Important roles of tachykinins in the development of allergic nasal hyperresponsiveness in guinea-pigs.

BACKGROUND: Although it has been suggested that the use of tachykinin receptor antagonists might prove to be an effective treatment for allergic rhinitis (AR), they are not used clinically. Therefore, we decided to examine the effects of tachykinin receptor antagonists on AR symptoms in an appropriate experimental model. OBJECTIVE: To evaluate newly developed tachykinin receptor antagonists in a Japanese cedar pollen-induced AR model and to determine their effect on allergen-induced sneezing, nasal blockage, and nasal hyperresponsiveness (NHR). METHODS: Sensitized guinea-pigs were challenged by forced inhalation of pollen once every week. Sneezing and nasal blockage were observed after pollen challenges. NHR (nasal blockage) to an intranasal application of leukotriene D(4) was assessed 2 days after an antigen challenge. We also evaluated whether intranasal dosing with a tachykinin causes NHR. NK(1) and NK(2) receptor antagonists were administered before an intranasal treatment with antigen or tachykinin. Amounts of tachykinins present in nasal cavity lavage fluid were measured by an enzyme immunoassay. RESULTS: Although an NK(1) and NK(2) receptor dual antagonist showed no effect on pollen-induced sneezing and biphasic nasal blockage, it did completely suppress the development of NHR. Experiments using specific NK(1) or NK(2) receptor antagonists revealed that NK(2) receptor activation was preferentially involved in the development of hyperresponsiveness. Increases in the levels of substance P (SP) and neurokinin A (NKA) in the nasal tissue were noted 20 min-1 h after the challenge. Intranasal instillation of either SP or NKA-induced NHR, which was almost completely inhibited by NK(2) receptor antagonists and partially inhibited by NK(1) receptor antagonists. CONCLUSIONS: SP and NKA, which are released early after the challenge, mediate the development of NHR by preferentially activating NK(2) receptors. Therefore, NK(2) receptor antagonists might prove to be effective treatment of AR.

Effects of a novel hepatoprotective drug, ZNC-2381, on fas-induced hepatocellular caspase-3 activity and apoptosis in mice.

We examined the effects of ZNC-2381 (1-(4-aminophenyl)methyl-3-(3-nitrophenyl)-1,3-dihydroimidazo[4,5-b] pyridine-2-one), a new oral hepatoprotective agent, on hepatocellular caspase-3 activity and apoptosis induced by anti-mouse Fas antibody (anti-Fas ab) in mice. Oral ZNC-2381, administered at doses of 10, 30 and 100 mg/kg 1 h before inducing hepatic injury with anti-Fas ab, dose-dependently inhibited the increase in serum alanine aminotransferase (s-ALT) activity 8 h after injection of anti-Fas ab. Increases in DNA fragmentation (nucleosome assay) and caspase-3 activity in the liver 2 h after injection of anti-Fas ab were also inhibited by ZNC-2381 in a dose-dependent manner. As shown by histopathological examination, ZNC-2381 dose-dependently inhibited the appearance of TUNEL-positive apoptotic cells in the liver. Moreover, in studies in vitro, ZNC-2381 (1- 100 micromol/l) concentration-dependently inhibited increases in DNA fragmentation and caspase-3 activity caused by anti-Fas ab in isolated mouse hepatocytes. N- Acetyl-Asp-Glu-Val-Asp aldehyde (Ac-DEVD-cho), a caspase-3-specific inhibitor, inhibited hepatocellular apoptosis caused by anti-Fas ab both in vivo and in vitro, as well as the increase in s-ALT activity in vivo. These results demonstrate that orally administered ZNC-2381 inhibits hepatocellular apoptosis induced by anti-Fas ab and presents the progression of hepatic injury. We propose that the mechanism of action of ZNC-2381 may involve blockade of the signal transduction pathway (caspase-3) of apoptosis mediated by anti-Fas ab.

Effects of ZNC-2381, a new oral compound, on several hepatic injury models and on hepatocellular apoptosis in mice and rats.

