Aspen shaving versus chip bedding: effects on breeding and behavior

The choice of laboratory cage bedding material is often based on both practical and husbandry issues, whereas behavioral outcomes rarely appear to be considered. It has been noted that a breeding success difference appears to be associated with the differential use of aspen chip and aspen shaving bedding in our facility; therefore, we sought to analyze breeding records maintained over a 20-month period. In fact, in all four mouse strains analyzed, shaving bedding was associated with a significant increase in average weanlings per litter relative to chip bedding. To determine whether these bedding types also resulted in differences in behaviors associated with wellbeing, we examined nest building, anxiety-like, depressive-like (or helpless-like), and social behavior in mice housed on chip versus shaving bedding. We found differences in the nests built, but no overall effect of bedding type on the other behaviors examined. Therefore, we argue that breeding success, perhaps especially in more challenging strains, is improved on shaving bedding and this is likely due to improved nest-building potential. For standard laboratory practices, however, these bedding types appear equivalent.

Canagliflozin, a novel inhibitor of sodium glucose co-transporter 2, dose dependently reduces calculated renal threshold for glucose excretion and increases urinary glucose excretion in healthy subjects

Canagliflozin, a potent, selective sodium glucose co-transporter 2 inhibitor in development for treatment of type 2 diabetes, lowers plasma glucose (PG) by lowering the renal threshold for glucose (RT(G) ) and increasing urinary glucose excretion (UGE). An ascending single oral-dose phase 1 study investigated safety, tolerability and pharmacodynamics of canagliflozin in healthy men (N = 63) randomized to receive canagliflozin (n = 48) or placebo (n = 15). Canagliflozin (10, 30, 100, 200, 400, 600 or 800 mg q.d. or 400 mg b.i.d.) was administered to eight cohorts (six subjects/cohort: canagliflozin; two subjects/cohort: placebo). Dose dependently, canagliflozin decreased calculated 24-h mean RT(G) with maximal reduction to approximately 60 mg/dl, and increased mean 24-h UGE. At doses >200 mg administered before breakfast, canagliflozin reduced postprandial PG and serum insulin excursions at that meal. Canagliflozin was generally well tolerated; most adverse events were mild and no hypoglycaemia was reported. These results support further study of canagliflozin.

Topiramate ameliorates hyperglycaemia and improves glucose-stimulated insulin release in ZDF rats and db/db mice

Topiramate (TPM) is a novel neurotherapeutic agent. Clinical studies reported that TPM treatment reduced body weight and decreased fasting blood glucose levels in obese patients with or without type 2 diabetes. It is unclear whether the blood glucose-normalizing phenomenon observed during TPM treatment is a primary effect or the consequence of reduced food intake and weight loss. In the present studies, we chronically treated female Zucker diabetic fatty (ZDF) rats (fed with a diabetogenic diet) and db/db mice with TPM (30-300 mg/kg/day) to examine the effect of TPM on hyperglycaemia and its relationship with food intake and body weight gain. Our data showed that TPM treatment markedly reduced blood glucose levels in both ZDF rats and db/db mice without a significant reduction in body weight gain. Pair-fed db/db mice treated with the vehicle alone did not exhibit a significant decrease in blood glucose levels compared with mice fed ad libitum. TPM treatment increased glucose-stimulated insulin release by 2-3-fold during an oral glucose tolerance test in both ZDF rats and db/db mice. We also observed a 1.4-fold increase of pancreatic insulin content and heightened insulin immunostaining in pancreatic beta cells in db/db mice treated with TPM. Our data suggest that the antidiabetic effect of TPM is independent of the changes in body weight gain and food intake. Improved glucose-induced insulin release may, in part, underlie the mechanisms by which TPM ameliorates the hyperglycaemia.

