Supplementation of rangeland primiparous Bos indicus x Bos taurus beef heifers during lactation. 1. Effects on dam milk production and liveweight, bull calf growth, live carcass characteristics and metabolic hormone concentrations.

The practice of feeding replacement-breeding bulls on high energy diets after weaning to meet liveweight (LW) and carcass expectations between 18 and 24 months of age negatively affects reproductive potential. This experiment reports upon the effects of an alternative management strategy aimed at improving calfhood nutrition in rangeland-reared bulls to enhance LW and live carcass characteristics at 2 years. Following artificial insemination (AI cohort; n = 26), or natural mating, subsequent to the addition of bulls at 39 d post-AI (NM cohort; n = 36), primiparous Santa Gertrudis heifers grazing rangeland pastures with bull calf progeny were allocated at parturition to receive either nil supplement (control; CON) or provided with unrestricted access to a pelleted vegetable protein meal-based supplement containing 35% CP (SUPP) until weaning at 199 ± (SD) 26 d. The mean estimated pellet consumption by SUPP heifers during lactation was 2.6 ± (SEM) 0.5 kg DM daily. Grazing diet quality measurements indicated nutritional restriction of CON heifers until at least 115 d of lactation. This was confirmed by lower blood urea nitrogen concentrations at 88 d (P < 0.001) and greater mean NEFA (P < 0.001) concentrations. Rainfall during mid-lactation subsequently improved grazing diet quality; thus the CON heifers experienced moderate nutritional restriction across lactation, but sufficient to reduce milk yield by 1.6 kg/d (P < 0.001) and maternal LW at weaning by 18.4 kg (P < 0.001). Bulls reared by SUPP heifers were 17.5 kg heavier at weaning (P = 0.001) and had elevated IGF-I and leptin concentrations between 4 and 4.5 months of age (P < 0.05). Effects on metabolic hormones during calfhood were cohort specific, with greater concentrations of IGF-I confined to AISUPP bulls and NMSUPP bulls demonstrating greater concentrations of leptin. Bulls were amalgamated at weaning and grazed common pastures without supplementation until the experiment concluded at 675 d. Pre-weaning plane of nutrition did not affect the LW, carcass fat depth, IGF-I or leptin concentrations of bulls after weaning. Mean eye muscle area (EMA) was greater in SUPP compared to CON bulls (68.5 ± 0.9 cm2vs 65.2 ± 0.9 cm2; P < 0.05) and AISUPP bulls tended to have greater EMA (P = 0.06) than AICON bulls from 495 d of age. Thus when primiparous heifers experience moderate nutritional restriction during lactation, supplementation may have persistent effects upon increasing carcass muscle characteristics of bull progeny.

Supplementation of rangeland primiparous Bos indicus x Bos taurus beef heifers during lactation. 2. Effects upon the reproductive development of bull calf progeny.

This experiment evaluated the effect of pre-weaning plane of nutrition of dams upon reproductive development in Bos indicus x Bos taurus bull offspring reared under extensively managed conditions in the northern Australia rangelands. Following artificial insemination (AI cohort; n = 26), or natural mating (NM cohort; n = 36), grazing primiparous heifers received either nil supplement (Control; CON), thereby experiencing a moderate nutritional restriction, or were provided a protein supplement (SUPP) between parturition and weaning at mean age 199 ± (SD) 26 d. Bull progeny grazed rangeland pastures without supplementation from weaning until the experiment concluded at 675 d. At 120 ± 3 d and 140 d ± 10 d age, within the AI and NM cohort, respectively, bull calves were subjected to a GnRH challenge (1.5 µg/kg of body weight i.m.). Jugular blood samples collected immediately before and at 60 min after administration of GnRH were analysed for LH, FSH, testosterone and inhibin concentrations. Overall mean concentrations of testosterone in SUPP bulls were greater in both the AI cohort (P = 0.05) and the NM cohort (P = 0.06). At 60 d intervals during the post-weaning period, scrotal circumference (SC) was measured and semen collected to assess concentration, progressive motility and morphology of sperm. Bulls reared by SUPP heifers had greater (P = 0.05) SC at 375 d and tended to have greater (P = 0.09) mean percentage of morphologically normal sperm (PNS). Within the NM cohort, NMSUPP bulls had greater (P = 0.04) overall mean SC and tended (P = 0.07) to demonstrate both greater progressive motility and PNS. A greater incidence of sperm morphological abnormalities, associated with sexual immaturity, were observed in CON bulls. Consequently, NMCON bulls demonstrated delayed (P = 0.03) age of sexual maturity as compared to NMSUPP bulls. In summary, improving the plane of nutrition supplied to Bos indicus x Bos taurus bulls between parturition and weaning via moderate supplementation of grazing dams reduces age at sexual maturity with consequent economic advantages to the producer.

