The master circadian clock, located in the mammalian suprachiasmatic nuclei (SCN), generates and coordinates circadian rhythmicity, i.e., internal organization of physiological and behavioral rhythms that cycle with a near 24-h period. Light is the most powerful synchronizer of the SCN. Although other nonphotic cues also have the potential to influence the circadian clock, their effects can be masked by photic cues. The purpose of this study was to investigate the ability of scheduled feeding to entrain the SCN in the absence of photic cues in four lines of house mouse (Mus domesticus). Mice were initially housed in 12:12-h light/dark cycle with ad libitum access to food for 6 h during the light period followed by 4 -6 mo of constant dark under the same feeding schedule. Wheel running behavior suggested and circadian PER2 protein expression profiles in the SCN confirmed entrainment of the master circadian clock to the onset of food availability in 100% (49/49) of the line 2 mice in contrast to only 4% (1/24) in line 3 mice. Mice from line 1 and line 4 showed intermediate levels of entrainment, 57% (8/14) and 39% (7/18), respectively. The predictability of entrainment vs. nonentrainment in line 2 and line 3 and the novel entrainment process provide a powerful tool with which to further elucidate mechanisms involved in entrainment of the SCN by scheduled feeding. nonphotic entrainment; scheduled feeding; suprachiasmatic; PER2; wheel running activity THE SUPRACHIASMATIC NUCLEI (SCN) of the anterior hypothalamus are the master circadian (near 24 h) clock in mammals, entraining clocks located in other brain regions and peripheral organs (26,33). The clock mechanism consists of molecular feedback loops containing positive and negative elements, i.e., clock gene products, that cycle with a near 24-h period in the absence of external signals (26). Light, the strongest natural zeitgeber or timing cue, shifts the clock so that it can entrain to the external light/dark (LD) cycle (28). Scheduled food availability is one of several nonphotic periodic signals (24, 25) that have been shown to entrain behavioral rhythms (17,19,22). Although entrainment of the master circadian clock was inferred in these studies (17,19,22), it was not confirmed at the level of the SCN (12).When feeding is dissociated from the normal activity period by allowing animals to eat only during their inactive period, two behavioral activity components result. One component entrains to and is in anticipation of onset of food availability, i.e., food anticipatory activity (FAA), which is controlled by an SCN-independent food-entrainable clock. The other is the animal's normal nocturnal or light-entrainable activity (LEA) component, which is controlled by the SCN when food access is not limited and has been presumed to be controlled by the SCN when access to food is temporally limited (8). The likelihood of the free-running LEA component being entrained by scheduled daily feeding in constant dark (DD) is species dependent. Hamsters typically show behavior...

Background. The people living in Arctic and Subarctic environments have adapted to cold temperatures, short growing seasons, and low precipitation, but their traditional ways are now changing due to increased contact with Western society. The rapid alteration of circumpolar cultures has led to generational changes in diet from traditional foods to the processed groceries common in modern stores. Objectives. Develop a link between changing traditional diets and mental health that may have substantial consequences for circumpolar peoples. Methods. Review of English language literature pertaining to the northern circumpolar environments of the world that consist of the Arctic and Subarctic areas. Electronic resources such as ISI Web of Science and PubMed were utilized, using keywords such as arctic, circumpolar, diet, omega-3 fatty acids, mental health, seasonal affective disorder, and suicide. In addition, we used the cited references of obtained articles and the extensive University of Alaska Fairbanks library collections to identify additional publications that were not available from the electronic resources. The years covered were not restricted to any particular period, although 83% of the sources were published in the last 16 years. Conclusion. The change in traditional diets has already led to increased health problems, such as obesity, cardiovascular disease, and diabetes, while the mental health of circumpolar peoples has also declined substantially during the same time period. The decline in mental health is characterized by increased rates of depression, seasonal affective disorder, anxiety, and suicide, that now often occur at higher rates than in lower-latitude populations. Studies in non-circumpolar peoples have shown that diet can have profound effects on neuronal and brain development, function, and health. Therefore, we hypothesize that diet is an important risk factor for mental health in circumpolar peoples.

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Prolonged dietary exposure of female B6C3F1 mice to the trichothecene vomitoxin results in hyperproduction of immunoglobulin A (IgA) with a concurrent immunopathology that mimics human IgA nephropathy. To assess the role of gender and strain in the mouse model, semipurified AIN-76A diet containing 25 ppm vomitoxin was fed to B6C3F1 male mice and to B6C3F1, BALB/c, C3H/HeN, C3H/HeJ, and C57BL/6 female mice for 8 wk, and immunopathologic indicators of IgA nephropathy were compared to mice fed clean diet. At the cessation of the experiment, all treatment groups weighed less than respective controls. Serum IgA was increased in male and female B6C3F1 mice as well as in C3H/HeJ, C57BL/6, and BALB/c female mice compared to corresponding controls. Serum IgA levels were two- to sixfold higher in B6C3F1 male treatment animals compared to female treatment groups from all strains. In contrast, at wk 8 serum IgG levels were unaffected or decreased, and serum IgM was decreased in all groups at wk 8. There was a trend toward increased IgA production by Peyer's patch (PP) lymphocytes isolated from treatment mice as compared to controls in all groups except the C3H/HeJ mice. Notably, IgA levels were 18-fold higher in B6C3F1 male treatment PP cultures than in B6C3F1 female treatment cultures. Hematuria was significantly greater in treatment mice than respective controls at both wk 4 and 8. Increased mesangial IgA deposition was also detectable in all treatment groups except the C57BL/6 mouse. The results suggested that the male B6C3F1 mouse and the five strains of female mice exhibited many of the immunopathologic effects found in IgA nephropathy and that IgA elevation was more marked in male B6C3F1 than female B6C3F1 mice.