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A S Fleming

Publications and source records attributed to A S Fleming.

At least 55 records · Page 3Linked to original sources
PubMed1988

Effects of photoperiod, the pineal gland and the gonads on agonistic behavior in female golden hamsters (Mesocricetus auratus).

Four studies were conducted to determine the role of photoperiod, the pineal gland and the gonads in the regulation of intrasex agonistic behavior in female hamsters. In the first experiment animals maintained under Long or Short photoperiods were tested in same or opposite photoperiod pairs. Under both testing conditions, Short-day animals tended to exhibit a higher ratio of offensive to defensive behaviors, which was due primarily to a reduced level of defensive behavior in Short-day groups. In the second experiment animals under Long and Short photoperiods were tested following sham surgery or pinealectomy. Short-day sham animals exhibited the highest level of offensive behavior, the lowest level of defensive behaviors and the highest offensive/defensive ratio; pinealectomy eliminated the Short-day advantage. In the third experiment, Long-day animals receiving exogenous melatonin showed a higher level of agonistic responding than animals injected with control vehicle, indicating that Short-day effects are probably mediated through pineal melatonin. The results of the last experiment in which ovariectomy to Long-day animals was not able to mimic the effects of photoperiod or exogenous melatonin indicated that the photoperiod effects on aggression are probably not mediated through the gonads.

Aggression↗
PubMed1988

Factors influencing maternal responsiveness in humans: usefulness of an animal model.

In this article we review some of the hormonal, sensory and experiential factors that regulate the onset and early maintenance of maternal responsiveness in rat and human mothers. We discuss data suggesting that, in humans, pregnancy is associated with changes in feelings and attitudes that may bear on adjustment to motherhood postpartum. Preliminary studies indicate that these changes are probably not hormonally mediated but are associated with a variety of psychosocial factors. Once women give birth, there is some suggestion that they undergo a period of elevated "responsiveness" which may be influenced by puerperal hormones and during which experiences with the newborn take on a special salience. Following the early postpartum period, a variety of factors influence maternal responsiveness, including the mother's affective state, her social relationships, and experiences caring for young. We discuss the relative contributions of psychological and physiological influences to maternal responsiveness at different stages of the maternity cycle.

Animals↗
PubMed1988

Changes in the marital relationship during the transition to first time motherhood: effects of violated expectations concerning division of household labor.

This research combined cross-sectional and longitudinal analyses to evaluate the hypothesis that violated expectations with respect to sharing child care and housekeeping responsibilities contribute to women's dissatisfactions with their marital relationships after the birth of their first child. The cross-sectional sample consisted of 670 women who completed questionnaires at one of six phases in relation to birth. The longitudinal sample consisted of 48 women who filled out questionnaires late in pregnancy and at three periods postpartum. The results showed, consistent with previous findings, that women reported less positive feelings about their husbands during the postpartum period than during pregnancy, and that women reported doing much more of the housework and child care than they had expected. Moreover, regression analyses indicated, as predicted, that violated expectations concerning division of labor were related to negative feelings postpartum concerning some aspects of the marital relationship. Additional findings suggested that the negative implications of the birth of a baby for the marital relationship may not be as great as has been emphasized in previous literature, and that expectancy violations affect some parts of the relationship but not necessarily the core affective feeling.

Adolescent↗
PubMed1987

Food cravings, mood, and the menstrual cycle.

The primary objective of the present investigation was to document positive changes in food cravings, food consumption, and mood changes over the menstrual cycle and to explore the relation between these factors and dieting habits. A total of 32 female undergraduates completed daily self-reports of food cravings, foods eaten, and mood, for 5 or more weeks. Comparisons of these measures in the 10 days preceding (luteal phase) and 10 days following menstruation onset (follicular phase) revealed that both food cravings and amount eaten were greater in the luteal phase than in the follicular phase. Although women also experienced less positive affect in the luteal phase, there was no correlation between mood and either cravings or amount eaten. Women rated as chronic dieters craved less than those rated an nondieters. The findings on mood and eating confirm previous research, whereas those on cravings extend such research by suggesting that carbohydrate cravings may be augmented by the luteal phase in healthy women.

