bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Estradiol and Soy Phytoestrogens on Choline Acetyltransferase and Nerve Growth Factor mRNAs in the Frontal Cortex and Hippocampus of Female Rats
Authors: Pan Yuanlong , Anthony Mary , Clarkson Thomas B.
Published: November 2003

We report here the effects of oral micronized estradiol and soy phytoestrogens on uterine weight, choline acetyltransferase (ChAT) and nerve growth factor (NGF) mRNAs in the frontal cortex and hippocampus of ovariectomized young and retired breeder rats. Within each age category, 15 bilaterally ovariectomized rats were randomized equally into three groups: control (OVX), estradiol (E2), and soy phytoestrogens (SBE). The OVX rats were fed a casein/lactalbumin‐based control diet; the E2 rats were fed with the control diet with added estradiol; and the SBE rats were fed with the control diet with added soy phytoestrogens. After 8 weeks of treatment, blood, uteri, frontal cortex, and hippocampus were collected at necropsy. Results showed that the uterine weights and serum estradiol concentrations were significantly higher in the E2 group compared with those in the OVX and SBE groups. In the hippocampus of young rats, E2 treatment resulted in significantly higher NGF mRNA levels than no treatment (OVX), and NGF mRNA levels in the SBE group were intermediate between the E2 and OVX groups. ChAT mRNA levels were significantly higher in the frontal cortex of E2 and SBE‐treated retired breeder rats compared to OVX retired breeder rats. There were no differences among treatment groups for ChAT mRNA levels in the frontal cortex of young rats and in the hippocampus of both young and retired breeder rats. Our data suggest that soy phytoestrogens may function as estrogen agonists in regulating ChAT and NGF mRNAs in the brain of female rats.
Brain Aromatase in Control Versus Castrated Norway Brown, Sprague‐Dawley and Wistar Adult Rats
Authors: Mathias Lori J. , Jacobson Nathan A. , Rhees Reuben W. , Lephart Edwin D.
Published: November 2003

Brain aromatase cytochrome P450 converts androgens to estrogens that play a critical role in the development of sexually dimorphic neural structures, the modulation of neuroendocrine function(s), and the regulation of sexual behavior. We characterized the influence of surgical castration on brain aromatase in Norway Brown and Wistar adult rats and compared their responses to Sprague‐Dawley rats that were surgically or biochemically castrated (with flutamide, a known androgen receptor blocker). Aromata enzyme activity was measured by the tritiated water release assay in the medial basal hypothalmus/preoptic area (MBH/POA) and amygdala brain regions. The present results demonstrate that independent of the rat strain examined, MBH/POA aromatase is regulated by androgens (in Sprague‐Dawley, Norway Brown and Wistar males). However, intact Wistar animals displayed significantly higher MBH/POA aromatase levels compared to Sprague‐Dawley control values. Conversely, in the amygdala region, there was an apparent lack of androgen hormone action upon aromatase enzyme activity in some of the rat strains tested. The importance of brain aromatase regulating estrogen biosynthesis and influencing brain development and function is covered.
Brain Aromatase and 5α‐Reductase, Regulatory Behaviors and Testosterone Levels in Adult Rats on Phytoestrogen Diets
Authors: Weber K. Scott , Jacobson Nathan A. , Setchell Kenneth D. , Lephart Edwin D.
Published: November 2003

The purpose of this study was to examine the short‐term effects of phytoestrogens in the diet on regulatory behaviors (food/water intake and locomotor activity), prostate weight, testosterone levels, and brain androgen metabolizing enzyme activity levels in adult male rats. Sprague‐Dawley rats were fed phytoestrogen‐containing versus phytoestrogen‐free diets for 29 days. Standard methods were used to measure open field behavior, reproductive, hormonal parameters, and enzymatic activity levels. The phytoestrogen diet contained ≈200 μg/g of isoflavones whereas in the phytoestrogen‐free diet, no phytoestrogens were detected by HPLC analysis. There were no significant differences in any of the regulatory behaviors (food/water intake or locomotor activity), prostate weight, or testosterone levels between the treatment groups. Furthermore, there was no significant influence of phytoestrogens on brain aromatase activity levels, in either the medial basal hypothalamic‐preoptic area (MBH‐POA) or amygdala brain tissue sites examined. However, significant alterations in MBH‐POA and amygdala 5α‐reductase activities were detected in animals receiving the phytoestrogen‐containing versus the phytoestrogen‐free diets.
Inhibition of Water Permeability in the Rat Collecting Duct: Effect of Imidazoline and Alpha‐2 Compounds2
Authors: Kudo Lúcia H. , Hébert Connie A. , Rouch Alexander J.
Published: November 2003

