[Glycohistochemical analysis of rat eyelid epithelium]

The glycoconjugates in eyelids of adult rats were examined by lectin histochemistry and in situ hybridization histochemistry. Since Maackia amurensis lectin II and jacalin bound to the cell membranes of basal and apical epithelial cells, sialic acid alpha 2,3 galactose (Gal) beta 1,3 N-acetylgalactosamine (GalNAc) sequence is present in the glycoconjugates of their cell membranes. Peanut agglutinin bound to the cell membranes of spinous cells in the middle of the epithelium, suggesting that Gal beta 1, 3 GalNAc sequence is present in their glycoconjugates. The mRNA of Gal beta 1,3 GalNAc alpha 2,3-sialyltransferase was detected in the cytoplasm of the epithelial cells other than the basal cells. This observation suggests that sialoglycoconjugates may be newly synthesized in the spinous and apical cells, while the glycoconjugates in the cell membranes of basal cells may be produced at an early stage of development and are stable without turnover.

Inhibitory effects of oren-gedoku-to and its components on cholesteryl ester synthesis in cultured human hepatocyte HepG2 cells: evidence from the cultured HepG2 cells and in vitro assay of ACAT

The pharmacological effects of Oren-gedoku-to (OGT), a Japanese-Chinese traditional herbal medicinal mixture on lipid biosynthesis were investigated in cultured human hepatocyte HepG2 cells. The addition of OGT (0.5 and 4.2 mg/ml), which had no effect on cell proliferation and cellular protein content, caused a marked decrease in the cellular cholesterol content, particularly cholesteryl ester content following 24 h incubation. The incorporation of 14C-oleate into cellular cholesteryl ester fraction was also reduced remarkably during incubation for 6 and 24 h. The effects of OGT, its components and its main active chemicals on acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity were studied in vitro to explore the mechanism by which OGT inhibits cholesteryl ester formation. The data confirmed that OGT, in a dose-dependent manner, and its components (Scutellaria baicalensis, Coptis japonica, Gardenia jasminoides and Phellodendron amurense) remarkably inhibit ACAT activity. Among the main active chemicals of OGT, baicalein, a kind of flavonoid, decreased ACAT activity in a dose-dependent fashion from the level of 10(-6)M. These results strongly suggest that OGT reduces the cholesteryl ester formation in human hepatocytes by inhibiting ACAT, and that baicalein may, in part, be responsible for ACAT inhibition.

Up-regulation of sodium channel subunit mRNAs and their cell surface expression by antiepileptic valproic acid: activation of calcium channel and catecholamine secretion in adrenal chromaffin cells

Treatment of cultured bovine adrenal chromaffin cells with a therapeutic concentration (0.6 mM) of valproic acid (VPA) for > 24 h caused a time-dependent (t1/2 = 74 h) increase in [3H]saxitoxin binding up to 1.4-fold without altering the KD value; it was prevented by the simultaneous treatment with cycloheximide (an inhibitor of protein synthesis). VPA also raised Na+ channel alpha- and beta 1-subunit mRNA levels 1.4- and 1.7-fold at 24 h, and 1.6- and 1.8-fold at 72 h, respectively. Chronic (but not acute) exposure to VPA enhanced 22Na+ influx caused by various concentrations of veratridine 1.4-2.1-fold, even when assayed in the presence of Na+,K(+)-ATPase inhibitor, but did not change the EC50 value of veratridine. Ptychodiscus brevis toxin-3 allosterically potentiated veratridine-induced 22Na+ influx by approximately 2-fold in VPA-treated cells as in nontreated cells. Long-term treatment with VPA augmented veratridine-induced 45Ca2+ influx via voltage-dependent Ca2+ channels and catecholamine secretion, but had no effect on 45Ca2+ influx and catecholamine secretion caused by high K+ (a direct activation of voltage-dependent Ca2+ channels). Chronic treatment with VPA also enhanced nicotine-induced 22Na+ influx via the nicotinic receptor-ion channel complex 1.2-1.4-fold with little change in the EC50 value of nicotine, thereby increasing the nicotine-induced 45Ca2+ influx via voltage-dependent Ca2+ channels and catecholamine secretion. These results suggest that chronic treatment with VPA up-regulates cell surface expression of Na+ channels via the transcription/translation-dependent mechanisms, and probably of nicotinic receptors, thereby resulting in the enhancement of Ca2+ channel gating and catecholamine secretion.

Nitric oxide-dependent and -independent norepinephrine release in rat mesenteric arteries

The role of nitric oxide (NO) in endogenous norepinephrine (NE) release in the perfused isolated rat mesenteric vasculature was examined. NE overflow elicited by electrical field stimulation (EFS) at various frequencies was significantly smaller at 24 than at 37 degrees C. The pressor response upon EFS at 8 and 10 Hz, however, was higher at 24 than at 37 degrees C. When production of NO was blocked by N omega-nitro-L-arginine (L-NNA), NE overflow upon EFS at each frequency of stimulation was diminished by 50% at 37 degrees C but remained unchanged at 24 degrees C, whereas the pressor response elicited by EFS became greater at 37 than at 24 degrees C. These effects of L-NNA were reversed by L-arginine, but not by its D-enantiomer. Sodium nitroprusside, an NO donor, increased EFS-elicited NE overflow at 24 degrees C but had no effect at 37 degrees C. These results demonstrate that NE release is NO dependent and NO independent. The NO-dependent mechanism is more sensitive to cooling than the NO-independent mechanism. The increase in EFS-elicited perfusion pressure at 24 degrees C may be due to reduction in synthesis of NO (a potent vasodilator), thus unmasking the effect of NE and other noncatecholamine vasoconstrictors.

