Evidence for differences in the circadian organization of hamsters exposed to short day photoperiod

Puchalski, W.; Gr, Lynch

doi:10.1007/bf00612490

Cited by 101 publications

(77 citation statements)

References 23 publications

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“…Twenty percent of hamsters adapted to SP (N=10) were considered reproductively non-responsive to photoperiod because testes mass was greater than 2 standard deviations below the average paired testes mass of hamsters exposed to LP. This value ranges between 15 and 30% in previous studies (Puchalski and Lynch, 1986;Nelson, 1987) and probably reflects the current genetic make-up of our colony. These non-responding hamsters were removed from the study.…”

Section: Materials and Methods Animalsmentioning

confidence: 49%

Sleep deprivation attenuates endotoxin-induced cytokine gene expression independent of day length and circulating cortisol in male Siberian hamsters (Phodopus sungorus)

Ashley

Walton

Haim

et al. 2013

Journal of Experimental Biology

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SUMMARYSleep is restorative, whereas reduced sleep leads to negative health outcomes, such as increased susceptibility to disease. Sleep deprivation tends to attenuate inflammatory responses triggered by infection or exposure to endotoxin, such as bacterial lipopolysaccharide (LPS). Previous studies have demonstrated that Siberian hamsters (Phodopus sungorus), photoperiodic rodents, attenuate LPS-induced fever, sickness behavior and upstream pro-inflammatory gene expression when adapted to short day lengths. Here, we tested whether manipulation of photoperiod alters the suppressive effects of sleep deprivation upon cytokine gene expression after LPS challenge. Male Siberian hamsters were adapted to long (16h:8h light:dark) or short (8h:16h light:dark) photoperiods for >10weeks, and were deprived of sleep for 24h using the multiple platform method or remained in their home cage. Hamsters received an intraperitoneal injection of LPS or saline (control) 18h after starting the protocol, and were killed 6h later. LPS increased liver and hypothalamic interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF) gene expression compared with vehicle. Among LPS-challenged hamsters, sleep deprivation reduced IL-1 mRNA levels in liver and hypothalamus, but not TNF. IL-1 attenuation was independent of circulating baseline cortisol, which did not increase after sleep deprivation. Conversely, photoperiod altered baseline cortisol, but not pro-inflammatory gene expression in sleep-deprived hamsters. These results suggest that neither photoperiod nor glucocorticoids influence the suppressive effect of sleep deprivation upon LPSinduced inflammation.

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Section: Materials and Methods Animalsmentioning

confidence: 49%

Sleep deprivation attenuates endotoxin-induced cytokine gene expression independent of day length and circulating cortisol in male Siberian hamsters (Phodopus sungorus)

Ashley

Walton

Haim

et al. 2013

Journal of Experimental Biology

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“…they do not display gonadal regression or reductions in body mass and fat stores). These individuals are referred to as photoperiodic non-responders (Puchalski and Lynch, 1986). Because we wanted to directly match body mass loss of the SD-AL and LD-FR groups, we needed to exclude the photoperiodic non-responders from our calculations of the SD-AL body mass loss trajectory (Mauer and Bartness, 1997).…”

Section: Experimental Methodsmentioning

confidence: 99%

Body mass affects seasonal variation in sickness intensity in a seasonally-breeding rodent

Carlton

Demas

2015

Journal of Experimental Biology

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Species that display seasonal variation in sickness intensity show the most intense response in the season during which they have the highest body mass, suggesting that sickness intensity may be limited by an animal's energy stores. Siberian hamsters (Phodopus sungorus) display lower body masses and less intense sickness when housed in short, winter-like days as opposed to long, summer-like days. To determine whether reduced sickness intensity displayed by short-day hamsters is a product of seasonal changes in body mass, we food restricted long-day hamsters so that they exhibited body mass loss that mimicked the natural photoperiod-induced loss of body mass in short-day hamsters. We then experimentally induced sickness with lipopolysaccharide (LPS) and compared sickness responses among long-day food-restricted and long-and short-day ad libitum fed groups, predicting that long-day food-restricted hamsters would show sickness responses comparable to those of short-day ad libitum fed hamsters and attenuated in comparison to long-day ad libitum fed hamsters. We found that long-day food-restricted hamsters showed attenuated LPSinduced anorexia, loss of body mass and hypothermia compared with long-day ad libitum fed animals; however, anorexia remained elevated in long-day food-restricted animals compared with short-day ad libitum fed animals. Additionally, LPS-induced anhedonia and decreases in nest building were not influenced by body mass. Results of hormone assays suggest that cortisol levels could play a role in the attenuation of sickness in long-day food-restricted hamsters, indicating that future research should target the roles of glucocorticoids and natural variation in energy stores in seasonal sickness variation.

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“…A number of mammalian species exhibit variation in reproductive responsiveness to photoperiod, including Siberian hamster (P. sungorus) [27, 28], deer mice (P. maniculatus) [29], meadow voles (M. pennsylvanicus) [21, 30], and white-footed mice (P. leucopus) [31]. Given the variable nature of photoperiodic effects on the GnRH system in hamsters and other rodents, it is surprising that most studies fail to address this variation.…”

Section: Discussionmentioning

confidence: 99%

Photoperiod Affects the Gonadotropin- Releasing Hormone Neuronal System of Male Prairie Voles <bolditalic>(Microtus ochrogaster)</bolditalic>

Kriegsfeld

Nelson²

1999

Neuroendocrinology

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In order to maximize survival, animals inhabiting temperate and boreal latitudes exhibit numerous adaptations to changing seasons. Central among this suite of coping strategies is the cessation of breeding during the suboptimal conditions of winter. Many nontropical rodents inhibit reproduction well in advance of winter in response to short day lengths. Male prairie voles (Microtus ochrogaster) are small temperate-zone rodents that vary in their reproductive response to photoperiod. Some male voles undergo complete gonadal regression during short days (responders) while others fail to inhibit reproduction when exposed to short day lengths (nonresponders). The neuroendocrine mechanisms regulating this differential response to photoperiod have not been investigated in this species. Presumably, photoperiod can act at any or all levels of the hypothalamo-pituitary-gonadal (HPG) axis to regulate reproduction. The present study sought to determine the contribution of the GnRH system to this variable reproductive response to photoperiod. Male prairie voles were housed in either long or short day lengths for 10 weeks. As shown with immunohistochemistry, voles that underwent gonadal regression in response to short photoperiods exhibited increased GnRH neuron numbers in the preoptic area/anterior hypothalamus (POA/AH) relative to both long-day animals and short-day voles that maintained reproductive function. Mean optical density of staining and cell size did not differ among groups. These data suggest that the differential reproductive response to photoperiod in male voles is mediated, in part, by alterations in the GnRH neuronal system.

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Evidence for differences in the circadian organization of hamsters exposed to short day photoperiod

Cited by 101 publications

References 23 publications

Sleep deprivation attenuates endotoxin-induced cytokine gene expression independent of day length and circulating cortisol in male Siberian hamsters (Phodopus sungorus)

Sleep deprivation attenuates endotoxin-induced cytokine gene expression independent of day length and circulating cortisol in male Siberian hamsters (Phodopus sungorus)

Body mass affects seasonal variation in sickness intensity in a seasonally-breeding rodent

Photoperiod Affects the Gonadotropin- Releasing Hormone Neuronal System of Male Prairie Voles <bolditalic>(Microtus ochrogaster)</bolditalic>

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