Multiple cross mapping (MCM) markedly improves the localization of a QTL for ethanol-induced activation

This study examines the use of multiple cross mapping (MCM) to reduce the interval for an ethanol response QTL on mouse chromosome 1. The phenotype is the acute locomotor response to a 1.5-g/kg i.p. dose of ethanol. The MCM panel consisted of the six unique intercrosses that can be obtained from the C57BL/6J (B6), DBA/2J (D2), BALB/cJ (C) and LP/J (LP) inbred mouse strains (N > or = 600/cross). Ethanol response QTL were detected only with the B6xD2 and B6xC intercrosses. For both crosses, the D2 and C alleles were dominant and decreased ethanol response. The QTL information was used to develop an algorithm for sorting and editing the chromosome 1 Mit microsatellite marker set (http://www.jax.org). This process yielded a cluster of markers between 82 and 85cM (MGI). Evidence that the QTL was localized in or near this interval was obtained by the analysis of a sample (n = 550) of advanced cross heterogenous stock animals. In addition, it was observed that one of the BXD recombinant inbred strains (BXD-32) had a recombination in the interval of interest which produced the expected change in behavior. Overall, the data obtained suggest that the information available within existing genetic maps coupled with MCM data can be used to reduce the QTL interval. In addition, the MCM data set can be used to interrogate gene expression data to estimate which polymorphisms within the interval of interest are relevant to the QTL.

Supersensitivity to anandamide and enhanced endogenous cannabinoid signaling in mice lacking fatty acid amide hydrolase

The medicinal properties of marijuana have been recognized for centuries, but clinical and societal acceptance of this drug of abuse as a potential therapeutic agent remains fiercely debated. An attractive alternative to marijuana-based therapeutics would be to target the molecular pathways that mediate the effects of this drug. To date, these neural signaling pathways have been shown to comprise a cannabinoid receptor (CB(1)) that binds the active constituent of marijuana, tetrahydrocannabinol (THC), and a postulated endogenous CB(1) ligand anandamide. Although anandamide binds and activates the CB(1) receptor in vitro, this compound induces only weak and transient cannabinoid behavioral effects in vivo, possibly a result of its rapid catabolism. Here we show that mice lacking the enzyme fatty acid amide hydrolase (FAAH(-/-)) are severely impaired in their ability to degrade anandamide and when treated with this compound, exhibit an array of intense CB(1)-dependent behavioral responses, including hypomotility, analgesia, catalepsy, and hypothermia. FAAH(-/-)-mice possess 15-fold augmented endogenous brain levels of anandamide and display reduced pain sensation that is reversed by the CB(1) antagonist SR141716A. Collectively, these results indicate that FAAH is a key regulator of anandamide signaling in vivo, setting an endogenous cannabinoid tone that modulates pain perception. FAAH may therefore represent an attractive pharmaceutical target for the treatment of pain and neuropsychiatric disorders.

Further characterization and high-resolution mapping of quantitative trait loci for ethanol-induced locomotor activity

Differential sensitivity to the stimulant effects of ethanol on locomotor activity is determined in part by genetic differences. Among inbred strains of mice, moderate doses of ethanol (1-2 g/kg) stimulate locomotor activity in some strains, e.g., the DBA/2J (D2), but only mildly affect activity in other strains, e.g., C57BL/6J (B6) (Crabbe et al., 1982, 1983; Crabbe, 1986; Dudek and Phillips, 1990; Dudek et al., 1991; Dudek and Tritto, 1994). Quantitative trait loci (QTL) for the acute ethanol (1.5 g/kg) locomotor response has been identified in the BXD recombinant inbred (RI) series (N = 25 strains), a C57BL/6J x DBA/2J (B6D2) F2 intercross (N = 1800), and heterogeneous stock (HS) mice (N = 550). QTLs detected (p < .01) in the RI series were found on chromosomes 1, 2, and 6 and these QTLs were expressed in a time-dependent fashion. The QTLs on chromosomes 1 and 2 were confirmed in the F2 intercross at p < 10(-7) or better. HS mice from G32 to G35 were used to fine-map the chromosome 2 QTL. Compared to the consensus map, the genetic map in the HS animals was expanded 10- to 15-fold. Over the region flanked by D2Mit94 to D2Mit304, three separate QTLs were detected in the HS animals. The data obtained confirm the usefulness of HS mice for the fine-mapping of QTLs to a resolution of 2 cM or less.