The hepatoprotective effect of ZNC-2381 (1-(4-aminophenyl) methyl-3-(3-nitrophenyl)-1,3-dihydroimidazo[4,5-b]pyridine-2-one), a novel 2-one dihydroimidazopyridine derivative, has been evaluated in several experimental models of hepatic injury. In mice, oral ZNC-2381, administered at doses of 3, 10 or 30 mgkg(-1), 1 h before induction of hepatic injury with concanavalin A, dose-dependently inhibited increases in serum alanine aminotransferase (ALT) activity. Apoptosis of liver cells, as indicated by DNA fragmentation (nucleosome assay) and DNA-ladder formation (electrophoresis), was also inhibited dose-dependently. ZNC-2381 dose-dependently inhibited concanavalin A-induced increases in serum tumour necrosis factor (TNF)-alpha levels, and TNF-alpha mRNA expression in the liver. Oral ZNC-2381 also dose-dependently inhibited increases in serum ALT activity in mice with hepatic injury induced by Propionibacterium acnes and a bacterial lipopolysaccharide (LPS) or D-galactosamine-LPS, and in rats with D-galactosamine-induced hepatic injury. These results indicate that oral ZNC-2381 inhibits cytokine (TNF-alpha) production and cytokine-related hepatocellular apoptosis, and might thus prevent different types of hepatic injury.

Age-depending effects of methotrexate treatment on systemic bone turnover in experimental adjuvant arthritis.

Adjuvant arthritis was induced in rats in the growth stage (aged 6 weeks) and those in the mature stage (aged 4 months), and changes in the systemic bone turnover and the effects of methotrexate (MTX, CAS 133073-73-1) were compared. After induction of adjuvant arthritis, the paw edema ratio and the urinary deoxypyridinoline (u-Dpy) level increased in both age groups. No marked changes were observed in the serum osteocalcin (s-OC) level in either group. In the 6-week-old rats, arthritis completely inhibited the bone mass, and strength of the femur and lumbar vertebral body. The 4-month-old rats showed more marked changes than the 6-week-old rats in the bone mass and strength of the lumbar, vertebral body. MTX administration (0.05, 0.1 and 0.2 mg/kg/day) resulted in significant dose-dependent inhibition of arthritis-induced changes, and the effects of MTX were similar between the two age groups. MTX was useful at each age. These results suggest that 4-month-old rats with arthritis are more appropriate as a model for evaluation of drugs for bone metabolic turnover in human chronic rheumatoid arthritis.

Effects of concanavalin A treatment on CD8 mRNA expression in mouse liver.

The administration of concanavalin A (Con A) (0.2 mg/mouse) into mice induced significant elevation of plasma alanine aminotransferase (ALT) at 8.5 hr after Con A treatment. CD8 mRNA, which is a marker of cytotoxic T-cell, was strongly induced at 16 and 24 hr after Con A treatment. Although pretreatment with cyclosporine A (CsA) (50 and 100 mg/kg, i.p.) inhibited Con A-induced elevation of plasma ALT, it did not inhibit Con A-induced CD8 mRNA expression. Morphological study revealed lymphoid cell infiltration in the liver, but the lymphoid cells were not present at the site of hepatocyte necrosis. These results suggest that Con A-induced CD8+ T-cell infiltration has a minimal effect in the development of hepatitis.

Effect of gadolinium chloride treatment on concanavalin A-induced cytokine mRNA expression in mouse liver.

The effect of Kupffer cell depression on concanavalin A (Con A)-induced cytokine mRNA expression in the liver was studied. Gadolinium chloride (GdCl3) is a commonly used Kupffer cell inhibitor. GdCl3 (40 mg/kg, i.p.) was injected into each mouse, and 24 hr later, Con A (0.2 mg/mouse) was administered. Plasma was obtained at 24 hr after Con A treatment for alanine aminotransferase (ALT) measurement. GdCl3 treatment inhibited Con A-induced elevation of ALT. However, it did not inhibit Con A-induced interleukin-2 or tumor necrosis factor-alpha mRNA expression. The present results suggest that Kupffer cells are not responsible for Con A-induced cytokine expression in the liver.