Neurochemical analysis of the psychotoxicity of methamphetamine and cocaine by microdialysis in the rat brain

To examine the neurochemical mechanism underlying the development of psychotoxicity by methamphetamine and cocaine, the levels of dopamine, serotonin and their metabolites were determined by in vivo microdialysis in the brains of freely moving rats. Methamphetamine (0.5 mg/kg, s.c.) or cocaine (10 mg/kg, i.p.) was repeatedly administered for 8 to 21 experiment days, and after confirming the development of sensitization to the stimulating effect of the drugs on spontaneous motor activity, a microdialysis probe was implanted into the nucleus accumbens (N.Acc.) or striatum of the brain of the treated rats. Then, each test drug was readministered to the rats and dopamine and DOPAC or serotonin and 5-HIAA concentrations were determined. In the N.Acc. of untreated control rats, methamphetamine increased dopamine to about 4 times the preadministration value along with a decrease of DOPAC. Methamphetamine also increased serotonin to about twice the preadministration value along with no change in 5-HIAA. Cocaine increased dopamine to about 4 times along with a slight decrease in DOPAC. In the treated rats as compared with the untreated rats, the increasing effect of methamphetamine on dopamine in the N.Acc. was enhanced but that of cocaine was not. Also, the serotonin levels were lower than in the untreated rats and 5-HIAA was unchanged. In the striatum of untreated rats, methamphetamine increased dopamine to about 3 times the preadministration value along with a slight decrease in DOPAC. In the treated rats, the increasing effect of methamphetamine on dopamine in the striatum was enhanced, and the DOPAC level was higher than in the treated rats. The present study suggests that the dopamine level at the N.Acc. does not necessarily reflect the sensitization to spontaneous motor activity, and that enhancement of the motor activity does not seem to be the best model for psychotoxic manifestation.

Up-regulation of functional voltage-dependent sodium channels by insulin in cultured bovine adrenal chromaffin cells

Treatment of cultured bovine adrenal chromaffin cells with 100 nM insulin raised [3H]saxitoxin ([3H]-STX) binding in a time-dependent manner (t1/2 = 26 h). Insulin (100 nM for 4 days) increased the Bmax of [3H]STX binding by 49% without changing the KD value and also augmented the maximal influx of 22Na+ due to 560 microM veratridine by 39% without altering the EC50 value of veratridine. The stimulatory effect of insulin on 22Na+ influx was concentration-dependent with an EC50 of 3 nM, whereas insulin-like growth factor (IGF)-I had little effect at 1 nM. Ptychodiscus brevis toxin-3 allosterically potentiated veratridine (100 microM)-induced 22Na+ influx by approximately twofold in both insulin-treated cells and untreated cells. Veratridine-induced 45Ca2+ influx via voltage-dependent Ca2+ channels and catecholamine secretion were also enhanced by insulin treatment, whereas insulin did not alter nicotine-induced 22Na+ influx via the nicotinic receptor-ion channel complex and high-K+ (direct activation of voltage-dependent Ca2+ channels)-induced 45Ca2+ influx. Stimulatory effects of insulin on [3H]-STX binding and veratridine-induced 22Na+ influx were nullified by simultaneous treatment with either 5,6-dichlorobenzimidazole riboside, an inhibitor of RNA synthesis, or cycloheximide, an inhibitor of protein synthesis, whereas insulin treatment did not appreciably increase the level of mRNA encoding the Na+ channel alpha-subunit. These results suggest that the binding of insulin to insulin (but not IGF-I) receptors mediates the up-regulation of functional Na+ channel expression at plasma membranes; this up-regulation may be due, at least in part, to the de novo synthesis of an as yet unidentified protein(s).

[Comparison of the effects of nicotine and methamphetamine on extracellular dopamine in the nucleus accumbens of behaviorally sensitized rats]

Repeated administration of nicotine (NCT) and methamphetamine (MAP) produced a progressive enhancement (sensitization) in the increasing effects on spontaneous motor activity in rats. The purpose of this study was to compare the effects of NCT and MAP on the extracellular levels of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) in the nucleus accumbens of behaviorally sensitized rats by in vivo microdialysis. NCT 0.5 mg/kg, sc did not change the DA and DOPAC levels in drug-naive rats, but it showed an increase in the DA levels in rats sensitized to NCT. MAP 0.5 mg/kg, sc increased DA levels and decreased DOPAC levels in drug-naive rats, but it showed a smaller increase in DA levels in rats sensitized to MAP than in drug-naive rats. On the other hand, the basal levels of DA were increased in sensitized rats produced by MAP, but not in those produced by NCT. The present results suggest that NCT and MAP produce behavioral sensitization through the action on the mesolimbic dopaminergic system, but the manner of action of these drugs is different.

Receptors for atrial natriuretic peptide in adrenal chromaffin cells

Receptors for atrial natriuretic peptide (ANP) in isolated bovine adrenal chromaffin cells were characterized. 125 I-ANP specifically bound to the cells with a Kd of 103 pM and a Bmax of 5.6 fmol/10(6) cells (16.5 fmol/mg of cell protein). C-ANF, a highly selective ligand for ANP-C receptors of natriuretic peptides, did not compete for 125 I-ANP binding at concentrations up to 10nM. Chemical cross-linking of 125I-ANP to the cells showed a single molecular size of the 120 kDa binding site on SDS gel electrophoresis under reducing conditions. CNP, a specific peptide for the ANP-B receptor, was much less potent than ANP in inhibiting 125 I-ANP binding and in displacing 125 I-ANP from the 120 kDa band. These results suggest that ANP specifically binds to the ANP-A receptor of 120 kDa and that there is no ANP-C receptor in bovine adrenal chromaffin cells.

