague-Dawley rats were used. The first group received a chronic liquid diet containing ethanol (37%) for 3 weeks. The second group was pair-fed a liquid diet with dextrin substituted for ethanol isocalorically. The third group received Purina rat lab chow and water ad libitum. N-methyl-D-aspartate-stimulated [3H]catecholamine overflow from brain tissue slices was determined. N-methyl-D-aspartate (50-2000 microM) produced a concentration-dependent increase in [3H]norepinephrine overflow from cortical and hippocampal slices with no significant alteration of the response following chronic ethanol treatment. [3H]Dopamine overflow from striatal slices of the chronic ethanol group was significantly different at 1000 microM N-methyl-D-aspartate. The response of the chronic ethanol-treated group at the 1000 microM N-methyl-D-aspartate concentration was 30% and 40% lower than the pair-fed and ad libitum controls, respectively. Ethanol when added in vitro (30-200 mM) produced a concentration-dependent inhibition of N-methyl-D-aspartate (150 microM) stimulated efflux in all brain regions, and chronic ethanol treatment did not alter the inhibitory response. These results indicate an apparant lack of adaptation in N-methyl-D-aspartate-stimulated transmitter release following chronic ethanol treatment in this particular paradigm.

Correlation of rates of calcium entry and endogenous dopamine release in mouse striatal synaptosomes.

The time course of simultaneous Ca2+ entry and endogenous dopamine release was examined in mouse striatal synaptosomes depolarized by 30 mM KCl. Ca2+ entry and endogenous dopamine release exhibited fast and slow phase processes. The fastest rates occurred between 0 and 1 s. Ca2+ uptake and dopamine release dropped off quickly with 5-15 s rates at 13 and 10%, respectively, of the 0-1 s rate. Both processes were maintained at relatively high rates at the 1-3 and 3-5 s intervals suggesting mixed fast and slow phase processes. Uptake of Ca2+ and release of dopamine occurred in parallel over the entire 30 s measurement period; however, approximately 70% of the Ca2+ uptake and dopamine release occurred within the first 5 s following depolarization. A calculated ratio of Ca2+ entry versus dopamine release showed that approximately 1-2 Ca2+ ions were required to cause the release of one dopamine molecule. This ratio remained constant from 1 to 15 s following depolarization. Our results suggest that Ca2+ entry is coupled to endogenous dopamine release for both the fast and slow phase process.

Development of tolerance in brain mitochondria for calcium uptake following chronic ethanol ingestion.

Brain mitochondria isolated from rats following 10 weeks of chronic exposure to ethanol were not deficient in respiratory function or in rates of calcium uptake under control conditions. Ethanol (80 mM) in the incubation medium caused significant depression in the respiratory and ATP-dependent rates of calcium uptake in control mitochondria, but did not affect mitochondria from ethanol-tolerant rats. Chronic exposure to ethanol causes mitochondria to take calcium up at a normal rate when challenged acutely by ethanol.