Exercise and insulin resistance in PCOS: muscle insulin signalling and fibrosis.

OBJECTIVE: Mechanisms of insulin resistance in polycystic ovary syndrome (PCOS) remain ill defined, contributing to sub-optimal therapies. Recognising skeletal muscle plays a key role in glucose homeostasis we investigated early insulin signalling, its association with aberrant transforming growth factor ß (TGFß)-regulated tissue fibrosis. We also explored the impact of aerobic exercise on these molecular pathways. METHODS: A secondary analysis from a cross-sectional study was undertaken in women with (n = 30) or without (n = 29) PCOS across lean and overweight BMIs. A subset of participants with (n = 8) or without (n = 8) PCOS who were overweight completed 12 weeks of aerobic exercise training. Muscle was sampled before and 30 min into a euglycaemic-hyperinsulinaemic clamp pre and post training. RESULTS: We found reduced signalling in PCOS of mechanistic target of rapamycin (mTOR). Exercise training augmented but did not completely rescue this signalling defect in women with PCOS. Genes in the TGFß signalling network were upregulated in skeletal muscle in the overweight women with PCOS but were unresponsive to exercise training except for genes encoding LOX, collagen 1 and 3. CONCLUSIONS: We provide new insights into defects in early insulin signalling, tissue fibrosis, and hyperandrogenism in PCOS-specific insulin resistance in lean and overweight women. PCOS-specific insulin signalling defects were isolated to mTOR, while gene expression implicated TGFß ligand regulating a fibrosis in the PCOS-obesity synergy in insulin resistance and altered responses to exercise. Interestingly, there was little evidence for hyperandrogenism as a mechanism for insulin resistance.

Quantification of viable granulosa cells in murine ovarian follicles.

Ovarian follicle growth and oocyte maturation depend on the viability of granulosa cells (GC). We quantified GC in whole mouse follicles. Single follicles were isolated from adult mouse ovaries and stained with DAPI or Live-Dead stain before fixation. An objective image analysis protocol for counting fluorescent labeled GC was developed that used Image J software to measure GC cytoplasmic and nuclear areas. These data were compared to the number of GC obtained by disaggregating 96 follicles with enzymes to produce a suspension of GC, which then was stained with trypan blue and assessed using a hemocytometer. We found a linear relation between GC/follicle and follicle diameter. Viability of GC/follicle ranged from 40 ± 11 to 72 ± 7%. The coefficient of variation for image analysis of DAPI stained GC by different assessors was 4%, but the number of GC obtained from image analysis was approximately 50% less than from disaggregated follicles. The number of GC in intact mouse follicles was greater than the number reported earlier for fixed ovarian sections. We found that the number of GC was less in fluorescence labeled follicles; it is possible that the three-dimensional structure of the intact follicles obscured the fluorescent signal. Direct quantification of viable GC isolated from follicles appears to be the most accurate method.

Maternal periconceptional and first trimester protein restriction in beef heifers: effects on placental parameters and fetal and neonatal calf development.

Few studies have investigated the effects of nutrition during the periconception and early gestation periods on fetal and placental development in cattle. In this study, nulliparous yearling heifers (n=360) were individually fed a diet high or low in protein (HPeri and LPeri) beginning 60 days before conception. From 24 to 98 days after conception, half of each treatment group was changed to the alternative high- or low-protein diet (HPost and LPost) yielding four groups in a 2×2 factorial design. A subset of heifers (n=46) was necropsied at 98 days after conception and fetoplacental development assessed. Placentome number and volume decreased in response to LPeri and LPost diets respectively. Absolute lung, pancreas, septum and ventricle weights decreased in LPost versus HPost fetuses, whereas the post-conception diet altered absolute and relative liver and brain weights depending on sex. Similarly, changes in fetal hepatic gene expression of factors regulating growth, glucose output and lipid metabolism were induced by protein restriction in a sex-specific manner. At term, neonatal calf and placental measures were not different. Protein restriction of heifers during the periconception and early gestation periods alters fetoplacental development and hepatic gene expression. These changes may contribute to functional consequences for progeny, but this may not be apparent from gross morphometry at birth.