Adult↗
PubMed1987

Hormonal influences on the duration of postpartum maternal responsiveness in the rat.

These studies investigated the role of gestational hormones in controlling the duration of the postpartum period of elevated maternal responsiveness in rats. In the first study, females had pregnancies terminated by Caesarean section, and had ovaries removed on day 16 or 22 of pregnancy. Removal of the ovaries did not prevent the sustaining of an elevated maternal responsiveness for 7 days after pregnancy termination on either day. In the second study, changes in concentrations of estrogen and progesterone during pregnancy, and following parturition, were determined by radioimmunoassay. Levels of these hormones postpartum were found to decline to virgin levels by 7 days postpartum and could not therefore explain the elevated maternal behavior seen at this time. In the third study, ovariectomized virgins were given a pregnancy-mimicking schedule of estradiol and progesterone, with and without prolactin, and were tested for maternal behavior 2 and 7 days later. A 22-day estradiol-progesterone schedule induced rapid maternal behavior within 2 days, but did not sustain it for 7 days. Adding prolactin to the 22-day estradiol-progesterone schedule sustained some components of maternal behavior, notably nest-building and retrieval, but not maternal behavior as a whole.

Animals↗
PubMed1987

Experience with pups sustains maternal responding in postpartum rats.

In these studies, we investigated the sustaining of postpartum maternal responsiveness through pup experience. In the first study, females were tested for maternal behavior at various times after pregnancy termination by Caesarean section (CS) at term. The females remained rapidly responsive to young for 7 days after pregnancy termination, but were no more responsive than virgins after 10 days. In the second study, females were allowed varying times of complete access to pups, beginning 24 hours after CS, and were tested for maternal behavior 10 days later. Females who retrieved and cared for pups for 30 minutes during exposure, remained rapidly maternal 10 days after CS; those who were allowed only 15 minutes of caring for pups did not. In the third study, females received 24 hours of exposure to distal sensory stimuli from pups, beginning 24 hours after CS. The proportion of females who became maternal within 24 hours of the beginning of maternal testing, 10 days after CS, was greater than that among females who received no exposure to pups.

Animals↗
PubMed1987

Affect and nurturance: mechanisms mediating maternal behavior in two female mammals.

This review will discuss hormonal and psychological factors involved in the initiation and maintenance of maternal behavior during the postpartum period in rat and human mothers. Research on primiparous rats suggests that among the ways hormones act to promote maternal responsiveness are by increasing the mother's attraction to odors of young pups, decreasing her natural neophobia and fearfulness, and increasing the ease with which experiences obtained during initial mother-young contacts are retained. Long-term maintenance of elevated maternal responsiveness in the rat is not directly under hormonal control but instead depends on a minimal period of direct interaction with young during the early postpartum. In human first-time mothers, the onset of maternal responsiveness is also directly affected by their mood state as well as their attraction to infants; these factors are, in turn, influenced by the amount of prior experience women have had caring for young. While the role of hormones in mediating maternal behavior in women is still unclear, initial results indicate they may facilitate responsiveness during the puerperium.

Affect↗
PubMed1986

Photoperiodic and pineal effects on food intake, food retrieval, and body weight in female Syrian hamsters.

Food intake, food retrieval, and body weight changes were measured in female Syrian hamsters maintained under long and short photoperiods, and in animals sustaining pinealectomy or sham surgery. Animals maintained under short photoperiods gained more weight, ingested more food, and brought more food from more distant compartments into their nest compartments than did animals maintained under long photoperiods. Pinealectomy prevented the short-day elevations in body weight and food retrieval during the period of gonadal recrudescence, but it did not produce significant changes during the period of gonadal regression; in contrast, pinealectomy prevented the short-day increases in food intake only during initial weeks of the period of gonadal regression: The effects of photoperiod or pinealectomy were not evident for any of the dependent measures during pregnancy. The role of the pineal gland in mediating short-day effects is discussed.