Arginine vasopressin (AVP) increases water permeability in the collecting duct of the nephron via activation of adenylyl cyclase. Alpha‐2 (α2) agonists inhibit AVP‐stimulated water permeability via binding to α2 adrenoceptors that have been divided into 3 subtypes‐ α2A, α2B, and α2C. Some biological effects mediated by α2 agonists result from nonadrenergic imidazoline receptors that exist in the rat kidney. Thus, α2‐inhibition of AVP‐stimulated water permeability in the rat collecting duct could be caused by imidazoline receptors. The purpose of this study was to test agonists and antagonists selective for α2 and imidazoline receptors on AVP‐stimulated water permeability in the rat inner medullary collecting duct (IMCD). Some experiments were conducted where water permeability was stimulated by a nonhydrolyzable analog of adenosine 3′, 5′‐cyclic monophosphate (cAMP). Agonists included dexmedetomidine, clonidine, oxymetazoline, agmatine and rilmenidine. The latter two are selective imidazoline agonists. Antagonists included yohimbine, RX821002, atipamezole, prazosin, WB4101, idazoxan, and BU239. Prazosin and WB4101 demonstrate selectivity for the α2B and α2C subtypes, respectively, and oxymetazoline and RX821002 are selective for the α2A subtype. BU239 is selective for imidazoline receptors. Wistar rat terminal IMCDs were isolated and perfused to determine the osmotic water permeability coefficient (Pf). All agonists except agmatine inhibited AVP‐stimulated Pf. Inhibition by rilmenidine indicated a different mechanism of action from other agonists. Dose‐response data show dexmedetomidine to be the most potent inhibitor. Oxymetazoline and clonidine inhibited cAMP‐stimulated Pf indicating that the mechanism involves postcAMP cellular events. It was reported previously that dexmedetomidine inhibits cAMP‐stimulated Pf (1). All antagonists except prazosin and WB4101 reversed α2‐inhibition of AVP‐stimulated Pf. BU239 was effective at 1 μM but not at 100 nM. Results suggest that α2A adrenoceptors modulate water permeability in the IMCD. The involvement of imidazoline receptors is inconclusive.
Copper Deprivation Potentiates Oxidative Stress in HL‐60 Cell Mitochondria
Authors: Johnson W. Thomas , Thomas Anne C.
Published: November 2003

Cytochrome‐c oxidase is the copper‐dependent terminal respiratory complex (complex IV) of the mitochondrial electron transport chain whose activity in a variety of tissues is lowered by copper deficiency. Because inhibition of respiratory complexes increases the production of reactive oxygen species by mitochondria, it is possible that copper deficiency increases oxidative stress in mitochondria as a consequence of suppressed cytochrome‐c oxidase activity. In this study, the activities of respiratory complex I + III, assayed as NADH:cytochrome‐c reductase, complex II + III, assayed as succinate:cytochrome‐c reductase, complex IV, assayed as cytochrome‐c oxidase, and fumarase were measured in mitochondria from HL‐60 cells that were grown for seven passages in serum‐free medium that was either unsupplemented or supplemented with 50 n M CuSO4. Fumarase activity was not affected by copper supplementation, but the complex I + III:fumarase and complex IV:fumarase ratios were reduced 30% and 50%, respectively, in mitochondria from cells grown in the absence of supplemental copper. This indicates that copper deprivation suppressed the electron transfer activity of copper‐independent complex I + III as well as copper‐dependent complex IV. Manganese superoxide dismutase (MnSOD) content was also increased 49% overall in the cells grown in the absence of supplemental copper. Furthermore, protein carbonyl groups, indicative of oxidative modification, were present in 100‐kDa and 90‐kDa proteins of mitochondria from copper‐deprived cells. These findings indicate that in cells grown under conditions of copper deprivation that suppress cytochrome‐c oxidase activity, oxidative stress in mitochondria is increased sufficiently to induce MnSOD, potentiate protein oxidation, and possibly cause the oxidative inactivation of complex I.
The I/D Polymorphism of Angiotensin‐Converting Enzyme Gene but not the Angiotensinogen Gene is Associated with Insulin Response to Oral Glucose in Japanese
Authors: Duc Cong Nguyen , Hamaguchi Kazuyuki , Saikawa Tetsunori , Hara Masahide , Sakata Toshiie
Published: November 2003

Polymorphisms of angiotensin‐converting enzyme (ACE) and angiotensinogen (AGT) genes have been reported to be associated with myocardial infarction and coronary artery disease, both of which are closely related to atherosclerosis and insulin resistance. In this study, we investigated the association between ACE and AGT genotypes and insulin sensitivity in a sample of 142 nondiabetic and 64 noninsulin‐dependent diabetes mellitus (NIDDM) Japanese subjects, aged 62.7 ± 9.5 years. The insulin response to the 75‐g oral glucose tolerance test (OGTT) was significantly lower in subjects with the ACE D/D genotype compared to those with the I allele (I/D and I/I genotypes) in both nondiabetic (P < 0.05) and NIDDM subjects (P < 0.005). These homozygous D/D subjects also had lower insulin area under the curve of plasma insulin concentrations during OGTT compared to those with the I allele in nondiabetic (P < 0.05) and NIDDM subjects (P < 0.01). However, there was no significant association between AGT genotypes and either insulin response or insulin area under the curve during OGTT, in either nondiabetic or NIDDM subjects. From a viewpoint that insulin response to oral glucose is significantly correlated with insulin sensitivity, these results suggest that polymorphic variations at the ACE gene, but not the AGT gene, may be involved in the genetic regulation of insulin sensitivity in both nondiabetic and NIDDM Japanese subjects.
Neurochemical Alterations During Age‐Related Anorexia
Authors: Blanton Cynthia A. , Horwitz Barbara A. , McDonald Roger B.
Published: November 2003

