Postpartum Females Research Articles

Disturbances in dexamethasone suppression test and lower availability of Ł-tryptophan and tyrosine in early puerperium and in women under contraceptive therapy

This study investigates the function of the hypothalamic-pituitary-adrenal (HPA)-axis and the availability of L-tryptophan and tyrosine to the brain in postpartum women and in women taking long-term oral contraceptives. To this end, we have measured the following parameters in 50 women (i.e. 9 normal controls, 10 women taking oral contraceptives, and 31 postpartum females): plasma cortisol, L-tryptophan, tyrosine and the amino acids (CAA) known to compete with them for transport through the blood-brain barrier. We have determined the effects of 1 mg of dexamethasone on the above-mentioned biological markers in postpartum females. Plasma cortisol and tyrosine were significantly higher and lower, respectively, in puerperium and in women under contraceptive therapy as opposed to normal controls. L-Tryptophan was significantly lower in postpartum females, whilst the L-tryptophan/ CAA ratio did not differ across the three study groups. Postpartum females revealed a significant negative relationship between the availability of L-tryptophan to the brain and postpartum mood, as measured by Zung's Depression and Anxiety Scales and State Anxiety Inventory. Dexamethasone had a significant suppressive effect on L-tryptophan/CAA and tyrosine/CAA ratios, with cortisol non-suppression appearing in 82% of the postpartum females.

Pituitary and ovarian responses to luteinizing-hormone-releasing hormone during pregnancy and after parturition in brown hares (Lepus europaeus)

Female hares were given an i.v. injection of 5 micrograms luteinizing-hormone-releasing hormone (LHRH) between Days 7 and 19 (n = 21), 20 and 33 (n = 17) and 34 and 41 (n = 17) of pregnancy, and in the 3 days after parturition (n = 16). Whatever the stage of pregnancy, the LHRH injection induced a release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and an acute secretion of progesterone; these hormonal responses increased significantly during pregnancy, to reach values similar to those observed in nonpregnant, nonpseudopregnant females during the breeding season in the 3 days after parturition. However, the release of LH remained monophasic in pregnant and post-partum females, in contrast to the unmated females during the reproductive season, in which there was a biphasic profile. The proportion of ovulating females after LHRH treatment was approximately 60% at the beginning and end of pregnancy; and, after parturition, fell to 23% between Days 20 and 33. After Day 33, the pituitary response to LHRH was significantly higher in ovulating than in nonovulating females. At the beginning of pregnancy, 67% of females aborted after LHRH injection; after Day 20, the incidence of abortion decreased significantly and was 0% from Day 34. The amplitude and duration of progesterone secretion by the new corpora lutea resulting from ovulation after LHRH injection were similar to those of corpora lutea induced in nonpregnant females during the breeding season.(ABSTRACT TRUNCATED AT 250 WORDS)

Sperm competition, pregnancy initiation and litter size: influence of the amount of copulatory behaviour in Mongolian gerbils, Meriones unguiculatus

Mongolian gerbils live in cooperative pairs or family groups, but they mate promiscuously. To investigate the reproductive outcome of alternative male and female mating strategies a series of laboratory studies was carried out. The number of ejaculations received by postpartum or cyclic oestrous females, mating with one or two males, was controlled. The paternity of juveniles was determined by the genetic marker of coat colour morph. When presented with one male, 70% of the postpartum oestrous females delivered a litter following one ejaculatory series, whereas all females delivered following two or more. When females were presented with two males in succession, and there was only one ejaculatory series, 90% of the females in postpartum oestrus, but only 35% of the cyclic oestrous females delivered a litter. Whether the sire was the cage-mate of the female or a strange male had no effect. Litter size increased significantly, and its variance decreased, with the total number of ejaculatory series. When two males copulated with the same female, the male with relatively more ejaculatory series sired a larger proportion of the litter, irrespective of mating order. When two males were allowed the same number of ejaculatory series, there was a shift from first-male advantage, to no order effect, to last-male advantage following one, to two or three, to four or five ejaculatory series from each male. The relative reproductive outcome of the first male was influenced more by the copulatory effort of the second male than by his own effort. The consequences of number and mating order of sires for average litter size and paternity are analysed.