Protein kinase C-mediated down-regulation of voltage-dependent sodium channels in adrenal chromaffin cells

Treatment of cultured bovine adrenal chromaffin cells with 12-O-tetradecanoylphorbol 13-acetate (TPA), an activator of protein kinase C (PKC), decreased [3H]saxitoxin ([3H]STX) binding in a concentration (IC50 = 19 nM)- and time (t1/2 = 4.5 h)-dependent manner. TPA (100 nM for 15 h) lowered the Bmax of [3H]STX binding by 53% without altering the KD value. Phorbol 12,13-dibutyrate (PDBu) also reduced [3H]STX binding, whereas 4 alpha-TPA, an inactive analogue, had no effect. The inhibitory effect of TPA was abolished when H-7 (an inhibitor of PKC), but not H-89 (an inhibitor of cyclic AMP-dependent protein kinase), was included in the culture medium for 1 h before and during TPA treatment. Simultaneous treatment with TPA in combination with either actinomycin D or cycloheximide, an inhibitor of protein synthesis, nullified the effect of TPA. TPA treatment also attenuated veratridine-induced 22Na+ influx but did not alter the affinity of veratridine for Na channels as well as an allosteric potentiation of veratridine-induced 22Na+ influx by brevetoxin. These results suggest that an activation of PKC down-regulates the density of Na channels without altering their pharmacological features; this down-regulation is mediated via the de novo synthesis of an as yet unidentified protein(s), rather than an immediate effect of Na channel phosphorylation.

Up-regulation of functional voltage-dependent sodium channels by cyclic AMP-dependent protein kinase in adrenal medulla

Treatment of cultured bovine adrenal chromaffin cells with dbcAMP increased [3H]STX binding with an EC50 of 126 microM and a half-effective time of 12 h; dbcAMP (1 mM x 18 h) raised the Bmax approximately 1.5-fold without altering the Kd value. Forskolin (0.1 mM) or IBMX (0.3 mM) also increased [3H]STX binding, while dbcGMP had no effect. Effects of dbcAMP and forskolin were abolished by H-89, an inhibitor of cAMP-dependent protein kinase. Cycloheximide (10 microgram/ml) and actinomycin D (10 microgram/ml), inhibitors of protein synthesis, nullified the stimulatory effect of dbcAMP, whereas tunicamycin, an inhibitor of protein glycosylation, had no effect. Treatment with dbcAMP augmented veratridine-induced 22Na influx, 45Ca influx via voltage-dependent Ca channels and catecholamine secretion, while the same treatment did not alter 45Ca influx and catecholamine secretion caused by high K (a direct activation of voltage-dependent Ca channels) [25]. Na influx via single Na channel calculated from 22Na influx and [3H]STX binding was quantitatively similar between non-treated and dbcAMP-treated cells. Brevetoxin allosterically enhanced veratridine-induced 22Na influx approximately 3-fold in dbcAMP-treated cells as in non-treated cells. These results suggest that cAMP-dependent protein kinase is involved in the modulation of Na channel expression in adrenal medulla.

Large- and small-conductance Ca(2+)-activated K+ channels: their role in the nicotinic receptor-mediated catecholamine secretion in bovine adrenal medulla

In cultured bovine adrenal chromaffin cells, charybdotoxin and iberiotoxin (inhibitors of the large-conductance Ca(2+)-activated K+ channel) as well as apamin (an inhibitor of the small-conductance Ca(2+)-activated K+ channel), at 1-100 nM, suppressed carbachol-induced 86RB+ efflux, augmented carbachol-induced 45Ca2+ influx via voltage-dependent Ca2+ channels and catecholamine secretion and had no effect on carbachol-induced 22Na+ influx via nicotinic receptors, a prerequisite for Ca2+ channel activation by carbachol. 45Ca2+ influx caused by high K+ (a direct activation of voltage-dependent Ca2+ channels) was also enhanced by these K+ channel inhibitors, with the concentration-response curves being similar to those for carbachol-induced 45Ca2+ influx. Dendrotoxin and mast cell degranulating peptide (inhibitors of voltage-dependent K+ channels), on the other hand, did not alter carbachol-induced 86Rb+ efflux or 45Ca2+ influx. These results suggest that the stimulation of nicotinic receptors eventually opens large- and small-conductance Ca(2+)-activated K+ channels, and that the blockade of these Ca(2+)-activated K+ channels results in gating of voltage-dependent Ca2+ channels and thereby augments catecholamine secretion from bovine adrenal chromaffin cells.

Mutations in the Norrie disease gene: a new mutation in a Japanese family

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Combined effects of pravastatin and probucol on high-density lipoprotein apolipoprotein A-I kinetics in cholesterol-fed rabbits

The combined effects of pravastatin and probucol on high- density lipoprotein (HDL) apolipoprotein (apo) A-I kinetics in cholesterol (Ch)-fed rabbits were investigated. Japanese White rabbits were treated with 0.15% pravastatin and 0.5% Ch (group 1) or 0.15% pravastatin plus 1% probucol and 0.5% Ch (group 2) for 2 months. After treatment, the serum total cholesterol levels in groups 1 and 2 had significantly (p < 0.01) increased (37.4 +/- 6.7 mg/dl vs 117.1 +/- 46.4 mg/dl, and 31.4 +/- 4.9 mg/dl vs 143.0 +/- 84.5 mg /dl, respectively). The serum HDL-cholesterol levels in both groups decreased (18.2 +/- 2.8 mg/dl, vs 16.2 +/- 3.7 mg/dl p < 0.01 for group 1; 18.2 +/- 1.9 mg/dl vs 15.5 +/- 4.5 mg/dl, ns for group 2). Apo A-I kinetics were assessed by injecting (125)I-labeled HDL intravenously into both groups of rabbits, and taking blood samples periodically for 6 days. Kinetic parameters calculated from apo A-I specific radioactivity decay curves showed that the apo A-I fractional catabolic rates in rabbits fed pravastatin and Ch (group 1) were significantly less than those in rabbits fed pravastatin plus probucol and Ch (group 2) (0.546 +/- 0.017 /day vs 0.730 +/- 0.126 /day, p < 0.05), while the synthetic rate of apo A-I was lower in group 2 than in group 1 (14.76 +/- 1.71 mg/kg per day vs 11.21 +/- 2.38 mg/kg per day, respectively, p < 0.01). These data indicate that pravastatin and probucol have different effects on HDL-apo A-I kinetics in a diet which includes cholesterol.