Unexplained weight loss during the latter stages of aging is commonly preceded by a spontaneous diminution in food intake. Multiple etiologies of age‐related anorexia in humans, ranging from social isolation to impaired gastrointestinal function, have been proposed. The observation of this phenomenon in older laboratory animals suggests that physiological changes play a significant causal role. A continually expanding body of information on the neurochemical control of food intake supports a contribution of altered neurochemistry to dysregulated feeding behavior. This review provides an update on the relationship between declining food intake during advanced age and physiological (specifically neurochemical) function. The complexity of the control of food intake as well as the variety of investigative methods used in this field of study render the identification of definitive causes difficult. Evidence presented here is evaluated and possible etiologic factors are suggested.
Hemodynamic and Renal Effects of ProANF31–67 in Hypertensive Rats
Authors: Villarreal Daniel , Reams Garry P. , Taraben Amir , Freeman Ronald H.
Published: November 2003

It has been demonstrated previously that the atrial natriuretic factor prohormone fragment 31–67 (ProANF31–67) circulates in animals and possesses natriuretic and vasodilating actions. Although the plasma levels of the peptide are reportedly elevated in patients with high blood pressure, its role and actions in hypertension are unknown. In the present study, synthetic human ProANF31–67 was infused intravenously at doses of 0, 10, 30, and 100 ng/kg/min into respective groups of anesthetized normotensive and spontaneously hypertensive rats. Mean arterial pressure (MAP), urine flow rate (UV), and sodium excretion (UNaV) were measured during two consecutive 30‐min periods. In both strains of rats, reductions in MAP with ProANF31–67 were similar in magnitude and dose‐related. Sodium excretion responses to the peptide infusions also were remarkably similar in both normotensive and hypertensive rats, and the responses demonstrated 3‐ to 5‐fold (P < 0.05) increments compared to control at the doses of 10 and 30 ng/kg/min. However, in the two strains of rats, attenuation of natriuresis occurred with the highest infusion dose of 100 ng/kg/min and was probably related to the large decreases in MAP of 17–23 mmHg at this dose of the peptide. The present results indicate the ProANF31–67 has important hemodynamic and renal effects in hypertension and may represent one compensatory mechanism involved in this disease.
Serum Leptin Concentrations in Response to Acute Exercise in Postmenopausal Women With and Without Hormone Replacement Therapy
Authors: Kraemer R. R. , Johnson L. G. , Haltom R. , Kraemer G. R. , Hebert E. P. , Gimpel T. , Castracane V. D.
Published: November 2003

The purpose of the study was to examine the effects of acute exercise and hormone replacement therapy on serum leptin concentrations in postmenopausal women. Subjects were 15 healthy, postmenopausal women, 8 on hormone replacement therapy (HRT) and 7 not on hormone replacement therapy (NHRT). Group comparisons indicated no significant differences between HRT and NHRT groups with respect to age, height, weight, BMI, sum of skinfolds, or VO2max, and verified significant differences in estradiol and FSH concentrations. After an overnight fast, each subject completed 30 min of treadmill exercise at ≈80% VO2max. Over 2 hr and 10 min, baseline, exercise, and recovery blood samples were collected from an intravenous catheter. A control session conducted a month later consisted of the same blood sampling protocol without exercise. Leptin concentrations declined significantly over the course of both the exercise and control sessions, gradually decreasing from baseline levels to −1.54 ± 0.49 ng · ml−1 postexercise, and continuing to decline to a low of −2.89 ± 0.59 ng · ml−1 at the end of the session. There was no significant difference between groups with respect to this decline. This is the first study to document that diurnal changes in leptin concentrations in postmenopausal women are not altered by acute treadmill exercise or HRT status. The study underscores the need to account for a diurnal reduction in leptin over the course of an exercise trial.
Immune Function in Transgenic Mice Overexpressing Growth Hormone (GH) Releasing Hormone, GH or GH Antagonist
Authors: Dialynas Emmanuel , Brown‐Borg Holly , Bartke Andrzej
Published: November 2003

Effects of life‐long exposure to high levels of homologous or heterologous growth hormone (GH) and effects of GH resistance on selected parameters of immune function were studied in adult male transgenic mice overexpressing GH releasing hormone (GHRH), bovine (b) GH or an antagonistic bGH analog. In metallothionein I (MT)‐bGH transgenic mice with high peripheral levels of bovine GH, there were significant increases in the absolute weight of the thymus and the spleen and in the mitogenic responses of splenocytes to concanavalin A (ConA), lipopolysaccharide (LPS) and phytohemagglutinin (PHA), as compared to age‐matched normal animals. There were no significant differences between MT‐bGH transgenic and normal mice in splenocyte viability or in delayed‐type hypersensitivity measured by the allergic contact dermatitis response to oxazolone. Similar results, including significant stimulation of splenocyte responses to ConA, LPS, and PHA, were obtained in MT‐hGHRH transgenic mice in which overexpression of GHRH leads to striking pituitary enlargement and massive elevation of peripheral levels of homologous (mouse) GH. In MT‐bGH‐antagonist transgenic mice in which overexpression of an antagonistic bGH analog interferes with the actions of endogenous GH, spleen weight was reduced but proliferative responses of splenocytes to ConA, LPS, and PHA were not affected. It is concluded that overexpression of heterologous or homologous GH in transgenic mice can lead to significant stimulation of some parameters of immune function, whereas antagonism of GH action by expression of an antagonistic GH analog does not affect splenocyte responses to mitogens.
Atrial Natriuretic‐Like Peptide and its Prohormone Within Metasequoia
Authors: Yang Qun , Gower Jr. William R. , Li Chunxiang , Chen Peiji , Vesely David L.
Published: November 2003

