Pineal Gland: Influence on Gonads of Male Rats Treated with Androgen Three Days after Birth

Reíter, Russel J.; Hoffmann, Joan C.; Rubin, Peter

doi:10.1126/science.160.3826.420

Cited by 34 publications

(17 citation statements)

References 7 publications

(1 reference statement)

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“…1). This result was consistent with previous reports that the Wistar strain is a reproductively nonphotoperiodic strain, while the F344 strain is sensitive to photoperiod (11,12,14,17,28).…”

Section: Photoperiodic Regulation Of Gonadal Growth In F344 Strain Busupporting

confidence: 93%

“…On the other hand, laboratory rats have been bred for many generations to obtain maximal reproductive efficiency under constant temperature and light conditions with ad libitum food availability; this has resulted in the loss of reproductive responsiveness to photoperiod (27). Indeed, the Wistar and Sprague-Dawley inbred rat strains are generally regarded as nonseasonal breeders (23,28,36). Nevertheless, some experimental treatments such as neonatal androgen injection, chronic exposure to exogenous testosterone, and olfactory bulbectomy can induce a reproductive responsiveness to photoperiod in these rat strains (23,28,34,36).…”

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confidence: 99%

“…Indeed, the Wistar and Sprague-Dawley inbred rat strains are generally regarded as nonseasonal breeders (23,28,36). Nevertheless, some experimental treatments such as neonatal androgen injection, chronic exposure to exogenous testosterone, and olfactory bulbectomy can induce a reproductive responsiveness to photoperiod in these rat strains (23,28,34,36). Extreme lighting conditions, such as constant darkness or blinding, also inhibit gonadal development in Wistar rats (15).…”

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confidence: 99%

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Differential response of type 2 deiodinase gene expression to photoperiod between photoperiodic Fischer 344 and nonphotoperiodic Wistar rats

Yasuo¹,

Watanabe²,

Iigo³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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The molecular basis of seasonal or nonseasonal breeding remains unknown. Although laboratory rats are generally regarded as photoperiod-insensitive species, the testicular weight of the Fischer 344 (F344) strain responds to photoperiod. Recently, it was clarified that photoperiodic regulation of type 2 iodothyronine deiodinase (Dio2) in the mediobasal hypothalamus (MBH) is critical in photoperiodic gonadal regulation. Strain-dependent differences in photoperiod sensitivity may now provide the opportunity to address the regulatory mechanism of seasonality by studying Dio2 expression. Therefore, in the present study, we examined the effect of photoperiod on Dio2 expression in photoperiod-sensitive F344 and photoperiod-insensitive Wistar rats. A statistically significant difference was observed between short and long days in terms of testicular weight and Dio2 expression in the F344 strain, while no difference was observed in the Wistar strain. These results suggest that differential responses of the Dio2 gene to photoperiod may determine the strain-dependent differences in photoperiod sensitivity in laboratory rats. mediobasal hypothalamus; testicular weight; photoperiodism FOR MANY SPECIES living in temperate zones, annual changes in photoperiod are the primary factor that regulates the timing of reproduction. The photoperiodic response allows animals to bear their offspring during the food-abundant season to maximize survival. On the other hand, laboratory rats have been bred for many generations to obtain maximal reproductive efficiency under constant temperature and light conditions with ad libitum food availability; this has resulted in the loss of reproductive responsiveness to photoperiod (27). Indeed, the Wistar and Sprague-Dawley inbred rat strains are generally regarded as nonseasonal breeders (23,28,36). Nevertheless, some experimental treatments such as neonatal androgen injection, chronic exposure to exogenous testosterone, and olfactory bulbectomy can induce a reproductive responsiveness to photoperiod in these rat strains (23,28,34,36). Extreme lighting conditions, such as constant darkness or blinding, also inhibit gonadal development in Wistar rats (15). These reports indicate that neuroendocrine components that regulate photoperiodic response are still preserved in the Wistar and SpragueDawley strains. In contrast, the Fischer 344 (F344) inbred strain of rat exhibits robust photoresponsiveness, even under normal conditions, exhibiting slower gonadal growth on exposure to short days (11,14). Gonadal development of F344 rats is also inhibited by blinding (17) or by melatonin injection (12). A recent study has also reported that the ACI, PVG, and BUF inbred rat strains are also photoperiod sensitive (6), suggesting that sensitivity to photoperiod varies across different rat strains. However, the underlying mechanism that regulates the variation in photoresponsiveness is not well understood.In mammals, the photoperiodic response of gonads is regulated by a daily cycle of melatonin secretion from the ...

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Section: Photoperiodic Regulation Of Gonadal Growth In F344 Strain Busupporting

confidence: 93%

mentioning

confidence: 99%

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confidence: 99%

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Differential response of type 2 deiodinase gene expression to photoperiod between photoperiodic Fischer 344 and nonphotoperiodic Wistar rats

Yasuo¹,

Watanabe²,

Iigo³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Thus, photoperiodic changes in the nocturnal duration of melatonin production and locomotor activity-compressed during long days and decompressed during short days-are likely to reflect changes in the SCN itself, suggesting that the nucleus is involved in processing photoperiodic information from the environment. Although the rat is only marginally photoperiodic (22,23), it may be sensitized to the effects of photoperiod by neonatal treatment with testosterone propionate (24), olfactory bulbectomy (25), or undernutrition (26).…”

Section: Discussionmentioning

confidence: 99%

The rat suprachiasmatic nucleus is a clock for all seasons.