[Distribution of alpha 2,3-sialyltransferase mRNA in rat iris and ciliary body]

The distribution of alpha 2,3-sialyltransferase (alpha 2,3-ST) mRNA in the rat iris and ciliary body was investigated with in situ hybridization histochemistry. Strong expression of alpha 2,3-ST mRNA was detected in the inner epithelial layer of the ciliary body and weak expression in the iris epithelium. Since the synthesis of sialoglycoconjugates is completed by terminal sialylation by the action of sialyltransferase (ST), the ST-expressed portions are considered to produce sialoglycoconjugates. Hence, the source of the sialoglycoconjugates found in the inner epithelial layer of the ciliary body in previous histochemical studies is the same epithelial cell.

Pharmacological effects of dai-saiko-to on lipid biosynthesis in cultured human hepatocyte HepG2 cells

The pharmacological effects of Dai-saiko-to, a Japanese and Chinese traditional medicinal mixture (Kampohozai), on lipid biosynthesis were investigated in cultured human hepatocyte HepG2 cells. The addition of Dai-saiko-to (0.5 mg/ml), which had no significant effect on cell proliferation, caused a marked decrease in the intracellular triglyceride content with no significant changes in the other lipid fraction. At the same time, the incorporation of 14C-acetate or 3H-glycerol into the triglyceride or diglyceride fractions also decreased significantly. These results suggest that Dai-saiko-to decreases hepatic triglyceride biosynthesis, which might contribute to a reduction in plasma VLDL levels.

[Binding of amaranthin in human retina]

The binding of amaranthin, specific for Gal beta 1,3 GalNAc and sialic acid Gal beta 1,3 GalNAc sequences, to the human retina was investigated with avidin biotinylated peroxidase. Amaranthin bound to the cone and rod photoreceptors, inner plexiform layer, ganglion cells, and nerve fibers. Since peanut agglutinin, specific for Gal beta 1,3 GalNAc, selectively binds to cones, we conclude that O-glycoside-linked glycoconjugates are present on the surfaces of both cones and rods: Gal beta 1,3 GalNAc and sialic acid Gal beta 1,3 GalNAc are terminal sugars of the glycoconjugates around cones and rods, respectively.

Reinforcing effect as a function of infusion speed in intravenous self-administration of nicotine in rhesus monkeys

The influence of infusion speed on the reinforcing effect of nicotine (NIC) 30 micrograms/kg/infusion was studied in rhesus monkeys using intravenous self-administration at infusion speeds of 5.2, 1.3, and 0.3 micrograms/s under a fixed-ratio 5 schedule with a 15-min time-out after each intake. The 24-h self-administration rate was observed in 3 periods of 8 days each for each speed, separated by saline self-administration periods of 2 weeks each. As a result, when a fixed infusion speed of 5.2 micrograms/s was used throughout the 3 periods, the average rates of NIC were not significantly different each other, but when the infusion speed was changed from 5.2 to 1.3, and then to 0.3 micrograms/s, the average rates significantly decreased. The plasma level following a single-dose infusion of NIC 30 micrograms/kg positively correlated with the infusion speeds. These results indicate that the reinforcing effect of NIC is a function of the infusion speed, most likely through elevation of the peak level of NIC in the plasma.

Serum lipoprotein(a) levels before and after subtotal thyroidectomy in subjects with hyperthyroidism

Lipoprotein(a) [Lp(a)], a lipoprotein that structurally resembles low-density lipoprotein (LDL), contains apolipoprotein(a) [apo(a)] and apolipoprotein B-100 (apo B). There exists a close inverse correlation between serum concentrations of LDL or apo B and concentrations of thyroid hormone in patients with thyroid disease, probably due to a change in LDL receptor activity. To clarify the relations between thyroid hormone and Lp(a), we measured serum Lp(a) levels in 13 hyperthyroid subjects before treatment (stage H), during the euthyroid stage induced immediately before performing a subtotal thyroidectomy (stage E), and during the hypothyroid stage observed transiently after the operation (stage L). The mean serum concentration of Lp(a) increased significantly (P = .01) from 9.4 mg/dL in stage H to 26.8 in stage L through the level of 15.5 mg/dL in stage E. There was no significant difference between the mean serum concentration of Lp(a) in these patients in stage E and healthy controls (14.2 mg/dL). There was a low but statistically significant negative correlation between the Lp(a) level and the serum free thyroxine (fT4) concentration (r = .31, P < .05). The results suggest that thyroid hormone is a potent modulator of Lp(a) metabolism.

Novel mutation at the initiation codon in the Norrie disease gene in two Japanese families

We have identified a new mutation of Norrie disease (ND) gene in two Japanese males from unrelated families; they showed typical ocular features of ND but no mental retardation or hearing impairment. A mutation was found in both patients at the initiation codon of exon 2 of the ND gene (ATG to GTG), with otherwise normal nucleotide sequences. Their mothers had the normal and mutant types of the gene, which was expected for heterozygotes of the disease. The mutation of the initiation codon would cause the failure of ND gene expression or a defect in translation thereby truncating the amino terminus of ND protein. In view of the rarity and marked heterogeneity of mutations in the ND gene, the present apparently unrelated Japanese families who have lived in the same area for over two centuries presumably share the origin of the mutation.