Metasequoia glyptostroboides was one of the dominant conifers in North America, Asia, and Europe for more than 100 million years since the late Cretaceous Albian Age, but Quaternary glaciations drove the Metasequoia population to apparent extinction. A small pocket of Metasequoia, however, was found in central China in the 1940s representing the only surviving population of this “living fossil” species. Atrial natriuretic peptide, a 28‐amino‐acid peptide hormone that causes sodium and water excretion in animals, has been found to be part of the first peptide hormonal system in lower plants. The existence of this hormonal system has never been examined within trees of any genus. High‐performance gel permeation chromatography of the leaves and stems (i.e., branches) of Metasequoia followed by atrial natriuretic peptide radioimmunoassay revealed an ANP‐like peptide and its prohormone (i.e., ≈ 13,000 mol wt) were present in both leaves and stems of this conifer. The elution profile of ANP‐like peptide in stems of Metasequoia had a shoulder to the left of where pure synthetic ANP elutes suggesting the possibility of a slightly larger peptide eluting within this shoulder secondary to alternate processing of the ANP‐like prohormone and similar to what occurs with the kidney of animals. The elution profile of ANP‐like peptide in the leaves of Metasequoia revealed two peaks; one where ANP elutes and a second peak suggesting a smaller peptide that has been metabolically processed. The presence of the ANP‐like prohormone strongly suggests that ANP‐like gene expression is occurring in both leaves and stems of Metasequoia since this prohormone is the gene product of this hormonal system. The presence of the ANP‐like hormonal system in trees implies that this hormonal system may have been present early in land plant evolution to allow trees to reach heights of greater than 30 feet where a water flow‐enhancing substance is absolutely necessary for water flow to occur to these heights.
Opposing Actions of Dehydroepiandrosterone and Corticosterone in Rats
Authors: McIntosh M. , Bao H. , Lee C.
Published: November 2003

The purpose of this study was to determine the impact of dehydroepiandrosterone (DHEA) and corticosterone (CORT) treatment, using implants as a route of administration, on specific hormones, metabolites, and enzymes involved in energy metabolism. Sixty male Sprague‐Dawley rats, 325 g initial weight, were implanted subcutaneously for 3 weeks with time‐release pellets containing either DHEA or CORT at doses of 0, 10, 25, 50, or 100 mg in this 2 × 5 factorial experiment. In general, body weights and food intakes decreased as the level of steroid hormones increased. In contrast to DHEA treatment, rats receiving the 50‐ and 100‐mg doses of CORT had lighter thymus glands and spleens and heavier epididymal and retroperitoneal fat pads than their controls. Rats treated with 100 mg of DHEA had lowered serum levels of triglycerides and lipid hydroperoxides whereas rats treated with 100 mg of CORT had higher levels of these blood lipids compared to their respective controls. In contrast to DHEA treatment, there was a dose‐dependent increase in liver lipid content and the specific activities of the hepatic lipogenic enzymes glucose‐6‐phosphate dehydrogenase, malic enzyme, and fatty acid synthase in response to CORT treatment. Rats treated with 100 mg of DHEA had higher serum levels of IGF‐1 than control rats. Conversely, rats treated with 100 mg of CORT had lower serum levels of IGF‐1 and higher serum levels of testosterone, progesterone, and insulin than their controls. These data demonstrate the lipogenic actions of corticosterone in rats. Conversely, DHEA treatment reduced serum and hepatic lipids. Furthermore, these data suggest that using implants instead of bolus injections of steroids may be a more physiological approach for studying the influence of these steroids on lipid metabolism.
Efficacy of Providing Nicotine in a Liquid Diet to Rats
Authors: Halladay Alycia K. , Schwartz Michael , Wagner George C. , Iba Michael M. , Sekowski Anna , Fisher Hans
Published: November 2003

To determine if rats would consume nicotine at psychoactive levels, a nutritionally balanced diet with 0, 20, 60, or 200 mg of nicotine tartrate per kg of diet was provided. Diet consumption and body weight differences were recorded for 14 days after which, following 16 hr of withdrawal, animals were given access to a two‐bottle choice of the previously presented diet and a nicotine‐free diet. Spontaneous horizontal motor activity was recorded 8, 16, and 24 hr after withdrawal. By Day 14, all animals showed a significant increase in diet consumption and significant weight gain compared to Day 1. Animals consumed an average of 2.1, 6.8, or 19.5 mg/kg/day of nicotine on the low, medium, and high‐nicotine diets, respectively. However, animals receiving the high‐nicotine diet consumed less diet and gained less weight than the control, low, and medium nicotine groups. During only the first 4 hr of the two‐bottle choice (16–20 hr postwithdrawal), the high‐nicotine group consumed significantly higher amounts of nicotine base than the other groups, but also consumed more of the control diet during the first 2 hr. In a replicate experiment, animals receiving the medium‐nicotine diet showed an increased consumption of the nicotine diet and increased preference for nicotine following a 14‐day exposure compared to the control‐fed animals and compared to a baseline preference test. Also, this group showed differences in locomotor activity consistent with other studies using an injection regimen or subcutaneuos pumps to induce dependence. Finally, animals in all three groups exhibited high plasma nicotine and cotinine (a major nicotine metabolite) levels. Because animals in all groups tolerated the diet well, gained weight, selected the nicotine diet in a choice test, and showed withdrawal symptoms, we conclude that the liquid diet proved to be a satisfactory method of inducing nicotine dependence in rats.
Carboxypeptidase E (CPE) Deficiency in Mice with the Fat Mutation Have Reduced Stomach Function
Authors: Gomez Pablo , Hallberg Lance , Greeley Jr. George H.
Published: November 2003

