Intraperitoneal administration of choline increases serum glucose in rat: involvement of the sympathoadrenal system.

Intraperitoneal injection of choline (40, 80 or 120 mg/kg) produced a dose-dependent increase in serum glucose and choline levels in rats. The increases in serum glucose and choline were associated with an increase of serum insulin as well as plasma levels of epinephrine and norepinephrine. The increases in serum glucose and plasma catecholamine concentrations induced by choline (120 mg/kg) were blocked by pretreatment with the ganglionic nicotinic receptor antagonist hexamethonium (15 mg/kg), but were not affected by pretreatment with atropine (5 mg/kg). The choline-induced rise in serum insulin was blocked by pretreatment with atropine and with hexamethonium each. The increase in serum glucose evoked by choline (120 mg/kg) was blocked by alpha-adrenoceptor blockade and bilateral adrenalectomy each. Blockade of beta-adrenoceptor by propranolol or chemical sympathectomy by 6-hydroxydopamine failed to alter the hyperglycemic response to choline. These results show that choline, a precursor of the neurotransmitter acetylcholine, increases serum glucose and insulin levels. The effect of choline on serum insulin is mediated by both muscarinic and nicotinic acetylcholine receptors, whereas the effect of choline on serum glucose is mediated solely by nicotinic receptors. The stimulation of adrenal medullary catecholamine release and subsequent activation of alpha-adrenoceptors apparently mediates the hyperglycemic effect of choline.     

Caffeine potentiates the enhancement by choline of striatal acetylcholine release.

We investigated the effect of peripherally administered caffeine (50 mg/kg), choline (30, 60, or 120 mg/kg) or combinations of both drugs on the spontaneous release of acetylcholine (ACh) from the corpus striatum of anesthetized rats using in vivo microdialysis. Caffeine alone or choline in the 30 or 60 mg/kg dose failed to increase ACh in microdialysis samples; the 120 mg/kg choline dose significantly enhanced ACh during the 80 min following drug administration. Coadministration of caffeine with choline significantly increased ACh release after each of the choline doses tested. Peak microdialysate levels with the 120 mg/kg dose were increased 112% when caffeine was additionally administered, as compared with 54% without caffeine. These results indicate that choline administration can enhance spontaneous ACh release from neurons, and that caffeine, a drug known to block adenosine receptors on these neurons, can amplify the choline effect.     

Combination of AT-101/cisplatin overcomes chemoresistance by inducing apoptosis and modulating epigenetics in human ovarian cancer cells

We investigated the effects of AT-101/cisplatin combination treatment on the expression levels of apoptotic proteins and epigenetic events such as DNA methyltransferase (DNMT) and histone deacetylase (HDAC) enzyme activities in OVCAR-3 and MDAH-2774 ovarian cancer cells. XTT cell viability assay was used to evaluate cytotoxicity. For showing apoptosis, both DNA Fragmentation and caspase 3/7 activity measurements were performed. The expression levels of apoptotic proteins were assessed by human apoptosis antibody array. DNMT and HDAC activities were evaluated by ELISA assay and mRNA levels of DNMT1 and HDAC1 genes were quantified by qRT-PCR. Combination of AT-101/cisplatin resulted in strong synergistic cytotoxicity and apoptosis in human ovarian cancer cells. Combination treatment reduced some pivotal anti-apoptotic proteins such as Bcl-2, HIF-1A, cIAP-1, XIAP in OVCAR-3 cells, whereas p21, Bcl-2, cIAP-1, HSP27, Clusterin and XIAP in MDAH-2774 cells. Among the pro-apoptotic proteins, Bad, Bax, Fas, phospho-p53 (S46), Cleaved caspase-3, SMAC/Diablo, TNFR1 and Cytochrome c were induced in OVCAR-3 cells, whereas, Bax, TRAILR2, FADD, p27, phospho-p53 (S46), Cleaved caspase-3, Cytochrome c, SMAC/Diablo and TNFR1 were induced in MDAH-2774 cells. Combination treatment also inhibited both DNMT and HDAC activities and also mRNA levels in both ovarian cancer cells. AT-101 exhibits great potential in sensitization of human ovarian cancer cells to cisplatin treatment in vitro, suggesting that the combination of AT-101 with cisplatin may hold great promise for development as a novel chemotherapeutic approach to overcome platinum-resistance in human ovarian cancer.     

