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Influence of melatonin on reproductive behavior in male rats.

The influence of melatonin on reproductive behavior was examined by administering it to pinealectomized male rats for 30 consecutive days. After the 30-d administration of melatonin or vehicle, each male rat was introduced into a female rat's cage on the day of proestrus and allowed to mate overnight. All rats administered the vehicle and the pinealectomized rats copulated; five of the twelve melatonin (8.0 mg/kg)-treated rats did not copulate. These findings suggest that melatonin inhibits the reproductive behavior of male rats.

Animals

Effects of prenatal testosterone and ATD on reproductive behavior in guinea pigs.

Most sexual dimorphisms in reproductive behavior are hormonally organized in the guinea pig. The study sought to determine whether the sexually dimorphic requirement for the aromatization of testosterone in the activation of mounting is organized by testosterone prenatally and whether aromatization of testosterone contributes to the organization of mounting behavior. Pregnant females were treated with testosterone, the aromatase inhibitor ATD, or vehicle from days 28-65 of gestation. The offspring were gonadectomized and tested as adults for lordosis and androgen-activated mounting behavior. Prenatal testosterone treatments altered the hormonal requirements for androgen-activated mounting in females such that they resembled normal males, and did not require aromatization as adults. Prenatal inhibition of aromatase activity decreased mounting activity in females but not in males. This treatment had no influence on lordosis in either sex. The results support the hypothesis that the same hormones that activate mounting behavior in the adult guinea pig are responsible for the organization of mounting behavior.

Androstatrienes

The effects of photoperiod on androgen-induced reproductive behavior in male ring doves, Streptopelia risoria.

The effect of photoperiod on reproductive behavior in male ring doves (Streptopelia risoria) was studied in androgen-injected castrates maintained under long (16L:8D) or short (86:16D) photoperiods. Behavioral recordings were made over a 2-week period during which each male was paired with a female for 6.5 hr/day. There was some indication that males held on long days display higher levels of courtship activity during the initial period following pairing, but the evidence was not conclusive. Day length had no effect upon copulatory behavior. Long-day males exhibited consistently higher levels of nest building than short-day males, indicating that photoperiod affects building through some mechanism other than changes in endogenous androgen levels.

Animals

Social and reproductive behaviors in surrogate-reared squirrel monkeys (Saimiri sciureus).

A colony of 16 surrogate-reared squirrel monkeys was observed for the adequacy of social and reproductive behaviors at maturity. Aside from some self-directed abnormalities centering around nonnutritive orality, this group was behaviorally normal in spite of having no contacts with mother-reared, older conspecifics. Half (N=5) of the females gave birth, with four infants viable. One infant has remained with the colony and is thriving. The other three remained with the group for as long as 42 days before death or removal. Maternal care appeared adequate. Mean estimated conception age for females was 35 months, and the mean impregnation age for males was estimated to be 42 months.

Animals

Luteinizing hormone-releasing factor (LRF) and reproductive behavior in male doves exposed to long and short photoperiods.

In order to determine whether the variable degree of nest-building behavior displayed by male doves exposed to different photoregimes is related to differences in luteinizing hormone-releasing factor (LRF) levels, androgen-treated castrates held on long (16L:8D) or short (8L:16D) daylengths were treated with 20 microgram LRF or saline daily. Birds in both groups exhibited higher levels of initial courtship and nest-building when held on long days. LRF treatment had no effect on any of the behavior patterns examined. The results suggest that photoperiod does not affect reproductive behavior in male doves through changes in endogenous levels of LRF.

Animals

Household crowding and reproductive behavior.

Ethological studies suggest that animal populations that live in crowded conditions display a number of behaviors that tend to limit the size of the population, such as aberrant forms of sexual behavior, small litter sizes, a higher incidence of spontaneous abortion, ineffectual maternal care, and even cannibalism of their young. Studies of household crowding in North America cities have produced only modest and selective evidence that crowding has similar effects among humans. In this paper, we examine the effect of household crowding on marital sexual relations, on desire for additional children, and on fetal and child loss in Bangkok, Thailand, a city with a much wider range of household crowding than is typically found in North America. In spite of the wider range, and higher mean level of crowding, we find that both the objective and subjective dimensions of crowding have only modest selective effects on sexual and reproductive behavior.