An obese mouse model (Cpefat/Cpefat) that has hyperproinsulinemia and late onset obesity has been described. Cpefat/Cpefat mice have a missense mutation in carboxypeptidase E (CPE), a processing enzyme essential for production of biologically active endocrine and neuroendocrine peptides. We have reported previously that CPE activity was absent in the antrum of the stomach and that processing of progastrin to the amidated biologically active form of gastrin is reduced. Since gastrin is a major secretagogue for gastric acid secretion, the purpose of the present experiments was to examine gastric acid secretion in Cpefat/Cpefat mice. In addition, secretion of amidated gastrin in response to inhibition of acid secretion was tested in Cpefat/Cpefat. Both gastric acid and challenged gastrin secretion are reduced in Cpefat/Cpefat mice. We conclude that stomach CPE activity is essential for gastric secretory activity and for challenged gastrin release.
Comparison of Verapamil and Felodipine Treatment on Lipid and Glucose Metabolism in Obese Female SHHF/Mcc‐facp Rats
Authors: Park Sonhee C. , Radin M. Judith , Hoepf Toni , McCune Sylvia A.
Published: November 2003

Calcium channel blockers, verapamil or felodipine, were given to genetically obese 6 and 11‐month‐old female SHHF/Mcc‐facp (SHHF: Spontaneous Hypertension Heart Failure) rats for 8 weeks to investigate their effects on glucose and lipid metabolism and obesity. Both antihypertensive agents significantly decreased systolic blood pressure. In 11‐month‐old rats, verapamil treatment significantly decreased body weight after 4 weeks whereas with felodipine it was only significantly reduced after 8 weeks. In 6‐month‐old rats, verapamil significantly curtailed body weight gain. Subcutaneous fat depots were smaller, and abdominal fat depots were larger in verapamil rats compared to felodipine or control rats. Oral glucose tolerance tests in the 6‐month‐old verapamil and the 11‐month‐old felodipine groups showed improved glucose tolerance compared to their respective control groups. After 8 weeks of treatment, fasting plasma glucose levels were lower in 6‐month‐old verapamil rats compared to felodipine and control rats and were decreased by both verapamil and felodipine treatments as compared to control in 11‐month‐old rats. During the oral glucose tolerance test in 6‐month‐old rats, both fasting plasma insulin and the area under the insulin curve were increased in verapamil compared to both control and felodipine groups. When compared to controls, plasma cholesterol was increased by verapamil in both age groups, but was significantly decreased by felodipine after 8 weeks of treatment in the 11‐month‐old group. Plasma triglycerides increased in all control rats compared to initial levels; however, verapamil and felodipine groups showed lower triglycerides in both age groups. In 6‐month‐old rats, the percentages of plasma HDL significantly increased in both treatment groups as compared to control. This study shows that verapamil and felodipine depressed body weight gain in the young rats, reduced body weight in the old rats, improved lipid parameters and glucose tolerance, but had the opposite effects on body fat distribution and insulin levels in obese female SHHF rats.
Changes in Ryanodine Receptor‐Mediated Calcium Release During Skeletal Muscle Differentiation
Authors: Wingertzahn Mark A. , Ochs Raymond S.
Published: November 2003

We have observed a disparity between the actions of caffeine and ryanodine, two agents known to affect the same site of intracellular calcium (Ca2+) release in muscle. The site of intracellular Ca2+ release, the ryanodine receptor (RyR), is established as the route of Ca2+ movement from the sarcoplasmic reticulum (SR) to the cytosol during excitation‐contraction coupling. We measured Ca2+ release fluorimetrically in both saponin‐permeabilized and intact L6 cells, in response to known modulators (i.e., caffeine and ryanodine), during differentiation in vitro. The undifferentiated L6 cells showed little response to caffeine. However, a substantial caffeine‐induced calcium release (caffCR) was evident by Day 3 of differentiation, and was nearly maximal by Day 7 of differentiation. By contrast, ryanodine failed to stimulate Ca2+ release until Day 4, lagging behind the caffeine response. Ryanodine‐stimulated Ca2+ release was also maximal by Day 7. Higher concentrations of ryanodine, known to inhibit Ca2+ release, only began to affect caffCR at Day 4, indicating that cells were insensitive to both ryanodine stimulation and ryanodine inhibition prior to this time. Most of the results could be obtained both in permeabilized and intact cells. Using intact cells, we measured the time course of K+ ‐dependent (i.e., depolarization‐induced) Ca2+ release. This time course matched caffeine and not ryanodine‐induced Ca2+ release suggesting the action of caffeine was not due to Ca2+ release unrelated to excitation‐contraction coupling. These findings suggest that ryanodine binding sites on the RyR may not be functional at early stages of muscle development, that ryanodine sensitivity is a poor indicator of Ca2+ flux through the RyR, or that other proteins are involved in Ca2+ release under certain circumstances.
Regulation of PreB Cell Apoptosis by Aryl Hydrocarbon Receptor/Transcription Factor‐Expressing Stromal/Adherent Cells
Authors: Near Richard I. , Matulka Raymond A. , Mann Koren K. , Gogate Shaila U. , Trombino Anthony F. , Sherr David H.
Published: November 2003