Animals↗
PubMed1985

Chemosensory and neural influences on photoperiodic responsiveness of laboratory rats.

Olfactory bulbectomy unmasks photoperiodic responsiveness in normally nonphotoperiodic rats. We assessed whether the photoperiodic effects of bulbectomy reflect disruption of chemosensory input. At 26-28 days of age, male Sprague-Dawley rats were subjected to removal of their vomeronasal organ (VNO) complex, a sham-VNO ablation or large electrolytic lesions aimed at the pyriform cortex or corticomedial nuclei of the amygdala. Other rats were infused with (1) 7.5% ZnSO4, a treatment that destroys the olfactory neuroepithelium, (2) 0.09% saline, or (3) air in each external nare every 4 days; rats from each treatment condition were assigned either to a long (LD 14:10) or short (LD 8:16) day lighting regimen and were autopsied at 90 days of age. Seminal vesicle and paired testes weights did not differ significantly among long-day groups. Mean seminal vesicle and paired testes weights were decreased only in short-day rats treated with ZnSO4. These results indicate that the VNO does not mediate the effects of photoperiod on rat reproduction. Olfactory information, not transduced by the amygdala, or nonsensory components of the olfactory bulbs appear to mask photoperiodism in intact rats.

Amygdala↗
PubMed1983

Lesions of the medial preoptic area prevent the facilitation of maternal behavior produced by amygdala lesions.

In the present study we tested the hypothesis that the facilitation of maternal behavior produced by amygdala lesions is mediated through the medial preoptic area. Different groups of animals sustained lesions of the corticomedial amygdala (Group AM), the medial preoptic area (Group MPOA), both regions (Group AM-MPOA), the corticomedial amygdala and non MPOA control sites (Group AM-CX), and control sites (Groups LC or SC). Animals were tested for their maternal responses to foster pups presented daily for an 11 day period. It was found that groups sustaining lesions of the amygdala (Group AM and AM-CX) became maternal more rapidly than did Control Groups (LC and SC), Group MPOA, and Group AM-POA. However, animals in Group AM-POA were similar to Groups AM and AM-CX in that they did not avoid pups, whereas groups not sustaining lesions of the amygdala did. These results, taken together, suggest that amygdala-induced facilitation of maternal behavior in the nulliparous females is mediated through the MPOA. They suggest, moreover, the primary effect of removing the amygdala is to reduce avoidance of pups, with only secondary effects on maternal responsiveness.

Amygdala↗
PubMed1983

Variation of fat intake with estrous cycle, ovariectomy and estradiol replacement in hamsters (Mesocricetus auratus) eating a fractionated diet.

Intakes of fats, proteins, and carbohydrates were measured daily for a 3 month period in female hamsters maintained on a fractionated diet consisting of the dietary constituents, dextrose, fat and soybean meal. In the first study, hamsters showed variations in body weight and fat intake across the estrous cycle and following ovariectomy, with elevations during diestrous and after ovariectomy when endogenous estrogens are reduced. In the second study, the effects of exogenous estradiol or cholesterol on intake patterns of ovariectomized hamsters were determined. Hamsters lost weight and decreased fat intake when implanted with a silastic containing estradiol and gained weight and increased fat intake when exposed to cholesterol treatment. In neither of the two studies were the intakes of protein or carbohydrates significantly affected by the animals' hormonal status. These results suggest that in the hamster, estrogenic effects on food intake are specific to some dietary constituents and not to others.

Animals↗
PubMed1983

Food intake, body weight, and sweetness preferences over the menstrual cycle in humans.

