A missense mutation in Kcnc3 causes hippocampal learning deficits in mice.

Although a wide variety of genetic tools has been developed to study learning and memory, the molecular basis of memory encoding remains incompletely understood. Here, we undertook an unbiased approach to identify novel genes critical for memory encoding. From a large-scale, in vivo mutagenesis screen using contextual fear conditioning, we isolated in mice a mutant, named Clueless, with spatial learning deficits. A causative missense mutation (G434V) was found in the voltage-gated potassium channel, subfamily C member 3 (Kcnc3) gene in a region that encodes a transmembrane voltage sensor. Generation of a Kcnc3G434V CRISPR mutant mouse confirmed this mutation as the cause of the learning defects. While G434V had no effect on transcription, translation, or trafficking of the channel, electrophysiological analysis of the G434V mutant channel revealed a complete loss of voltage-gated conductance, a broadening of the action potential, and decreased neuronal firing. Together, our findings have revealed a role for Kcnc3 in learning and memory.

Dexamethasone-sparing on days 2-4 with combined palonosetron, neurokinin-1 receptor antagonist, and olanzapine in cisplatin: a randomized phase III trial (SPARED Trial).

BACKGROUND: This study evaluated the non-inferiority of dexamethasone (DEX) on day 1, with sparing on days 2-4 in cisplatin-based chemotherapy. METHODS: Patients with malignant solid tumors who were treated with cisplatin (≥50 mg/m²) were randomly assigned (1:1) to receive either DEX on days 1-4 (Arm D4) or DEX on day 1 (Arm D1) plus palonosetron, NK-1 RA, and olanzapine (5 mg). The primary endpoint was complete response (CR) during the delayed (24-120 h) phase. The non-inferiority margin was set at -15%. RESULTS: A total of 281 patients were enrolled, 278 of whom were randomly assigned to Arm D4 (n = 139) or Arm D1 (n = 139). In 274 patients were included in the efficacy analysis, the rates of delayed CR in Arms D4 and D1 were 79.7% and 75.0%, respectively (risk difference -4.1%; 95% CI -14.1%-6.0%, P = 0.023). However, patients in Arm D1 had significantly lower total control rates during the delayed and overall phases, and more frequent nausea and appetite loss. There were no significant between-arm differences in the quality of life. CONCLUSION: DEX-sparing is an alternative option for patients receiving cisplatin; however, this revised administration schedule should be applied on an individual basis after a comprehensive evaluation. CLINICAL TRIALS REGISTRY NUMBER: UMIN000032269.

The emerging emetogenicity of trifluridine/tipiracil (TAS­102) from patient self-reporting: a multicenter, prospective, observational study.

BACKGROUND: Trifluridine/tipiracil (TAS-102) is an oral anticancer drug with adequate efficacy in unresectable colorectal cancer, but frequently also induces chemotherapy-induced nausea and vomiting (CINV). To investigate the occurrence of CINV and antiemetic therapy in patients with colorectal cancer treated with TAS-102 (JASCC-CINV 2001). METHODS: We conducted a multicenter, prospective, observational study in patients with colorectal cancer who received TAS-102 without dose reduction for the first time. Primary endpoint was the incidence of vomiting during the overall period. Secondary endpoints were the incidence of nausea, significant nausea, anorexia, other adverse events (constipation, diarrhea, insomnia, fatigue, dysgeusia) and patient satisfaction. Patient diaries were used for primary and secondary endpoints. All adverse events were subjectively assessed using PRO-CTCAE ver 1.0. and CTCAE ver 5.0. RESULTS: Data from 100 of the 119 enrolled patients were analyzed. The incidence of vomiting, nausea, and significant nausea was 13%, 67%, and 36%, respectively. The incidence of vomiting in patients with and without prophylactic antiemetic therapy were 20.8% and 10.5%, respectively. Prophylactic antiemetics were given to 24% of patients, of whom 70% received D2 antagonists. Multivariate Cox proportional hazards analysis showed that experience of CINV in previous treatment tended to be associated with vomiting (hazard ratio [HR]: 7.13, 95% confidence interval [CI]: 0.87-58.5, P = 0.07), whereas prophylactic antiemetic administration was not (HR: 1.61, 95 CI: 0.50-5.21, P = 0.43). With regard to patient satisfaction, the proportion of patients who were "very satisfied," "satisfied," "slightly satisfied" or "somewhat satisfied" was 81.8%. CONCLUSIONS: The low incidence of vomiting and high patient satisfaction suggest that TAS-102 does not require the use of uniform prophylactic antiemetic treatments. However, patients with the experience of CINV in previous treatment might require prophylactic antiemetic treatment.