Polycyclic aromatic hydrocarbons (PAH) are environmental chemicals that mediate immunosuppression. In long‐term bone marrow B‐cell lymphopoiesis models, PAH induce apoptosis in immature (preB) lymphocytes. Since the biologic function of PAH is often mediated by the aryl hydrocarbon receptor/transcription factor (AhR), the role of the AhR or AhR‐regulated genes was assessed in preB cell apoptosis. Specifically, a bone marrow–derived preB cell line (BU‐11) was cultured on monolayers of the AhR + bone marrow–derived stromal cell line BMS2, hepatoma sublines that express various levels of AhR activity (Hepa‐1c1c7 and variants), AhR+ thymic epithelial cells, and primary bone marrow stromal cells from wildtype or AhR−/− mice. Cultures were treated with one of two prototypic PAH, 7,12‐dimethylbenz[a] anthracene (DMBA) or benz[a]pyrene (B[a]P), and the percentage of cells undergoing apoptosis measured. The data demonstrated that: 1) bone marrow‐ and hepatic‐derived stromal/adherent cells support preB cell growth and regulate apoptosis induced by DMBA or B[a]P; 2) B[a]P is more effective than DMBA when preB cells are maintained on Hepa‐1c1c7 monolayers than when maintained on BMS2 monolayers; 3) DMBA is more effective than B[a]P when preB cells are cultured on BMS2 monolayers; 4) α‐naphthoflavone, an AhR antagonist and cytochrome P‐450 inhibitor, blocks preB cell apoptosis in both BU‐11/Hepa‐1c1c7 and BU‐11/BMS2 cultures; 5) although preB cells grow well in Hepa‐1c1c7 or BMS2 supernatants, addition of PAH in the absence of hepatic– or bone marrow–derived adherent cells does not result in preB cell apoptosis; 6) preB cell apoptosis is dependent on AhR activity in adherent hepatic‐ or bone marrow–derived stromal cells; and 7) apoptosis is induced by DMBA when preB cells are maintained on primary bone marrow stromal cell monolayers from wildtype but not from AhR−/− mice. Collectively, the data indicated that AhR‐regulated activities in the hematopoietic microenvironment influence the susceptibility of immature lymphocytes to low‐dose PAH exposure.
Differential Depressant Effects of General Anesthetics on the Cardiovascular Response to Cocaine in Mice
Authors: Wang Ju‐Feng , Hampton Thomas G. , DeAngelis Joseph , Travers Kerry , Morgan James P.
Published: November 2003

In recent years, murine models have gained increasing importance for studies of cardiovascular physiology and pharmacology, largely due to the development of transgenic strains with specific alterations in phenotype. Differential effects of general anesthetic agents on the cardiovascular responses to cocaine have been reported in larger mammals; therefore, we studied the effects of commonly used anesthetics on heart function and on blood pressure responses to cocaine in Swiss Webster mice. We positioned a polyethylene catheter (PE‐10) in the right carotid artery or left ventricle of mice anesthetized with equivalent anesthetic dose of either ketamine‐xylazine (KX, 40 mg/kg + 5 mg/kg), pentobarbital (PEN, 40 mg/kg) or α‐chloralose‐urethane (CU, 80 mg/kg + 100 mg/kg). Cocaine (0.3 mg/kg, 1 mg/kg and 3 mg/kg) was administrated via the left jugular vein by bolus injection. In the KX group, the basal mean arterial pressure (MAP) and systolic left ventricular pressure (LVP) were 110 ± 12 and 120 ± 13 mmHg, respectively, close to conscious values. However, PEN and CU significantly decreased the basal parameters (P < 0.01 compared to the KX group). The lowest dose of cocaine (0.3 mg/kg) elicited minimal changes. Significant responses were obtained with a 1‐mg/kg dose of cocaine (P < 0.01 compared to baseline). However, at 3 mg/kg, a toxic effect of cocaine appeared in all three anesthetic groups. Compared to published conscious animal data, anesthetic agents attenuated the cardiovascular effects of cocaine. Taken together, our results indicate that minimally effective doses of general anesthetics may significantly alter the basal hemodynamic state and the responses to sympathomimetic agents in the murine model, as has been reported in larger mammalian species. We concluded that anesthesia with ketamine‐xylazine provides baseline hemodynamic values close to reported values in conscious animals, but also attenuates the hemodynamic response to cocaine.
Mushrooms, Tumors, and Immunity
Authors: Borchers Andrea T. , Stern Judith S. , Hackman Robert M. , Keen Carl L. , Gershwin M. Eric
Published: November 2003

Medicinal properties have been attributed to mushrooms for thousands of years. Mushroom extracts are widely sold as nutritional supplements and touted as beneficial for health. Yet, there has not been a critical review attempting to integrate their nutraceutical potential with basic science. Relatively few studies are available on the biologic effects of mushroom consumption, and those have been performed exclusively in murine models. In this paper, we review existing data on the mechanism of whole mushrooms and isolated mushroom compounds, in particular (1→3)‐β‐D‐glucans, and the means by which they modulate the immune system and potentially exert tumor‐inhibitory effects. We believe that the antitumor mechanisms of several species of whole mushrooms as well as of polysaccharides isolated from Lentinus edodes, Schizophyllum commune, Grifola frondosa, and Sclerotinia sclerotiorum are mediated largely by T cells and macrophages. Despite the structural and functional similarities of these glucans, they differ in their effectiveness against specific tumors and in their ability to elicit various cellular responses, particularly cytokine expression and production. Unfortunately, our data base on the involvement of these important mediators is still rather limited, as are studies concerning the molecular mechanisms of the interactions of glucans with their target cells. As long as it remains unclear what receptors are involved in, and what downstream events are triggered by, the binding of these glucans to their target cells, it will be difficult to make further progress in understanding not only their antitumor mechanisms but also their other biological activities.
Endothelin‐1 and Endothelin Receptor Antagonists in Cardiovascular Remodeling
Authors: Kirchengast Michael , Münter Klaus
Published: November 2003