Evidence summaries and recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome: assessment and treatment of infertility.

STUDY QUESTION: What is the recommended assessment and management of infertile women with polycystic ovary syndrome (PCOS), based on the best available evidence, clinical expertize and consumer preference? SUMMARY ANSWER: International evidence-based guidelines, including 44 recommendations and practice points, addressed prioritized questions to promote consistent, evidence-based care and improve the experience and health outcomes of infertile women with PCOS. WHAT IS KNOWN ALREADY: Previous guidelines on PCOS lacked rigorous evidence-based processes, failed to engage consumer and multidisciplinary perspectives or were outdated. The assessment and management of infertile women with PCOS are inconsistent. The needs of women with PCOS are not being adequately met and evidence practice gaps persist. PARTICIPANTS/MATERIALS SETTING METHODS: Governance included a six continent international advisory and a project board, a multidisciplinary international guideline development group (GDG), consumer and translation committees. Extensive health professional and consumer engagement informed the guideline scope and priorities. The engaged international society-nominated panel included endocrinology, gynaecology, reproductive endocrinology, obstetrics, public health and other experts, alongside consumers, project management, evidence synthesis and translation experts. Thirty-seven societies and organizations covering 71 countries engaged in the process. Extensive online communication and two face-to-face meetings over 15 months addressed 19 prioritized clinical questions involving nine evidence-based reviews and 10 narrative reviews. Evidence-based recommendations (EBRs) were formulated prior to consensus voting within the guideline panel. STUDY DESIGN SIZE DURATION: International evidence-based guideline development engaged professional societies and consumer organizations with multidisciplinary experts and women with PCOS directly involved at all stages. A (AGREE) II-compliant processes were followed, with extensive evidence synthesis. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework was applied across evidence quality, desirable and undesirable consequences, feasibility, acceptability, cost, implementation and ultimately recommendation strength. The guideline was peer-reviewed by special interest groups across our partner and collaborating societies and consumer organizations, was independently assessed against AGREE II criteria and underwent methodological review. This guideline was approved by all members of the GDG and has been approved by the NHMRC. MAIN RESULTS AND THE ROLE OF CHANCE: The quality of evidence (QOE) for the EBRs in the assessment and management of infertility in PCOS included very low (n = 1), low (n = 9) and moderate (n = 4) quality with no EBRs based on high-quality evidence. The guideline provides 14 EBRs, 10 clinical consensus recommendations (CCRs) and 20 clinical practice points on the assessment and management of infertility in PCOS. Key changes in this guideline include emphasizing evidence-based fertility therapy, including cheaper and safer fertility management. LIMITATIONS REASONS FOR CAUTION: Overall evidence is generally of low to moderate quality, requiring significantly greater research in this neglected, yet common condition. Regional health systems vary and a process for adaptation of this guideline is provided. WIDER IMPLICATIONS OF THE FINDINGS: The international guideline for the assessment and management of infertility in PCOS provides clinicians with clear advice on best practice based on the best available evidence, expert multidisciplinary input and consumer preferences. Research recommendations have been generated and a comprehensive multifaceted dissemination and translation program supports the guideline with an integrated evaluation program. STUDY FUNDING/COMPETING INTERESTS: The guideline was primarily funded by the Australian National Health and Medical Research Council of Australia (NHMRC) supported by a partnership with ESHRE and the American Society for Reproductive Medicine (ASRM). GDG members did not receive payment. Travel expenses were covered by the sponsoring organizations. Disclosures of conflicts of interest were declared at the outset and updated throughout the guideline process, aligned with NHMRC guideline processes. Dr Costello has declared shares in Virtus Health and past sponsorship from Merck Serono for conference presentations. Prof. Norman has declared a minor shareholder interest in the IVF unit Fertility SA, travel support from Merck and grants from Ferring. Prof. Norman also has scientific advisory board duties for Ferring. The remaining authors have no conflicts of interest to declare.This article was not externally peer-reviewed by Human Reproduction Open.