Synthesis of novel acridine and bis acridine sulfonamides with effective inhibitory activity against the cytosolic carbonic anhydrase isoforms II and VII

4-Amino-N-(4-sulfamoylphenyl)benzamide was synthesized by reduction of 4-nitro-N-(4-sulfamoylphenyl)benzamide and used to synthesize novel acridine sulfonamide compounds, by a coupling reaction with cyclic-1,3-diketones and aromatic aldehydes. The new compounds were investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1), and more precisely the cytosolic isoforms hCA I, II and VII. hCA I was inhibited in the micromolar range by the new compounds (K_Is of 0.16–9.64 μM) whereas hCA II and VII showed higher affinity for these compounds, with K_Is in the range of 15–96 nM for hCA II, and of 4–498 nM for hCA VII. The structure–activity relationships for the inhibition of these isoforms with the acridine–sulfonamides reported here were also elucidated.     

Bystander suppression of collagen-induced arthritis in mice fed ovalbumin

We wanted to assess whether B-cell and/or T-cell responses to collagen and thereby the course of collagen-induced arthritis could be suppressed by regulatory mechanisms associated with oral tolerance to an unrelated protein. DBA/1 mice were fed ovalbumin (OVA)-containing pellets ad libitum for 1 week and subsequently coimmunized twice, with a mixture of bovine collagen type II (BCII) and OVA in Freund's complete adjuvant. Mice fed OVA before coimmunization with BCII and OVA had significantly lower arthritic scores than mice immunized with BCII only. Their body weight increased during the study period and their anti-BCII antibody activity was significantly IgG_2a lower. The frequency of spleen cells producing IgG anti-BCII antibody was also reduced. Coimmunization per se slightly ameliorated the development of arthritis, resulting in an early, transient reduction. It resulted in significantly higher IgG₁ anti-BCII antibody activity and increased splenocyte secretion of IFN-γ and IL-10 in response to BCII. Our findings demonstrate that OVA-specific regulatory events induced by feeding OVA, i.e. bystander suppression, reduced the severity of arthritis in animals immunized with BCII and OVA. Anti-BCII specific antibody responses and cytokine secretion by types 1 and 2 T helper cells were also decreased.     

Free and phospholipid-bound choline concentrations in serum during pregnancy,after delivery and in newborns

The aims of this study were to determine whether serum free choline and phospholipid-bound choline concentrations change during the pregnancy or after childbirth and to determine if the serum choline concentrations of the mother and newborn are correlated. Serum free and bound choline concentrations were 10.7 +/- 0.5 microM and 2780 +/- 95 microM in control, non-pregnant women, and rose significantly (p < 0.001) to 14.5 +/- 0.6 microM and 3370 +/- 50 microM or to 16.5 +/- 0.7 microM and 3520 +/- 150 microM after 16-20 weeks or 36-40 weeks of pregnancy, respectively. Serum free and phospholipid-bound choline fell by 14-22% (p < 0.05-01) after either vaginal delivery or caesarian section, and remained low (by 15-42%; p < 0.05-0.001) for 12 h and then rose toward the baseline within 24 h. In amniotic fluid, free choline and phospholipid-bound choline concentrations were 22.8 +/- 1.0 and 19.6 +/- 0.8 microM or 24.0 +/- 1.5 and 516 +/- 43 microM at 16-20 weeks of gestational age or at term, respectively. In newborns, serum free choline concentrations were higher (p < 0.001) and phospholipid-bound choline concentrations were lower (p < 0.001) than in their mothers. These results show that serum free choline and phospholipid-bound choline concentrations are elevated during the pregnancy, which may be required for an adequate maternal supply of choline to the fetus. These observations are clinically important to determine the ideal dietary intake of choline during the pregnancy.     