Effects of glucokinase activator, DS-7309, on embryo-fetal developmental toxicity in rats and rabbits.

The toxicological effects of DS-7309, a glucokinase activator, on pregnancy and embryo-fetal development in rats and rabbits and maternal blood glucose levels were examined. DS-7309 was administered at 3, 10, or 100 mg/kg to rats from Days 7-17 of pregnancy or at 10, 30, or 100 mg/kg to rabbits from Days 6-18 of pregnancy. In rats, maternal hypoglycemia (approximately 50 mg/dL) was seen at 3 and 10 mg/kg, but it recovered 7 h after dosing, leading to no toxic changes. In contrast, continuous severe maternal hypoglycemia (approximately 40 mg/dL, ≥7 h), fetal eye anomalies, and decreased fetal body weight were noted at 100 mg/kg. In rabbits, no fetal anomalies were seen at 10 and 30 mg/kg where maternal blood glucose level dropped to approximately 60-90 mg/dL, but recovered by 7 h after dosing at the latest. In contrast, at 100 mg/kg, severe hypoglycemia (around 60 mg/dL) was maintained and did not recover until 24 h after dosing; it resulted in decreased fetal viability and increased fetal skeleton anomalies. These findings indicate that DS-7309 could lead to embryo-fetal toxicity in rats and rabbits, with such toxicity considered to be related to continuous severe maternal hypoglycemia.

Period2 3'-UTR and microRNA-24 regulate circadian rhythms by repressing PERIOD2 protein accumulation.

We previously created two PER2::LUCIFERASE (PER2::LUC) circadian reporter knockin mice that differ only in the Per2 3'-UTR region: Per2::Luc, which retains the endogenous Per2 3'-UTR and Per2::LucSV, where the endogenous Per2 3'-UTR was replaced by an SV40 late poly(A) signal. To delineate the in vivo functions of Per2 3'-UTR, we analyzed circadian rhythms of Per2::LucSV mice. Interestingly, Per2::LucSV mice displayed more than threefold stronger amplitude in bioluminescence rhythms than Per2::Luc mice, and also exhibited lengthened free-running periods (∼24.0 h), greater phase delays following light pulse, and enhanced temperature compensation relative to Per2::Luc Analysis of the Per2 3'-UTR sequence revealed that miR-24, and to a lesser degree miR-30, suppressed PER2 protein translation, and the reversal of this inhibition in Per2::LucSV augmented PER2::LUC protein level and oscillatory amplitude. Interestingly, Bmal1 mRNA and protein oscillatory amplitude as well as CRY1 protein oscillation were increased in Per2::LucSV mice, suggesting rhythmic overexpression of PER2 enhances expression of Per2 and other core clock genes. Together, these studies provide important mechanistic insights into the regulatory roles of Per2 3'-UTR, miR-24, and PER2 in Per2 expression and core clock function.

A Prospective Trial Evaluating the Safety of a Shortened Infusion of Ramucirumab in Patients with Gastrointestinal Cancer.