Expression of cytokine mRNA in extrahepatic organs in a mouse concanavalin A-hepatitis model.

The liver injury in the concanavalin A (Con A)-induced mouse hepatitis model has been well studied. However, there has been little study on the effects of Con A on extrahepatic organs. The aim of the present work was to determine the effects of Con A on the spleen, kidney and lung. A histopathological study showed that Con A (15 mg/kg, i.v.) administration affects not only the liver, but also all these extrahepatic organs. Messenger RNA expression was studied by the using polymerase chain reaction. Treatment with Con A induced interleukin-2 mRNA in the spleen, but only slightly induced it in the kidney. The mRNAs of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) were induced in all these organs. At 24 hr after Con A treatment, the expression of IFN-gamma mRNA, but not that of TNF-alpha mRNA, was inhibited by cyclosporine A (50 mg/kg, i.p.), suggesting that Con A induced these cytokine mRNAs through different mechanisms. In the kidney and lung, CD4+ and CD8+ T-cell infiltration was suggested by the Con A-induced CD4 and CD8 mRNAs. The present study showed the histopathological effects of Con A and Con A-induced cytokine mRNA expression on the spleen, kidney and lung.

Induction of CPP32-like activity and inhibition of interleukin 1beta converting enzyme activity in the liver of a mouse concanavalin A-induced hepatitis model.

The objective of the present study was to determine the effects of concanavalin A (Con A) administration on the interleukin 1beta converting enzyme (ICE) activity and CPP32-like activity in mouse liver. Treatment with Con A (0.2 mg/mouse, i.v.) caused an elevated plasma alanine aminotransferase (ALT) level at 8 hr after Con A injection. ICE activity was decreased at 8 and 24 hr after Con A treatment. In contrast, CPP32-like activity was increased at 24 hr after Con A injection. Since CPP32-like activity was induced after ALT had increased, the induction of CPP32-like activity may not be involved in Con A-induced hepatitis.

Methotrexate suppresses nitric oxide production ex vivo in macrophages from rats with adjuvant-induced arthritis.

We examined the effects of methotrexate (MTX) on the level of nitric oxide (NO) produced by peritoneal macrophages from rats with adjuvant-induced arthritis (AA) ex vivo. During the development of AA, paw swelling increased and LPS enhanced the capacity of peritoneal macrophages to produce NO and prostaglandin E2 (PGE2). MTX (0.1 mg/kg, p.o.) treatment for 21 days reduced the paw swelling, and inhibited the increased NO and PGE2 production. However, when MTX (0.1 mg/kg, p.o.) was administered to rats with established AA, these parameters were not significantly influenced. In normal rats, MTX (0.1 mg/kg, p.o.) treatment for 21 days did not change NO and PGE2 production of LPS-stimulated macrophages. On the other hand, macrophages from normal and AA rats cultured in the presence of MTX (1, 10 and 100 microM), were activated by LPS in vitro. MTX did not influence NO or PGE2 production by LPS-stimulated macrophages in normal and AA rats. By contrast, indomethacin (IM) (1.0 mg/kg, p.o.) treatment for 21 days reduced the paw swelling, and inhibited NO and PGE2 production in AA rats. IM inhibited significantly PGE2 production, but did not influence NO production by LPS-stimulated macrophages in vitro. These results suggest that MTX treatment reduces NO production in peritoneal macrophages in AA rats, and these actions of MTX may have an inhibitory effect without the modulation of PGE2.

Changes in urinary deoxypyridinoline level and vertebral bone mass in the development of adjuvant-induced arthritis in rats.

