Genetic analyses of photoresponsiveness in the Djungarian hamster,Phodopus sungorus

Gr, Lynch; Cb, Lynch; Rm, Kliman

doi:10.1007/bf00610441

Cited by 68 publications

(49 citation statements)

References 25 publications

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“…A number of previous studies have shown body weight to be a poor predictor of sperm count [29], and photoperiod can affect body weight independently of testis size in rodents (e.g., [30,31]). Our previous work on F344 rats [18] showed similar qualitative results using adjusted or unadjusted measurements of testis size.…”

Section: Discussionmentioning

confidence: 98%

Food and Neonatal Androgen Interact with Photoperiod to Inhibit Reproductive Maturation in Fischer 344 Rats1

Heideman

Deibler

York

1998

Biology of Reproduction

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Laboratory rats generally do not respond reproductively to short days (SD) unless they are given treatments that unmask reproductive inhibition in SD. While young Fischer 344 (F344) rats are unusual among rat strains in that SD substantially inhibit their reproductive response, the inhibition is not as strong as in the classically photoresponsive species. Rats may have two components to photoresponsivenes: 1) an obligate inhibition by SD, and 2) a facultative inhibition in response to biologically relevant challenges. This study tested whether maturing male F344 rats, which clearly have an obligate inhibition of reproduction in SD, also have an additional, facultative inhibition of reproduction in SD in response to food restriction, a biologically reasonable challenge, or to neonatal androgen treatment, a pharmacological treatment that presumably alters organizational events in the development of the reproductive axis. Food restriction over a period of 13 wk strongly enhanced the inhibition of testicular growth by SD. Similarly, testosterone propionate (TP) treatment at 3 days of age strongly enhanced the inhibition of testicular growth by SD. Neonatal TP treatment along with SD inhibited testicular development almost as strongly as that observed in some commonly studied photoresponsive rodents, but for only half as many weeks. Thus, F344 rats possess an obligate inhibition of testicular development in SD that can be enhanced facultatively by food restriction and even more greatly enhanced by neonatal TP treatment. This combination of obligate and facultative responses to SD may have been important to wild rats ancestral to laboratory rats.

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Section: Discussionmentioning

confidence: 98%

Food and Neonatal Androgen Interact with Photoperiod to Inhibit Reproductive Maturation in Fischer 344 Rats1

Heideman

Deibler

York

1998

Biology of Reproduction

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“…This result contrasts with several studies concerned with the effects of environmental factors on reproductive processes, in which highly inbred hamsters or rats were subjected to experimentation (Blank 1992). In those studies, observed consistent physiological responses to manipulated conditions were due to the avoiding of among-animal variation that characterizes outbreeding stocks (Lynch et al 1989). Nonetheless, Horton and Rowsemitt (1992) emphasized the importance of individual variation in response to environmental information.…”

Section: Discussionmentioning

confidence: 99%

Female reproductive responses to photoperiod and male odours in the subterranean rodentCtenomys talarum

Fanjul

Zenuto

2008

Acta Theriol

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The propitious timing of reproductive efforts favours the survival of both parents and the offspring at the time when conditions and/or resources to support the care and rearing of offspring are assured (Bronson 1989, Ims 1990. Reproduction is controlled by physiological interactions mediated by hormones which are ultimately induced by environmental and social factors including photoperiod, temperature, [73] Acta Theriologica 53 (1): 73-85, 2008. . 2008. Female reproductive responses to photoperiod and male odours in the subterranean rodent Ctenomys talarum. Acta Theriologica 53: 73-85.The tuco-tuco Ctenomys talarum Thomas, 1898 is a solitary subterranean rodent that breeds seasonally in coastal sand-dune grasslands from Argentina. We assessed whether short-day photoperiod determines the onset of reproduction by an increase in female's receptivity and whether male odour interacts with photoperiod as a cue by producing a greater response in receptivity. Receptivity was measured by an increase in the percentage of vaginal epithelial cells, particularly cornified cells. Females were trapped during their non-reproductive season (summer-long days) and randomly assigned to different day-length experimental groups: constant summer (CS), early winter (EW), and natural (NA) photoperiod. We examined the vaginal epithelium using vaginal smears during the first experimental phase (120 days) to test the effect of photoperiod. In the second experimental phase (15 days), we presented the females with male-soiled shavings to test the effect of photoperiod and male odor. Ctenomys talarum females showed some evidence of reproductive responsiveness to photoperiodic cuing. The proportion of epithelial cells peaked earlier in females when winter day-length was advanced than in females under natural photoperiod. Contrary to that expected, male odours did not stimulate female receptivity. These results suggest that, while photoperiod may participate in regulating reproduction, the integration of other environmental and social factors, as well as the identification of bodily conditions that lead to differences in individual response needs further consideration.

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“…Variation in reproductive photoresponsiveness can be seen among species, among geographical populations of the same species, ad even among individuals of the same geographical population (reviewed by [1]). In the latter regard, it has been shown now in laboratory stocks of Peromyscus, Microtus, Clethrionomys, Phodopus, and even in the highly domesticated Mesocricetus that some individuals undergo total reproductive regression when maintained on short day lengths, while other individuals of the same stock and species remain reproductively functional, and still others show intermediate levels of responsiveness (e.g., [2][3][4][5][6][7][8]). Selection experiments have established that at least some of this individual variation is genetically based [5,7,9,10].…”

Section: Introductionmentioning

confidence: 99%

Variation in Reproductive Photoresponsiveness in a Wild Population of Meadow Voles1

Kerbeshian

Bronson

Bellis

1994

Biology of Reproduction

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Individual variation in reproductive photoresponsiveness has been documented in laboratory colonies of several species of rodents. When maintained on short day lengths, some individuals experience complete gonadal regression, others undergo little if any gonadal regression, and still others show intermediate levels of responsiveness. In the present research, a combination of laboratory and field studies explored the potential importance of this kind of variation for the control of seasonal breeding in a wild population of meadow voles (Microtus pennsylvanicus). A sample of adult males was trapped in central Pennsylvania during the summer when all were in breeding condition. When exposed to short day lengths in the laboratory, these males showed the entire range of variation in responsiveness noted above and, correlatively, variation in the loss in body weight induced by this treatment. A sample of males trapped in the wild just before the winter solstice showed the same distribution of variation as did the males housed on short day lengths in the laboratory, and thus, as might be expected, a few pregnant and lactating females were also trapped at this time. Longitudinal studies over a 42-wk period revealed that the variation reflects the degree to which the testes regress in response to short-day exposure rather than the rate at which they regress. Finally, studies with laboratory-born voles demonstrated that the variation is independent of age. In total, these studies demonstrate that the variation in reproductive photoresponsiveness previously seen only in laboratory colonies of rodents indeed has relevance for understanding the seasonal control of reproduction in the wild.

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Genetic analyses of photoresponsiveness in the Djungarian hamster,Phodopus sungorus

Cited by 68 publications

References 25 publications

Food and Neonatal Androgen Interact with Photoperiod to Inhibit Reproductive Maturation in Fischer 344 Rats1

Food and Neonatal Androgen Interact with Photoperiod to Inhibit Reproductive Maturation in Fischer 344 Rats1

Female reproductive responses to photoperiod and male odours in the subterranean rodentCtenomys talarum

Variation in Reproductive Photoresponsiveness in a Wild Population of Meadow Voles1

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