LESSONS LEARNED: A shortened infusion of ramucirumab (from 60 to 20 minutes) was safe and feasible without infusion-related reactions.Twenty-minute infusions of ramucirumab can be an option for patients with no infusion-related reactions during the first 60-minute treatment. BACKGROUND: Ramucirumab is usually administered over 60 minutes, during which it is unlikely to cause infusion-related reactions (IRRs). This prospective study evaluated the safety of a shortened infusion of ramucirumab. METHODS: Patients who received their first dose of ramucirumab in a 60-minute infusion without developing IRRs were eligible and received their second ramucirumab dose for 20 minutes. The primary study endpoint was incidence of IRR during the first short-term infusion, and the secondary endpoints were incidence of IRR at any time and adverse events other than IRR. RESULTS: Of the 40 patients enrolled (median age, 68.5 years), 20 (55%) were male, 27 (67.5%) had stage IV gastric cancer, 25 (62.5%) received ramucirumab in combination with taxane-based chemotherapy, and 24 (60%) received only a single administration of ramucirumab prior to their enrollment. Notably, no IRR was observed during the first short-term infusion (IRR rate, 0%; 95% confidence interval [CI], 0%-0.72%). Among the 149 short-term infusions performed, there were no instances of IRRs or unexpected adverse events related to the treatment (Table 1). CONCLUSION: For patients without development of IRRs upon the first ramucirumab administration, shortening infusion time (from 60 to 20 minutes) is safe and feasible.

Investigating toxicity specific to adjuvanted vaccines.

In an attempt to understand the unique toxicity of adjuvanted vaccines, we studied how toxicity develops over time following vaccine administration. In addition to on- and off-target toxicity typically observed with general pharmaceuticals, we observed toxicity associated with both the generation and the broad action of effectors (antibodies and/or cytotoxic T lymphocytes, CTLs). The impact on effector generation appears to be related to local tolerance specific to the adjuvant. The vaccine immune response by effectors serves to demonstrate species relevance as outlined in the recent WHO guideline on the nonclinical evaluation of adjuvanted vaccines. When regarded as pharmaceuticals that function at sites of local administration, adjuvants have inherent on- and off-target toxicity. On-target toxicity of the adjuvant is typically associated with effector generation, and could vary depending on animal species. Therefore, the use of species with sensitivity to adjuvants described in the WHO guidelines is required to evaluate the toxicity of the vaccine associated with effector generation. Changes in safety pharmacology endpoints would be considered off-target and further studies are conducted only if changes in these endpoints are observed in nonclinical or clinical studies. Thus our decision tree does not recommend the routine conduct of stand-alone safety pharmacology studies.

The incidence of drug-induced interstitial lung disease caused by epidermal growth factor receptor tyrosine kinase inhibitors or immune checkpoint inhibitors in patients with non-small cell lung cancer in presence and absence of vascular endothelial growth factor inhibitors: a systematic review.

Interstitial lung disease (ILD) or pneumonitis caused by epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) or immune checkpoint inhibitors (ICI) is a major concern in the treatment of non-small cell lung cancer (NSCLC). Whether the addition of vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) inhibitors can reduce the incidence of drug-induced ILD remains unclear. We conducted a systematic review to assess the incidence of ILD induced by EGFR-TKIs or ICIs in the presence or absence of VEGF/VEGFR inhibitors in relevant randomized trials between January 2009 and October 2023. The primary outcome was the odds ratio for the incidence of ILD in all patients worldwide and Asians. Secondary outcomes were the odds ratios (ORs) of the incidence at grade-3 or higher ILD in all patients worldwide and Asians. We identified 13 randomized studies, one sub-analysis in the EGFR-TKI group, and three randomized studies in the ICI group. In the EGFR-TKI group, the OR of ILD incidence at any grade with VEGF/VEGFR inhibitors was 0.54 (95% CI, 0.32-0.90; p = 0.02), which represented a significantly lower incidence than that without VEGF/VEGFR inhibitors. Contrarily, the OR of ILD incidence at grade ≥ 3 with VEGF/VEGFR inhibitors was 1.00 (95% CI, 0.43-2.36; p = 0.99). In all subjects in the ICI group, the OR of ILD incidence at any grade with VEGF/VEGFR inhibitors was 0.78 (95% CI, 0.51-1.21; p = 0.27). The systematic review demonstrated that the addition of VEGF/VEGFR inhibitors could reduce the incidence of drug-induced ILD at any grade caused by EGFR-TKI in patients with NSCLC but could not reduce that at grade ≥ 3. The ILD induced by ICIs remains undetermined owing to the limited number of randomized trials for which ILD data are available. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=409534, identifier CRD42023409534.