Morphometric and gene expression analyses of stromal expansion during development of the bovine fetal ovary.

During ovarian development stroma from the mesonephros penetrates and expands into the ovarian primordium and thus appears to be involved, at least physically, in the formation of ovigerous cords, follicles and surface epithelium. Cortical stromal development during gestation in bovine fetal ovaries (n=27) was characterised by immunohistochemistry and by mRNA analyses. Stroma was identified by immunostaining of stromal matrix collagen type I and proliferating cells were identified by Ki67 expression. The cortical and medullar volume expanded across gestation, with the rate of cortical expansion slowing over time. During gestation, the proportion of stroma in the cortex and total volume in the cortex significantly increased (P<0.05). The proliferation index and numerical density of proliferating cells in the stroma significantly decreased (P<0.05), whereas the numerical density of cells in the stroma did not change (P>0.05). The expression levels of 12 genes out of 18 examined, including osteoglycin (OGN) and lumican (LUM), were significantly increased later in development (P<0.05) and the expression of many genes was positively correlated with other genes and with gestational age. Thus, the rate of cortical stromal expansion peaked in early gestation due to cell proliferation, whilst late in development expression of extracellular matrix genes increased.

Peri-conception and first trimester diet modifies reproductive development in bulls.

Nutritional perturbation during gestation alters male reproductive development in rodents and sheep. In cattle both the developmental trajectory of the feto-placental unit and its response to dietary perturbations is dissimilar to that of these species. This study examined the effects of dietary protein perturbation during the peri-conception and first trimester periods upon reproductive development in bulls. Nulliparous heifers (n=360) were individually fed a high- or low-protein diet (HPeri and LPeri) from 60 days before conception. From 24 until 98 days post conception, half of each treatment group changed to the alternative post-conception high- or low-protein diet (HPost and LPost) yielding four treatment groups in a 2×2 factorial design. A subset of male fetuses (n=25) was excised at 98 days post conception and fetal testis development was assessed. Reproductive development of singleton male progeny (n=40) was assessed until slaughter at 598 days of age, when adult testicular cytology was evaluated. Low peri-conception diet delayed reproductive development: sperm quality was lowered during pubertal development with a concomitant delay in reaching puberty. These effects were subsequent to lower FSH concentrations at 330 and 438 days of age. In the fetus, the low peri-conception diet increased the proportion of seminiferous tubules and decreased blood vessel area in the testis, whereas low first trimester diet increased blood vessel number in the adult testis. We conclude that maternal dietary protein perturbation during conception and early gestation may alter male testis development and delay puberty in bulls.

Bench to bedside in appetite research: Lost in translation?

Despite substantial progress in our understanding of the complex bio-machinery involved in the regulation of appetite and energy homeostasis, few weight loss drugs are currently government-approved in the USA or Europe. While acknowledging novel drug monotherapies (such as Belviq® & Saxenda®), this review focuses on the various drug polytherapies that are currently attracting so much research interest. Unfortunately, however, the dependent variables in these new studies remain firmly rooted in outcome measures i.e. reduced food intake and bodyweight. Such evidence is clearly essential, as are physiological data bearing upon potential 'off-target' effects of any new treatment. However, as emphasised by many authors, this profiling has to be matched by sophisticated behavioural analysis addressing fundamental 'process' questions such as how such reductions in intake and/or bodyweight have been achieved. The value of behavioural analysis is exemplified, and it is argued that such a process-led approach should optimise the translation from preclinical to clinical development of candidate drugs, and avoid yet further expensive blind alleys.

Subacute ruminal acidosis reduces sperm quality in beef bulls.