Adult

The effect of subsidized family planning services on reproductive behavior in the United States, 1969-1974.

This paper evaluates the impact of federally subsidized family planning programs in the United States, from 1969 to 1974, on the reproductive behavior of ever-married women, 15-44 years old. The study began with an experimental design and the random assigment of areas to treatment and control but was completed as a multivariate analysis, treating program input as an interval-scaled independent variable. Using "before" and "after" area sample surveys and patient service data from operating programs, the demographic impact of the program was estimated. The impact detected was nonsignificant; according to our analysis, overall use of physician-administered contraception was not affected by the subsidized programs. The only program-induced change of activity related to reproduction that we recorded was increased use of subsidized services in study areas with high program input and increased use of private physician services where program input was low. These findings need to be interpreted with the caution usually exercised in evaluating imperfect field experiments.

Adolescent

[Reproductive behavior and health: reflections on the supply of services].

The aim of this article is to put forward a series of reflections on the role that service providers have played in defining the interactions between reproductive behavior and health. In the first section some approximations are presented of what could constitute a framework for analyzing the topic under study, including demographic aspects and the ones involving the provision of services as well as the aspects related to the epistemology of health and a commentary on the importance of norms in the provision of services. In the second section a couple of recent experiences related to the provision of services in a context of "having an impact on reproduction for the purpose of improving health" discussed. The source of information used were two national surveys (Encuesta Nacional sobre Factores de Riesgo en la Anticoncepción Hormonal, or National Survey on Risk Factors in Hormonal Contraception, and Encuesta Nacional sobre Fecundidad y Salud, or National Fertility and Health Survey) made in 1984 and 1987 with women of childbearing age and health service providers (the first of the two surveys mentioned). Based on the experience stated by the female users of the contraceptive methods most frequently used by Mexicans, and on the responses of service providers, an evaluation is made of the medical norms of the institutions belonging to the Mexican health sector, and some hypotheses are suggested on the possible reasons why there are deficiencies in the observance of these norms. Lastly, some lines to prompt a discussion along this subject are proposed.

Child Welfare

Modifications in gonadotropin control and reproductive behavior in the female rat by hypothalamic and preoptic lesions.

Effects of small hypothalamic and preoptic area lesions on vaginal cyclicity, ovulation and ovarian weights of female rats were examined. Animals were then gonadectomized and tested for lordosis behavior following injections of estrogen alone and estrogen plus progesterone. Male sex behavior was also measured during daily treatment with testosterone. Relative to sham operated rats, lesions in the dorsal preoptic area produced a significant increase in lordosis behavior, virtual elimination of male sex behavior, and only marginal effects on ovarian function. Animals with lesions in the ventral preoptic area showed constant vaginal cornification, lack of ovulation and significantly smaller ovaries than the other groups. These rats also tended to show more female sex behavior and less male sex behavior than sham operated rats. Animals with lesions in the anterior hypothalamus and dorsomedial hypothalamus showed normal ovarian function and levels of female and male sex behavior comparable to the ventral preoptic lesioned rats. Animals with lesions in the ventromedial hypothalamus tended to show lower levels of lordosis behavior than sham animals but displayed a dramatic and significant increase in male copulatory behavior relative to the other groups. These data indicate a clear dissociation between the neural control of cyclic gonadotropin activity and sex specific reproductive behavior.

Animals

Social modulation of behavioral reproductive senescence in female rats.

During aging, the lordosis reflex of female rats changes from a state of cyclic lordosis, when the lordosis reflex can be elicited by manual palpation only on proestrus, to a state of constant lordosis (CL), when it can be elicited daily. Social signals from other females altered this pattern of behavioral senescence. Group living decreased the lordosis reflex intensity in both old and young rats and delayed the onset of CL. Long-term group living delayed CL until late in the life span, while temporary group living delayed it only until rats returned to isolation. Long-term group living also changed the temporal relationship between CL and the acyclic, anovulatory state of estrus. Finally, the lordosis reflex intensity, measured by manual palpation, predicted the old rats' receptivity to a male, indicating that constant lordosis is a biomarker for other aspects of behavioral reproductive senescence.

