Discovery and preliminary SAR studies of a novel, nonsteroidal progesterone receptor antagonist pharmacophore

A series of 6-aryl-1,2-dihydro-2,2,4-trimethylquinolines was synthesized and tested for functional activity on the human progesterone receptor isoform B (hPR-B) in mammalian (CV-1) cells. The lead compound LG001447 (1,2-dihydro-2,2, 4-trimethyl-6-phenylquinoline) was discovered via directed high throughput screening of a defined chemical library utilizing an hPR-B cotransfection assay. Electron-withdrawing substituents at the meta position of the C(6) aryl group afforded substantial improvements in hPR modulatory activity. Several analogues were able to potently block the effects of progesterone in vitro. Two compounds, 10 (LG120753) and 11 (LG120830) with potencies comparable or equal to the steroidal hPR antagonist onapristone (ZK98,299), were demonstrated to act as antiprogestins in vivo after oral administration to rodents. This is the first disclosure of orally active nonsteroidal antiprogestins.

Preparation, resolution, and biological evaluation of 5-aryl-1, 2-dihydro-5H-chromeno[3,4-f]quinolines: potent, orally active, nonsteroidal progesterone receptor agonists

Two potent nonsteroidal progestins from the 5-aryl-1, 2-dihydro-5H-chromeno[3,4-f]quinoline class (LG120746 and LG120747) were selected for scale-up, resolution, and biological evaluation of the purified enantiomers. For each quinoline, the levorotatory enantiomer was determined to be the more potent agonist of the human progesterone receptor isoform B (hPR-B) (EC50 < 3 nM), but the dextrorotatory enantiomers retained significant PR modulatory activity (EC50 < 200 nM). In two in vivo rodent models of progestational activity, a pregnancy maintenance assay and a uterine wet weight assay, the two eutomers displayed potent progesterone-like effects. In a third model for progestational activity, the mammary end bud assay, these compounds were significantly less active. These studies demonstrate that certain members of this class of selective progesterone receptor modulators display encouraging and potentially useful tissue-selective progestational effects.

Rescue from apoptosis in early (CD34-selected) versus late (non-CD34-selected) human hematopoietic cells by very late antigen 4- and vascular cell adhesion molecule (VCAM) 1-dependent adhesion to bone marrow stromal cells

Monoclonal antibodies to very late antigen 4 (VLA-4) recognize the alpha4beta1 integrin receptor. This monoclonal antibody blocks the adhesion between early hematopoietic progenitor cells (CD34-selected cells) and stromal cells when added to cultures of these cells. Addition of the VLA-4 monoclonal antibody to cultures of stromal cells and CD34-selected cells was shown to induce apoptosis of CD34-selected cells in these CD34-selected cell/stromal cell cocultures, as measured by the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling method. In contrast to these experiments with early hematopoietic progenitor cells (CD34+), the level of adhesion between more differentiated cells (unfractionated hematopoietic cells) and stromal cells was not significantly altered by addition of the anti-VLA-4 monoclonal antibody. Similarly, the level of apoptosis of unfractionated hematopoietic cells was not significantly increased by the addition of anti-VLA-4 monoclonal antibody to cultures of the latter cells with stromal cells. The binding of the unfractionated cells is less than that of the CD34-selected cells. Given that there is no difference between the alpha4beta1 integrin expression level of the early and late myeloid cells, there may be a difference in the functional state of the integrin between the early and late myeloid cells. We also show that CD34+-selected precursor cells proliferate at a higher rate when these cells are plated on recombinant vascular cell adhesion molecule 1 molecules. These data indicate that the alpha4beta1 integrin receptor (VLA-4) plays a central role in the apoptosis rescue function that results from the anchorage-dependent growth of the CD34-selected early hematopoietic cells on stromal cells. The data suggest that these apoptosis rescue pathways have less significance as the cells mature and become anchorage independent in their growth. These data should assist in the design of systems for the ex vivo proliferation and transduction of early hematopoietic cells for genetic therapy.

Perception of body shape in elderly white and black men

In assessing the effects of age, physical activity and ethnic identity on perception of body shape in a group of 110 elderly men, the difference was significant for perception of current and ideal body shape, with the greatest difference for the 49 physically active black elderly men.

