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M B Kristal

Publications and source records attributed to M B Kristal.

At least 37 records · Page 2Linked to original sources
PubMed1990

An adaptable microcomputer program for recording behavior durations.

A versatile and easy to use program is described for monitoring and recording behavior durations on IBM-compatible microcomputers. The program also records frequencies and provides latency information. Among its more prominent attributes are its ability to accommodate a broad range of behavioral assays and the facility with which its operation can be mastered. It requires no specialized hardware and is capable of being used in conjunction with a number of commercially available software packages for statistical analysis.

Animals↗
PubMed1989

Enhancement of opioid-mediated analgesia by ingestion of amniotic fluid: onset latency and duration.

Ingestion of placenta and amniotic fluid has been shown to enhance opioid-mediated analgesia produced by morphine injection, footshock, vaginal/cervical stimulation, and during late pregnancy in rats. The present study was designed to determine how soon after ingestion the enhancement begins and how long it lasts. Tail-flick latencies in Long-Evans rats were determined before and during vaginal/cervical stimulation; analgesia was measured as the percent increase in tail-flick latency during vaginal stimulation. After determination of baseline, rats were intubated with 0.25 ml of either amniotic fluid or beef bouillon. We found that analgesia enhancement was detectable as early as 5 minutes after ingestion of amniotic fluid, and the effect lasted at least 30 minutes, but no longer than 40 minutes.

Amniotic Fluid↗
PubMed1988

Dose-dependent enhancement of morphine-induced analgesia by ingestion of amniotic fluid and placenta.

Ingestion of amniotic fluid and placenta by rats has been shown to enhance opioid-mediated analgesia. The present studies were designed to examine the effect of several doses and volumes of placenta and amniotic fluid on tail-flick latency in rats treated with 3 mg/kg morphine. The optimal dose of amniotic fluid was found to be 0.25 ml, although 0.50 and 1.0 ml also produced significant enhancement. Doses of 0.125 and 2 ml of amniotic fluid were ineffective, as was a dose of 0.25 ml diluted to 2 ml with saline. The optimal dose of placenta was found to be 1 placenta, although the resulting enhancement was not significantly greater than that produced by 025, 0.50, 2.0 or 4.0 placentas. Doses smaller than 0.25 placenta or larger than 4.0 placentas were ineffective. The most effective doses of amniotic fluid and placenta correspond to the amounts delivered with each pup during parturition.

Amniotic Fluid↗
PubMed1987

Sensory innervation of the external and internal genitalia of the female rat.

Using a whole-nerve recording method, the genitalia of the female rat were found to receive afferent innervation as follows. Pelvic nerve: vagina, cervix, and perineal skin; hypogastric nerve: cervix and proximal three fifths of the uterus; pudendal nerve: skin of perineum, inner thigh, and clitoral sheath. It is probable that the pudendal and pelvic nerves are activated during copulation, and that all 3 nerves are activated during parturition.

Action Potentials↗
PubMed1987

Induction of maternal behavior in rats: effects of pseudopregnancy termination and placenta-smeared pups.

The onset of maternal behavior in Long-Evans rats was examined after pseudopregnancy (PsP) termination, both with and without exogenous estrogen administration, and in response to either clean or placenta-smeared stimulus pups. Natural (spontaneous) PsP termination was as effective in hastening the onset of maternal behavior as ovariectomy plus estrogen injection. If clean foster pups were presented as soon as pseudopregnancy terminated (first proestrus or cornified smear), maternal behavior was exhibited within 2 days; placenta-smeared foster pups presented at the same time elicited maternal behavior within 2 hr. The combination of initiating maternal-behavior testing immediately after the natural termination of pseudopregnancy and proffering placenta-smeared pups apparently simulates the hormonal milieu as well as the environmental cues present at parturition, noninvasively, producing optimal conditions for the rapid induction of maternal behavior.

Animals↗
PubMed1986

Ingestion of amniotic fluid enhances opiate analgesia in rats.