Characterization of [3H]brevetoxin binding to voltage-dependent sodium channels in adrenal medullary cells

We have previously reported that in bovine adrenal chromaffin cells Ptychodiscus brevis toxin-3 (PbTx-3) does not alter the veratridine-induced 22Na influx when given alone, but increases the influx of 22Na when co-applied with either alpha- or beta-scorpion venom (Wada et al. 1992). In the present study, we characterized [3H]PbTx-3 binding in bovine adrenal chromaffin cells. [3H]PbTx-3 binding was saturable, reversible and of high-affinity with an equilibrium dissociation constant (Kd) of 32.0 +/- 4.9 nmol/l and a maximum binding capacity (Bmax) of 6.2 +/- 1.2 pmol/4 x 10(6) cells (4.5 +/- 0.9 pmol/mg cell protein). A Hill plot revealed the lack of cooperative interaction among the binding sites. Unlabelled PbTx-3 inhibited [3H]PbTx-3 binding with an IC50 of 31 nmol/l. However, tetrodotoxin, veratridine, alpha- and beta-scorpion venom, or veratridine in combination with either alpha- or beta-scorpion venom did not alter [3H]PbTx-3 binding. All these results suggest that PbTx-3 binds to a site (site 5) distinct from the previously known four toxin binding sites, which does not gate voltage-dependent Na channels by itself, but is specifically involved in the allosteric modulation of Na channels in adrenal medullary cells.

Dietary modifications of the biliary bile acid glycine:taurine ratio and activity of hepatic bile acid-CoA:amino acid N-acyltransferase (EC 2.3.1) in the rat

Effects of dietary manipulations on the biliary bile acid glycine:taurine (G:T) ratio and the activity of hepatic bile acid-CoA:amino acid N-acyltransferase (EC 2.3.1) in the post-mitochondrial fraction of liver homogenates were examined in the rat. The G:T ratio in rats fed on the diet containing 100 g pectin/kg (2.18) was markedly higher than that in the animals fed on the diet containing 100 g cellulose/kg (0.09). The diets containing either 10 g cholesterol/kg or 5 g sodium cholate/kg, especially the latter, also increased the G:T ratio (0.77 and 2.33 respectively) compared with a control diet free of these steroids (0.34). When the saturating concentrations of taurine (20 mM) and glycine (100 mM) were the substrates, dietary pectin relative to cellulose significantly increased the activity of both taurine- and glycine-dependent bile acid-CoA:amino acid N-acyltransferase, but neither dietary bile acid nor cholesterol influenced it. In spite of the marked difference in the G:T ratio among the rats given various types of experimental diet, the bile acid-CoA:amino acid N-acyltransferase reaction produced taurine-but little glycone-conjugated bile acid when both taurine and glycine coexisted at physiological concentration ranges in the assay media. Dietary manipulations modified the hepatic taurine concentrations and the changes were inversely correlated with those in the G:T ratio. However, hepatic concentration of taurine (1.67-4.82 mumol/g) in rats given various types of experimental diet was comparable with or even higher than the reported Michaelis constant (Km) value of N-acyltransferase for this compound (0.8-2.5 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Functional relation between nitric oxide and noradrenaline for the modulation of vascular tone in rat mesenteric vasculature

As previously reported, N omega-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide (NO) synthesis, decreased transmural field stimulation (TFS)-induced noradrenaline overflow from the isolated perfused rat mesenteric vasculature attached to the intestine. The decrease was attenuated by L-arginine. This suggests that NO may increase noradrenaline release (Yamamoto et al. 1993). The present experiments with this preparation were done in order to monitor changes in vascular perfusion pressure caused by TFS or by noradrenaline infusion in parallel with those in the noradrenaline outflow caused by TFS in the presence of atropine (0.1 mumol/l) (to block acetylcholine-induced release of endothelial NO) and of indomethacin (3 mumol/l) (to inhibit L-NNA-induced production of vasoconstrictor prostanoids). (1) TFS (2-10 Hz) caused a frequency-dependent increase in noradrenaline overflow and perfusion pressure. (2) L-NNA (10 and 30 mumol/l) caused a concentration-dependent inhibition of TFS-induced noradrenaline overflow, whereas the TFS-induced pressure increase was augmented by L-NNA in a concentration-dependent manner. At any given concentration of L-NNA, the potentiation of vasoconstriction by L-NNA became greater in magnitude as the frequency of the TFS was raised. (3) Infusion of noradrenaline (0.38-6 nmol) caused a dose-dependent increase in perfusion pressure up to a value comparable with that caused by TFS. The pressure increase in response to noradrenaline infusion was also enhanced by L-NNA, relatively, to a greater extent than the enhancement, by L-NNA, of the pressure response to TFS.(ABSTRACT TRUNCATED AT 250 WORDS)

[Rotational behavior induced by methamphetamine and cocaine in rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal dopamine system]

The purpose of this study was to compare the ability of intravenously administered methamphetamine and cocaine to facilitate dopaminergic transmission, based on the ability of these drugs to induce rotational behavior in rats with unilateral 6-hydroxydopamine lesions of the substantia nigra. The doses of methamphetamine and cocaine ranged from 0.25 mg/kg to 4 mg/kg which was equivalent to 50% of the minimum dose which caused convulsion. Methamphetamine induced more marked ipsilateral rotational behavior than did cocaine. The present results suggest that methamphetamine produces longer duration of the facilitation of dopaminergic transmission both in the nucleus accumbens and in the striatum than does cocaine.

Effects of simvastatin, a cholesterol synthesis inhibitor, on phosphatidylcholine synthesis in HepG2 cells

The effects of the addition of a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, simvastatin, to the medium on sterol synthesis and phosphatidylcholine (PC) synthesis were studied in HepG2 cells. The cells were cultured with simvastatin at concentrations of 10(-7) and 10(-6) mol/L for 6 hours, and radioactive lipid precursors were added 1 hour before harvesting. Simvastatin inhibited cholesterol synthesis from [14C]acetate in a dose-dependent manner. It also decreased the incorporation of [14C]choline into PC by 30%; this decrease was accompanied by a decrease in phosphocholine cytidylyltransferase activity in cell homogenates. Simvastatin had no significant effects on the incorporation of [3H]glycerol into phospholipids. These data indicate that simvastatin has two different functions: inhibition of HMG-CoA reductase and depression of de novo synthesis of PC via the cytidine diphosphate-choline pathway, which, in turn, may result in a decrease in plasma lipid levels.