Rapid changes in the reproductive cycle of wild-caught tsetse, Glossina pallidipes Austen, when brought into the laboratory

This paper describes differences in reproductive and nutritional conditions that develop within 2 weeks of the transfer of wild-caught female Glossina pallidipes Austen to apparently ideal laboratory conditions. In order to investigate the relative sampling efficiency of baited NG2B traps for female G. pallidipes and the flies’ changing feeding behaviour on different days of the pregnancy cycle, samples of female G. pallidipes taken directly from the field and those held in the laboratory for a known number of days after larviposition were subjected to both ovarian dissection (including the measurement of the uterine content and the two largest ovarioles) and fat and haematin analysis. Under the laboratory conditions of slightly lower mean temperature (buffered against diurnal fluctuations), lower activity and higher feeding frequency than in the field, the interlarval period was prolonged, the third larval instar was disproportionately prolonged, the ovarioles and larvae in utero showed differential growth rates, pupal size was increased and the fat reserves of post-partum females was depleted. It is concluded that tsetse are very responsive to the precise environmental conditions in which they find themselves and that absolute quantitative measurements made in the laboratory cannot be applied directly to the field situation.

Foraging characteristics of female northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus)

The foraging characteristics of northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus) from San Miguel Island, California, were studied during the 1985 summer breeding season. A radio transmitter was attached to 25 postpartum females of each species and used to determine their locations at sea and the frequency and duration of their feeding trips. Northern fur seals usually foraged in the oceanic zone where the mean water depth was 933 m (n = 12). California sea lions principally were found in the neritic zone, where water depth averaged 323 m (n = 9). Most fur seals (92%) were found northwest of San Miguel Island, whereas the sea lions were commonly found to the northwest (55%) or in areas south (22%) of the island. Although both species evidently foraged at similar distances from the island, foraging trips of fur seals [Formula: see text] were over twice as long as those of sea lions [Formula: see text]. Fur seals were ashore less time [Formula: see text] than were sea lions [Formula: see text] between foraging trips. Analysis of scats revealed that fur seals and sea lions ate similar prey (northern anchovy, Engraulis mordax; Pacific whiting, Merluccius productus; juvenile rockfish, Sebastes spp.; market squid, Loligo opalescens; and nail squid, Onychoteuthis borealijaponicas), although the relative proportions of these prey differed. Factors influencing the observed foraging characteristics probably were availability of prey and phylogenetic constraints associated with life-history traits of northern fur seals and California sea lions.

Modulation of luteal activity in postpartum beef cows through changes in dietary lipid.

Studies were conducted to evaluate the normal changes in lipid metabolism occurring in the suckled Brahman crossbred female during the postpartum period (Exp. 1) and to examine the function of induced corpora lutea (CL) in postpartum cows fed diets with normal (2.8%) lipid or elevated (8%) lipid content (Exp. 2). Multiparous and primiparous females (n = 20), maintained on pasture without energy or protein supplementation, were used in Exp. 1. A linear increase (P less than .001) in plasma lipid metabolites was observed between the 1st and 8th wk after calving, reaching a plateau of 221 +/- 18.3 and 74 +/- 3.4 mg/dl for total cholesterol and triglycerides, respectively. Seventy percent of all postpartum females exhibited luteal activity within 50 d (x = 34.7 d), and 59% of these animals exhibited short luteal phases (less than 12 d). In Exp. 2, primiparous and multiparous females (n = 32) were assigned to receive a control (n = 16) or high-lipid (HL) diet (n = 16; 30% whole cottonseed) between d 1 and d 38 after calving. The HL diet increased (P less than .001) total cholesterol and triglycerides 1.7- and 1.4-fold, respectively, relative to controls, and increased (P less than .05) the spontaneous occurrence of low-level progesterone elevations. Forty-eight-hour calf removal and gonadotropin-releasing hormone (GnRH; .22 mg/kg BW i.v.) were employed between d 21 and 26 after calving to induce ovulations. Mean concentrations of progesterone in the HL group were markedly higher (P less than .01) than in controls between d 5 and 8 of the induced cycle, and average lifespan of induced CL was approximately twice that of controls (P less than .01).

