Ibipinabant attenuates ß-cell loss in male Zucker diabetic fatty rats independently of its effects on body weight.

AIM: To test the antidiabetic efficacy of ibipinabant, this new cannabinoid receptor 1 (CB1) antagonist was compared with food-restriction-induced weight loss, rosiglitazone (4 mg/kg) and rimonabant (3 and 10 mg/kg), using parameters of glycaemic control in male Zucker diabetic fatty (ZDF) rats. METHODS: Body weight, food and water intake, fasted and non-fasted glucose and insulin, glucose tolerance and glycosylated haemoglobin (HbA1c) were all assessed over the course of the 9-week study. Pancreatic insulin content and islet area were also evaluated. RESULTS: At the end of the study, vehicle-treated ZDF rats were severely hyperglycaemic and showed signs of ß-cell decline, including dramatic reductions in unfasted insulin levels. Ibipinanbant (10 mg/kg) reduced the following relative to vehicle controls: fasting glucose (-61%), glucose excursion area under the curve (AUC) in an oral glucose tolerance test (OGTT, -44%) and HbA1c (-50%). Furthermore, non-fasting insulin, islet area and islet insulin content were all increased (71, 40 and 76%, respectively) relative to vehicle controls by the end of the study. All of these effects were similar to those of rimonabant and rosiglitazone, where ibipinabant was slightly more effective than rimonabant at the lowest dose and somewhat less effective than rosiglitazone at all doses. These antidiabetic effects appear independent of weight loss because none of the parameters above were consistently improved by the comparable weight loss induced by food restriction. CONCLUSIONS: Ibipinabant may have weight loss-independent antidiabetic effects and may have the potential to attenuate ß-cell loss in a model of progressive ß-cell dysfunction.

Novel piperidine sigma receptor ligands as potential antipsychotic drugs.

sigma receptor ligands represent a new class of potential antipsychotic drugs. This paper presents the structure-activity relationships leading to novel disubstituted piperidine sigma ligands, which have little or no affinity for dopamine D2 receptors. Selectivity for sigma sites over dopamine D2 or serotonin 5-HT2 receptors appears to be governed by the chemical nature of the piperidine nitrogen substituent, its distance from the basic nitrogen, and its orientation relative to the other piperidine substituent. Several of these compounds have good oral potency in some animal models used to evaluate potential antipsychotic drugs. The N-cyclopropylmethyl ketones and ethers (e.g. 6i (DuP 734), 6q, 18a, and 18n) have the best in vivo potency. Compounds 6i (DuP 734) and 6q did not cause catalepsy in the rat, even at very high doses. On the basis of the pharmacology profiles of these sigma ligands, we propose these compounds may be effective antipsychotic drugs, which do not induce extrapyramidal side effects or tardive dyskinesia.

Attenuation of fear conditioning by antisense inhibition of brain corticotropin releasing factor-2 receptor.

Corticotropin releasing factor (CRF) is an important regulator of the endocrine, behavioral, autonomic and immune responses to stress. Two high affinity CRF receptors have been identified, which are distributed in distinct anatomical regions. CRF(1) receptors have been relatively well characterized and antagonists to this receptor effectively block stress-induced behaviors in rodents. The function of CRF(2) receptors, which are highly expressed in limbic brain regions, is less well understood. Therefore, an antisense oligonucleotide approach was used to study the role of CRF(2) receptors in the lateral septum in rats. An antisense oligonucleotide directed against the CRF(2) receptor mRNA reduced expression of CRF(2) receptors by 60--80%. In shock-induced freezing tests, animals administered the antisense oligonucleotide exhibited a significant reduction in freezing duration. However, pain sensitivity and locomotor activity were unaltered. A four-base mismatch of the antisense sequence had no significant effects on CRF(2) receptor density and on freezing behavior. These data support the involvement of CRF(2) receptors in fear conditioning. CRF(1) receptor antagonists also reduce freezing in this test. Additional studies to determine the effects of simultaneous inhibition of both receptor subtypes show that rats receiving both CRF(2) receptor antisense oligonucleotide and CRF(1) receptor antagonist froze significantly less than animals treated with either agent alone. These results provide additional evidence for the role of CRF(2) receptors in mediating the stress-induced actions of endogenous CRF.

Cumulative dose-effect curves in a conflict test with incremental shock.

Cumulative dose-effect curves were generated for chlordiazepoxide, diazepam, meprobamate, pentobarbital, morphine, and d-amphetamine in a Geller-Seifter conflict test with incremental shock. The anxiolytics increased responses in conflict significantly at one or more doses, whereas the non-anxiolytics d-amphetamine and morphine produced dose-related decreases. Results were consistent with previous data from the conventional one-dose-per-session design.

Metoclopramide potentiates d-amphetamine-induced hypermotility and stereotypy in rat.