[Withdrawal characteristics following frequent intravenous administration of several opioids in rats]

Characteristics of withdrawal signs of several opioids were compared in rats after short-term frequent intravenous infusions. Male Sprague-Dawley rats with catheters implanted in the jugular veins were infused with a fixed dose of a drug hourly for 72 hrs. Thirty min after the final infusion, naloxone 4 mg/kg, s.c. was administered and withdrawal signs were observed for 1 hr and the severity of the withdrawal signs was scored, classified into a behavioral sign score, autonomic sign score, and body weight loss score. As a result, total withdrawal scores of morphine, methadone, d-propoxyphene, loperamide, tramadol, and pentazocine were significantly higher than that of saline, with the highest score being observed for 4 mg/kg or more of morphine. The total score of ethylketocyclazocine was slightly but significantly higher than that of saline. Buprenorphine and thebaine produced no observable withdrawal signs. The behavioral sign score tended to be higher than the other 2 scores in the drugs showing relatively low but significant total scores such as tramadol, pentazocine, and ethylketocyclazocine, while the score of autonomic signs or the body weight loss tended to be higher in drugs showing high total scores. Thus, in the case of opioids, it is considered that the severity of withdrawal signs was mainly derived from the autonomic signs including diarrhea which may result in body weight loss.

Effects of methamphetamine, dopamine and noradrenaline administered into the nucleus accumbens of rats discriminating subcutaneous methamphetamine

Since the nucleus accumbens has been hypothesized to centrally mediate the discriminative effects of psychomotor stimulants, the discriminative effects of methamphetamine (MA) as well as dopamine (DA) and noradrenaline (NA) were observed by intracerebral administration of these drugs into the nucleus accumbens in rats discriminating subcutaneous MA from saline. These rats were trained and maintained to discriminate between MA at 0.5 mg/kg, s.c. and saline under a fixed ratio 10 schedule for food reinforcement in a 2-lever operant chamber situation. Guide cannulae were implanted bilaterally into the nucleus accumbens. In the substitution tests, the drug was administered into the nucleus accumbens. MA at 10 micrograms per rat substituted for subcutaneous MA in 4 out of 5 rats but neither DA at 10-40 micrograms per rat (n = 7) nor NA at 10-40 micrograms per rat (n = 4) substituted for subcutaneous MA. On the other hand, the same drugs administered into the nucleus accumbens induced increased spontaneous motor activity as also observed in six other untrained rats. MA, DA or NA alone each at 10 micrograms per rat increased spontaneous motor activity. The discriminative effects of MA are considered to be mediated in the nucleus accumbens of rats. Although DA or NA alone administered into the nucleus accumbens showed similar increasing motor activity effects as those of MA, the discriminative effects of exogenous DA or NA alone administered into the same brain area were different from those of MA in the present experimental condition.

[The value of an aseptic intermittent catheterization program in the early management of spinal cord injury patients]

From 1979 to 1989, 269 patients with spinal cord injury were managed by an aseptic intermittent catheterization program during the acute phase of their injuries at the Spinal Injuries Center. One hundred fifty one patients with incomplete cord lesion and 36 males with complete tetraplegia were managed by program I, which protects the shocked bladder from overdistention. In contrast, 82 patients with complete cord lesion excluding male tetraplegia were managed by program II, which allows overdistention of the bladder. Of the 187 patients managed by program I, 137 (73.3%) achieved trigger voiding function, 61.3% of whom were completely dry. Of the 82 patients managed by program II, 62 (75.6%) were put to self- or assisted catheterization, 67.7% of whom were dry. The incidence of a grade I, which means normal bladder configuration, was 88.0% for program I and 87.3% for program II during the follow up course. Upper urinary tract deterioration occurred in only one case. Surgical treatment for urinary tract complications was performed in 14 cases (5.2%). These results suggest that the patients with incomplete cord lesion managed by non-distension regimen of the bladder (program I) and those, especially female, with complete cord lesion managed by overdistention regimen of the bladder (program II) achieve urinary continence with excellent urinary prognosis.

The discriminative effects of nicotine and their central sites in rats

The mediations in the central sites of the discriminative effects of nicotine were studied. Rats were trained to discriminate between the effects of nicotine at 0.5 mg/kg, sc and saline under a fixed ratio 10 schedule, for food reinforcement in a 2-lever operant chamber situation. After the establishment of discrimination behavior, guide cannulae were implanted bilaterally into the lateral ventricle (n = 10), the nucleus accumbens (n = 11), the ventral tegmental area (n = 7), and the dorsal hippocampus (n = 9). In substitution tests, nicotine at 100 and 120 micrograms per rat administered into the lateral ventricle and this drug at 100 micrograms per rat administered into the nucleus accumbens substituted for subcutaneous nicotine. On the other hand, neither nicotine at 10-80 micrograms per rat administered into the ventral tegmental area, nor this drug at 5-20 micrograms per rat administered into the dorsal hippocampus substituted for the subcutaneous nicotine. In antagonism tests, mecamylamine was administered into each brain area in combination with nicotine at 0.5 mg/kg, sc. Mecamylamine at 180 micrograms per rat administered into the nucleus accumbens blocked the discriminative effects of the subcutaneous nicotine while mecamylamine, administered into the ventral tegmental area and the dorsal hippocampus, did not. These results may indicate that the discriminative effects of subcutaneous nicotine are at least partially mediated in the nucleus accumbens.

