Parturition in the Rat: Description and Assessment

Holloway, William R.; Dollinger, Mark J.; Denenberg, Victor H.

doi:10.1007/978-94-011-6287-6_1

Cited by 14 publications

(10 citation statements)

References 25 publications

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“…The duration of parturition, measured from the birth of the first pup until the mother crouched over the pups to provide access to her nipples, was comparable across groups (Table 2). Together, these observations rule out disturbances in the mothers' parturition behavior similar to those that have been reported following infraorbital denervation [38] or olfactory bulbectomy [39]. In these reports, alterations in sensory processing led to notable impairments in delivery, removal of the amniotic sac, nest building, retrieving, and grouping of pups and delayed nursing onset.…”

Section: Discussionmentioning

confidence: 72%

Maternal Reproductive Experience Enhances Early Postnatal Outcome Following Gestation and Birth of Rats in Hypergravity1

Ronca

Baer

Daunton

et al. 2001

Biology of Reproduction

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A major goal of space life sciences research is to broaden scientific knowledge of the influence of gravity on living systems. Recent spaceflight and centrifugation studies demonstrate that reproduction and ontogenesis in mammals are amenable to study under gravitational conditions that deviate considerably from those typically experienced on Earth (1 x g). In the present study, we tested the hypothesis that maternal reproductive experience determines neonatal outcome following gestation and birth under increased (hyper) gravity. Primigravid and bigravid female rats and their offspring were exposed to 1.5 x g centrifugation from Gestational Day 11 either through birth or through the first postnatal week. On the day of birth, litter sizes were identical across gravity and parity conditions, although significantly fewer live neonates were observed among hypergravity-reared litters born to primigravid dams than among those born to bigravid dams (82% and 94%, respectively; 1.0 x g controls, 99%). Within the hypergravity groups, neonatal mortality was comparable across parity conditions from Postnatal Day 1 through Day 7, at which time litter sizes stabilized. Maternal reproductive experience ameliorated neonatal losses during the first 24 h after birth but not on subsequent days, and neonatal mortality was associated with changes in maternal care patterns. These results indicate that repeated maternal reproductive experience affords protection against neonatal losses during exposure to increased gravity. Differential mortality of neonates born to primigravid versus bigravid dams denotes gravitational load as one environmental mechanism enabling the expression of parity-related variations in birth outcome.

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Section: Discussionmentioning

confidence: 72%

Maternal Reproductive Experience Enhances Early Postnatal Outcome Following Gestation and Birth of Rats in Hypergravity1

Ronca

Baer

Daunton

et al. 2001

Biology of Reproduction

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“…One might therefore suspect that deprivation could have affected the results. Although we cannot completely exclude the factor of deprivation from our consideration, it is pertinent to mention that in normal circumstances it takes up to 3 hr for the dam to deliver the litter, and nursing does not begin until approximately 40 min after the last pup is born (Holloway et al, 1980). Thus, 4 hr of maternal deprivation may be viewed as reasonably natural and ecologically relevant for pups of this particular age.…”

Section: Discussionmentioning

confidence: 97%

A New Model of Ethanol Self‐Administration in Newborn Rats: Gender Effects on Ethanol Ingestion Through a Surrogate Nipple

Petrov

Cheslock

Spear

1999

Alcoholism Clin & Exp Res

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Gender differences in responsiveness or sensitivity to ethanol can be detected in rat pups as early as a few hours after birth. The results suggest a leftward shift in the dose-response curve for females compared with males, indicating that female neonates are more sensitive or more responsive than males to ethanol. The similarity of suckling behaviors produced by moderate concentrations of ethanol and milk suggests a certain unity in their reinforcing mechanisms in the context of the first suckling episode.

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“…Mor¬ phine decreased the incidence of maternal behaviour during parturition, the lower survival being due to neglect rather than cannibalism. Maternal behaviour is usually expressed rapidly at parturition (Holloway, Dollinger & Denenberg, 1980) and this involves cen¬ trally released oxytocin (Fahrbach, Morrell & Pfaff, 1985;Pedersen, Caldwell, Johnson et al 1985;van Leengoed, Kerker & Swanson, 1987). The onset of maternal behaviour has been shown in several nonparturient rat models to be disrupted by morphine (Grimm & Bridges, 1983).…”

Section: Discussionmentioning

confidence: 99%

Interruption of parturition in rats by morphine: a result of inhibition of oxytocin secretion

Russell

Gosden²,

Humphreys³

et al. 1989

Journal of Endocrinology

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Oxytocin secretion is inhibited by opioids, and oxytocin is important in parturition. The effects on parturition of morphine, a relatively selective mu-opioid receptor agonist, were studied in the rat. Morphine or vehicle with or without the opiate antagonist naloxone were administered immediately after the birth of the second pup and the subsequent course of parturition was recorded in a total of 80 rats. Both s.c. morphine (10 mg/kg) and intracerebroventricular (i.c.v.) morphine (18 micrograms through a previously implanted cannula) interrupted parturition, delaying the birth of the sixth pup after treatment to 187.3 +/- 35.9 (S.E.M.) min and 195.4 +/- 19.5 min respectively, compared with 46.4 +/- 3.7 and 66.1 +/- 17.5 min after vehicle alone. The dose of morphine given i.c.v. had no effect when given s.c. Naloxone given concurrently prevented the effects of morphine. Eventually the rate of parturition in the morphine-treated groups recovered. Perinatal pup mortality rate was not increased when morphine was given to the mothers, but it did inhibit the expression of normal intrapartum maternal behaviour. Pup mortality was increased 48 h post partum by morphine given during parturition, and it reduced the proportion of rats with normal maternal behaviour 24 h post partum. Morphine did not affect spontaneous or oxytocin-stimulated contractile activity of the parturient uterus in vitro. The concentration of oxytocin in trunk blood plasma was decreased 40 min after i.c.v. morphine (24.3 +/- 3.9 vs 39.3 +/- 6.5 pmol/l in controls), as was vasopressin (7.2 +/- 1.5 vs 19.7 +/- 4.5 pmol/l in controls). Intravenous infusion of oxytocin (2-5 mU/min for 144.3 +/- 8.2 min; total infused 448.5 +/- 61.9 mU) after i.c.v. morphine re-started parturition; all pups were born to these rats (mean time to pup 6, 110.3 +/- 12.7 min) before the i.v. vehicle-infused rats given i.c.v. morphine re-started (mean time to pup 6, 406.3 +/- 125.2 min). It is concluded that morphine given during parturition acts centrally through opioid receptors to inhibit oxytocin secretion, and impairs the expression of maternal behaviour. Reversal of the effects of morphine on parturition by i.v. oxytocin demonstrates the important role of oxytocin in fetus ejection and expulsion.

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Parturition in the Rat: Description and Assessment

Cited by 14 publications

References 25 publications

Maternal Reproductive Experience Enhances Early Postnatal Outcome Following Gestation and Birth of Rats in Hypergravity1

Maternal Reproductive Experience Enhances Early Postnatal Outcome Following Gestation and Birth of Rats in Hypergravity1

A New Model of Ethanol Self‐Administration in Newborn Rats: Gender Effects on Ethanol Ingestion Through a Surrogate Nipple

Interruption of parturition in rats by morphine: a result of inhibition of oxytocin secretion

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