This study was designed to determine the effect of bone resorption on the development of generalized osteopenia in adjuvant-induced arthritic rats. Thirty of a total of sixty male SD rats, 6 weeks of age, were injected with killed mycobacterium butyricum suspended in mineral oil into the right hind paw and assigned to six groups of 5 animals each. The other thirty animals served as the age-matched noninjected controls. Animals were sacrificed at 4, 7, 10, 14, 21, and 28 days post-injection after measuring the bilateral hind-paw volumes. Twenty-four-hour urinary samples were obtained before sacrifice and the levels of deoxypyridinoline (D-Pyr) and creatinine (CR) were measured. Plasma intact osteocalcin levels were measured by a sandwich enzyme immunoassay at the start, 14 and 28 days after injection. Bone mineral measurement and histomorphometrical analyses were performed on specimens of the third lumbar vertebral body. On the seventh day after injection, arthritic rats showed significant decreases in the values of bone mineral content (BMC) and density (BMD) when compared to controls. Urinary D-Pyr/Cr ratios, however, did not increase on the seventh day, showing a significant increase on the tenth day after injection. The serum osteocalcin level was significantly reduced on the fourteenth day. The trabecular bone volume (BV/TV) in the arthritic rats showed a significant decrease from the seventh day. The trabecular thickness (Tb.Th) value significantly decreased on the seventh day after injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Important role of peptide leukotrienes (p-LTs) in the resting tonus of isolated human bronchi.

The quality of the resting tonus in isolated human bronchi was investigated using a peptide leukotriene (p-LT) antagonist, a 5-lipoxygenase inhibitor and others. (E)-2,2-Diethyl-3'-[2-[2-(4-isopropyl)-thiazoyl]ethenyl]succina nilic acid sodium salt (MCI-826), a newly synthesized compound that is a highly selective antagonist to LTD4 and LTE4, markedly relaxed the isolated human bronchi at low concentrations. A selective and competitive arachidonate 5-lipoxygenase inhibitor, 2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA-861), also potently lowered the tonus. In addition, a large amount of spontaneously formed p-LTs was detected in the isolated human bronchial tissue as well as the lung parenchymal tissue. The isolated human bronchi responded to indomethacin treatment with contractions and the acceleration of p-LT formation. Atropine, an anticholinergic; mepyramine, an antihistaminic; and OKY-046, a thromboxane synthetase inhibitor, all showed no effect on the resting tonus. Taking into consideration the high responsiveness of the human airway smooth muscle to p-LTs and the present results, which were different from those on isolated guinea pig tracheas, it is strongly suggested that the spontaneously formed p-LTs largely participate in the resting tonus of the majority of isolated human bronchi.

Effect of beta-alanyl-L-histidinato zinc on bone metabolism in rats with adjuvant arthritis.

The effect of a new zinc compound, beta-alanyl-L-histidinato zinc (AHZ), on osteopenia was investigated in rats with adjuvant arthritis. Arthritis was induced in female rats by administering 1% Mycobacterium butyricum (MB) into the subplantar surface of the right hind paw. AHZ (10, 30 and 100 mg/kg body weight) was orally administered to MB-treated rats 28 times at 24-h intervals, and the rats were bled 24 h after the last administration. Treatment with MB caused a remarkable increase in paw volume and a corresponding decrease in the ratio of albumin per globulin in serum, indicating that the treatment induces inflammation. These alterations were not significantly changed by the administration of AHZ (10, 30 and 100 mg/kg). Serum calcium and zinc concentrations are significantly decreased in rats with adjuvant arthritis. These decreases were completely restored by the administration of AHZ (30 and 100 mg/kg). Furthermore, the inflammation-induced decreases in alkaline phosphatase activity and calcium content in the femoral diaphysis were clearly blocked by the administration of AHZ (30 and 100 mg/kg). Also, the larger doses of AHZ (30 and 100 mg/kg) produced a significant increase in femoral-diaphyseal deoxyribonucleic acid and in the zinc content in rats with adjuvant arthritis. These results suggest that AHZ has a stimulating effect on bone formation in the femoral diaphysis of rats with adjuvant arthritis, although the compound did not have an anti-arthritic effect.

Beta-alanyl-L-histidinato zinc enhances various bone-regulating factors' effects on bone alkaline phosphatase activity in tissue culture.