[Absorption, tissue distribution, and excretion of zinc acexamate in rats]

beta = 11.6 h. The bioavailability was about 52.8%. After ig [3H]ZA (4.44 MBq.kg-1), higher radioactivities were observed in kidney, liver, and gastrointestinal tract but lower in brain, fat, and femur.

CONCLUSION

ZA given i.g. in rats was absorbed rapidly and distributed widely to most of the organs and tissues.

Synthesis and biological activity of novel nonsteroidal progesterone receptor antagonists based on cyclocymopol monomethyl ether

A novel class of nonsteroidal progesterone receptor antagonists has been synthesized and was shown to exhibit moderate binding affinity for hPR-A, the ability to inhibit the transcriptional activity of human progesterone receptor (hPR) in cell-based assays, and anti-progestational activity in a murine model. Cyclocymopol monomethyl ether, a component of the marine alga Cymopolia barbata was weakly active in random screening against PR. Investigations into the SAR surrounding the core of this natural product lead structure resulted in improved in vitro activity. In contrast to the cross-reactivity profiles observed with known steroidal antiprogestins, compounds of the general structural class described display a high degree of selectivity for the progesterone receptor and no functional activity on the glucocorticoid receptor.

Activity of progesterone and anti-progestins in a rat mammary primary cell culture system

A primary culture system of virgin rat mammary epithelial cells, grown in a serum-free medium, was developed as a means of assaying the efficacy of compounds with known anti-progestational properties. Cells were grown in 24-well plates on hydrated collagen gels and could be cultured for at least seven days. Experiments were routinely stopped three days after overnight attachment of cells using fibronectin (4 micrograms/ml). DNA synthesis, measured by thymidine incorporation, was significantly increased by the addition of ovine prolactin (43 nM; P < 0.01) or progesterone (0.15 microM; P < 0.05) or both (P < 0.01) to the basal medium. When added to medium containing progesterone plus prolactin (complete medium), RU486 (mifepristone) and ZK98734 (lilopristone) significantly depressed DNA synthesis in a dose-dependent manner using doses ranging from 0.015 microM to 15 microM. Maximum inhibition was achieved at 15 microM for both compounds. DNA synthesis was 24.5 +/- 2.6% (mean +/- SEM, n = 4) and 32.0 +/- 2.2% (n = 3) of that in complete medium for RU486 and ZK98734, respectively (both P < 0.001). There was no inhibitory effect of either compound in basal medium or basal medium plus prolactin, indicating the absence of toxicity and that the inhibitory effect is specific for a progesterone-mediated process.

Diabetogenic effects of salmon calcitonin are attributable to amylin-like activity

During the development of synthetic calcitonins for therapeutic use in bone disease, a "diabetogenic" (hyperglycemic) effect was observed, particularly with salmon calcitonin. The effect was attributed by some to inhibition of insulin secretion. We have recently reported high-affinity (28 pmol/L) amylin-binding sites in certain areas of rat brain, and found that these sites also bind salmon but not rat calcitonin with comparable high affinity. Rat amylin and salmon calcitonin have been determined to have significant structural homology. In vitro and in vivo studies indicate that rat amylin can exert calcitonin-like effects on osteoclasts and on plasma calcium. Here we report that salmon calcitonin mimics the actions of rat amylin on skeletal muscle glycogen metabolism in vitro; it stimulates glycogenolysis and inhibits incorporation of radiolabeled glucose into glycogen (50% effective concentration [EC50], 0.4 +/- 0.11 nmol/L log and 8.4 +/- 0.05 nmol/L log, respectively). In anesthetized rats, salmon calcitonin, like rat amylin, rapidly increases plasma lactate concentration, followed by a slower increase in glucose concentration. Like amylin, salmon calcitonin also inhibits the insulin response to 2 mmol infused glucose (insulin increments suppressed by 52% and 57% at 10 minutes for salmon calcitonin and amylin). Other shared actions, such as suppression of appetite, stimulation of renin secretion, inhibition of gastric acid secretion, and inhibition of gastric emptying, further affirm our proposal that the exogenous peptide, salmon calcitonin, is a mimic of endogenous amylin in the rat.

