Daily Timed Sexual Interaction Induces Moderate Anticipatory Activity in Mice

Anticipation of resource availability is a vital skill yet it is poorly understood in terms of neuronal circuitry. Rodents display robust anticipatory activity in the several hours preceding timed daily access to food when access is limited to a short temporal duration. We tested whether this anticipatory behavior could be generalized to timed daily social interaction by examining if singly housed male mice could anticipate either a daily novel female or a familiar female. We observed that anticipatory activity was moderate under both conditions, although both a novel female partner and sexual experience are moderate contributing factors to increasing anticipatory activity. In contrast, restricted access to running wheels did not produce any anticipatory activity, suggesting that an increase in activity during the scheduled access time was not sufficient to induce anticipation. To tease apart social versus sexual interaction, we tested the effect of exposing singly housed female mice to a familiar companion female mouse daily. The female mice did not show anticipatory activity for restricted female access, despite a large amount of social interaction, suggesting that daily timed social interaction between mice of the same gender is insufficient to induce anticipatory activity. Our study demonstrates that male mice will show anticipatory activity, albeit inconsistently, for a daily timed sexual encounter

Palatable Meal Anticipation in Mice

The ability to sense time and anticipate events is a critical skill in nature. Most efforts to understand the neural and molecular mechanisms of anticipatory behavior in rodents rely on daily restricted food access, which induces a robust increase of locomotor activity in anticipation of daily meal time. Interestingly, rats also show increased activity in anticipation of a daily palatable meal even when they have an ample food supply, suggesting a role for brain reward systems in anticipatory behavior, and providing an alternate model by which to study the neurobiology of anticipation in species, such as mice, that are less well adapted to "stuff and starve" feeding schedules. To extend this model to mice, and exploit molecular genetic resources available for that species, we tested the ability of wild-type mice to anticipate a daily palatable meal. We observed that mice with free access to regular chow and limited access to highly palatable snacks of chocolate or “Fruit Crunchies” avidly consumed the snack but did not show anticipatory locomotor activity as measured by running wheels or video-based behavioral analysis. However, male mice receiving a snack of high fat chow did show increased food bin entry prior to access time and a modest increase in activity in the two hours preceding the scheduled meal. Interestingly, female mice did not show anticipation of a daily high fat meal but did show increased activity at scheduled mealtime when that meal was withdrawn. These results indicate that anticipation of a scheduled food reward in mice is behavior, diet, and gender specific

A conserved circadian function for the Neurofibromatosis 1 gene

Summary: Loss of the Neurofibromatosis 1 (Nf1) protein, neurofibromin, in Drosophila disrupts circadian rhythms of locomotor activity without impairing central clock function, suggesting effects downstream of the clock. However, the relevant cellular mechanisms are not known. Leveraging the discovery of output circuits for locomotor rhythms, we dissected cellular actions of neurofibromin in recently identified substrates. Herein, we show that neurofibromin affects the levels and cycling of calcium in multiple circadian peptidergic neurons. A prominent site of action is the pars intercerebralis (PI), the fly equivalent of the hypothalamus, with cell-autonomous effects of Nf1 in PI cells that secrete DH44. Nf1 interacts genetically with peptide signaling to affect circadian behavior. We extended these studies to mammals to demonstrate that mouse astrocytes exhibit a 24-hr rhythm of calcium levels, which is also attenuated by lack of neurofibromin. These findings establish a conserved role for neurofibromin in intracellular signaling rhythms within the nervous system. : Bai et al. show that the gene mutated in the disease Neurofibromatosis 1 is required for maintaining levels or cycling of calcium in circadian neurons in Drosophila and in mammalian cells. These effects likely account for effects of Nf1 on circadian behavior in Drosophila and may be relevant in explaining sleep phenotypes in patients. Keywords: circadian rhythms, neurofibromatosis 1, Drosophila, peptide signaling, cycling of calcium, mouse astrocyte