Effect of genetic cross on the detection of quantitative trait loci and a novel approach to mapping QTLs

A genome-wide scan was conducted in two F(2) intercrosses, C57BL/6J (B6)xDBA/2J (D2) and BALB/cJ (C)xLP/J (LP), for three different phenotypes: basal locomotor activity, ethanol-induced locomotor activity, and haloperidol-induced catalepsy. For basal activity, significant quantitative trait loci (QTLs, LOD> or =4.3) were detected on chromosomes 9 and 19 for the CxLP intercross and chromosome 1 for the B6xD2 intercross. Significant QTLs for ethanol-induced activation were detected on chromosome 6 for the CxLP intercross, and on chromosomes 1 and 2 for the B6xD2 intercross. For haloperidol-induced catalepsy, significant QTLs were detected on chromosome 14 (two different QTLs) in the CxLP intercross, and chromosomes 1 and 9 in the B6xD2 intercross. These data illustrate the importance of the genetic cross for QTL detection. Finally, the data reported here, and elsewhere, are also used to demonstrate a novel approach to QTL detection and localization.

Identification and time dependence of quantitative trait loci for basal locomotor activity in the BXD recombinant inbred series and a B6D2 F2 intercross

A complimentary two-phase strategy was used to detect and map quantitative trait loci (QTLs) associated with the basal locomotor response to a saline challenge (10 ml/kg). In phase 1, putative QTLs, significant at p < 0.01 or better, were identified by analysis of the strain means for 25 strains of the B x D recombinant inbred series. QTLs were identified on chromosomes 1, 3, 5, 9, 10, 16, and 18. Some of these QTLs were detected across the entire experimental period (0-20 min), while others were associated with specific 5-min blocks. Eighteen hundred C57BL/6J (B6) x DBA/2J (D2) F2 intercross animals were phenotyped for the basal locomotor response, and of this group, 500 to 700 individuals, pseudo-randomly selected, were used for a genomewide scan to confirm the RI-generated QTLs and to detect new QTLs. No new QTLs were detected but the QTLs on chromosome 1 were confirmed at p < 10(-5) to p < 10(-9), depending on the time interval. In addition, the QTLs on chromosomes 5 and 9 were confirmed at p < 0.001, providing a combined probability (RI + F2) which exceeds the threshold for a significant association. Two additional phenotypes which showed significant RI strain differences were examined--adaptation and thigmotaxis. Adaptation mapped to the same region of chromosome 9 and thigmotaxis to the same region of chromosome 1 as the distance-traveled QTL. Overall, the data presented here and elsewhere (Flint et al., 1995; Gershenfeld et al., 1997) illustrate that QTLs for basal activity are both robust and reliable.

Identification of an acute ethanol response quantitative trait locus on mouse chromosome 2

A two-stage strategy was used to identify and confirm quantitative trait loci (QTLs) associated with the changes in locomotor activity induced by a 1.5 gm/kg ethanol challenge. For stage 1, putative QTLs were identified by analysis of the strain means for 25 strains of the BXD recombinant inbred (RI) series (males only). QTLs were identified on chromosomes 1, 2, 4, and 6. The activity response to chlordiazepoxide generated similar QTLs on chromosomes 2 and 6. None of the QTLs were similar to those generated from analysis of the saline response data. For stage 2, 900 male C57BL/6J (B6) x DBA/2J (D2) F2 intercross animals were phenotyped for ethanol response, and the phenotypic extremes (those animals > and <1 SD from the mean) were identified. These extremes differed by >10,000 cm/15 min in their response to ethanol. The extreme progeny were used for a genome-wide scan both to confirm the putative RI-generated QTLs and to detect new QTLs. The F2 analysis generated no new QTLs with logarithm of the likelihood for linkage (LOD) scores >3. For RI-generated QTLs, only the QTL on chromosome 2 was confirmed (LOD = 5.3). The position of the peak LOD was estimated to be 47 cM with a 20 cM 1 LOD support interval; this QTL accounted for 6% of the phenotypic variance. The 1 LOD support interval overlaps with QTLs previously identified for alcohol preference and acute ethanol withdrawal (;; ).