Placenta ingestion has recently been shown to enhance opiate-mediated analgesia produced by morphine injection, footshock, or vaginal/cervical stimulation. The enhancement of the effect of endogenous opiates (especially analgesia) may be one of the principal benefits to mammalian mothers of placentophagia at delivery. During labor and delivery, however, mothers also ingest amniotic fluid (AF) which, unlike placenta, becomes available during, or even before expulsion of the infant. The present experiments were undertaken to determine whether AF ingestion, too, enhances analgesia; if so, whether the effect requires ingestion of, or merely exposure to, AF; whether the effect can be produced by AF delivered directly to the stomach by tube; and whether the enhancement, if it exists, can be blocked by administering an opiate antagonist. Nulliparous Long-Evans rats were tested for analgesia using tail-flick latency. We found that rats that ingested AF after receiving a morphine injection showed significantly more analgesia than did rats that ingested a control substance; AF ingestion, alone, did not produce analgesia; ingestion of AF, rather than just smelling and seeing it, was necessary to produce analgesia enhancement; AF produced enhancement when oropharyngeal factors were eliminated by delivering it through an orogastric tube; and treatment of the rats with naltrexone blocked the enhancement of morphine-induced analgesia that results from AF ingestion.

Amniotic Fluid↗
PubMed1986

Effects of hypothalamic knife cuts and experience on maternal behavior in the rat.

Recent investigations suggest that the disruption of placentophagia, pup-directed maternal behavior, and nestbuilding seen after lesions of the medial preoptic area (MPO) or the lateral hypothalamus may be due to the interruption at different points of a single longitudinal neural system mediating these behaviors. To test this, we compared the effects of knife cuts on the lateral border of the MPO, and of the posterior medial forebrain bundle (MFB), with asymmetrical cuts combining a unilateral MPO cut with a contralateral MFB cut. We observed placentophagia, nestbuilding, and pup-directed maternal behaviors at, and after, parturition in both primiparous and biparous rats. In primiparae, MPO cuts (a) disrupted placentophagia, (b) delayed the onset of crouching and pup-licking, and (c) eliminated retrieval and nestbuilding. MFB cuts (a) disrupted placentophagia, (b) delayed the onset of maternal behavior, and (c) eliminated nestbuilding. Asymmetrical cuts (a) disrupted placentophagia, and (b) delayed the onset of maternal behavior. In biparous rats, MPO cuts eliminated nestbuilding and retrieval. MFB cuts (a) disrupted placentophagia, and (b) eliminated nestbuilding. Asymmetrical cuts (a) delayed nestbuilding. These results suggest the involvement of a longitudinal neural system in the production of immediate pup-directed maternal behavior, placentophagia, and nestbuilding in parturient primiparae, but which is not critical for the eventual display of maternal behavior and nestbuilding in maternally naive rats, nor for the immediate onset of placentophagia and maternal behavior in maternally experienced rats.

Animals↗
PubMed1986

Placenta ingestion enhances analgesia produced by vaginal/cervical stimulation in rats.

Ingestion of placenta has previously been shown to enhance opiate-mediated analgesia (measured as tail-flick latency) induced either by morphine injection or by footshock. The present study was designed to test whether placenta ingestion would enhance the partly opiate-mediated analgesia produced by vaginal/cervical stimulation. Nulliparous Sprague-Dawley rats were tested for analgesia, using tail-flick latency, during and after vaginal/cervical stimulation; the tests for vaginal/cervical stimulation-induced analgesia were administered both before and after the rats ate placenta or ground beef. Placenta ingestion, but not beef ingestion, significantly heightened vaginal/cervical stimulation-induced analgesia. A subsequent morphine injection provided evidence that, as in a previous report, placenta ingestion, but not beef ingestion, enhanced morphine-induced analgesia.

Amniotic Fluid↗
PubMed1985

Placenta ingestion enhances opiate analgesia in rats.