Genetic suppression of the circadian Clock mutation by the melatonin biosynthesis pathway.

Most laboratory mouse strains including C57BL/6J do not produce detectable levels of pineal melatonin owing to deficits in enzymatic activity of arylalkylamine N-acetyltransferase (AANAT) and N-acetylserotonin O-methyl transferase (ASMT), two enzymes necessary for melatonin biosynthesis. Here we report that alleles segregating at these two loci in C3H/HeJ mice, an inbred strain producing melatonin, suppress the circadian period-lengthening effect of the Clock mutation. Through a functional mapping approach, we localize mouse Asmt to chromosome X and show that it, and the Aanat locus on chromosome 11, are significantly associated with pineal melatonin levels. Treatment of suprachiasmatic nucleus (SCN) explant cultures from Period2(Luciferase) (Per2(Luc)) Clock/+ reporter mice with melatonin, or the melatonin agonist, ramelteon, phenocopies the genetic suppression of the Clock mutant phenotype observed in living animals. These results demonstrate that melatonin suppresses the Clock/+ mutant phenotype and interacts with Clock to affect the mammalian circadian system.

Public perceptions of physician-pharmaceutical industry relationships and trust in physicians.

BACKGROUND: In Japan, as elsewhere, physicians meet with and receive gifts from pharmaceutical representatives (PRs). This study aimed to clarify the Japanese public perceptions of physicians' relationships with PRs, examine the association between these perceptions and their trust in physicians, and compare the public's and physicians' awareness, acceptance, and perceptions of the influence of physician-PR relationships. METHODS: A cross-sectional, self-administered, anonymous, internet-panel survey was conducted involving 1,000 participants from the general public. The survey implementation was contracted to Cross Marketing Inc. RESULTS: The mean age of the 1000 participants was 44.8 years (standard deviation 18.3). Forty-eight percent were female. Many of our participants were unaware of certain physician-PR relationships. The public was more acceptable with physicians' receiving stationery and/or medical textbooks and attending promotional drug seminars at their workplaces compared with receiving meals at restaurants. Many thought that physicians' involvement in promotional activities influenced their prescribing habits and estimated that the majority of physicians received office stationery and meals from PRs. They were divided as to whether they would like to know about their physicians' relationships with the industry. Factors associated with higher trust in physicians included participants being 65 years or older, having a primary care physician, being in better health, the belief that physicians' involvement in promotional activities is acceptable, and their high estimate that physicians are not receiving gifts from PRs. Compared to the physicians, the public had lower awareness of and was more accepting of physicians' involvement in promotional activities. Meanwhile, the public believed that physician-PR relationships influenced physicians' prescribing habits more than the physicians themselves. CONCLUSION: Our survey provided insights into Japanese public perceptions of physician-pharmaceutical industry relationships and their impact on trust in physicians. Physicians should be aware of these perceptions and carefully consider how to foster appropriate relationships with the industry.

Changes in Japanese physicians' relationships with the pharmaceutical industry between 2008 and 2021: A national survey.