Daily Timed Sexual Interaction Induces Moderate Anticipatory Activity in Mice

Anticipation of resource availability is a vital skill yet it is poorly understood in terms of neuronal circuitry. Rodents display robust anticipatory activity in the several hours preceding timed daily access to food when access is limited to a short temporal duration. We tested whether this anticipatory behavior could be generalized to timed daily social interaction by examining if singly housed male mice could anticipate either a daily novel female or a familiar female. We observed that anticipatory activity was moderate under both conditions, although both a novel female partner and sexual experience are moderate contributing factors to increasing anticipatory activity. In contrast, restricted access to running wheels did not produce any anticipatory activity, suggesting that an increase in activity during the scheduled access time was not sufficient to induce anticipation. To tease apart social versus sexual interaction, we tested the effect of exposing singly housed female mice to a familiar companion female mouse daily. The female mice did not show anticipatory activity for restricted female access, despite a large amount of social interaction, suggesting that daily timed social interaction between mice of the same gender is insufficient to induce anticipatory activity. Our study demonstrates that male mice will show anticipatory activity, albeit inconsistently, for a daily timed sexual encounter

Food anticipatory activity on a calorie-restricted diet is independent of Sirt1

A number of studies have demonstrated that the Sirtuin family member, Sirt1, is a key integrator of growth, metabolism, and lifespan. Sirt1 directly interacts with and deacetylates key regulators of the circadian clock, positioning it to be an important link between feeding and circadian rhythms. In fact, one study suggests that Sirt1 is necessary for behavioral anticipation of limited daily food availability, a circadian process termed food anticipatory activity (FAA). In their study, mice overexpressing Sirt1 had enhanced FAA, while mice lacking Sirt1 had little to no FAA. Based on the supposition that Sirt1 was indeed required for FAA, we sought to use Sirt1 deletion to map the neural circuitry responsible for FAA. We began by inactivating Sirt1 using the cell-type specific Cre-driver lines proopiomelanocortin, but after observing no effect on body weight loss or FAA we then moved on to more broadly neuronal Cre drivers Ca2+/calmodulin-dependent protein kinase II and nestin. As neither of these neuronal deletions of Sirt1 had impaired FAA, we then tested 1) a broad postnatal tamoxifen-inducible deletion, 2) a complete, developmental knockout of Sirt1, and 3) a gene replacement, catalytically inactive, form of Sirt1; but all of these mice had FAA similar to controls. Therefore, our findings suggest that FAA is completely independent of Sirt1

Single Gene Deletions of Orexin, Leptin, Neuropeptide Y, and Ghrelin Do Not Appreciably Alter Food Anticipatory Activity in Mice

Timing activity to match resource availability is a widely conserved ability in nature. Scheduled feeding of a limited amount of food induces increased activity prior to feeding time in animals as diverse as fish and rodents. Typically, food anticipatory activity (FAA) involves temporally restricting unlimited food access (RF) to several hours in the middle of the light cycle, which is a time of day when rodents are not normally active. We compared this model to calorie restriction (CR), giving the mice 60% of their normal daily calorie intake at the same time each day. Measurement of body temperature and home cage behaviors suggests that the RF and CR models are very similar but CR has the advantage of a clearly defined food intake and more stable mean body temperature. Using the CR model, we then attempted to verify the published result that orexin deletion diminishes food anticipatory activity (FAA) but observed little to no diminution in the response to CR and, surprisingly, that orexin KO mice are refractory to body weight loss on a CR diet. Next we tested the orexigenic neuropeptide Y (NPY) and ghrelin and the anorexigenic hormone, leptin, using mouse mutants. NPY deletion did not alter the behavior or physiological response to CR. Leptin deletion impaired FAA in terms of some activity measures, such as walking and rearing, but did not substantially diminish hanging behavior preceding feeding time, suggesting that leptin knockout mice do anticipate daily meal time but do not manifest the full spectrum of activities that typify FAA. Ghrelin knockout mice do not have impaired FAA on a CR diet. Collectively, these results suggest that the individual hormones and neuropepetides tested do not regulate FAA by acting individually but this does not rule out the possibility of their concerted action in mediating FAA