Sperm competition in deer mice (Peromyscus maniculatus bairdi)

Six experiments were conducted to determine the effects of mode of estrus (cycling versus postpartum) and intervals between matings on sperm competition in deer mice. When there was no lengthy interval between matings by different males, sperm competition matings by different males, sperm competition with females in postpartum estrus was the same as that with females in cyclin estrus (i.e., no male order effect). Imposition of 4 h delays between males did not engender a mating advantage when females were in postpartum estrus. When 4 h intervals were imposed with females in cycling estrus and tests were begun relatively early in the dark phase, there was a secondmale advantage with respect to the number of pups sired. When minimal delays were imposed with females in cycling estrus the time of testing within the dark phase did not affect the pattern of sperm competition, but larger litters were born following matings later in the dark phase. When 4 h delays were imposed with the first male mating late in the dark phase a first-male advantage resulted. It is hypothesized that for females in cycling estrus there is a period of peak fertilizability. There is no straight-forward effect of delays between males per se; rather, effects must be analyzed in relation to the period of peak fertilizability. The timing of insemination appears less critical for postpartum females.

Induction of keratinocyte type-I transglutaminase in epithelial cells of the rat

Using immunogold-silver techniques, we have demonstrated that, in rats, type-I (keratinocyte) transglutaminase is expressed primarily in stratified squamous epithelia of the integument, the upper digestive tract, and the lower female genital tract. In these epithelia, the enzyme was found to be present predominantly in the granular layer, but was evident at low levels even in the basal layer, especially in the genital tract. No immunoreactivity was detected in glandular, columnar, or transitional epithelia or in soft tissues. However, considerable enzyme antigenicity was observed in the endometrium and in major ducts of the pancreas and mammary glands of near-term pregnant and early postpartum females. In cultures, substantial immunoreactivity was readily identifiable not only in epidermal, vaginal, and esophageal epithelial cells (immunopositive in vivo), but also in urinary bladder, seminal vesicle, and tracheal epithelial cells (immunonegative in vivo). Primary epithelial outgrowths from bladder and seminal vesicle tissue explants were immunopositive, demonstrating rapid adaptation to the culture environment. These results reveal three distinct levels of regulation of transglutaminase expression in various cell types: (1) during the differentiation of keratinocytes, (2) during pregnancy. being evident principally in the endometrium but detectable elsewhere as well, and (3) during the cultivation of certain epithelia which do not normally express the enzyme in vivo. We conclude that type-I transglutaminase may be a valuable marker for elucidating the regulation of normal epithelial differentiation and squamous metaplasia.

Induction of keratinocyte type-I transglutaminase in epithelial cells of the rat

Using immunogold-silver techniques, we have demonstrated that, in rats, type-I (keratinocyte) transglutaminase is expressed primarily in stratified squamous epithelia of the integument, the upper digestive tract, and the lower female genital tract. In these epithelia, the enzyme was found to be present predominantly in the granular layer, but was evident at low levels even in the basal layer, especially in the genital tract. No immunoreactivity was detected in glandular, columnar, or transitional epithelia or in soft tissues. However, considerable enzyme antigenicity was observed in the endometrium and in major ducts of the pancreas and mammary glands of near-term pregnant and early postpartum females. In cultures, substantial immunoreactivity was readily identifiable not only in epidermal, vaginal, and esophageal epithelial cells (immunopositive in vivo), but also in urinary bladder, seminal vesicle, and tracheal epithelial cells (immunonegative in vivo). Primary epithelial outgrowths from bladder and seminal vesicle tissue explants were immunopositive, demonstrating rapid adaptation to the culture environment. These results reveal three distinct levels of regulation of transglutaminase expression in various cell types: (1) during the differentiation of keratinocytes, (2) during pregnancy, being evident principally in the endometrium but detectable elsewhere as well, and (3) during the cultivation of certain epithelia which do not normally express the enzyme in vivo. We conclude that type-I transglutaminase may be a valuable marker for elucidating the regulation of normal epithelial differentiation and squamous metaplasia.