Breeding bulls are commonly fed high-energy diets, which may induce subacute ruminal acidosis (SARA). In this experiment, 8 Santa Gertrudis bulls (age 20 ± 6 mo) were used to evaluate the extent and duration of effects of SARA on semen quality and the associated changes in circulating hormones and metabolites. The bulls were relocated and fed in yards with unrestricted access to hay and daily individual concentrate feeding for 125 d before SARA challenge. Semen was collected and assessed at 14-d intervals before the challenge to ensure acclimatization and the attainment of a stable spermiogram. The challenge treatments consisted of either a single oral dose of oligofructose (OFF; 6.5 g/kg BW) or an equivalent sham dose of water (Control). Locomotion, behavior, respiratory rate, and cardiovascular and gastrointestinal function were intensively monitored during the 24-h challenge period. Rumen fluid samples were retained for VFA, ammonia, and lactate analysis. After the challenge, semen was then collected every third day for a period of 7 wk and then once weekly until 12 wk, with associated blood collection for FSH, testosterone, inhibin, and cortisol assay. Percent normal sperm decreased in bulls dosed with OFF after the challenge period ( < 0.05) and continued to remain lower on completion of the study at 88 d after challenge. There was a corresponding increase in sperm defects commencing from 16 d after challenge. These included proximal cytoplasmic droplets ( < 0.001), distal reflex midpieces ( = 0.01), and vacuole and teratoid heads ( < 0.001). Changes in semen quality after challenge were associated with lower serum testosterone ( < 0.001) and FSH ( < 0.05). Serum cortisol in OFF bulls tended to be greater ( = 0.07) at 7 d after challenge. This study shows that SARA challenge causes a reduction in sperm quality sufficient to preclude bulls from sale as single sire breeding animals 3 mo after the event occurred.

Quantitative elemental analysis of bovine ovarian follicles using X-ray fluorescence imaging.

The X-ray Fluorescence Micro-spectroscopy (XFM) beamline at the Australian Synchrotron was used to image 97 follicle histological sections from 45 different bovine ovaries focusing on healthy antral follicles ranging from small (<4 mm) up to preovulatory sizes (>16 mm) and on antral follicles undergoing atresia. This analysis identified five elements (Cu, Fe, Zn, Se and Br) consistently present within the ovarian tissue with Fe, Zn and Se localised to specific structures. GeoPIXE v6.4g was subsequently used to extract quantitative information pertaining to the elemental concentrations surrounding each of these follicles. Statistical analysis suggested that significant elemental differences were evident between follicle groups sorted according to their health status (Fe and Br), and their size (Se). Se appeared to be the element which most greatly distinguished large antral follicles from smaller counterparts. The ability to use synchrotron radiation to measure trace element distributions in bovine follicles at such high resolutions could have a significant impact on understanding the mechanisms of follicular development. This research is intended to form a baseline study of healthy cycling ovaries which could later be extended to disease states, thereby improving our current understanding of infertility and endocrine diseases involving the ovary.

Correction: X-Ray fluorescence imaging and other analyses identify selenium and GPX1 as important in female reproductive function.

Correction for 'X-Ray fluorescence imaging and other analyses identify selenium and GPX1 as important in female reproductive function' by M. J. Ceko et al., Metallomics, 2014, DOI: .

X-Ray fluorescence imaging and other analyses identify selenium and GPX1 as important in female reproductive function.

Studies of selenium (Se) status indicate that Se is necessary for fertility but how precisely is not known. We aimed to show that Se was important in bovine female reproductive function. The elemental distribution in the bovine ovary (n = 45 sections) was identified by X-ray fluorescence (XRF) imaging. Se was consistently localized to the granulosa cell layer of large (>10 mm) healthy follicles. Inductively Coupled Plasma - Mass Spectrometry revealed tenfold higher Se in the bovine follicle wall compared to corpora lutea. Gene expression analysis of selenoprotein genes GPX1, GPX3, VIMP and SELM in bovine granulosa cells revealed that only GPX1 was significantly up-regulated in large healthy follicles compared to the small healthy or atretic follicles (P < 0.05). Western immunoblotting identified GPX1 protein in bovine granulosa cells of large healthy follicles, but not of small healthy follicles. To assess if GPX1 was important in human follicles, cumulus cells from women undergoing IVF/ICSI with single embryo transfer were collected. Oocytes and embryos were cultured and transferred independently in 30 patients undergoing elective single embryo transfer. Gene expression of GPX1 was significantly higher in human cumulus cells from cumulus-oocyte complexes yielding a pregnancy (P < 0.05). We present the first XRF imaging of mammalian ovaries showing that Se is consistently localized to the granulosa cells of large healthy follicles. We conclude that Se and selenoproteins are elevated in large healthy follicles and may play a critical role as an antioxidant during late follicular development.