The substituted benzamide metoclopramide has been reported to block the behavioral effects of dopamine agonists, whereas its congener sulpiride potentiates these effects. We injected metoclopramide 2.0, 4.0, or 8.0 mg/kg PO into rats 2 hr before d-amphetamine 1.5 mg/kg IP and measured locomotion for 3 hr. We injected metoclopramide 8.0 mg/kg PO into rats 2 hr before d-amphetamine 1.5, 3.0, or 6.0 mg/kg IP and measured stereotypy for 3 hr. Metoclopramide potentiated the effects of all doses of d-amphetamine on both measures; peak effects occurred in the second or third hr after d-amphetamine injection. Metoclopramide alone tended to reduce behavior. The results suggest that metoclopramide is qualitatively similar to sulpiride in its interaction with d-amphetamine, and that metoclopramide's mechanism of action is not a simple dopaminergic antagonism. Clinicians are advised that metoclopramide, which is presently extensively for gastrointestinal and other disorders, may interact adversely with drugs that affect dopaminergic function.

Effect of beta-phenylethylamine and d-amphetamine on electrical self-stimulation of brain.

beta-phenylethylamine (PEA) has been viewed as amphetamine-like in its effects on behavior. Support for this putative similarity of action has been derived primarily from observations that both of these structually related compounds increase locomotor activity in a dose-related manner and at higher doses evoke stereotypies. Since d-amphetamine (d-A) produces a dose-related increase in the rate of bar pressing for electrical stimulation of the medial forebrain bundle, the effect of PEA on this behavioral paradigm was examined. Male Long-Evans rats implanted with bipolar electrodes self-administered 250 msec 60 Hz constant current sine wave trains over a 30-70 micronA range of intensities in daily 20-min tests. Over a range of 1-40 mg/kg IP of PEA, a dose-related decrease in self-stimulation rate was observed; pretreatment with para-chlorophenylalanine or alpha-methyl-para-tyrosine did not alter the response to 2.5 or 3o mg/kg IP of PEA. Since within the dose range of PEA used in this study a dose-related increase in locomotor activity was observed, and since d-A increases self-stimulation rate at doses that increase locomotor activity, it would seem that there are qualitative differences in the actions of d-A and PEA on behavior.

DuP 734 [1-(cyclopropylmethyl)-4-(2'(4''-fluorophenyl)-2'- oxoethyl)piperidine HBr], a potential antipsychotic agent: preclinical behavioral effects.

It has been suggested that sigma receptors may be involved in the etiology of psychosis and that 5-hydroxytryptamine2 (5-HT2) antagonists may have utility in treating the negative symptoms of psychosis as well as reducing the side effects associated with the typical antipsychotic haloperidol. We have evaluated the potential antipsychotic effects of 1-(cyclopropylmethyl)-4-(2'(4''-fluorophenyl)-2'-oxoethyl)piper i din e HBr (DuP 734), a selective and potent sigma and 5-HT2 receptor ligand with weak affinity for D2 receptors, in behavioral animal models that are not necessarily dependent on dopamine antagonism. DuP 734 potently blocked mescaline-induced scratching (ED50 = 0.35 mg/kg, p.o.) and aggressive activity (ED50 = 1.9 mg/kg, p.o.) and was relatively much weaker as an apomorphine antagonist (ED50 = 12 mg/kg, p.o.). This was in contrast to the typical antipsychotic agents such as haloperidol and chlorpromazine, which were very potent in all three tests. In rats, DuP 734 did not antagonize avoidance behavior or induce catalepsy, and, therefore, differed from the potent dopamine receptor antagonist antipsychotics. It did, however, reduce lever response rates in a random interval 60-sec food reward schedule of reinforcement (ED50 = 6.0 mg/kg, p.o.) in rats. The results suggest that DuP 734 may have antipsychotic activity without the liability of motor side effects typical of neuroleptics. Although DuP 734 itself did not antagonize avoidance activity, it significantly enhanced the potency of haloperidol in blocking avoidance behavior by 3-fold (by shifting the ED50 from 0.94 to 0.36 mg/kg, p.o.), whereas the ED50 of haloperidol for blockade of escape behavior and induction of catalepsy was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritional requirements and biochemical activities of pineapple pink disease bacterial strains from Hawaii.

Bacteria which cause pink disease of pineapple, identified on the basis of their nutritional and biochemical activities, were found to belong to three genera. These bacteria include the following species: Gluconobacter oxydans, Acetobacter aceti, and Erwinia herbicola. Several pink disease strains required one to three vitamins for growth. Both G. oxydans strains 303D and 180 required biotin, nicotinic acid, and pantothenic acid for growth; E. herbicola 189 required only nicotinic acid; however, A aceti 295 was able to grow without any added supplements in glucose mineral salts medium. Optimal vitamin concentrations for maximal growth and optimal pH for the maximal number of generations per hour was established for a few pink disease strains.