Anti-progesterone effects on maternal recognition and behaviour imprinted during first pregnancy in mice

Anti-progesterone treatment using specific anti-progesterone antibodies or a progesterone receptor (PR) antagonist during first pregnancy impairs postpartum maternal behaviour in mice. This effect is demonstrable only if the treatment is given during pregnancy but not immediately after parturition. The purpose of the present studies was to investigate if maternal behaviour is also impaired by anti-progesterone treatment in subsequent pregnancies. Studies with a monoclonal antibody to progesterone (DB3; 4.5 nmol/mouse) showed that injection of females on day 17 of second pregnancy did not cause maternal rejection but the latency of pup retrieval was prolonged especially during the first 3 days of lactation. This phenomenon was not observed in animals that had previous experience of full length lactation. Experiments were carried out with mifepristone (RU486; 10 micrograms/mouse) injected at day 17 of first, second or third pregnancies. Pup rejection (22.5% vs 12.3%) and prolongation of the retrieval latency (62.3 +/- 13.3 vs 19.7 +/- 6.5 s; P < 0.02) were observed following the first pregnancy. No abnormal behavioural effects were found in mothers treated in second or third pregnancy who had prior full length lactation experience. Control females subjected to only one pup retrieval test after first delivery rejected their pups if treated in their second pregnancy (27.3% vs 4.4%; P < 0.001) and displayed a marginal prolongation of the retrieval latency period (20.9 +/- 7.0 vs 7.4 +/- 2.6 s). Anti-progesterone treatment had no negative influence when administered during third pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Progesterone and oestrogen receptors in the decidualized mouse uterus and effects of different types of anti-progesterone treatment

Pseudopregnant mice were treated systemically with monoclonal anti-progesterone antibody (DB3) (model 1), or progesterone receptor antagonists RU486 or ZK98,299 (ZK299) (model 2) on day 3 post coitum. On day 4, sesame oil was administered intraluminally into one uterine horn to induce decidualization. On day 7, the average mass of the oil-injected horn was 335.2 +/- 52.4 mg, eight times greater than that of the non-injected horn (40.8 +/- 5.3 mg; P < 0.001). After treatment with DB3, RU486 or ZK299, the masses of the injected horns did not differ significantly from those of non-injected horns. In the control group, concentrations of progesterone receptors (ligand-binding assay) increased twofold in the decidualized (52.2 +/- 7.4 fmol mg-1) compared with the non-injected horn (26.0 +/- 7.6 fmol mg-1; P < 0.05), whereas oestrogen receptor content (ligand-exchange assay) decreased by 53% (104.9 +/- 18.2 versus 224.3 +/- 18.1 fmol mg-1; P < 0.001). In model 1, antibody-treated animals showed a tenfold increase in the concentration of progesterone receptors (261.7 +/- 81.1 fmol mg-1; P < 0.001), but there was no differential distribution of progesterone or oestrogen receptors in the oil-injected versus non-injected uterine horns. In model 2, uterine progesterone and oestrogen receptors again showed no differential response between injected and non-injected horns regardless of the route of administration (systemic or intraluminal). Concentrations of progesterone receptors in RU486-treated (35.8 +/- 9.4 fmol mg-1) and ZK299-treated (32.0 +/- 10.2 fmol mg-1) mice were comparable to those in non-injected horns (35.3 +/- 6.3 and 34.2 +/- 5.1 fmol mg-1, respectively) and were not significantly different from the control group (26.0 +/- 7.6 fmol mg-1). The results show that oil-induced decidualization is accompanied by increased concentrations of progesterone receptors and decreased concentrations of oestrogen receptors. When decidualization is blocked by anti-progesterone treatment (antibody against progesterone or progesterone receptor antagonist), there are differing effects on receptor responses with an increase in progesterone receptors and decrease in oestrogen receptors after passive immunization, and no change in progesterone receptors and a reduction in oestrogen receptors after anti-progestins. The anti-decidualization effect in the two models was therefore achieved via dissimilar uterine receptor responses.