A fixative suitable for in situ hybridization histochemistry

We compared the morphology and stability of hybridization signals between paraffin sections of rat retina fixed with commonly used 4% paraformaldehyde/PBS and those fixed with a fixative containing glutaraldehyde in in situ hybridization histochemistry, using a digoxigenin-labeled RNA probe complementary for beta-galactoside alpha 2,6-sialyltransferase mRNA. Retinal detachment was frequently observed in the sections fixed with 4% paraformaldehyde-PBS, whereas the morphology was satisfactorily preserved in those fixed with either 0.5% glutaraldehyde, 4% paraformaldehyde-PBS, or 2.5% glutaraldehyde-PBS. Without glutaraldehyde, it was difficult to determine the most appropriate length of proteinase K digestion of tissue sections for facilitating probe penetration, since the optimal time for definite hybridization was variable among the retinal cells in heterogeneous layers. By addition of glutaraldehyde to paraformaldehyde or with glutaraldehyde alone, it was easy to establish the appropriate time for the unmasking procedure, since intense mRNA signals were constant throughout the retina by proteinase K digestion for more than 30-40 min. Using a fixative that causes stronger cross-linking (e.g., glutaraldehyde) is recommended to improve not only the morphology but also the stability of hybridization signals in in situ hybridization histochemistry with paraffin embedding and digoxigenin-labeled RNA probes.

Developmental change of distribution of beta-galactoside alpha 2,6-sialyltransferase mRNA in rat retina

A substantial change in the glycoconjugates of the rat interphotoreceptor matrix (IPM) has recently been shown to occur between post-natal day (P) 14 and P16 in rat retinas using lectin histochemistry. This suggests that the sialic acid content on the terminus of N-glycoside linked carbohydrate chains of the IPM increases between P14 and P16. In the present study, to test this hypothesis, we examined the developmental change of distribution of beta-galactoside alpha 2,6-sialyltransferase mRNA in rat retina using in situ hybridization histochemistry. C-DNA of rat alpha 2,6-sialyltransferase was isolated by PCR and cloned into the polylinker site of Bluescript KS (+). Antisense and sense RNA probes were labelled with digoxigenin-UTP by in vitro transcription with T3 and T7 RNA polymerases, respectively. Paraffin sections of rat retinas between P12 and P42 were incubated with the antisense or sense RNA probes. Specific labelling with the antisense probe was observed strongly in the cytoplasm of all ganglion cells and weakly in partial cells of the inner nuclear layers throughout the examined postnatal days. A remarkable change was observed in the photoreceptor cells between P14 and P16. Hybridization signals of the outer nuclear layer was observed from P14, while those of the inner segments were detected on P16 and thereafter. The alpha 2,6-sialyltransferase newly expressed in the inner segments on P16 appears to sialylate the Gal beta 1, 4GlcNAc residue of N-glycosidically linked glycoconjugates of the IPM, resulting in the change of lectin staining profiles.

[Overview of the progress in drug dependence studies--mainly focussing on psychic dependence]

The technical term 'drug dependence' was officially adopted by WHO's Expert Committee on Addiction in 1964. Until this, to describe a state of dependence, terms such as 'poisoning', 'habit', 'ism', and 'addiction' had been used from time to time. Until the 1950's, investigators were mainly focussed on the phenomena of physical dependence. However, once the concept of psychic dependence had been introduced, behavioral and neuropharmacological studies on the modes of drug action that produce psychic dependence were activated and have progressed in the last two decades, and among the points clarified by these studies are the following: 1. The critical drug properties that produce psychic dependence are those of rewarding subjective and reinforcing effects of drugs but these effects are not the properties that produce physical dependence, although the development of physical dependence on particular drugs such as opiates may substantially enhance craving for the drugs. 2. The mesolimbic and mesocortical dopamine systems in the brain and also the N. Accumbens play a primary or at least a partial role in producing the subjective and reinforcing effects of major dependence-producing drugs such as cocaine, opiates, barbiturates, benzodiazepines, and ethanol. 3. Many drugs such as naltrexone, methadone, and some dopamine antagonists and serotonin reuptake inhibitors or antagonists were found to be effective in the pharmacotherapy of the dependence on opiates, cocaine, or ethanol.

Effects of an antitussive mixture and its constituents in rats discriminating methamphetamine from saline

The discriminative effects of over-the-counter antitussive syrup containing dihydrocodeine (DHC), methylephedrine (MEP), caffeine (CAF), and chlorpheniramine (CPA) were compared with those of methamphetamine (MA) in a drug discrimination experiment using rats. Rats were trained to discriminate the effects of MA at 0.5 mg/kg SC and saline for food reinforcement under the fixed-ratio 10 schedule in a two-lever operant chamber situation. In substitution testing using a cumulative dose procedure by the subcutaneous route, DHC (4 and 8 mg/kg, expressed hereafter as referred to cumulative dose) or CPA (16-64 mg/kg) individually did not produce MA lever selection. On the other hand, MEP (128 mg/kg) and CAF (64 mg/kg) produced MA lever selection 41.5 and 57.2% of the time, respectively. The complete mixture (16 mg/kg DHC + 32 mg/kg MEP + 33.2 mg/kg CAF + 6.4 mg/kg CPA) produced MA level selection 65.8% of the time. The partial mixture containing only MEP + CAF at the above doses produced MA lever selection 95.6% of the time. Thus, the complete mixture only partially substituted for MA in rats while the partial mixture containing MEP and CAF completely substituted for MA.

[Studies on the involvement of the nucleus accumbens in the discriminative effects of nicotine in rats]

The central mechanism mediating the discriminative effects of nicotine was studied using rats. Rats were trained to discriminate subcutaneously administered nicotine at 0.5 mg/kg from saline in a 2-lever operant chamber situation for food reinforcement. 1) Nicotine administered into the lateral ventricle at both 100 micrograms and 120 micrograms substituted for subcutaneously administered nicotine at 0.5 mg/kg. This result indicates that the discriminative effects of nicotine are mediated centrally. 2) Among the drugs, acetylcholine at 0.5-10 micrograms administered into the lateral ventricle and methamphetamine at 5-40 micrograms and dopamine at 1-10 micrograms administered into the nucleus accumbens, none substituted for subcutaneously administered nicotine. These results indicate that the discriminative effects of nicotine differ from those of the above drugs. 3) Nicotine at 100 micrograms administered into the nucleus accumbens almost completely substituted for subcutaneously administered nicotine. In addition, mecamylamine at 180 micrograms administered into the nucleus accumbens attenuated the discriminative effects of subcutaneously administered nicotine. These results suggest that nicotinic receptors in the nucleus accumbens may be involved in the discriminative effects of nicotine. However, further studies are needed, since the nucleus accumbens is regarded not to be a major site of action of nicotine for these effects because of its low susceptibility to nicotine and mecamylamine.