Deletion of α-neurexin II results in autism-related behaviors in mice.

Autism is a common and frequently disabling neurodevelopmental disorder with a strong genetic basis. Human genetic studies have discovered mutations disrupting exons of the NRXN2 gene, which encodes the synaptic adhesion protein α-neurexin II (Nrxn2α), in two unrelated individuals with autism, but a causal link between NRXN2 and the disorder remains unclear. To begin to test the hypothesis that Nrxn2α deficiency contributes to the symptoms of autism, we employed Nrxn2α knockout (KO) mice that genetically model Nrxn2α deficiency in vivo. We report that Nrxn2α KO mice displayed deficits in sociability and social memory when exposed to novel conspecifics. In tests of exploratory activity, Nrxn2α KO mice displayed an anxiety-like phenotype in comparison with wild-type littermates, with thigmotaxis in an open field, less time spent in the open arms of an elevated plus maze, more time spent in the enclosure of an emergence test and less time spent exploring novel objects. However, Nrxn2α KO mice did not exhibit any obvious changes in prepulse inhibition or in passive avoidance learning. Real-time PCR analysis of the frontal cortex and hippocampus revealed significant decreases in the mRNA levels of genes encoding proteins involved in both excitatory and inhibitory transmission. Quantification of protein expression revealed that Munc18-1, encoded by Stxbp1, was significantly decreased in the hippocampus of Nrxn2α KO mice, which is suggestive of deficiencies in presynaptic vesicular release. Our findings demonstrate a causal role for the loss of Nrxn2α in the genesis of autism-related behaviors in mice.

Behavioural profile of exendin-4/naltrexone dose combinations in male rats during tests of palatable food consumption.

RATIONALE: The glucagon-like peptide 1 receptor (GLP-1R) agonist exendin-4 potently suppresses food intake in animals and humans. However, little is known about the behavioural specificity of this effect either when administered alone or when co-administered with another anorectic agent. OBJECTIVES: The present study characterises the effects of exendin-4, both alone and in combination with naltrexone, on behaviours displayed by male rats during tests with palatable mash. METHODS: Experiment 1 examined the dose-response effects of exendin-4 (0.025-2.5 µg/kg, IP), while experiment 2 profiled the effects of low-dose combinations of the peptide (0.025 and 0.25 µg/kg) and naltrexone (0.1 mg/kg). RESULTS: In experiment 1, exendin-4 dose dependently suppressed food intake as well as the frequency and rate of eating. However, these effects were accompanied by dose-dependent reductions in all active behaviours and, at 2.5 µg/kg, a large increase in resting and disruption of the behavioural satiety sequence (BSS). In experiment 2, while exendin-4 (0.25 µg/kg) and naltrexone each produced a significant reduction in intake and feeding behaviour (plus an acceleration in the BSS), co-treatment failed to produce stronger effects than those seen in response to either compound alone. CONCLUSION: Similarities between the behavioural signature of exendin-4 and that previously reported for the emetic agent lithium chloride would suggest that exendin-4 anorexia is related to the aversive effects of the peptide. Furthermore, as low-dose combinations of the peptide with naltrexone failed to produce an additive/synergistic anorectic effect, this particular co-treatment strategy would not appear to have therapeutic significance.

On the behavioural specificity of hypophagia induced in male rats by mCPP, naltrexone, and their combination.

RATIONALE: Serotonergic (5-hydroxytryptamine, 5-HT) and opioidergic mechanisms are intimately involved in appetite regulation. OBJECTIVES: In view of recent evidence of positive anorectic interactions between opioid and various non-opioid substrates, our aim was to assess the behavioural specificity of anorectic responses to the opioid receptor antagonist naltrexone, the 5-HT2C/1B receptor agonist mCPP and their combination. METHODS: Behavioural profiling techniques, including the behavioural satiety sequence (BSS), were used to examine acute drug effects in non-deprived male rats tested with palatable mash. Experiment 1 characterised the dose-response profile of mCPP (0.1-3.0 mg/kg), while experiment 2 assessed the effects of combined treatment with a sub-anorectic dose of mCPP (0.1 mg/kg) and one of two low doses of naltrexone (0.1 and 1.0 mg/kg). RESULTS: Experiment 1 confirmed the dose-dependent anorectic efficacy of mCPP, with robust effects on intake and feeding-related measures observed at 3.0 mg/kg. However, that dose was also associated with other behavioural alterations including increased grooming, reductions in locomotion and sniffing, and disruption of the BSS. In experiment 2, naltrexone dose-dependently reduced food intake and time spent feeding, effects accompanied by a behaviourally selective acceleration in the BSS. However, the addition of 0.1 mg/kg mCPP did not significantly alter the behavioural changes observed in response to either dose of naltrexone given alone. CONCLUSIONS: In contrast to recently reported positive anorectic interactions involving low-dose combinations of opioid receptor antagonists or mCPP with cannabinoid CB1 receptor antagonists, present results would not appear to provide any support for potentially clinically relevant anorectic interactions between opioid and 5-HT2C/1B receptor mechanisms.