Ethanol-induced expression of c-Fos differentiates the FAST and SLOW selected lines of mice

The effect of ethanol on the number of Fos-like immunoreactive (Fos-li) neurons was previously studied in the C57BL/6J (B6) and DBA/2J (D2) inbred mouse strains (Hitzemann and Hitzemann, 1997). Data obtained suggested that the locomotor activation response to ethanol found in the D2 but not the B6 strain was associated with an increase in the number of Fos-li neurons (a putative measure of synaptic activity) in the central nucleus of the amygdala (CeA), but not in other brain regions, including the basal ganglia. Supporting results were obtained in B6D2 F2 intercross animals (Demarest et al., 1998) those animals exhibiting a marked locomotor activation response to ethanol also showed a significant increase in the number of Fos-li neurons in the CeA. The current study extends this line of investigation to the FAST and SLOW selected lines of mice (Shen et al., 1995). Twenty-eight SLOW and FAST mice (taken evenly from both replicate lines) were randomly assigned to receive either saline or ethanol (1.5 g/kg). One hour later, the animals were sacrificed, and the number of Fos-li neurons were determined using standard immunocytochemical techniques. Both the FAST and SLOW lines showed a marked increase (>300%) in the number of Fos-li neurons in the lateral aspect of the CeA; however, in the capsular division, only the FAST line showed an increase (>500%). In several brain regions, the basal (saline) response was markedly higher in the SLOW line; these regions included the subthalamic nucleus, the entopeduncular nucleus, the substantia nigra compacta, and the ventral tegmental area. Furthermore, it was found that ethanol decreased the number of Fos-li neurons in the ventral tegmental area of the SLOW but not FAST mice. These data suggest a substantial involvement of the basal ganglia in the segregation of the FAST and SLOW lines.

Genetics of ethanol-induced locomotor activation: detection of QTLs in a C57BL/6J x DBA/2J F2 intercross

Moderate doses of ethanol (1-2 g/kg) markedly increase locomotor activity in some inbred mouse strains, for example, the DBA/2J (D2), but have relatively little effect in other strains, for example, the C57BL/6J (B6). In the present study, we conducted a genome-wide search in a B6D2 F2 intercross (N = 925) for quantitative trait loci (QTLs) associated with the locomotor response. A QTL with a LOD score of 8.4 was detected on Chromosome (Chr) 2; this QTL accounted for 11.4% of the phenotypic variance and approximately 30% of the genetic variance. The QTL on Chr 2 is in the same general region as QTLs previously described for ethanol preference/consumption (Rodriguez et al. Alcohol Clin Exp Res 19, 367, 1995; Melo et al. Nat Genet 13, 147, 1996; Phillips et al. Mamm Genome, in press), acute ethanol withdrawal (Buck et al. J. Neurosci 17, 3946, 1997) and nitrous oxide withdrawal severity (Belknap et al. Behav Genet 23, 213, 1993). A logical candidate gene in the region of interest is the enzyme which synthesizes GABA, glutamic acid decarboxylase 1 (GadI).

Further evidence that the central nucleus of the amygdala is associated with the ethanol-induced locomotor response

The effect of ethanol on the number of Fos-like immunoreactive (Fos-li) neurons was previously studied in the C57BL/6J (B6) and DBA/2J (D2) inbred mouse strains (Hitzemann and Hitzemann, Alcohol. Clin. Exp. Res. 21:1497-1507, 1997). The data obtained suggested that the locomotor activation response to ethanol found in the D2 but not the B6 strain was associated with an increase in the number of Fos-li neurons (a putative measure of synaptic activity) in the central nucleus of the amygdala (CeA), but not in other brain regions, including the basal ganglia. The current study was performed to obtain data supporting a role for the CeA in the locomotor response. B6D2 F2 intercross animals were phenotyped for their locomotor response to ethanol (1.5 g/kg). The animals from the extreme phenotypes (> 1 SD from the mean) were denoted as very high and very low activity (HH, LL) and differed in their ethanol response by >9,000 cm/15 min (baseline activity was similar in both phenotypes: 5,500 cm/15 min). These extremes especially differed from the parental strains in that the LL group showed a significant ethanol-induced inhibition of activity. After 2 weeks, HH and LL animals were rechallenged with 1.5 g/kg of ethanol or saline and the number of Fos-li neurons determined 1 hr later. In the HH group, ethanol increased the number of Fos-li neurons >600%, whereas in the LL group the increase was 170% (difference: p < 0.001). The increase in the HH group was principally located in the GABA neuron-rich lateral aspect of the CeA and not in the medial posterior-ventral division or the caps division. No significant difference was found between groups in the Fos response for the basolateral or lateral amygdala. Other brain regions were also examined, including the basal ganglia, the hippocampus (CA1, CA3, and dentate gyrus), the bed nucleus of the stria terminalis, and several cortical regions. In some regions (e.g., the bed nucleus), a significant ethanol effect was detected, but it did not differentiate the HH and LL groups. Overall, the data obtained further argue that the CeA has an important role in regulating the acute locomotor response to ethanol.