Specific interactions of progestins and anti-progestins with progesterone antibodies, plasma binding proteins and the human recombinant receptor

This structure-activity study compares the affinity of a series of progestins, progesterone metabolites and anti-progestins for a panel of monoclonal antibodies to progesterone, coypu (Myocastor coypus) or guinea pig plasma progesterone-binding proteins (PPBPs) and the human recombinant progesterone receptor A form (PR-A). The compounds tested were progesterone, Promegestone (R5020), Mifepristone (RU486), ZK98,734, Onapristone (ZK98,299), 11 alpha-hydroxyprogesterone, 11 alpha-progesterone hemisuccinate, androsterone, etiocholanolone, 5 alpha- and 5 beta-pregnane-3,20-diones, and 20 alpha- and 20 beta-hydroxyprogesterones. The Ki values for these ligands were determined by competitive binding assays using radiolabelled progesterone as the binding site ligand. For anti-progesterone antibodies (e.g. DB3 and 11/32), only progesterone (3.6-8.8 nM), the 11 alpha-derivatives (1.0-5.5 nM) used to prepare the immunogen and the two 5-pregnanediones (20.9-45.1 nM) were bound with high affinity. For PR-A, high affinity binding was found with receptor agonists (Ki = 1.1-6.2 nM), both 5- and 20-reduced metabolites, and antagonists (0.6-28.0 nM), but not with the 11 alpha-derivatives (950 nM-1.0 microM). In contrast, the PPBPs displayed high affinity interactions with progesterone (3.5-4.2 nM) and both 5 alpha- and 20 alpha-reduced metabolites (2.4-3.4 nM). Binding with the beta-isomers and R5020 was less pronounced (22-170 nM) and there was no evidence of high affinity binding with PR antagonists (> 1.0 microM). Analogs with the 17-keto group did not bind to any of the binders studied. Thus, commonalities among the three types of protein binders were their comparable binding affinities for progesterone (3.5-8.8 nM) and 5-pregnanedione isomers (2.4-330 nM), and a lack of binding for two C17-keto steroids (androsterone and etiocholanolone). The results imply that the tertiary features of the binding domain of these three types of proteins are sufficiently different to result in unique binding structures.

Anti-progesterone antibody administration and the impairment of postpartum maternal care in mice

Passive transfer of a monoclonal antibody against progesterone produces a high incidence of maternal rejection in mice after recovery from antibody-induced infertility. To investigate the mechanisms involved in this reduction of maternal care, we have examined whether the effect is due to long-term exposure to antibody. Antibody was administered i.p. either on day 2 or day 17 of pregnancy. When a low dose (1.0 nmol) was given on day 2, pregnancy proceeded normally but 44.8% pups delivered at term were rejected compared with 12.7% in the control group. When a higher dose (4.5 nmol) of antibody was given on day 17, pregnancy continued normally to term and the rejection rate was 48.8% (control: 11.1%). When the same amount of antibody was injected after delivery (day 1 of lactation), no detrimental effect was found on subsequent maternal care to the young, the rejection rate being comparable between antibody-treated and control groups (5.3% vs 4.6%). To determine if the presence of antibody interfered with lactation or suckling, a bolus injection of 10 microCi [3H]H2O was given to mice treated at day 17 with antibody or saline. The levels of radioactivity present in both mothers and pups and the first 5-day pup growth curves showed identical patterns, indicating that milk availability and the suckling process were not affected. Crossfostering studies revealed that antibody-treated mothers rejected 25.5% of fostered pups compared with 8.5% found in the control females when antibody was administered on day 17 of pregnancy and the entire litters were crossfostered between the two groups immediately after delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Aberrant maternal behaviour in mice treated with a progesterone receptor antagonist during pregnancy

The rapid onset of normal maternal behaviour after parturition in mice, consisting of cleaning, warming, feeding and protection of offspring, is primed by oestrogen, progesterone and oxytocin. Previous studies showed that passive transfer of monoclonal antibodies against progesterone significantly increases the incidence of maternal rejection of pups. To test the hypothesis that aberrant maternal behaviour is due to partial progesterone withdrawal leading to hormonal imbalance during late pregnancy, maternal rejection was assessed following treatment with a progesterone receptor antagonist. Mifepristone (RU486) was given subcutaneously on either day 2 (100 micrograms) or day 17 (50 micrograms) of pregnancy, or on the first day of lactation (100 micrograms). Maternal behaviour was monitored twice daily for the first 6 days of lactation and pup rejection recorded for a further 15 days. Maternal rejection was significantly greater after mifepristone administration on either day 2 or day 17 (28.6% and 38.3%) compared with controls (11.1% and 5.2% respectively). Rejection was negligible in both treated and control groups if mifepristone was given after parturition. When mothers were treated at day 17, the length of the latent period before pups were retrieved and returned to the nest was markedly increased in mifepristone-treated mothers (46.3 s) compared with controls (4.4 s) though the effect was transient. The results indicate that mifepristone interferes with the hormonal priming mechanism(s) necessary for the onset of normal maternal behaviour by a receptor-mediated effect. The similarity of the present results and those obtained with anti-progesterone antibodies implies that receptor antagonism or antibody scavenging of progesterone influence a common central nervous mechanism that is essential for the normal priming process.

