Timing of parturition and postpartum mating in norway rats: Interaction of an interval timer and a circadian gate

Gilbert, Avery N.; Rosenwasser, Alan M.; Adler, Norman T.

doi:10.1016/0031-9384(85)90078-2

Cited by 14 publications

(15 citation statements)

References 17 publications

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“…Postpartum estrus was studied in a group of 23 Sprague-Dawley females that gave birth on Day 22 by Gilbert et al (1985). They found a mean interval of between parturition and postpartum 9.78(Ϯ 0.38) hr mating (i.e., lordosis response), which is in agreement with an earlier unpublished study by Sachs, Warden, and Pollak (1971).…”

Section: Discussionsupporting

confidence: 57%

“…Mitchell and Yochim (1970) have shown that with light phases of (and 14 hr ) all parturitions occur during the light phase 22 hr but are distributed over Days 21, 22, and 23. Dukes, Chester, and Atkinson (1974) Gilbert, Rosenwasser, and Adler (1985), who used a 14 : 10 photoperiod cycle (lights on at ), and found that 80% 0930 hr (23/29) of the Sprague-Dawley females gave birth between on Day 22. Also similar to our 1200 -2000 hr findings are those of Murakami et al (1987), who studied Sprague-Dawley and Wistar primiparous females that were pregnant under a 14 : 10 photoperiod cycle (lights on at ).…”

Section: Discussionmentioning

confidence: 97%

“…parturitions on Days 21 and 22 during the light phases between 1000 and with a small proportion of 1900 hr, parturitions occurring during the intervening dark phase. Breeding of Sprague-Dawley females under the conditions used by Gilbert et al (1985) and Murakami et al (1987) has the advantage that a shift in photoperiod is not required yet parturitions occur on Day 22 and are concentrated at reasonable hours. A disadvantage of both of these methods is that mating might be difficult to observe because females are most likely to be in heat during the night.…”

Section: Discussionmentioning

confidence: 99%

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A method for regulating the duration of pregnancy and the time of parturition in Sprague-Dawley rats (Charles River CD strain)

Mayer

Rosenblatt

1998

Dev. Psychobiol.

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A method of shifting the dark phase of the 12/12 hr photoperiod cycle on Day 7 of pregnancy is described for regulating the duration of pregnancy to 22 days and assuring that most parturitions take place between 1100 and 1500 hr. This method, in addition, has the added convenience that matings can occur during normal laboratory hours between 0700 and 1900 hr during the dark phase of the photoperiodic cycle. Litter sizes are normal (mostly 14–16 pups) and postpartum estrus behavior occurs at the normal interval of 4 to 11½ hr after parturition. © 1998 John Wiley & Sons, Inc. Dev Psychobiol 32: 131–136, 1998

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Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

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A method for regulating the duration of pregnancy and the time of parturition in Sprague-Dawley rats (Charles River CD strain)

Mayer

Rosenblatt

1998

Dev. Psychobiol.

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“…The circadian timekeeping system plays an important role in the coordination of a variety of physiological and behavioral processes essential for mammalian reproduction. In some mammals, including many rodents, the timing of ovulation is regulated by this system (for review, see de la Iglesia and Schwartz, 2006), and rhythms in mating behavior have been observed in multiple species (Beach and Levinson, 1949; Dobson and Michener, 1995; Gilbert et al, 1985; Hansen et al, 1979; Harlan et al, 1980; Mahoney and Smale, 2005). This probably optimizes the likelihood of successful fertilization.…”

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confidence: 99%

Changes in and dorsal to the rat suprachiasmatic nucleus during early pregnancy

2010

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Circadian rhythms in behavior and physiology change as female mammals transition from one reproductive state to another. The mechanisms responsible for this plasticity are poorly understood. The suprachiasmatic nucleus (SCN) of the hypothalamus contains the primary circadian pacemaker in mammals, and a large portion of its efferent projections terminate in the ventral subparaventricular zone (vSPZ), which also plays important roles in rhythm regulation. To determine whether these regions might mediate changes in overt rhythms during early pregnancy, we first compared rhythms in Fos and Per2 protein expression in the SCN and vSPZ of diestrous and early pregnant rats maintained in a 12:12 light/dark cycle. No differences in the Fos rhythm were seen in the SCN core, but in the SCN shell, elevated Fos expression was maintained throughout the light phase in pregnant, but not diestrous, rats. In the vSPZ, the Fos rhythm was bimodal in diestrous rats, but this rhythm was lost in pregnant rats. Peak Per2 expression was phase-advanced by four hours in the SCN of pregnant rats, and some differences in Per2 expression were found in the vSPZ as well. To determine whether differences in Fos expression were due to altered responsivity to light, we next characterized light-induced Fos expression in the SCN and vSPZ of pregnant and diestrous rats in the mid-subjective day and night. We found that the SCN core of the two groups responded in the same way at each time of day, whereas the rhythm of Fos responsivity in the SCN shell and vSPZ differed between diestrous and pregnant rats. These results indicate that the SCN and vSPZ are functionally re-organized during early pregnancy, particularly in how they respond to the photic environment. These changes may contribute to changes in overt behavioral and physiological rhythms that occur at this time.