BACKGROUND: A national survey we conducted in 2008 showed that many Japanese physicians interacted with and received gifts from pharmaceutical representatives (PRs) and had a positive attitude toward relationships with PRs. The revised promotion code of the Japan Pharmaceutical Manufacturers Association in 2019 prohibited the provision of non-educational promotional aids including sticky notes, mouse pads, and calendars. During the COVID-19 pandemic in 2020, face-to-face meetings were socially restricted. This study assessed the extent of current Japanese physicians' involvement in pharmaceutical promotional activities and their attitudes toward relationships with PRs and to ascertain any changes between 2008 and 2021. We also examined the factors that predicted positive attitudes toward gifts from PRs. METHODS: From January to March 2021, we conducted a national mail survey of Japanese physicians in seven specialties: internal medicine, surgery, orthopedics, pediatrics, obstetrics-gynecology, psychiatry, and ophthalmology. RESULTS: There were 1636 participants and the response rate was 63.2%. Most physicians met face-to-face with PRs (78.8%), whereas only a minority received meals outside the workplace (4.5%). PRs were thought to have an important role in continuing medical education (66.1%) and to provide accurate information about new drugs (74.2%). Opinions were divided on the appropriateness of gifts from PRs. Most thought that stationery and meals provided by the industry did not affect prescribing behavior (89.7% and 75.8%, respectively). Factors that predicted a positive attitude toward gifts from PRs were male, orthopedic specialty vs. internal medicine, more interactions with PRs, a positive attitude toward informational value, and no rules banning meetings with PRs. CONCLUSION: Involvement in pharmaceutical promotional activities is still common among practicing physicians in Japan, although the extent of the involvement had declined. Rules banning meetings with PRs appear to continue being effective at limiting a physician's involvement with promotional activities and their critical attitudes toward gifts from PRs.

CKIepsilon/delta-dependent phosphorylation is a temperature-insensitive, period-determining process in the mammalian circadian clock.

A striking feature of the circadian clock is its flexible yet robust response to various environmental conditions. To analyze the biochemical processes underlying this flexible-yet-robust characteristic, we examined the effects of 1,260 pharmacologically active compounds in mouse and human clock cell lines. Compounds that markedly (>10 s.d.) lengthened the period in both cell lines, also lengthened it in central clock tissues and peripheral clock cells. Most compounds inhibited casein kinase Iepsilon (CKIepsilon) or CKIdelta phosphorylation of the PER2 protein. Manipulation of CKIepsilon/delta-dependent phosphorylation by these compounds lengthened the period of the mammalian clock from circadian (24 h) to circabidian (48 h), revealing its high sensitivity to chemical perturbation. The degradation rate of PER2, which is regulated by CKIepsilon/delta-dependent phosphorylation, was temperature-insensitive in living clock cells, yet sensitive to chemical perturbations. This temperature-insensitivity was preserved in the CKIepsilon/delta-dependent phosphorylation of a synthetic peptide in vitro. Thus, CKIepsilon/delta-dependent phosphorylation is likely a temperature-insensitive period-determining process in the mammalian circadian clock.

Impact of Corticosteroids for IrAEs on the Clinical Outcome of Immunotherapy in Patients With NSCLC.

BACKGROUND/AIM: The impact of corticosteroids for the treatment of immune-related adverse events (irAEs) on the antitumor effect of programmed cell death-1 (PD-1) inhibitor is unclear. PATIENTS AND METHODS: A total of 172 patients with non-small cell lung cancer (NSCLC) treated with PD-1 inhibitors were retrospectively reviewed. Patients were divided into four groups: those who did not develop irAEs [1] and those who developed irAE and were either not treated with corticosteroids [2] or treated with low [3] or high doses [4], and overall survival (OS) was analyzed by the time of corticosteroid treatment. Landmark analysis was performed using Cox proportional hazard model with time-dependent covariates. RESULTS: A high-dose steroid treatment within 60 days correlated with a significantly worse OS than that of the group with irAEs without steroids (p=0.004). Moreover, there was no significant difference in OS between the irAE without steroid and low-dose steroid groups. CONCLUSION: Early severe irAEs and high-dose corticosteroid treatment were poor prognostic factors in patients with NSCLC treated with PD-1 inhibitors.

Involvement of neurokinin receptors in the control of pulsatile luteinizing hormone secretion in rats.