The present investigation was undertaken to clarify the interaction of beta-alanyl-L-histidinato zinc (AHZ) and other bone-regulating factors on bone alkaline phosphatase in tissue culture. Calvariae were removed from weanling rats (3-week-old males) and cultured for periods up to 48 h in Dulbecco's modified Eagle medium. The experimental cultures contained 10(-5) mol/l AHZ which reveals in maximum effect on bone formation. Bone alkaline phosphatase activity was significantly increased by the presence of AHZ (10(-5) mol/l), insulin (10(-8) mol/l), sodium fluoride (10(-2) mol/l), aluminium sulfate (2 x 10(-3) mol/l), while the enzyme activity was not altered by estradiol (10(-9) mol/l), calcitonin (3 x 10(-8) mol/l), hydrocortisone (10(-8) mol/l), indomethacin (10(-6) mol/l) and imidazole (10(-3) mol/l). The presence of AHZ (10(-5) mol/l) clearly enhanced the calcitonin-, sodium fluoride- or diltiazem-increased bone alkaline phosphatase activity. Meanwhile, AHZ did not interact for the effects of other hormones and reagents. Moreover, the presence of cycloheximide (10(-6) mol/l), an inhibitor of protein synthesis, completely blocked the enhancement of bone alkaline phosphatase activity by AHZ. These findings suggest that AHZ has an effect different from bone cellular response for other bone-regulating factors, and that bone protein synthesis was a necessary component for AHZ action.

Preventive effect of beta-alanyl-L-histidinato zinc on the deterioration of bone metabolism in ovariectomized rats.

The preventive effect of beta-alanyl-L-histidinato zinc (AHZ) on the deterioration of bone metabolism was investigated in the femoral diaphysis of ovariectomized rats. AHZ (10, 30 and 100 mg/kg body weight/d) was orally administered to ovariectomized rats for 6 weeks. Ovariectomy produced a significant decrease in estradiol, calcitonin, calcium and inorganic phosphorus concentrations in the serum as compared with those from sham-operated rats. The dose of 30 and 100 mg AHZ/kg prevented any decrease in serum inorganic phosphorus concentration caused by ovariectomy. Alkaline phosphatase activity, deoxyribonucleic acid (DNA) and calcium contents in the femoral diaphysis of ovariectomized rats significantly decreased in comparison with those from sham-operated rats. These decreases were completely prevented by the dose of AHZ (10, 30 and 100 mg/kg). Electron microscopical analysis showed a rough alteration of bone matrix in the femoral diaphysis of ovariectomized rats. This alteration was clearly modified by the doses of AHZ (10, 30 and 100 mg/kg). Also, dosages of AHZ (30 and 100 mg/kg) restored the atrophy of osteoblasts and cartilage cells caused by ovariectomy. The present study suggests that oral administration of AHZ can prevent the deterioration of bone metabolism by ovariectomy. AHZ may have a therapeutic role in the treatment of osteoporosis.

Effect of a new non-steroidal anti-inflammatory combination of a histamine H2 antagonist and indomethacin on gastroduodenal mucosal membrane in rat.

The new non-steroidal anti-inflammatory drug (NSAID), N-(3-[3-(piperidinyl-methyl) phenoxy] propyl)-carbamoyl-methylthio]ethyl 1-(p-chlorobenzoyl) 5-methoxy-2-methyl-3-indolyl-acetate (CP 331, CAS 127966-70-5), a compound with a structure of an ester combining indomethacin (IM) and a histamine H2 antagonist, has been reported to have anti-inflammatory, analgesic and antipyretic effects. However, the influence of CP-331 on the gastroduodenal mucosa was not fully investigated. Therefore this study was undertaken to investigate the effect of CP-331 on the gastroduodenal mucosa membrane in rats. After single oral drug administration, the UD50 value (50% ulcerogenic dose) of CP-331 calculated from the incidence rate of gastric ulcer was higher than 1000 mg/kg; that for IM was 5.2 mg/kg. Moreover it was examined whether CP-331 had a preventive effect on NSAID-induced gastric damage. The results showed that the co-administration of CP-331 10-30 mg/kg prevented significantly the acute gastric mucosal injury caused by IM administration (20 mg/kg). CP-331 with anti-inflammatory activity does not cause gastric injury, moreover, because of its preventing and therapeutic effects on the damage to gastric mucous membrane induced by IM, CP-331 might be useful in the treatment of gastropathy caused by NSAID in clinic.