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“…One is that parturition has a strong diurnal component such that mammals usually give birth during their species-typical rest period (reviewed in Refs. 14,35,36,54): nocturnal mammals such as the rat during the day (28,39,52,61) and diurnal mammals such as sheep (Ref. 30; own observations), monkeys (15,16,56), and humans (9,10,29,49,55,64) during the night.…”

mentioning

confidence: 99%

Effect of photoperiod on the mechanical response of the pregnant rabbit uterus to oxytocin

Ninomiya-Alarcon

Hudson²,

Reyes-Guerrero³

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

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We present findings suggesting that photoperiod is important in determining the sensitivity of the late-pregnant rabbit uterus to oxytocin (OT). Longitudinal myometrial strips were taken from term-pregnant and estrous rabbits and mounted in an organ bath for isometric myographic recording at different times during a 16:8-h light-dark cycle (lights on 0600 -2200; n ϭ 5/group), and the strength of contractions was registered in response to the application of OT or KCl. Strength of contractions was dose dependent and was up to 200 times greater at doses three to four orders of magnitude lower in tissue taken from pregnant animals during the light phase (0700 and 1300) than during the dark phase (2400 and 0400). Strips from nonpregnant estrous females also showed greater sensitivity and contractile force when taken in the light (0700) than in the dark (0400), although the differences were not significant. Consistent with the influence of photoperiod on uterine sensitivity to OT, strips taken from two groups of pregnant females (n ϭ 5/group) maintained on a light-dark cycle advanced 12 h showed significantly greater sensitivity and force in response to OT during the new subjective light than during the new subjective dark phase. The photoperiod-dependent contractile response to OT was specific and not simply the result of a change in general mechanical properties of the muscle, because administration of KCl resulted in dose-dependent contractions of similar magnitude in both the light and dark phase. These results are consistent with the fact that rabbits, like other nocturnal mammals, typically give birth during the day. parturition; electromyographic uterine recording; circadian rhythmicity MUCH EFFORT HAS BEEN DIRECTED to understanding the processes triggering parturition, and although this is still not completely understood, some common features are emerging. One is that parturition has a strong diurnal component such that mammals usually give birth during their species-typical rest period (reviewed in Refs. 14,35,36,54): nocturnal mammals such as the rat during the day (28, 39, 52, 61) and diurnal mammals such as sheep (Ref. 30; own observations), monkeys (15,16,56), and humans (9,10,29,49,55,64) during the night. Moreover, in humans, births occurring at night are typically of shorter duration, require fewer interventions, and have an obstetrically better outcome than births occurring during the day (Refs. 3,9,55,60; reviewed in Ref. 36).A second common feature is the importance of the hormone oxytocin (OT), released at the time of parturition from the posterior pituitary into the bloodstream, in helping to initiate and sustain the uterine contractions necessary for expulsion of the fetus(es) (1, 11, 12, 17, 19, 23-25, 31, 33, 50, 67). In those species in which it has been studied, principally macaque monkeys and humans, there is a diurnal rhythm in circulating levels of OT, with the highest levels at night (18,20,33,34,36,65). This rhythm becomes more pronounced as gestation progresses and is most marked at the...

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Timing of parturition and postpartum mating in norway rats: Interaction of an interval timer and a circadian gate

Cited by 14 publications

References 17 publications

A method for regulating the duration of pregnancy and the time of parturition in Sprague-Dawley rats (Charles River CD strain)

A method for regulating the duration of pregnancy and the time of parturition in Sprague-Dawley rats (Charles River CD strain)

Changes in and dorsal to the rat suprachiasmatic nucleus during early pregnancy

Effect of photoperiod on the mechanical response of the pregnant rabbit uterus to oxytocin

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