Cholesterol-lowering effect of Agemaki, a kind of shellfish, in mice

Agemaki (Sinonovacula constricta) is an edible and popular shellfish in the western part of Japan. The present study demonstrated the effects of feeding Agemaki on cholesterol and triglyceride concentrations in mice plasma and liver. Mice were fed a diet containing 0.1% cholesterol and 0.1% Na-cholate for 1 week, and then a cholesterol-free diet or a cholesterol-enriched one for 2 weeks. To both diets, freeze-dried Agemaki was added at a 5% level. There was no statistically significant effect on the body-weight gain, food intake, and liver weight by feeding Agemaki in both dietary regimens. However, Agemaki significantly lowered the concentrations of plasma and liver cholesterol and also of plasma triglyceride in mice feeding on the cholesterol-rich diet. A similar tendency was also observed for the mice feeding on the cholesterol-free diet. The analysis of freeze-dried Agemaki revealed a relatively larger proportion of n-3 polyunsaturated fatty acids and plant sterols, which may possibly decrease plasma lipids. So far as we know, this is the first report showing hypolipidemic effect of Agemaki.

Observation of the development of tolerance to and physical dependence on barbital by cortical evoked potential in rats

To observe the dispositional and functional tolerance to and physical dependence on barbital, the influence of repeated administration of the drug on serum barbital levels, coordinative motion, body weight, and cortical evoked potential was assessed. Rats administered the first dose of barbital showed marked impairment of gross behavior and then loss of the righting reflex. While they were repeatedly treated with barbital for a 4-week period, the CNS depression became weaker and weaker, and loss of the righting reflex was no longer observed. Serum barbital levels after administration of barbital tended to decrease by the 28th day of repeated drug administration. Coordinative motion was markedly impaired after administration of the first dose, but gradually recovered during the repeated administration period. Barbital at 100 mg/kg, i.p., prolonged the latent time of the evoked potential in normal untreated rats but not in tolerant rats. During the withdrawal period, no particular change was observed in the animals' gross behavior. However, body weight loss and shortening of the latent time of the evoked potential were observed at 60 to 72 hours of withdrawal. These results suggest that cortical evoked potential can serve as a useful method for observing tolerance to and physical dependence on barbital.

Smoking and health: a review prepared by the Smoking and Health Subcommittee of the Tobacco Industries Council, a council formed by the Minister of Finance of Japan

Any definition of health is inevitably broad and contains various elements that may differ from one individual to another. Recent studies on the effects of smoking on physical and mental health have progressed remarkably and have great value in the fields of epidemiology, pathology, clinical medicine, and psychiatry. This report concludes that while smoking may have beneficial psychological effects on smokers, it may pose a risk to physical health.

Comparative study of combination chemotherapy of ovarian cancer: cyclophosphamide, adriamycin and cisplatin versus 5-fluorouracil, cyclophosphamide and mitomycin C

CAP, a multiple-drug combination therapy using cyclophosphamide (750 mg/m2), adriamycin (20-30 mg/m2) and cisplatin (50-75 mg/m2), was applied to 69 cases of epithelial ovarian cancer. The results of this therapy were compared with those of FAM (involving 5-fluorouracil, cyclophosphamide and mitomycin C) in 47 cases of the same cancer, retrospectively. The 5-year survival rate was 61.6% for cases treated with CAP and 56.3% for cases treated with FAM. All 9 patients at stage Ia treated with CAP are free of disease, however, 3 patients out of 13 at stage Ia treated with FAM experienced a recurrence of the disease and died. In stage III and IV cases with detectable lesions, a response was observed in 61.3% (19/31) treated with CAP and in 10.5% (2/19) treated with FAM.

Effect of tetrahydroisoquinoline (TIQ), one of endogenous substances inducing parkinsonism, on isolated rat vas deferens

1. The effect of tetrahydroisoquinoline (TIQ) was examined on isolated rat vas deferens. 2. TIQ shifted the concentration-response curve for norepinephrine towards lower concentrations: the pD2-value of norepinephrine in the presence of TIQ was significantly greater than in its absence. 3. Tyramine-induced contraction in the presence of TIQ decreased by a significant 35% more than in the absence of TIQ. 4. These results indicate that the pharmacological effect of TIQ is due to the inhibition of the neuronal uptake of catecholamines.

Mode of potentiating action of cocaine in morphine analgesia

The mechanism of antinociceptive interactions among morphine, cocaine and alcohol was studied in mice, guinea pigs and rabbits. In the tail-pressure test in mice, cocaine and alcohol alone showed almost no antinociceptive effects at doses up to 8 mg/kg, s.c., and 4 g/kg, respectively. Alcohol at 2 g/kg, i.g., also did not influence the effect of morphine, while cocaine at 4 mg/kg, s.c., significantly potentiated the antinociceptive effects of not only morphine but also pentazocine. In an analysis of serum and brain concentration levels of morphine in mice, when morphine and cocaine were simultaneously administered at 2 mg/kg, s.c., and 4 mg/kg, s.c., respectively, both serum and brain levels of morphine showed neither increase nor decrease in comparison with the levels in mice administered morphine alone. In myenteric plexus-longitudinal muscle preparations of isolated guinea pig ileum, 1 microM cocaine enhanced the agonistic effects of both pentazocine and ethylketocyclazocine. Furthermore, cocaine as well as ethylketocyclazocine showed naloxone-reversible agonistic effects in isolated rabbit vas deferens. These results indicate that cocaine may potentiate the antinociceptive effects of morphine and pentazocine by acting on the kappa-opioid receptors as an agonist.