The control of hyperacute rejection by genetic engineering of the donor species

Activation of endogenous complement is inhibited both in the soluble phase and at the membrane surface by a group of structurally similar proteins. A possible solution to hyperacute rejection is to produce donor animals transgenic for human complement regulators. Mouse cells expressing the human complement regulatory proteins decay accelerating factor (DAF) or membrane cofactor protein (MCP) were produced both by hybridoma technology and by transfection with the appropriate cDNAs. The expression of either or both of these products protected the mouse cell from lysis by human (though not rabbit) complement in the presence of naturally occurring human anti-mouse antibody. This effect could be abrogated by the addition of monoclonal antibody against DAF or MCP. Hyperacute rejection of discordant organ xenografts is mediated by human complement. A 6.5 kilobase minigene for DAF has been microinjected into porcine fertilised ova. Forty-five pigs transgenic for human DAF have been produced. Of these, 65% transcribe message. The amount of message produced varied substantially from animal to animal and was independent of copy number integrated. Expression of human DAF on the porcine lymphocyte surface could be detected and this was able to downregulate human complement activation. Amounts of protein expressed on different tissues varied both from pig to pig and within animals from tissue to tissue. The pigs grow and develop normally with no evidence of ill effects due to possession of the transgene.

Epstein-Barr virus-associated gastric adenocarcinoma in Taiwan

Fifty-five gastric carcinoma tumors from Chinese patients in Taiwan, including 40 tubular type (one lymphoepthelioma-like carcinoma subtype), eight signet ring cell type, one papillary type, and six mucinous type gastric carcinomas, were investigated for the presence of Epstein-Barr virus (EBV) transcripts by in situ hybridization using fluorescein-conjugated EBV oligonucleotides for EBERs (Epstein-Barr virus early RNAs) expression and the polymerase chain reaction for viral DNA. Epstein-Barr virus was detected in six of 55 lesions (11%), a significantly lower proportion than has been observed in a North American series. Epstein-Barr virus involvement was more common among male patients. Epstein-Barr virus DNA and its EBERs were specifically present within gastric carcinoma and adjacent dysplastic cells but were absent in surrounding lymphocytes and normal gastric mucosa. Epstein-Barr virus DNA and EBERs were found in one sample of lymphoepithelioma-like carcinoma (LELC) and five specimens of typical gastric adenocarcinoma. Among the EBV-positive gastric adenocarcinomas, four were tubular type of varied differentiation and one was signet ring cell type. Furthermore, we evaluated the expression of the latent membrane protein (LMP) with monoclonal antibodies. We found that LMP was expressed in two EBV-positive samples. In addition, the presence of the EBV receptor was studied by probing samples with CD21 monoclonal antibody. Epstein-Barr virus receptor was not detected in any sample. Southern blot analysis indicated single clonal proliferation of tumor cells. These findings confirm and extend the results of Shibata et al. They also indicate that EBV infection might be related to oncogenesis not only in rare gastric cancers that resemble nasopharyngeal lymphoepithelioma but also in typical gastric adenocarcinoma.

Abortifacient effects in the pregnant hamster of an antibody to progesterone are reversed by exogenous prolactin