In vitro permeability of eight beta-blockers through Caco-2 monolayers utilizing liquid chromatography/electrospray ionization mass spectrometry

It is demonstrated that the apparent permeability (P(app)) coefficients of beta-adrenoceptor antagonist drugs can easily be determined for Caco-2 cell culture intestinal models utilizing liquid chromatography/mass spectrometry (LC/MS). The LC/MS method with electrospray ionization in the single ion monitoring mode showed an increased sensitivity of 1000-fold compared with LC/UV detection and enhanced selectivity with respect to both LC/UV and radioactivity assays. The P(app) coefficients of beta-adrenoceptor antagonists determined by LC/MS have the same ranking order as those determined by LC/UV and radioactivity assays. However, the P(app) coefficients determined in this study showed significant discrepancies from those determined in other laboratories. There are several experimental factors that directly affect the absolute value of the P(app) coefficients, including pH gradients, additional diffusion barriers (i.e. unstirred water layer and type of filter support), analyte concentration, detection method and possibly cell culture variations. These parameters should be controlled when generating Caco-2 P(app) coefficients for different compounds.

Effect of the oxytocin antagonist atosiban (1-deamino-2-D-tyr(OET)-4-thr-8-orn-vasotocin/oxytocin) on nocturanl myometrial contractions, maternal cardiovascular function, transplacental passage, and fetal oxygenation in the pregnant baboon during the last third of gestation

The oxytocin antagonist, atosiban (1-deamino-2-D-tyr(OET)-4-thr-8-orn-vasotocin/oxytocin), was infused i.v. to chronically instrumented pregnant baboons in the last third of pregnancy. Atosiban (6 microg/kg per min) inhibited myometrial electromyographic activity associated with spontaneous myometrial contractions that occurred around the onset of darkness between 134 and 162 days gestation (term 180 days gestation). The effect of atosiban on maternal heart rate was minimal. Maternal blood pressure remained unaltered during atosiban infusion. Fetal carotid arterial PO2 was unchanged during a 2-h infusion of atosiban. Transplacental passage of atosiban from mother to fetus was assessed at cesarean section under halothane anesthesia in four baboons and in two chronically instrumented fetuses in the absence of anesthesia. The maternal:fetal concentration gradient ranged from 9.2 to 22.8. Maternal atosiban clearance rates were 9.2-16.9 ml/kg per min. In conclusion, atosiban was very effective at inhibiting spontaneously occurring nocturnal myometrial contractions during the last third of gestation in the pregnant baboon. Although atosiban crosses the placenta relatively freely, there was no effect on fetal oxygenation.

Phosphatase inhibitors--III. Benzylaminophosphonic acids as potent inhibitors of human prostatic acid phosphatase

Further investigation of the structural requirements of a series of benzylphosphonic acid inhibitors of human prostatic acid phosphatase has led to the highly potent series of alpha-aminobenzylphosphonic acids. The alpha-benzylaminobenzylphosphonic acid, with an IC50 = 4 nM, exhibited a 3500-fold improvement in potency over the carbon analogue, alpha-phenylethyl. The enhanced potency may be due to a combination of four favorable interactions including those with the phosphate binding region, the presence the hydrophobic moieties of the benzylamino and phenylphosphonic acid, and a rigid conformer produced by an internal salt bridge between the phosphonate and the alpha-amino group. Replacement of the phosphonic acid moiety with a phosphinic or carboxylic acid as well as deletion of the benzyl substitution of the alpha-amino group led to great reductions in potency.