Vacant postsynaptic densities on supraoptic dendrites of adult rats diminish in number with chronic stimuli.

In earlier ultrastructural studies of the supraoptic nucleus in adult rats we noted "free" and incompletely covered postsynaptic densities (collectively referred to here as vacant postsynaptic densities) on dendritic shafts. Free postsynaptic densities have been reported in other parts of the central nervous system of normal rodents. We investigated the possibility that physiological activation of the supraoptic cells, which produces changes in many aspects of their morphology, would alter the incidence of the free or incompletely covered postsynaptic densities on dendrites in the supraoptic basal dendritic zone. The cells of the supraoptic nucleus are activated to increase cell firing and secretion of oxytocin and/or vasopressin in response to dehydration, gestation, and lactation. We have examined: untreated virgin females; untreated males; 24 h water-deprived males; prepartum (21st day of gestation) females; postpartum females (on the day of parturition); lactating females (14 days of suckling); mothers 10 days after weaning their pups; females given 2% saline to drink (dehydrated) for 10 days; and females or males given 2% saline to drink for 10 days, then given tap water for 2 or 5 weeks to allow rehydration. Only long-term activation of the supraoptic nucleus by lactation or by drinking saline for 10 days brought about significant decreases in the percentage of dendrites with vacant postsynaptic densities. These densities did not reappear in saline treated rats which had been rehydrated for 2 weeks, but did return in both the 5-week rehydration and the 10-day postweaning groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Population dynamics of the Kaminuriak caribou herd, 1968 - 1985

The Kaminuraik caribou herd apparently declined from about 120 000 animals in 1950 to 63 000 in 1968. Beginning in 1968 documentation of herd trend was based on the estimate of the number of breeding (pregnant and post-partum) females on the calving ground during the birth peak. It appeared as if we understood the basic population processes responsible for the decline when we correctly predicted a drop from 14 800 breeding females in 1977 to 13 000 in 1980. However a three-fold increase, to 41 000 breeding females in 1982, and continued growth thereafter, was unanticipated. Most of that increase must have resulted from an immigration of cows to the herd's traditional calving ground around Kaminuriak Lake, although increased birth rates, and increased survival rates also contributed to herd growth. Immigrant cows probably came from the northeastern mainland of the NWT

Antibodies to microbial, leukocyte and organ antigens

Hemagglutinating antibodies to Mycoplasma hominis were present in 30 of 83 infertile, 15 of 40 pregnant and 5 of 20 post-partum females and 20 of 82 infertile males in contrast to only 2 of 21 fertile females and 5 of 25 fertile males. Their presence correlated with sperm antibody detection by TAT in Lab. 4. the immunobead-binding assay of Lab. 1 and the SIT of Lab. 11, but not with other sperm antibody assays. Immunofluorescent antibodies to Chlamydia trachomatis, on the other hand, did not correlate with the incidence of sperm antibodies. Among 305 serum samples tested, 12 were positive for testicular antibodies, 8 had antibodies to kidney, 7 to ovary and 15 to endometrium. A majority of serum samples positive for antibodies to testis and ovary, but not endometrium, reacted against sperm in different assays. Eight of 135 samples tested had antibodies to human leukocyte antigenic HLA-Aw19 (Aw19, A28, A29, A30 and A32) and/or B35 (B35, B5 and B15) complexes. Six of these samples were also positive for sperm antibodies by one or more antibody assays. Cross-reactive antigens may be present in sperm, M. hominis, testis, ovary and leukocytes.

Some aspects of female reproduction in the Grey-headed Flying-fox, Pteropus poliocephalus (Megachiroptera: Pteropodidae).