A single i.p. injection of 10 nmol of a monoclonal antibody to progesterone (mAb-P4) on Day 4 of pregnancy (day of nidation) interrupts pregnancy by Day 8 (Day 1 = sperm-positive smear) in 75% of treated hamsters (n = 8). This correlates with structural and functional luteolysis, significantly (p < 0.05) reduced serum prolactin (PRL), and a nonsignificant trend for reduced FSH (which constitute the minimal luteotropic complex of the hamster), but LH is unchanged. Embryos implant and develop normally for a while, but by Day 8 the uterus is distended with the resorbing products of conception. The abortifacient effects of passive immunization against progesterone are reversed 100% by s.c. injection of 100 micrograms PRL daily on Days 4-7; deferring PRL treatment until Days 6-7 maintained pregnancy in 75% of the animals, still significantly different from the untreated mAb-P4 group. Injection of 50 micrograms PRL on Days 4-7 maintains pregnancy in 50% of the mAb-P4-treated hamsters (not significantly different), whereas 10 micrograms PRL on Days 4-7 is wholly ineffective. No dose of FSH (0.1-10.0 micrograms) or LH (0.4-2.0 micrograms) on Days 4-7 reversed the effects of mAb-P4; neither did 10 micrograms PRL plus 0.4 or 2 micrograms of FSH. The maintenance of pregnancy after 100 micrograms PRL on Days 4-7 is associated with normal serum levels of PRL, FSH, and LH and no change in the serum concentration of the mAb-P4 antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Creatine kinase activity as an indicator of unopposed estrogen action in the mouse uterus associated with anti-progesterone treatment

The brain isozyme of creatine kinase (CKB) is a major component of the estrogen-induced proteins in the rat uterus. Hormonal specificity of this response was studied in cotransfection assays using the rat CKB promoter linked to the bacterial chloramphenicol acetyltransferase gene. Response was specific for estrogen as 17 beta-estradiol in the presence of estrogen receptor dramatically stimulated the CKB promoter. This induction was completely blocked by the estrogen antagonist ICI 164,384. Nuclear receptors for progesterone, androgen, glucocorticoid and vitamin D did not significantly activate the CKB promoter in the presence of their respective ligands. Creatine kinase (CK) activity was analyzed in decidualized mouse uterus to assess estrogenic activity in vivo. Upon oil stimulation, uterine horns of day 4 pseudopregnant mice underwent a dramatic outgrowth in response to endogenous progesterone. This response was accompanied by a significant decrease in CK activity from a control value of 1.44 +/- 0.25 to 0.38 +/- 0.08 IU/mg protein (P < 0.001), indicating that the action of estrogen was suppressed. Treatment of females one day prior to oil-stimulation with progesterone receptor antagonists, RU486 (Mifepristone) or ZK299 (Onapristone), or with a monoclonal antibody to progesterone (DB3), abolished decidualization, and also restored the CK activity to the control value. These results suggest that CK can be used as a specific cellular marker to detect unopposed estrogen action in the mouse uterus associated with progesterone withdrawal or receptor blockade.

[Puerperal infection of ureaplasma urealyticum]

Using indirect agglutination test (IAT), ELISA and metabolic inhibition test (MI), serum specific IgM antibodies to ureaplasma urealyticum (Un) was investigated in 160 women of late pregnancy during the period of 1991-1992. 81 cases (50.6%) were found positive. 65 out of 81 positive mothers had umbilical blood samples examined and placenta tissues cultured. Specific IgM was detected in the umbilical blood of 7 women (10.8%), and ureaplasma urealyticum was isolated from 6 placenta (9.2%). Among Un IgM positive women, 28 (34.6%) were complicated with puerperal fever, and 30 newborns suffered from neonatal pneumonia and fever, which were significantly higher than that in the Un IgM negative group (P < 0.05). This study indicated that ureaplasma urealyticum might be one of the important pathogens for puerperal and neonatal infection.

The variant mRNA isoform of human metastasis gene (CD44V) detected in the cell lines of human hepatocellular carcinoma

The interaction of the cell surface receptor CD44 molecular with its ligands (addressin, extracellular matrix etc.,) plays an important role in fulfilling the lymphocyte homing and immune reaction. Recently alternatively spliced products of CD44 gene are found to be involved in tumor metastasis as well. Our report found that CD44 prototype RNA (CD44S) was present in all five tumor cell lines. Isoform CD44 RNA (CD44V) was recognized in three metastasized hepatocellular carcinoma cell lines, J5, HCC36, HEP3B. In addition, the J5 CD44 RNA isoform expressed two distinct transcripts which are of the same size as MDA-231 breast tumor cell line. The MDA-231 CD44 RNA variant (CD44V) has been confirmed to contain metastasis domain 4 and 5. It is implicated that the alternative RNA splicing may also play a major role in hepatocellular carcinoma metastasis.