Progestational and androgenic receptor binding affinities and in vivo activities of norgestimate and other progestins

The progestational and androgenic in vitro receptor binding affinity and the in vivo activity of norgestimate was compared with that of its metabolites and other progestins. The relative binding affinities (RBAs) of norgestimate and its 17-deacetylated metabolite for rabbit uterine progestin receptors were similar to that of progesterone (P); those of 3-keto norgestimate and levonorgestrel were about five times that of P; those of gestodene and 3-keto desogestrel were about nine times that of P. The RBAs of norgestimate, P, and 3-keto norgestimate for rat prostatic androgen receptors were from 0.003 to 0.025 times that of dihydrotestosterone (DHT); those of 3-keto desogestrel, gestodene, and levonorgestrel were from 0.118 to 0.220 times that of DHT. The order of receptor level selectivity represented by the ratio of androgen:progestin IC50 values (with a greater ratio value reflecting a better selectivity) was norgestimate greater than P = 3-keto norgestimate greater than 17-deacetylated norgestimate greater than 3-keto desogestrel greater than gestodene greater than levonorgestrel. In vivo studies demonstrated similar profiles for norgestimate and its 17-deacetylated metabolite. These latter two steroids were equally potent as progestins in stimulating rabbit endometrium, and compared with the other progestins, both steroids exhibited minimal androgenicity as measured by the stimulation of rat prostate growth. In conclusion, these studies, as well as previous preclinical and clinical studies, provide evidence of the selectivity of norgestimate based on minimal androgenicity, indicating an improvement over other progestins used in oral contraceptives.

Vasopressin receptors in human pregnant myometrium and decidua: interactions with oxytocin and vasopressin agonists and antagonists

Saturation analysis and competition experiments were performed to identify and characterize [3H]arginine vasopressin binding to human myometrium and decidua in late pregnancy. [3H]Arginine vasopressin bound with affinity similar to that of [3H]oxytocin to both tissues (dissociation constant 1 to 2 nmol/L). The concentration of [3H]arginine vasopressin binding sites was high, particularly in decidua, but in all instances was about 50% to 60% of [3H]oxytocin binding. Analogs with selective oxytocic potency (4-threonine oxytocin, isotocin) had high affinity to both [3H]arginine vasopressin and [3H]oxytocin binding sites, as did analogs with both oxytocic and vasopressor activity (vasotocin). Analogs with selective antidiuretic activity (1-deamino-8-D-arginine vasopressin) showed drastically reduced affinity to [3H]oxytocin binding sites and relatively low but significantly higher affinity to [3H]arginine vasopressin binding sites. A new oxytocin antagonist (RW22164 or [1-deamino-2D-tyrosine-(O-ethyl)-4-threonine-8-ornithine]oxytocin) competitively bound to both binding sites. Its affinity to [3H]oxytocin binding sites was greater than to [3H]arginine vasopressin binding sites whereas the relative affinities of a predominantly vasopressor antagonist [Manning compound) were reversed, suggesting the presence of distinct receptors for oxytocin and arginine vasopressin in pregnant human myometrium and decidua.

Oxytocin antagonist (dTVT) and oxytocin receptors in myometrium and decidua

To investigate whether a putative oxytocin (OT) receptor blocker 1-deamino-[2-D-tyrosine (OEt)-4 threonine-8-ornithine]oxytocin (dTVT) inhibits OT binding to its receptors, we studied binding of [3H]OT to late-pregnant human, guinea pig, and rat myometrial and decidual membranes and competition of dTVT with this binding. Decidua as well as myometrium of all three species bound [3H]OT with high affinity (Kd 1-3 nM) and limited capacity. The concentration of binding sites in decidual membranes was slightly lower than in myometrial membranes in human and guinea pig uterus and twice that of myometrial membranes in day 20 pregnant rat uterus. dTVT competed with [3H]OT with highest affinity in guinea pig myomterium and decidua, the potency ratios ([dTVT]50: [OT]50) being 1.9 and 3.3, respectively. The potency ratios in rat uterine tissues and human decidua were slightly higher (4 to 5) and highest in human myometrium, 23.3. Excess dTVT completely inhibited [3H]OT binding in all six tissues, indicating binding to the same receptor sites. Because of the high-affinity binding of dTVT to oxytocin receptors in human decidua and myometrium, this oxytocin analogue may be a very effective tocolytic agent in the treatment of threatened preterm labor.