Anti-inflammatory, analgesic, and antipyretic effects and gastrointestinal toxicity of the new anti-inflammatory drug N-(3-[3-(piperidinylmethyl)phenoxy]propyl)-carbamoylmethylthio ]ethyl 1-(p-chlorobenzoyl) 5-methoxy-2-methyl-3-indolylacetate.

The anti-inflammatory, analgesic, and antipyretic effects and gastrointestinal toxicity of N-(3-[3-(piperidinylmethyl) phenoxy] propyl)- carbamoylmethylthio] ethyl 1-(p-chlorobenzoyl) 5-methoxy-2-methyl-3-indolylacetate (CP-331, CAS 127966-70-5), a new anti-inflammatory drug, were evaluated using indomethacin as a control. CP-331 exerted anti-inflammatory, analgesic and antipyretic effects on the models of carrageenin-induced paw edema, increased vascular permeability, ultraviolet light-induced erythema, granuloma proliferation, adjuvant arthritis, inflammatory pain, and yeast-induced fever. However, these effects were observed at a molar level similar to or higher than that of indomethacin. In addition, CP-331 influenced more markedly than indomethacin the delayed type hypersensitivity to sheep red blood cells. On the other hand, CP-331 did not damage the gastric mucosa even at a high dose of 1,000 mg/kg and also induced slighter damage to the intestinal mucosa than indomethacin. Thus, CP-331 exerted anti-inflammatory, analgesic, and antipyretic effects but without showing gastric toxicity, which is a common side effect of anti-inflammatory drugs. These results suggest the clinical applicability of this drug in the long-term therapy of inflammatory diseases such as rheumatoid arthritis.

beta-Alanyl-L-histidinato zinc prevents hydrocortisone-induced disorder of bone metabolism in rats.

The preventive effect of beta-alanyl-L-histidinato zinc (AHZ) on osteopenia was investigated in rats treated with hydrocortisone. Rats received hydrocortisone (75 mg/kg body weight per day) s.c. for 30 days. The steroid treatment caused a significant increase in serum alkaline phosphatase activity and parathyroid hormone (PTH-c) level, while serum calcium, inorganic phosphorus, and zinc concentrations were not significantly altered. The femoral-diaphyseal alkaline phosphatase activity, deoxyribonucleic acid (DNA), and calcium contents were significantly decreased by the treatment of steroid, although the bone zinc content was not appreciably altered. When AHZ (10, 30, and 100 mg/kg per day) was administered p.o. for 30 days to rats giving the steroid, the dose of AHZ (30 and 100 mg/kg) completely prevented the increases in serum alkaline phosphatase activity and PTH-c level and the decreases in femoral-diaphyseal alkaline phosphatase activity, DNA, and calcium contents caused by the steroid treatment. The dose of AHZ (10, 30, and 100 mg/kg) significantly increased zinc content in the femoral diaphysis. Present results indicate that the dose of AHZ can prevent the disorder of bone metabolism caused by hydrocortisone treatment. AHZ may have a therapeutic role in the steroid-induced osteopenia.

Preventive effect of beta-alanyl-L-histidinato zinc on bone metabolism in rats fed on low-calcium and vitamin D-deficient diets.