Evidence for release of free glucose from muscle during amylin-induced glycogenolysis in rats

Amylin, a 37 amino acid product of pancreatic beta-cells, inhibits insulin-stimulated radioglucose incorporation into muscle glycogen. In the current study, we exercised rats and then prelabelled the glycogen pool by infusing [3-3H]glucose along with glucose and insulin. Subsequent amylin administration increased the rate of appearance of tritiated water 6.4-fold, consistent with stimulation of glycogenolysis and passage of the released moieties through the hexose --> triose step of glycolysis. Further, there was an increase in plasma [3-3H]glucose after amylin, consistent with the release of free glucose previously sequestered in muscle glycogen. Calcitonin gene-related peptide (8-37), an amylin antagonist, prevented these actions.

Response to intravenous injections of amylin and glucagon in fasted, fed, and hypoglycemic rats

The actions of intravenous glucagon and amylin, a newly discovered hyperglycemic pancreatic islet hormone, have been compared in 20-h fasted and fed, lightly anesthetized rats, and in rats made hypoglycemic with an insulin infusion. In fasted animals, amylin (75 nmol/kg) was more effective than glucagon (90 nmol/kg) in increasing plasma glucose (glucose increment 4.55 vs. 1.71 mM, P < 0.001). Amylin elicited a marked increase in plasma lactate, as previously reported, whereas glucagon did not alter plasma lactate. In fed animals, glucagon elicited twice as much increase in plasma glucose as did amylin; amylin again elicited a marked lactate increase that was greater (increment 1.45 vs. 0.97 mM, P < 0.05) and more prolonged than in the fasted state, whereas glucagon was without effect on lactate levels. These findings are consistent with glucagon's known action to promote hyperglycemia from hepatic glycogenolysis and amylin's demonstrated action to promote muscle glycogenolysis and increase lactate supply to the liver. Infusions of sodium lactate that produced plasma lactate increments similar to those evoked by 75 nmol/kg amylin evoked patterns of glucose response in fasted and fed rats similar to those evoked by amylin. Thus increased lactate supply to the liver may account for amylin's hyperglycemic effects. Amylin and glucagon could each restore plasma glucose to control levels in fasted animals made hypoglycemic by insulin infusion (plasma glucose reduced to 3.3 mM). A bolus of 75 nmol/kg amylin was more effective than 180 nmol/kg glucagon, restoring basal glucose levels for > 3 h, whereas glucagon restored it for < 1 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose response characteristics for the hyperglycemic, hyperlactemic, hypotensive and hypocalcemic actions of amylin and calcitonin gene-related peptide-I (CGRP alpha) in the fasted, anaesthetized rat

Amylin, a 37 amino-acid peptide secreted from the pancreatic beta-cells, exerts marked effects on carbohydrate metabolism in intact rats. It has approximately 50% amino-acid identity with the calcitonin gene-related peptides (CGRP) as well as certain shared biological actions. In vivo potencies were determined for four responses (increases in plasma glucose, increases in plasma lactate, decreases in plasma calcium, and depression of arterial pressure). These responses were measured in fasted, lightly anaesthetized rats given single intravenous bolus injections of rat amylin or rat CGRP alpha at doses of 0.01, 0.1, 1, 10, 100 and 1000 micrograms (about 7 pmol/kg-700 nmol/kg). Control animals received an equal volume of saline. The order of potency for the different responses was as follows: (i) increase in plasma glucose concentration, amylin approximately 2 times more potent than CGRP (by ED50) with detectable responses occurring at doses 100-fold less; (ii) decrease in plasma total calcium concentration, CGRP of equal or greater potency than amylin; and (iii) decrease in arterial pressure, CGRP 44-fold more potent than amylin. An increase in plasma lactate occurred with amylin doses 1000-fold lower than the CGRP doses producing such effects. Saturation of the dose-dependent increase in lactate was not observed, so median effective doses (ED50) were not obtained. These results are consistent with the existence of separate receptor systems for amylin and CGRP. The effects of amylin on plasma glucose and lactate concentrations were demonstrable at doses of 0.1-1.0 micrograms (70-700 pmol/kg). These doses produced plasma levels that were within the concentration range previously reported for insulin-resistant rats, supporting the proposal that amylin is a physiologic endocrine regulator of carbohydrate metabolism in vivo.