The body weight and reported food intake of 34 women were measured at the midpoint of the follicular and luteal phases of the menstrual cycle. Both body weight and reported food intake were significantly higher during the luteal phase than during the follicular phase. In addition, sweetness (sucrose) preferences were measured on both occasions before and after a glucose load. Examination of the pre- to post-load changes revealed a significant decline during the luteal phase and the absence of such a decline in the follicular phase. The results were discussed in terms of the influence of ovarian hormones on food regulation and carbohydrate metabolism.

Adolescent↗
PubMed1983

Disruption of maternal behaviour in virgin and postparturient rats following sagittal plane knife cuts in the preoptic area-hypothalamus.

Parasagittal knife cuts along the medial preoptic area-medial anterior hypothalamus were placed at either the medial (near lateral or NL cuts) or lateral (far lateral or FL cuts) border o the medial forebrain bundle in separate groups of virgin (Experiment 1) and postparturient (Experiment 2) rats. FL cuts were placed so as to spare preoptic-hypothalamic efferent connections with the medial forebrain bundle. NL and FL knife cuts were equally effective in preventing the induction of maternal behaviour produced by repeated exposure of virgin rats to foster pups. Both types of cuts also reduced nest building in virgins. In postparturient rats, NL and FL cuts both abolished pup retrievaL and reduced nursing behaviour. However, only NL cuts disrupted lactation and nest building. NL cuts also produced chronic hyperthermia. The deficits in maternal behaviour and nest building may be independent of this hyperthermia, as shaving the fur in animals with NL cuts reduced body temperatures to control levels but did not restore these behaviours. These findings indicate that while preoptic/hypothalamic connections through the medial forebrain bundle are important for nest building and possibly lactation, other lateral connections must also be important for pup retrieval and nursing behaviour. The identity of these connections remains to be determined.

Animals↗
PubMed1983

Effects of diet on feeding and body weight regulation during pregnancy and lactation in the golden hamster (Mesocricetus auratus).

The hypothesis was tested that the weight loss shown by lactating hamsters constitutes a "regulated" weight loss. The results support the hypothesis: Prefattened overweight hamsters lost more weight from the time of mating to the end of lactation than did unmanipulated controls. However, the weight loss during lactation was reduced by giving hamsters access to a high-fat diet, a result indicating that a portion of the lactational weight loss may also be regulated by the diet provided. When lactating hamsters were given access to a fractionated diet consisting of pure fat, pure carbohydrate, or 45% protein, they increased their proportional intake of both protein and fat but not of carbohydrate. These studies show that hamsters differ from rats in their pattern of energy regulation during pregnancy, lactation, and the postsuckling period. Reasons for these species differences are discussed.

Animals↗
PubMed1980

Hormonal and sensory control of scent-marking in the desert woodrat (Neotoma lepida lepida).

In Experiment 1, the marking behavior of adult male and female woodrats was tested in a neutral environment. Males showed higher levels of ventral rubbing than females, whereas the reverse was true for the body-rolling response. In Experiment 2, the influence of testosterone propionate and estradiol-17 on scent-marking in female and male gonadectomized experimental animals was investigated. Animals were given a series of marking tests prior to an during social encounters with conspecifics. Ventral rubbing was found to be under androgenic control, and body rolling was partially under estrogenic control. In both sexes, high-dominance status and circulating testosterone were necessary for the occurrence of ventral rubbing during social encounters. In Experiment 3, the ventral rubbing of males in the cages of conspecifics was observed before and after social encounters with these animals. Before social encounters males showed higher levels of rubbing to conspecific odors than to neutral odors or to their own odors. After social encounters males increased their ventral rubbing in cages of females but not in cages of males. In Experiment 4, males preferred to ventral rub in areas soiled with the odor of other males rather than those soiled by females but preferred to roll in areas soiled by females. Estrogen-primed females preferred to roll in areas soiled by males over those previously soiled by females.

Animals↗