Antral follicles are found in both ovaries of non-breeding females throughout the year, but not in pregnant bats after May, or in post-partum females until January. Follicle sizes increase in the breeding season, but plasma oestradiol concentrations do not change; significant increases occur only in the later stages of pregnancy. During early gestation corpora lutea appear secretory but plasma progesterone concentrations are low. Later in pregnancy progesterone concentrations rise although the CL appears to regress. The placenta is presumably responsible for the high hormone levels observed at this time. Possible factors regulating female receptivity and breeding season are discussed.

Maternal aggression in mice: Effects of treatments with PCPA, 5-HTP and 5-HT receptor antagonists

Drug treatments which influence brain serotonergic systems were administered to lactating female mice during the early postpartum period, and their effects on aggressive behavior, locomotor activity and brain monoamines were examined. P-chlorophenylalanine (200 and 400 mg/kg) and 5-hydroxytryptophan (100 mg/kg) inhibited fighting behavior of postpartum mice toward unfamiliar male intruder mice. These drug-treated postpartum females showed increased latencies to attack male intruders and also reduced frequencies of attack. In addition, postpartum mice treated with the serotonin receptor antagonists, mianserin (2 and 4 mg/kg), methysergide (4 mg/kg) and methiothepin (0.25 and 0.5 mg/kg), displayed significantly less aggressive behavior than control mice, as measured by reduced number of attacks. Whole brain monoamine and monoamine metabolite levels were measured after drug treatments. The behavioral results are discussed in terms of drug-induced changes in brain chemistry and indicate a possible role for serotonin in the mediation of maternal aggressive behavior of mice.

The Timing of Mating by Postpartum Estrous Rats

Abstract and SummaryIn Norway rats (Rattus norvegicus) postpartum copulation began later, and was more rapid than mating during a cycling estrus. Faster postpartum mating was a result of shorter intervals between intromissions, rather than fewer intromissions. In addition, postpartum pairs showed a trend towards fewer ejaculatory series. Postpartum female sexual initiation and her attractiveness to the male produced rapid postpartum mating. Preliminary evidence indicates that pups' presence does not determine faster postpartum mating, yet postpartum females did exhibit time‐sharing relationships between their mating and maternal demands. We hypothesize that the rapid pace of postpartum mating is produced by intrinsic neuroendocrine changes characteristic of postpartum estrus and possibly by sexual experience.

Male capacity as related to sperm production, pregnancy initiation, and sperm competition in deer mice (Peromyscus maniculatus)

Limitations on male capacity may be important to the evolution of mating strategies and behavior. Sperm counts in successive ejaculates of deer mice (Peromyscus maniculatus) decreased progressively through six ejaculations and remained depressed the following day. Males were as effective in inseminating females in cycling estrus with their second two ejaculates as with their first two and as effective in inseminating postpartum females with their fifth as with their first. In sperm competition situations males competed with rested males as effectively with their fourth, fifth, and sixth ejaculates as with their first. Thus, although sperm counts decrease in successive ejaculates, males suffer no apparent functional deficiency as long as they continue ejaculating. It is not clear whether or not deer mice are “honest salesmen” but they appear to be “honest ejaculators” and usually are “honest intromitters.”

Pregnancy-Related Changes in Small Intestinal Myoelectric Activity in the Rat

To determine if changes in intestinal motility occur during pregnancy, we studied small intestinal myoelectric activity, using monopolar electrodes, in fasted pregnant rats from day 12 to day 18 of the 22-day gestation period. We also studied fasting myoelectric activity in postpartum, nonpregnant, and castrate females. In all rats, the interdigestive myoelectric complex was invariably present with recurring activity fronts appearing at the proximal electrode and moving slowly abroad. Intervals between fronts were similar in all four groups, ranging from 12.61 min to 14.58 min. In pregnant rats, however, there was loss of the periodicity characteristic of activity fronts in the other groups; intervals up to 43 min in length were occasionally noted. Unorganized, randomly occurring spike potentials characterized these intervals. The average coefficient of variation of interval length was significantly (p less than 0.05) greater in pregnant rats (0.401) than in castrate (0.197) and nonpregnant rats (0.248). These studies confirm the presence in rats of pregnancy-related changes in small intestinal myoelectric activity.