Endothelins build a peptide family composed of three isoforms, each of them containing 21 amino acids. Endothelin‐1 is the isoform mainly responsible for any cardiovascular action and therefore the sole scope of this review. Endothelin‐1 is the most potent endogenous vasoconstrictor known; in addition it acts as a potent (co)mitogen. There is a substantial body of experimental evidence that endothelin‐1 may contribute not only to sustained vasoconstriction, but also to remodeling within the cardiovascular system. Thus, with the help of endothelin receptor antagonists (available for a few years) the involvement of mainly ETA receptors in structural diseases such as heart failure, pulmonary hypertension, atherosclerosis, restenosis, systemic hypertension, and chronic renal failure has been shown. These data make endothelin receptor antagonists, and especially those selective for the ETA receptor, promising agents for the treatment of chronic cardiovascular diseases associated with remodeling. Currently several chemically distinct, orally available members of this novel class of therapeutic agents are under clinical investigation.
Food Restriction‐Like Effects of Dehydroepiandrosterone: Decreased Lymphocyte Numbers and Functions with Increased Apoptosis
Authors: Catalina Fernando , Kumar Vinay , Milewich Leon , Bennett Michael
Published: November 2003

Both dietary dehydroepiandrosterone (DHEA) and food restriction can prevent or modulate the initiation or progression of a number of diseases in rodents and prolong life span. We sought to determine if these interventions have common mechanisms of action in regulating lymphocyte functions and cell numbers. We observed that male C57BL/6 mice receiving DHEA in the diet (0.45%, w/w) ate approximately 50% as much food as mice on the DHEA‐free diet, and this was reflected in decreased body weights throughout a 10‐week period. Mice either fed the DHEA‐containing diet or pair‐fed to the DHEA‐treated mice had decreased spleen and thymus weights and lymphocyte cell numbers compared to mice having free access to the control diet. Mice were fed these diets for 2 weeks before and 2 weeks after exposure to sublethal irradiation (500 cGy). In mice fed DHEA or pair‐fed, there was a decrease in spleen cell numbers, and B cells were the most severely affected. The frequency of apoptosis in peripheral blood cells increased from <5% in nonirradiated controls to >50% within 4 days after starting DHEA or pair‐feeding. Shortly after irradiation, >87% of blood lymphocytes were hypodiploid (apoptotic) in all groups. By 9 days only 27% of lymphocytes in mice on the control diet were hypodiploid compared to 62% in DHEA and 74% in pair‐fed mice. In addition, both DHEA and pair‐fed mice had significant reductions in T‐cell function (contact hypersensitivity to dinitrofluorobenzene), B cell function (antibody response to trinitrophenolated‐lipopolysaccharide), and NK cell function (lung clearance of radiolabeled YAC‐1 tumor cells) 2 weeks after irradiation. In a complementary study, peripheral blood lymphocytes from naïve mice were treated overnight with various concentrations of either DHEA or hydrocortisone 21‐acetate. Only glucocorticoid‐treated cells underwent apoptosis. Thus, DHEA induces apoptosis in vivo but not in vitro. We conclude that dietary DHEA induces apoptosis and decreased lymphocyte production and function in C57BL/6 mice largely by reducing food intake.
Effect of Pregnancy, Postnatal Growth, and Gender on Renal Sulfate Transport
Authors: Lee Hwa Jeong , Balasubramanian Sathyamangalam V. , Morris Marilyn E.
Published: November 2003

Serum sulfate concentrations are increased in infants, young children, and pregnant women, compared with adult values. The objective of this investigation was to examine the influences of age, gender, and pregnancy on renal sulfate transport using guinea pigs as an animal model. Membrane vesicles were isolated from the kidney cortex of male animals at four different ages, from male and female adult animals, and from pregnant and nonpregnant female animals. There were no significant differences in marker enzymes for the brush‐border membrane (BBM) or basolateral membrane (BLM) among all groups examined. Uptake was determined by a rapid filtration method and membrane fluidity by measuring the steady‐state fluorescence anisotropy of 1,6‐diphenyl‐1,3,5‐hexatriene. The Vmax values for Na+ /sulfate co‐transport in BBM were significantly increased with decreasing age, whereas the Km for this process was unchanged. The Vmax and Km for Na + /sulfate co‐transport in BBM of pregnant animals were significantly higher than the values in the nonpregnant group. Bicarbonate‐driven anion exchange of sulfate in BLM was not different among the different age groups. The Vmax for the bicarbonate/sulfate exchange process in BLM was not different between pregnant and nonpregnant groups; however, the Km for this process in BLM of pregnant animals was significantly greater than the value in nonpregnant animals. There were no gender‐related differences in sulfate transport in BBM or BLM isolated from adult male and female animals. Renal BBM fluidity was increased with decreasing age and in pregnant animals, suggesting that altered membrane fluidity may represent one possible mechanism to explain the increased sodium/sulfate uptake in young and pregnant animals. The higher Vmax for Na+/sulfate co‐transport in young and pregnant animals suggests that there is an increased density of co‐transporter protein or an increase in the rate of movement of the carrier protein (i.e., turnover) once loaded with sodium and sulfate. This increased conservation of inorganic sulfate in young and pregnant guinea pigs may be related to the increased demand for sulfated substrates, such as sulfated glycosaminoglycans, during growth and development.
Prolactin and Growth Hormone Stimulation of Lactation in Mice Requires Thyroid Hormones
Authors: Capuco A. V. , Kahl S. , Jack L. J. W. , Bishop J. O. , Wallace H.
Published: November 2003