Mucin-positive epithelial mesotheliomas: a histochemical, immunohistochemical, and ultrastructural comparison with mucin-producing pulmonary adenocarcinomas.

Pathologists routinely use histochemistry, immunohistochemistry, and electron microscopy to differentiate epithelial mesotheliomas from pulmonary adenocarcinomas. Epithelial mesotheliomas are usually mucicarmine-, PAS-diastase, and carcinoembryonic antigen-negative, whereas about 60-75% of pulmonary adenocarcinomas are mucicarmine- and PAS-diastase-positive, and about 90% express polyclonal carcinoembryonic antigen. During a pathologic evaluation of pleural neoplasms between 1975 and 1990, 10 epithelial mesotheliomas were identified that were mucicarmine- and in some instances PAS-diastase-positive (diagnosis of mesothelioma confirmed by ultrastructural examination), with four mesotheliomas focally expressing carcinoembryonic antigen. The mucicarmine, PAS-diastase, and carcinoembryonic antigen staining were usually eradicated or reduced in intensity by pretreatment of the tissue sections with hyaluronidase, suggesting that hyaluronic acid was responsible for the positive mucin reactions. In three cases the epithelial mesotheliomas showed focal regions of mucicarmine, PAS-d-, and Alcian blue-hyaluronidase-resistant staining. In contrast, 10 mucicarmine-, PAS-diastase-, Alcian blue-, and carcinoembryonic antigen-positive pulmonary adenocarcinomas were not affected by hyaluronidase pretreatment of the tissue. Besides the usual ultrastructural features of well- to moderately well-differentiated epithelial mesotheliomas, the mucin-positive epithelial mesotheliomas often showed medium-electron-dense secretory material covering the microvilli, aggregates of medium electron-dense material in association with the microvilli, producing an ultrastructural morphology that has been observed only in epithelial mesotheliomas.

Role of apolipoprotein E and B gene variation in determining response of lipid, lipoprotein, and apolipoprotein levels to increased dietary cholesterol.

A large segment of the population is modifying its dietary cholesterol intake to achieve a healthier life-style. However, all individuals do not respond equally. We have investigated the effects that that two physiologically important polymorphisms in the apolipoprotein (apo) E and B genes have on the responses of plasma lipid, lipoprotein, and apolipoprotein levels to a high-cholesterol diet. Over a 6-wk period, individuals were prescribed two diets, one consisting of 300 mg dietary cholesterol/d for 3 wk and one consisting of 1,700 mg dietary cholesterol/d for 3 wk. Total cholesterol, low-density-lipoprotein cholesterol (LDL-C), and apo B levels were significantly increased on the high-cholesterol diet. Average total cholesterol (numbers in parentheses are SDs) went from 167.6 (23.4) mg/dl on the low-cholesterol diet to 190.8 (36.2) mg/dl on the high-cholesterol diet; LDL-C went from 99.9 (24.8) mg/dl to 119.2 (33.4) mg/dl, and apo B went from 74.9 (24.5) mg/dl to 86.8 (29.5) mg/dl. In 71 individuals, the frequencies of the apo epsilon 2, epsilon 3, and epsilon 4 alleles were .09, .84, and .07, respectively. The frequency of the longer, apo B signal peptide allele (5'beta SP27) was .68. Apo epsilon 2/3 individuals had significantly lower LDL-C levels than did epsilon 3/3 homozygotes, on both the low-cholesterol diet (LDL-C lower by 21 mg/dl) and the high-cholesterol diet (LDL-C lower by 27 mg/dl). Average triglyceride levels were significantly different among apo B signal peptide genotypes, with the 5'beta SP27/37 homozygotes having the lowest levels (70 mg/dl). When individuals were switched from the low-cholesterol diet to the high-cholesterol diet, in no case were the average responses in lipid levels significantly different among apo E or B genotypes. Therefore, these gene loci do not have a major effect on the response of lipid levels to increased dietary cholesterol.

RANK is essential for osteoclast and lymph node development.

The physiological role of the TNF receptor (TNFR) family member, RANK, was investigated by generating RANK-deficient mice. RANK(-/-) mice were characterized by profound osteopetrosis resulting from an apparent block in osteoclast differentiation. RANK expression was not required for the commitment, differentiation, and functional maturation of macrophages and dendritic cells from their myeloid precursors but provided a necessary and specific signal for the differentiation of myeloid-derived osteoclasts. RANK(-/-) mice also exhibited a marked deficiency of B cells in the spleen. RANK(-/-) mice retained mucosal-associated lymphoid tissues including Peyer's patches but completely lacked all other peripheral lymph nodes, highlighting an additional major role for RANK in lymph node formation. These experiments reveal that RANK provides critical signals necessary for lymph node organogenesis and osteoclast differentiation.