The contribution of observations on early pregnancy in the little sac-winged bat, Peropteryx kappleri, to an understanding of the evolution of reproductive mechanisms in monovular bats.

The reproductive biology of Peropteryx kappleri was investigated histologically in females collected during the onset of a synchronized breeding season. Many had recently given birth, although the interval between parturition and a new ovulation appeared to be variable. Successive ovulations in this monovular species tended to alternate between the ovaries, but this was restrained by partial dominance of the left ovary. Evidence of reproductive failures was noted in several post-partum females in which ovulation had not alternated. Although development usually proceeded to the blastocyst stage in the oviduct, shedding of the zona pellucida was deferred until the embryo passed into the uterus. Implantation was of the central type and always occurred at the cranial end of the uterine horn ipsilateral to the new corpus luteum. Immediately prior to and after ovulation the oviduct on the active side of the reproductive tract appeared preferentially stimulated. Its epithelial cells were usually larger and often contained more cytoplasmic glycogen than those of the other oviduct. During the tubal journey of the ovum, endometrial development was most pronounced at the prospective implantation site and was minimal in the opposite uterine horn. Many of the oviductal epithelial cell nuclei in all of the adult bats examined appeared extensively vacuolated. Histochemical tests established that this was attributable to the intranuclear presence of glycogen. The ability of P. kappleri (and of some other bats with bicornuate or duplex uteri) to alternate ovulations and to control the uterus via local pathways probably serves to decrease the interval required to recycle the female tract after either a reproductive failure or a previous pregnancy. This could be advantageous to species with low reproductive potentials and restricted breeding seasons. Retention of the ovum in the oviduct until the blastocyst stage probably favors subsequent successful development of the embryo in the uterus, only a small portion of which is maximally stimulated. The bats with simplex uteri appear to have evolved another means of efficiently recycling the uterus in the event of a nonfertile cycle. They eliminate much of the aging endometrium at the prospective implantation site by menstruating and regenerate a new one.

Reduced dopaminergic inhibition of thyrotrophin release in states of physiological hyperprolactinaemia.

We have tested the hypothesis that physiological puerperal hyperprolactinaemia may be secondary to reduced hypothalamic dopaminergic inhibition of prolactin (PRL) release. Nine post-partum females with physiological hyperprolactinaemia (aged 19-40 years; mean basal PRL +/- SE, 2099 +/- 257 mU/1, range 1002-3762 mU/1) were studied and results compared with fourteen normoprolactinaemic females (basal PRL less than 400 mU/1; aged 18-36 years). Puerperal hyperprolactinaemic females showed a reduced TSH response to dopamine (DA) receptor blockade with metoclopramide (10 mg i.v.) compared with normal females over a 60-min period following drug administration (total incremental TSH change, mean +/- SE, mU/1; 0.5 +/- 0.3 v. 3.1 +/- 1.0 P less than 0.005). This finding of reduced dopaminergic inhibition of TSH release in females with physiological puerperal hyperprolactinaemia supports the view that an overall reduction in hypothalamic dopaminergic tone may contribute towards hyperprolactinaemia in post-partum women.

Postpartum copulatory and maternal behaviour in Norway rats under seminatural conditions

Virgin female rats were mated at a freely cycling oestrus, and then again with the same males at the subsequent postpartum oestrus. Copulatory behaviour at each mating was compared and the temporal patterning of the female's mating and maternal behaviour was analysed. Postpartum females were found to conserve the number of ejaculatory series received, yet the series were shorter, resulting in a shorter time being occupied, by this mating. During mating, females spent little time with their litters, and then mainly in the post-ejaculatory intervals. Ejaculatory series were rarely disrupted by nesting. The postpartum female rat seems to engage in behavioural time-sharing.