Effect of different photoperiods and blinding on ovarian and testicular functions in normal and testosterone-treated rats

Hoffmann, Joan C.; Kordon, C.; Benoit, J

doi:10.1016/0016-6480(68)90016-6

Cited by 22 publications

(14 citation statements)

References 18 publications

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“…In addition, BLD in the NA rat has been observed to decrease the actual ovarian weight but not the ovarian weight per 100 g body weight [9,21], an observation that we have also noted. The decrease in uterine weight to BLD + ANOS has also been observed by previous investigators and has been attributed to a decrease in estrogen secretion by the atrophied ovary.…”

Section: Discussionsupporting

confidence: 50%

Influence of Blinding, Olfactory Bulbectomy and Pinealectomy on Plasma Prolactin Levels in the Neonatally Androgenized Female Rat

1983

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Female rats were neonatally androgenized (NA) by administering 1.25 mg of testosterone propionate at 3 days of age. At 21–23 days of age, groups of 12 animals each were blinded (BLD), olfactory bulbectomized (ANOS) and pineal-ectomized (PX) either alone or in combination. At 11 weeks of age all animals were ovariectomized, implanted with atrial catheters and given 0.5 mg polyestradiol phosphate. At 12 weeks of age, animals were attached to catheter extensions and blood samples obtained at 09.00, 11.00, 13.00, 15.00, 17.00, 19.00 and 21.00 h. The plasma prolactin (PRL) pattern of NA control animals consisted of elevated basal values at 11.00 and 13.00 h with an afternoon peak at 17.00 h. Anosmic and PX animals had a PRL pattern similar to that of the control. Animals BLD or BLD + ANOS had significantly lower plasma PRL values than sham-operated animals. Animals BLD + PX had PRL values comparable to PX alone. The diurnal PRL pattern observed for NA control animals was still evident in all experimental animals. Blinding + ANOS resulted in a significant decrease in ovarian and oviductal weights and attenuated the estrogen-induced increase in uterine weight. The evidence indicated that the elevated morning PRL levels observed in NA rats was not due to an altered function of the pineal gland and that BLD + ANOS blunted the action of exogenous estrogen on uterine weight.

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Section: Discussionsupporting

confidence: 50%

Influence of Blinding, Olfactory Bulbectomy and Pinealectomy on Plasma Prolactin Levels in the Neonatally Androgenized Female Rat

1983

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“…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.…”

mentioning

confidence: 77%

“…This hypothesis would be distinct from the case of F344 and Sprague-Dawley rats, because the reproductive system and regulatory system for body mass of Sprague-Dawley rats are unresponsive to melatonin signals, even if melatonin patterns are identical in both strains (25). The differences between Wistar and Sprague-Dawley rats are also obvious in the fact that gonadal development of Wistar rats is inhibited by constant darkness or melatonin injections (15,30), whereas that of Sprague-Dawley rats does not respond to these treatments (25). Instead, our data lead to the possibility that patterns of melatonin secretion under short-and long-day conditions may differ between Wistar and F344 strains.…”

mentioning

confidence: 99%

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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“…The effects are more pronounced in females: the vagina is persis tently covered with cornified mucosa, and the rats do not ovulate [1,4]. After neonatal androgenization the gonads of adult male rats are smaller than those of intact con trols [2,3,6,7], and the maximum steroidogenic capac ity is reduced [8].…”

Section: Introductionmentioning

confidence: 92%

Effect of Neonatal Androgenization on the Testosterone Feedback Sensitivity in Adult Rats in Two Lighting Conditions

et al. 1989

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Neonatally androgenized and intact adult male Wistar rats received daily, during 1 week, either testosterone propionate or sesame oil injections in periodic or constant light. Serum and pituitary gonadotropins and hypothalamic LHRH were measured. In periodic light, neonatal androgenization did not change the serum concentration or pituitary contents of gonadotropins, or the hypothalamic content of LHRH. Testosterone injections decreased serum concentration and pituitary content of gonadotropin of intact rats but failed to decrease the pituitary gonadotropin content of neonatally androgenized rats. In constant light, serum FSH was decreased in neonatally androgenized rats. Testosterone injections decreased both serum LH and FSH concentrations of intact rats but only serum LH of androgenized rats. Pituitary gonadotropin and hypothalamic LHRH contents remained unchanged. We conclude that neonatal androgenization renders the male rat hypothalamo-pituitary axis more resistant to changes of testosterone concentration in adulthood. Constant light did not sensitize the neonatally androgenized rats to testosterone, but on the contrary, testosterone injections were less effective in constant than in periodical light.

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Effect of different photoperiods and blinding on ovarian and testicular functions in normal and testosterone-treated rats

Cited by 22 publications

References 18 publications

Influence of Blinding, Olfactory Bulbectomy and Pinealectomy on Plasma Prolactin Levels in the Neonatally Androgenized Female Rat

Influence of Blinding, Olfactory Bulbectomy and Pinealectomy on Plasma Prolactin Levels in the Neonatally Androgenized Female Rat

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

Effect of Neonatal Androgenization on the Testosterone Feedback Sensitivity in Adult Rats in Two Lighting Conditions

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