Trait differences in response to chronic nicotine and nicotine withdrawal in rats.

INTRODUCTION: Understanding an individual's vulnerability to drug addiction has important implications for the development of effective personal treatment plans. Although theories acknowledge impulsive behaviour as a key component of drug addiction, little is known about the influence of trait impulsivity on an individual's susceptibility to the effects of psychostimulants on impulsivity at critical phases of the addiction cycle. METHODS: This study investigated the short and longer-term effects of chronic nicotine administration on impulsive choice in rats selected for high (HI) and low impulsivity (LI) on a delay discounting task. Rats prepared with subcutaneously osmotic mini-pumps received either nicotine (3.16 mg/kg/day [freebase]) or saline for 7 days. Performance was assessed during chronic treatment, early and late withdrawal, and in response to acute nicotine challenges following prolonged abstinence. RESULTS: Chronic nicotine increased impulsive choice in LI but not HI animals. Spontaneous withdrawal was associated with a nicotine abstinence syndrome, the early stages of which were characterised by opposing effects on impulsive choice in HI and LI animals. A transient decrease in impulsivity was observed in HI animals whilst the LI group remained more impulsive for up to 1 week following drug termination. Following normalisation of behaviour, acute nicotine challenges (0.125, 0.25, 0.5 mg/kg, SC) markedly increased impulsive choice regardless of trait impulsivity and drug history. CONCLUSION: The results indicate that only LI individuals are vulnerable to chronic drug- and withdrawal-induced impairments in self-control which may increase the likelihood of the transition to, and maintenance of, nicotine dependence.

Pancreatic islet basement membrane loss and remodeling after mouse islet isolation and transplantation: impact for allograft rejection.

The isolation of islets by collagenase digestion can cause damage and impact the efficiency of islet engraftment and function. In this study, we assessed the basement membranes (BMs) of mouse pancreatic islets as a molecular biomarker for islet integrity, damage after isolation, and islet repair in vitro as well as in the absence or presence of an immune response after transplantation. Immunofluorescence staining of BM matrix proteins and the endothelial cell marker platelet endothelial cell adhesion molecule-1 (PECAM-1) was performed on pancreatic islets in situ, isolated islets, islets cultured for 4 days, and islet grafts at 3-10 days posttransplantation. Flow cytometry was used to investigate the expression of BM matrix proteins in isolated islet ß-cells. The islet BM, consisting of collagen type IV and components of Engelbreth-Holm-Swarm (EHS) tumor laminin 111, laminin α2, nidogen-2, and perlecan in pancreatic islets in situ, was completely lost during islet isolation. It was not reestablished during culture for 4 days. Peri- and intraislet BM restoration was identified after islet isotransplantation and coincided with the migration pattern of PECAM-1(+) vascular endothelial cells (VECs). After islet allotransplantation, the restoration of VEC-derived peri-islet BMs was initiated but did not lead to the formation of the intraislet vasculature. Instead, an abnormally enlarged peri-islet vasculature developed, coinciding with islet allograft rejection. The islet BM is a sensitive biomarker of islet damage resulting from enzymatic isolation and of islet repair after transplantation. After transplantation, remodeling of both peri- and intraislet BMs restores ß-cell-matrix attachment, a recognized requirement for ß-cell survival, for isografts but not for allografts. Preventing isolation-induced islet BM damage would be expected to preserve the intrinsic barrier function of islet BMs, thereby influencing both the effector mechanisms required for allograft rejection and the antirejection strategies needed for allograft survival.