It has recently been shown that neurokinin B, a tachykinin, is associated with GnRH pulse generation in sheep and goats. The aim of the present study was to clarify the role of tachykinin receptors in the control of LH secretion in rats. To this end, we evaluated the effect of CS-003, an antagonist for all three neurokinin receptors (NK1, NK2 and NK3 receptors), on pulsatile LH secretion in both sexes of rats with different routes of administration. Both oral and third ventricular administration of CS-003 suppressed LH secretion in both sexes of gonadectomized animals. Furthermore, intact male rats with oral administration of CS-003 showed decreased serum testosterone levels, which might be due to suppressed LH secretion. None of the three subtype-specific neurokinin receptor antagonists showed a significant effect on LH secretion in ovariectomized rats when each antagonist was singly administered. The present results suggest that neurokinins play a role in the control of pulsatile GnRH/LH secretion via multiple neurokinin receptors in both male and female rats.

The value of juvenile animal studies: a Japanese industry perspective.

Pharmaceuticals have been used on adults and children; however, they were previously investigated only by adult human clinical studies and adult animal nonclinical studies. The US FDA finalized the guidance of juvenile animal toxicity studies in 2006, and EMEA was finalized in 2008. At that point, juvenile animal toxicity studies were encouraged to investigate the safety of the pediatric population. In Japan, the awareness of the development of pediatric drugs is increasing, and many scientific meetings about juvenile animal studies are being held. A Japanese guideline for juvenile animal toxicity studies has been long awaited by many Japanese pharmaceutical companies because concrete directionality has not been available in Japan thus far. The Ministry of Health, Labour, and Welfare started to prepare the guideline for nonclinical safety studies in juvenile animals since October 2010. After completion of the Japanese guideline, guidelines would exist in the three regions: Japan, US, and Europe. Then, global development of pediatric pharmaceuticals would be accelerated effectively.

Gene set enrichment in eQTL data identifies novel annotations and pathway regulators.

Genome-wide gene expression profiling has been extensively used to generate biological hypotheses based on differential expression. Recently, many studies have used microarrays to measure gene expression levels across genetic mapping populations. These gene expression phenotypes have been used for genome-wide association analyses, an analysis referred to as expression QTL (eQTL) mapping. Here, eQTL analysis was performed in adipose tissue from 28 inbred strains of mice. We focused our analysis on "trans-eQTL bands", defined as instances in which the expression patterns of many genes were all associated to a common genetic locus. Genes comprising trans-eQTL bands were screened for enrichments in functional gene sets representing known biological pathways, and genes located at associated trans-eQTL band loci were considered candidate transcriptional modulators. We demonstrate that these patterns were enriched for previously characterized relationships between known upstream transcriptional regulators and their downstream target genes. Moreover, we used this strategy to identify both novel regulators and novel members of known pathways. Finally, based on a putative regulatory relationship identified in our analysis, we identified and validated a previously uncharacterized role for cyclin H in the regulation of oxidative phosphorylation. We believe that the specific molecular hypotheses generated in this study will reveal many additional pathway members and regulators, and that the analysis approaches described herein will be broadly applicable to other eQTL data sets.

Study protocol for SPARED trial: randomised non-inferiority phase III trial comparing dexamethasone on day 1 with dexamethasone on days 1-4, combined with neurokinin-1 receptor antagonist, palonosetron and olanzapine (5 mg) in patients receiving cisplatin-based chemotherapy.

INTRODUCTION: Dexamethasone (DEX) is administered for multiple days to prevent chemotherapy-induced nausea and vomiting for patients receiving highly emetogenic chemotherapy (HEC); however, its notorious side effects have been widely reported. Although our multicentre randomised double-blind comparative study verified non-inferiority of sparing DEX after day 2 of chemotherapy when combined with neurokinin-1 receptor antagonist (NK1-RA) and palonosetron (Palo) for patients receiving HEC regimen, DEX sparing was not non-inferior in patients receiving cisplatin (CDDP)-based HEC regimens in subgroup analysis. Recently, the efficacy of the addition of olanzapine (OLZ) to standard triple antiemetic therapy on HEC has been demonstrated by several phase III trials. This study aims to confirm non-inferiority of DEX sparing when it is combined with NK-1RA, Palo and OLZ in patients receiving CDDP-based HEC regimens. METHODS AND ANALYSIS: This is a randomised, double-blind, phase III trial. Patients who are scheduled to receive CDDP ≥50 mg/m2 as initial chemotherapy are eligible. Patients are randomly assigned to receive either DEX on days 1-4 or DEX on day 1 combined with NK1-RA, Palo and OLZ (5 mg). The primary endpoint is complete response (CR) rate, defined as no emesis and no rescue medications during the delayed phase (24-120 hours post-CDDP administration). The non-inferiority margin is set at -15.0%. We assume that CR rates would be 75% in both arms. Two hundred and sixty-two patients are required for at least 80% power to confirm non-inferiority at a one-sided significance level of 2.5%. After considering the possibility of attrition, we set our final required sample size of 280. ETHICS AND DISSEMINATION: The institutional review board approved the study protocol at each of the participating centres. The trial result will be presented at international conferences and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: UMIN000032269.