Intraperitoneal administration of CDP-choline and its cholinergic and pyrimidinergic metabolites induce hyperglycemia in rats: involvement of the sympathoadrenal system

CDP-choline is an endogenous metabolite in phosphatidylcholine biosynthesis. Exogenous administration of CDP-choline has been shown to affect brain metabolism and to exhibit neuroprotective actions. On the other hand, little is known regarding its peripheral actions. Intraperitoneal administration of CDP-choline (200-600 micromol/kg) induced a dose- and time-dependent hyperglycemia in rats. Hyperglycemic response to CDP-choline was associated with several-fold elevations in serum concentrations of CDP-choline and its metabolites. Intraperitoneal administration of phosphocholine, choline, cytidine, cytidine monophosphate, cytidine diphosphate, cytidine triphosphate, uridine, uridine monophosphate, uridine diphosphate and uridine triphosphate also produced significant hyperglycemia. Pretreatment with atropine methyl nitrate failed to alter the hyperglycemic responses to CDP-choline and its metabolites whereas hexamethonium, the ganglionic nicotinic receptor antagonist which blocks nicotinic cholinergic neurotransmission at the autonomic ganglionic level, blocked completely the hyperglycemia induced by CDP-choline, phosphocholine and choline, and attenuated the hyperglycemic response to cytidine monophosphate and cytidine. Increased blood glucose following CDP-choline, phosphocholine and choline was accompanied by elevated plasma catecholamine concentrations. Hyperglycemia elicited by CDP-choline and its metabolites was entirely blocked either by pretreatment with a nonselective -adrenoceptor antagonist phentolamine or by the 2-adrenoceptor antagonist, yohimbine. Hyperglycemic responses to CDP-choline, choline, cytidine monophosphate and cytidine were not affected by chemical sympathectomy, but were prevented by bilateral adrenalectomy. Phosphocholine-induced hyperglycemia was attenuated by bilateral adrenalectomy or by chemical sympathectomy. These data show that CDP-choline and its metabolites induce hyperglycemia which is mediated by activation of ganglionic nicotinic receptors and stimulation of catecholamine release that subsequently activates 2-adrenoceptors.     

Choline status in newborns, infants, children, breast-feeding women, breast-fed infants and human breast milk

This study assessed the choline status in newborns, infants, children, breast-feeding women, breast milk, infant formula, breast-fed and formula-fed infants. The serum free choline level was 35.1+/-1.1 micromol/L at birth and decreased to 24.2+/-1.6, 18.1+/-0.8, 16.3+/-0.9, 14.3+/-0.8, 12.9+/-0.6 or 10.9+/-0.6 micromol/L at 22-28, 151-180, 331-365, 571-730, 731-1095 or 4016-4380 days after birth, respectively. The serum phospholipid-bound choline level was 1997+/-75 micromol/L at birth and increased gradually to 2315+/-190 or 2572 +/-100 micromol/L at 571-730 or 4016-4380 days after birth, respectively. In breast-feeding women, serum free and phospholipid-bound choline levels were doubled at 12-28 days after birth, they decreased toward the control values with time. Free choline, phosphocholine and glycerophosphocholine were major choline compounds in breast milk. Their concentrations in mature milk were much greater than in colostrum and serum. Choline contents of breast milk varied greatly between mothers, and milk free choline levels were correlated with serum free choline (r=.541; P<.001), phospholipid-bound choline (r=.527; P<.001) and glycerophosphocholine (r=.299; P<.01) concentrations and lactating days (r=.520; P<.001). In breast-fed infants, serum free choline concentrations were correlated with free choline (r=.47; P<.001), phosphocholine (r=.345; P<.002), glycerophosphocholine (r=.311; P<.01) and total choline (r=.306; P<.01) contents of breast milk. Serum free choline concentration in formula-fed infants was lower than breast-fed infants. These data show that (a) circulating choline status is elevated during infancy and lactation, (b) choline contents of breast milk vary between mothers and milk free choline contents are influenced by maternal circulating choline status, and (c) the choline contents of breast milk can influence infants' circulating choline status.