Sumová

Travnickova

Peters

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

163

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Seasonal changes of daylength (photoperiod) affect the expression of hormonal and behavioral circadian rhythms in a variety of organisms. In mammals, such effects might reflect photoperiodic changes in the circadian pacemaking system [located in the suprachiasmatic nucleus (SCN) of the hypothalamus] that governs these rhythms, but to date no functionally relevant, intrinsic property of the SCN has been shown to be photoperiod dependent. We have analyzed the temporal regulation of light-induced c-fos gene expression in the SCN of rats maintained in long or short photoperiods. Both in situ hybridization and immunohistochemical assays show that the endogenous circadian rhythm of light responsiveness in the SCN is altered by photoperiod, with the duration of the photosensitive subjective night under the short photoperiod 5-6 h longer than under the long photoperiod. Our results provide evidence that a functional property of the SCN is altered by photoperiod and suggest that the nucleus is involved in photoperiodic time measurement. Over the course of the year, most mammals respond to seasonal changes of daylength (photoperiod) with altered physiology and behavior. Photoperiodic information from the environment is conveyed to the organism by a circadian rhythm of melatonin production in the pineal gland (1-4). In the rat, rhythmic melatonin production is driven by a circadian rhythm of the activity of pineal N-acetyltransferase (NAT), which synthesizes the melatonin precursor N-acetylserotonin (5, 6). The NAT rhythm is controlled by a light-entrainable circadian pacemaking system in the suprachiasmatic nucleus (SCN) of the hypothalamus; SCN lesions abolish this rhythm (7). Norepinephrine released at night from sympathetic nerve endings in the pineal gland stimulates adrenergic receptors and the cAMP pathway; the resulting induction and activation of pineal NAT activity leads to high nighttime melatonin levels (8). In the rat, the NAT rhythm is entrained to the 24-h light-dark (LD) cycle primarily by light onset at dawn (9). With longer daylengths, light at an earlier dawn advances the phase of the morning NAT decline, while light at a later dusk delays the phase of the evening NAT rise (3, 10). The resulting alteration in the duration of the nocturnal melatonin signal, compressed during long summer days and decompressed during short winter days, appears to serve as an endogenous photoperiodic message (2,3,11).When rats and hamsters are transferred from a long to a short photoperiod, the decompression of the melatonin signal occurs gradually (12-14). Since high NAT activity can be induced independent of the photoperiod by administration of a ,B-adrenergic agonist (15), it seems likely that the neural substrate for this gradual decompression lies upstream of the pineal gland, perhaps in the SCN. Importantly, another circadian rhythm governed by the SCN is photoperiodic. The duration of nocturnal locomotor activity (a) in hamsters is also compressed during long days and decompressed during short days (16, 17)...

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“…The results of this study also suggest that the magnitude of response and the specific photoresponsive traits are likely to differ among strains. The fact that some non-inbred strains of rats that are not normally photoresponsive can be induced to show reproductive inhibition under SD photoperiods by treatments such as food restriction (Sorrentino et al 1971, Blask et al 1980, neonatal androgen treatment (Reiter et al 1968), adult androgen treatment (Wallen & Turek 1981, Wallen et al 1987, or olfactory bulbectomy (Reiter et al 1969, Reiter et al 1971, Nelson & Zucker 1981 (but see Peiper et al 1990), further adds to the complexity of photoperiodic responses among laboratory rats. Variable photoperiodic responses may be useful in the study of neuroendocrine variation in environmental control of reproduction and body mass (Bittner & Friedman 2000.…”

Section: Discussionmentioning

confidence: 99%

Short photoperiod inhibition of growth in body mass and reproduction in ACI, BUF, and PVG inbred rats

Francisco¹,

Raymond²,

Heideman³

2004

Reproduction

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Laboratory rats have been generally considered non-photoresponsive, but strains of laboratory rats have been found to be variable for this trait. Young males of both the Fischer (F344) and Brown Norway strains (BN) suppress reproductive development, food intake and body mass in short winter photoperiod (short days (SD); 8 h light:16 h darkness), and food restriction interacts with SD to enhance the effect of SD alone. Conversely, young male Harlan Sprague Dawley outbred rats, along with other outbred laboratory rats tested, have little or no response to SD except when unmasked by food restriction or other treatments, and have generally been considered nonphotoperiodic. In order to assess how widespread this trait might be among rat strains, and to test for uncoupling of reproductive and nonreproductive responses, we tested 3 additional inbred strains, including ACI, PVG and BUF rats, for photoresponsiveness and for unmasking of photoperiodic responses by food restriction. Young males of all three inbred strains exhibited photoresponsiveness in testis mass (5 -20% lower in SD), seminal vesicle mass (20-50% lower in SD), and body mass (5-10% lower in SD). Food restriction also suppressed reproduction, but there was little or no interaction with the effects of photoperiod. The results are consistent with the hypothesis that laboratory rats are genetically variable for photoperiodism, and that photoresponsiveness may be widespread among inbred rat strains, as all five inbred strains tested have shown photoperiodic responses. The results are particularly important because standard research protocols may unknowingly manipulate this pathway in rats, causing unsuspected variability among or within studies.

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Pineal Gland: Influence on Gonads of Male Rats Treated with Androgen Three Days after Birth

Cited by 34 publications

References 7 publications

Differential response of type 2 deiodinase gene expression to photoperiod between photoperiodic Fischer 344 and nonphotoperiodic Wistar rats

Differential response of type 2 deiodinase gene expression to photoperiod between photoperiodic Fischer 344 and nonphotoperiodic Wistar rats

The rat suprachiasmatic nucleus is a clock for all seasons.

Short photoperiod inhibition of growth in body mass and reproduction in ACI, BUF, and PVG inbred rats

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