Analgesia, produced by either a morphine injection or footshock, was monitored (using a tail-flick test) in nonpregnant female rats. Analgesia was induced within minutes of having the rats eat one of several substances. When the substance eaten was rat placenta, both the morphine- and shock-induced types of analgesia were significantly greater than in controls that ingested other substances (or nothing). When footshock (hind-paw) was administered in conjunction with the opiate antagonist naltrexone, the analgesia produced was attenuated but detectable; in this case, placenta ingestion did not enhance the analgesia, suggesting that the effect of placenta is specific to opiate-mediated analgesia. Placenta ingestion, in the absence of an analgesia-producing manipulation, did not elevate pain threshold. It is possible that this enhancement of analgesia is one of the principal benefits to mammalian mothers of ingesting the placenta and birth fluids (placentophagia) at delivery.

Analgesia↗
PubMed1983

Suppression of infanticide in mother rats.

In order to test the hypothesis that infanticidal tendencies are suppressed when rats become mothers, very young newborn pups, either naturally born or cesarean-delivered, were presented to virgin females and to newly delivered mothers. Provided that the pups were lively, uncleaned of fetal fluids or membranes, and presented without placentas, nearly all virgins killed and nearly all mothers did not. Newborns were also presented to Day 22 pregnant rats and to rats whose pregnancies had recently been surgically terminated. Large proportions of both groups either were nonkillers or were actively maternally responsive (and a smaller proportion were both) despite the fact that none of these rats had undergone parturition or cared for pups. These results indicate that, independent of its effect on maternal caretaking, pregnancy suppresses infanticide in previously infanticidal nulliparae even before they become mothers. Hence, infants are protected from their own parents. In addition, evidence was obtained in support of the idea that freshly delivered pups have stimulus properties that make them specially suited for promoting the onset of maternal caretaking.

Animals↗
PubMed1981

Placenta on pups' skin accelerates onset of maternal behaviour in non-pregnant rats.

Previous research has indicated that virgin rats (Rattus norvegicus) behave maternally (sensitize) more rapidly in close proximity with pups. Since both parturient rats and a large percentage of virgin rats avidly consume placenta, we tested whether placenta and amnionic fluid, pups and therefore hasten the onset of maternal behaviour. The results indicated that the procedure indeed shortened the maternal sensitization latency. Furthermore, this effect was not due to the wetness of the pups, to the presence of placenta in the cage, or to the adults having previously ingested placenta. Other attractive ingestibles applied to the pups' skin produced an intermediate, but not significant, shortening of the maternal sensitization latency.

Animals↗
PubMed1980

Placentophagia: a biobehavioral enigma (or De gustibus non disputandum est).

Although ingestion of the afterbirth during delivery is a reliable component of parturitional behavior of mothers in most mammalian species, we know almost nothing of the direct causes or consequences of the act. Traditional explanations of placentophagia, such as general or specific hunger, are discussed and evaluated in light of recent experimental results. Next, research is reviewed which has attempted to distinguish between placentophagia as a maternal behavior and placentophagia as an ingestive behavior. Finally, consequences of the behavior, which may also be viewed as ultimate causes in an evolutionary sense, are considered, such as the possibility of beneficial effects on maternal behavior or reproductive competence, on protection against predators, and on immunological protection afforded either the mother or the young.

Alleles↗
PubMed1977

Uterine distention facilitates the onset of maternal behavior in pseudopregnant but not in cycling rats.

The latency to onset of maternal behavior toward foster pups was examined in maternally-naive female rats treated either with uterine distention, a sham procedure, or no uterine manipulation. Uterine distention was achieved by intrauterine injection of hypertonic saline. The treatments were applied to either cycling, Day 10 pseudopregnant, or Day 11 pseudopregnant-decidualized virgins. The latency to onset of maternal behavior for both pseudopregnant groups was significantly shorter than that for the nonpseudopregnant group, when uterine distention was applied. The results suggest that uterine distention during pregnancy (during high progesterone level) may bring about both pregnancy termination (delivery) and the almost immediate maternal behavior seen at parturition, by the same hormonal mechanism.

Animals↗