The effect of beta-alanyl-L-histidinato zinc (AHZ) on bone metabolism in the femoral diaphysis of rats fed on low-calcium and vitamin D-deficient diets was investigated. Rats were orally administered AHZ (10, 30, and 100 mg/kg per day) for 14 days and were killed on the 15th day. Feeding with low-calcium and vitamin D-deficient diets caused a significant decrease in serum 25-hydroxy-vitamin D3, calcium, and inorganic phosphorus concentrations. These decreases were not prevented by AHZ administration. Meanwhile, the femoral-diaphyseal calcium and phosphorus contents were significantly reduced by feeding with the deficient diets. Decrease in bone calcium content was significantly prevented by the doses of 30 and 100 mg AHZ/kg. Furthermore, the dose of 100 mg AHZ/kg produced a significant increase in bone deoxyribonucleic acid (DNA) content and alkaline phosphatase activity in rats fed on the deficient diets. Bone zinc content in the deficient rats was significantly increased by the doses of AHZ (30 and 100 mg/kg). The present results suggest that oral administration of AHZ has a preventive effect in the development of deteriorating bone metabolism in rats fed on low-calcium and vitamin D-deficient diets.

Inhibitory effect of beta-alanyl-L-histidinato zinc on bone resorption in tissue culture.

The inhibitory effect of beta-alanyl-L-histidinato zinc (AHZ) on bone resorption in tissue culture was investigated. Calvaria were removed from weanling rats (3-week-old male) and cultured for periods up to 48 h in Dulbecco's modified Eagle medium (high glucose, 4.5%) supplemented with antibiotics and bovine serum albumin. The experimental cultures contained 10(-7) to 10(-4) mol/l AHZ. The bone-resorbing factors, parathyroid hormone (1-34) (PTH; 10(-7) mol/l), prostaglandin E2 (10(-5) mol/l), interleukin-1 alpha (IL1 alpha; 50 U/ml), and lipopolysaccharide (10 micrograms/ml), caused a significant decrease in bone calcium content. The decreases in bone calcium content induced by bone-resorbing factors were completely inhibited by the coexistence of AHZ (10(-6) to 10(-4) mol/l). Also, AHZ (10(-5) mol/l) completely inhibited the PTH (10(-7) mol/l) or IL1 alpha (50 U/ml)-induced increase in medium glucose consumption and lactic acid production by bone tissue. Furthermore, AHZ (10(-5) mol/l) fairly blocked both PTH (10(-7) mol/l)-increased acid phosphatase and decreased alkaline phosphatase activities of bone tissue. The inhibitory effect of AHZ (10(-5) mol/l) on PTH (10(-7) mol/l)-stimulated bone resorption was clearly prevented by the presence of 10(-4) mol/l dipicolinate, a chelator of zinc. However, zinc sulfate (10(-7) to 10(-4) mol/l) did not inhibit the PTH (10(-7) mol/l)-stimulated bone resorption in tissue culture. These findings indicate that AHZ had a direct inhibitory effect on bone resorption in vitro, and the AHZ effect was found in the chemical form of zinc-chelated dipeptide.

Effects of the new anti-ulcer drug nizatidine on prostaglandins in the rat gastric mucosa.

The effects of nizatidine (N-[2-[[[2-[(dimethylamino)methyl]- 4-thiazolyl]methyl]thio]ethyl]-N'-methyl-2-nitro-1,1-ethenediamine , CAS 76963-41-2), a new histamine H2-receptor antagonist, on the content of prostaglandins (PGs) in the rat gastric mucosa at doses that inhibit basal gastric acid secretion were compared with those of two other histamine H2-receptor antagonists, cimetidine and ranitidine. Nizatidine did not inhibit basal gastric acid secretion at a dose of 0.4 mg/kg but showed dose-dependent inhibition at doses of 10, 30, and 100 mg/kg. This drug had no effects on the content of PG in the gastric mucosa when subcutaneously administered at doses of 0.4, 10, 30 and 100 mg/kg once daily for 5 days. Cimetidine and ranitidine administered at doses that markedly inhibit basal gastric acid secretion (250 and 100 mg/kg/d, respectively) had no effects on the content of PG in the gastric mucosa. On the other hand, nizatidine, cimetidine, or ranitidine at concentrations of 1-100 mumols/l did not inhibit in vitro PGE2 synthesis using sheep seminal vesicle microsomes. These results suggest that nizatidine did not affect in vitro PGE2 synthesis and even doses that markedly inhibit gastric acid secretion had no effects on the content of PGs in the gastric mucosa.