This experiment tested the hypothesis that thyroid hormones are essential for a milk production response to growth hormone (GH) and prolactin (PRL). Prior to breeding, female transgenic mice expressing the herpes simplex type‐I thymidine kinase in the thyroid were treated with ganciclovir to ablate thyroid follicular cells. To provide for normal gestation, thyrocyte‐ablated mice were supplied thyroxine (T4) in drinking water (0.2 μg/ml) until 7 days before parturition. Litter size was adjusted to 9 pups, hormone administration began on Day 2 of lactation, and mice were sacrificed on Day 12. There were 5–6 mice in each of 7 treatments that included nonablated controls, thyrocyte‐ablated controls, and thyrocyte‐ablated mice treated with T4, GH, PRL, GH + T4, and PRL + T4. Thyroxine was administered in drinking water, and GH and PRL (20 μg/d) were administered by subcutaneous injection. Compared with thyrocyte‐ablated controls, litter weight gain was unaffected when dams were treated with GH, PRL, or T4 alone. However, when dams were treated with GH or PRL in combination with T4, litter weight gain increased 13% compared with thyrocyte‐ablated controls and 18% compared with GH or PRL‐treated mice. Concentration of T4 in serum of pups averaged 62 ng/ml and did not differ among treatments. Concentration of T4 in serum of dams averaged 76 ng/ml when T4‐treated. Thyroxine 5′‐deiodinase (5′D), the enzyme that converts T4 to triiodothyronine, was quantitated in liver, kidney, and mammary gland. Quantity of 5′D was lower in liver and kidney of thyrocyte‐ablated dams without T4 than in respective tissues of mice treated with T4, and there was no effect of GH or PRL. However, in mammary gland, 5′D was increased by treatment with GH, PRL, or T4. Data show that thyroid hormones are necessary for a galactopoietic response to GH and PRL and demonstrate a unique organ‐specific regulation of 5′D by galactopoietic hormones.
A New Neurological Mutant Rat with Symmetrical Calcification of Purkinje Cells in Cerebellum
Authors: Ando Yosuke , Ichihara Nobutsune , Takeshita Shigehito , Nagata Mayumi , Kimura Tsutomu , Tanase Hisao , Kikuchi Tateki
Published: November 2003

A new neurological mutant has been found in the inbred F344 strain of rats. The mutation is inherited as an autosomal recessive trait and is manifest clinically by a hesitant and wobbling gait with asynergic limbs and slight tremor. These symptoms begin at 16–18 days of age and remain essentially constant thereafter. Histologic examination revealed severe degeneration of the Purkinje cells and symmetrical calcification in these and in their dendritic branches in the cerebellar cortex. Such calcified Purkinje cells were intensely stained with the periodic acid‐Schiff (PAS) method. PAS‐positive substances in the Purkinje cells and extending diffusely over the lesioned sites in the molecular layer were also evident before calcification took place. We have named this neurological mutant the Cerebellar Calcification (CC) rat with the gene symbol cc. This offers a new animal model for the study of the Purkinje cell degeneration and intracranial calcification.
Effect of Hamster Pregnancy on Female Protein, a Homolog of Serum Amyloid P Component
Authors: Coe J. E. , Vomachka A. J. , Ross M. J.
Published: November 2003

Pentraxins such as human serum amyloid P component (SAP) and C reactive protein (CRP) represent an ancient family of proteins that are ubiquitous in nature and have evolved with little change in structure or regulation. The pentraxin in the Syrian hamster (Mesocricetus auratus) is unique because it is preferentially expressed in the female at high constitutive levels and accordingly called female protein (FP) or FP(SAP) due to its close homology with human SAP. The high levels of FP in female serum (100‐fold greater than male serum) suggested its role in hamster pregnancy, one of the shortest of any eutherian mammal. We determined the serum FP concentration in pregnant Syrian hamsters and found a marked decrease (>80%) at term with the nadir at parturition with subsequent increase. A similar downregulation of FP was found in the normal female Syrian hamster after injury (acute phase response), so in both cases the assumed beneficial effects were achieved with less, rather than more pentraxin, a paradoxical pentraxin response. The fall in serum FP concentration could represent a response to protect the fetus from the high and potentially toxic level of FP normally found in the female, that is harmful because of its association with amyloidosis. An FP that is 97.5% identical to Syrian hamster FP is found in the Turkish hamster (Mesocricetus brandti), although serum levels in females are much lower, and amyloid is very rare. During pregnancy/parturition of Turkish hamsters, the serum level of FP remained remarkably constant. In a more distantly related hamster, the Armenian hamster (Cricetulus migratorius), serum FP actually increased during pregnancy and at parturition in a manner similar to that found in the Armenian hamster during an acute phase response. The heterogeneity of FP kinetics during pregnancy in these three species of hamster indicates pleomorphic gene structure for regulation of their similar FPs, and suggests that this protein may have a different function in the pregnancy of each species.