Food Anticipatory Activity Behavior of Mice across a Wide Range of Circadian and Non-Circadian Intervals

When rodents are fed in a limited amount during the daytime, they rapidly redistribute some of their nocturnal activity to the time preceding the delivery of food. In rats, anticipation of a daily meal has been interpreted as a circadian rhythm controlled by a food-entrained oscillator (FEO) with circadian limits to entrainment. Lesion experiments place this FEO outside of the light-entrainable circadian pacemaker in the suprachiasmatic nucleus. Mice also anticipate a fixed daily meal, but circadian limits to entrainment and anticipation of more than 2 daily meals, have not been assessed. We used a video-based behavior recognition system to quantify food anticipatory activity in mice receiving 2, 3, or 6 daily meals at intervals of 12, 8, or 4-hours (h). Individual mice were able to anticipate as many as 4 of 6 daily meals, and anticipation persisted during meal omission tests. On the 6 meal schedule, pre-prandial activity and body temperature were poorly correlated, suggesting independent regulation. Mice showed a limited ability to anticipate an 18 h feeding schedule. Finally, mice showed concurrent circadian and sub-hourly anticipation when provided with 6 small meals, at 30 minute intervals, at a fixed time of day. These results indicate that mice can anticipate feeding opportunities at a fixed time of day across a wide range of intervals not previously associated with anticipatory behavior in studies of rats. The methods described here can be exploited to determine the extent to which timing of different intervals in mice relies on common or distinct neural and molecular mechanisms

Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.

BACKGROUND:Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. METHODS AND RESULTS:Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P=0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [P=0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates. CONCLUSIONS:Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500

Eating disorders: from twin studies to candidate genes and beyond

Substantial effort has been put into the exploration of the biological background of eating disorders, through family, twin and molecular genetic studies. Family studies have shown that anorexia (AN) and bulimia nervosa (BN) are strongly familial, and that familial etiologic factors appear to be shared by both disorders. Twin studies often focus on broader phenotypes or subthreshold eating disorders. These studies consistently yielded moderate to substantial heritabilities. In addition, there has been a proliferation of molecular genetic studies that focused on Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) AN and BN. Seven linkage regions have been identified in genome-wide screens. Many genetic association studies have been performed, but no consistent association between a candidate gene and AN or BN has been reported. Larger genetic association studies and collaborations are needed to examine the involvement of several candidate genes and biological pathways in eating disorders. In addition, twin studies should be designed to assist the molecular work by further exploring genetic determinants of endophenotypes, evaluating the magnitude of contribution to liability of measured genotypes as well as environmental risk factors related to eating disorders. In this manner twin and molecular studies can move the field forward in a mutually informative way

Analyzing the Number of Common Integration Sites of Viral Vectors – New Methods and Computer Programs

Vectors based on γ-retroviruses or lentiviruses have been shown to stably express therapeutical transgenes and effectively cure different hematological diseases. Molecular follow up of the insertional repertoire of gene corrected cells in patients and preclinical animal models revealed different integration preferences in the host genome including clusters of integrations in small genomic areas (CIS; common integrations sites). In the majority, these CIS were found in or near genes, with the potential to influence the clonal fate of the affected cell. To determine whether the observed degree of clustering is statistically compatible with an assumed standard model of spatial distribution of integrants, we have developed various methods and computer programs for γ-retroviral and lentiviral integration site distribution. In particular, we have devised and implemented mathematical and statistical approaches for comparing two experimental samples with different numbers of integration sites with respect to the propensity to form CIS as well as for the analysis of coincidences of integration sites obtained from different blood compartments. The programs and statistical tools described here are available as workspaces in R code and allow the fast detection of excessive clustering of integration sites from any retrovirally transduced sample and thus contribute to the assessment of potential treatment-related risks in preclinical and clinical retroviral gene therapy studies