Genetic analysis of daily physical activity using a mouse chromosome substitution strain.

There is considerable evidence for a genetic basis underlying individual differences in spontaneous physical activity in humans and animals. Previous publications indicate that the physical activity level and pattern vary among inbred strains of mice and identified a genomic region on chromosome 13 as quantitative trait loci (QTL) for physical activity. To confirm and further characterize the role of chromosome 13 in regulating daily physical activity level and pattern, we conducted a comprehensive phenotypic study in the chromosome 13 substitution strain (CSS-13) in which the individual chromosome 13 from the A/J strain was substituted into an otherwise complete C57BL/6J (B6) genome. The B6 and A/J parental strains exhibited pronounced differences in daily physical activity, sleep-wake structure, circadian period and body weight. Here we report that a single A/J chromosome 13 in the context of a B6 genetic background conferred a profound reduction in both total cage activity and wheel-running activity under a 14:10-h light-dark cycle, as well as in constant darkness, compared with B6 controls. Additionally, CSS-13 mice differed from B6 controls in the diurnal distribution of activity and the day-to-day variability in activity onset. We further performed a linkage analysis and mapped a significant QTL on chromosome 13 regulating the daily wheel running activity level in mice. Taken together, our findings indicate a QTL on chromosome 13 with dramatic and specific effects on daily voluntary physical activity, but not on circadian period, sleep, or other aspects of activity that are different between B6 and A/J strains.

Identification of genetic loci involved in diabetes using a rat model of depression.

While diabetic patients often present with comorbid depression, the underlying mechanisms linking diabetes and depression are unknown. The Wistar Kyoto (WKY) rat is a well-known animal model of depression and stress hyperreactivity. In addition, the WKY rat is glucose intolerant and likely harbors diabetes susceptibility alleles. We conducted a quantitative trait loci (QTL) analysis in the segregating F(2) population of a WKY x Fischer 344 (F344) intercross. We previously published QTL analyses for depressive behavior and hypothalamic-pituitary-adrenal (HPA) activity in this cross. In this study we report results from the QTL analysis for multiple metabolic phenotypes, including fasting glucose, post-restraint stress glucose, postprandial glucose and insulin, and body weight. We identified multiple QTLs for each trait and many of the QTLs overlap with those previously identified using inbred models of type 2 diabetes (T2D). Significant correlations were found between metabolic traits and HPA axis measures, as well as forced swim test behavior. Several metabolic loci overlap with loci previously identified for HPA activity and forced swim behavior in this F(2) intercross, suggesting that the genetic mechanisms underlying these traits may be similar. These results indicate that WKY rats harbor diabetes susceptibility alleles and suggest that this strain may be useful for dissecting the underlying genetic mechanisms linking diabetes, HPA activity, and depression.

Genetics of Circadian Rhythms.

In mammals, genetic influences of circadian rhythms occur at many levels. A set of core "clock genes" have been identified that form a feedback loop of gene transcription and translation. The core genetic clockwork generates circadian rhythms in cells throughout the body. Polymorphisms in both core clock genes and interacting genes contribute to individual differences in the expression and properties of circadian rhythms. The circadian clock profoundly influences the patterns of gene expression and cellular functions, providing a mechanistic basis for the impact of the genetic circadian system on normal physiological processes as well as the development of diseases.