Aging

The reproductive behavior of Aequidens paraguayensis (Pisces, Cichlidae).

The reproductive behaviour of aquarium-held Aequidens paraguayensis is described, with emphasis on a quantitative comparison of female-male parental roles. It is a biparental species. Eggs, laid on leaf litter, are guarded and aerated for about 32 hours (25--27 degrees C) and newly-hatched young are orally brooded for several days. Both sexes performed all parental activities; female-female did more fanning and mouthing of eggs, male-male more oral churning of young initially. The combination of substrate and oral brooding of young by both parents is rare among New World cichlids and is of interest for the study of the evolution of parental behaviour in fishes.

Aggression

[The genetic-demographic approach in anthropological research. XI. The structure of the reproductive behavior of Khakass families].

A detailed analysis of chronological intervals typical of reproduction process has been carried out in rural Khakassian populations to reveal the mechanisms of natural selection and gene drift. It is shown that the process of reproduction is connected with cultural traditions and economical activity of a population under study. The main characteristics of reproductive family behavior (the whole number of children and sex ratio, birth interval ect.) play a very important role in family and kin relationships, age, sex and marriage-migration structure of the population.

Anthropology, Physical

Effect of yohimbine on the reproductive behavior of the male Nile crocodile Crocodylus niloticus.

The effect of yohimbine, an alpha 2-adrenergic blocker, on the reproductive activity of 12-year-old male, captive Nile crocodiles was tested on 18 animals equally divided into 3 ponds. In each pond, there were 6 males and 30 females. In the first group, six of six males received yohimbine capsules of 30 mg, twice a day, for 1 week. In the second group, two males of a group of six were administered a similar dose of yohimbine. Another group of six males in a separate pond were used as a control group. The yohimbine treatment had a significant (p less than 0.05) effect on the frequency of headslap display (the main behavioral pattern of reproductive activity) in all treated animals but did not result in a significant increase in copulation frequency. In the two treated groups, the reproductive period was prolonged by 3 weeks, 8-11 weeks. We found a significant increase in the fertility percentage of eggs laid by females in the male-treated groups (30.5% in control group females, 34.1% in the partly treated, and 39.0% in the pond where all six males were treated), even though no increase in mating frequencies was noted. This might be due to more successful copulations. During the treatment period, the daily activity peak, when the male's headslap performance was the most frequent, was shifted from 5:00-6:00 p.m. in the control to 4:00-5:00 p.m. in the treated group. This effect caused females to enter the water earlier than in the control group.

Alligators and Crocodiles

Underlying family-size preferences and reproductive behavior.

Although about half the married women in a US survey said they wanted one or two children, underlying family-size preferences indicate a potential for many to have larger families. Using a measure of family-size preference that probes beyond single-valued statements, it is found that identical stated family-size desires or intentions may have different meanings for different people. Differences are systematically related to the stage in family building at which contraception begins, to current (or likelihood of future) use of effective methods, to the probability of continued childbearing, and to unwanted pregnancies.

Adolescent

Facilitative and inhibitory influences of reproductive behavior on sperm transport in rats.

Six experiments were performed to investigate the effects of the rat's copulatory behavior on sperm transport in the female's reproductive tract. Data showed that (a) transcervical sperm transport in rats requires 6--10 min after ejaculation for completion; (b) transcervical transport of large numbers of sperm requires that the vaginal plug remain lodged tightly in the vaginal-cervical junction; (c) maintenance of an immobile posture by the male, and possibly by the female, at ejaculation facilitates the deposition of a tightly lodged vaginal plug and the transport of large numbers of sperm through the cervix; (d) a single intromission occurring within 2 min after ejaculation disrupts sperm transport, but more copulatory stimulation is required to disrupt sperm transport when delivered between 4 and 10 min after ejaculation; and (e) the average postejaculatory interval is long enough to prevent a male from disrupting the transport of most of his own sperm from the preceding ejaculation.

Animals

Castration and reproductive behavior in the paradise fish, Macropodus opercularis (L.) (Osteichthyes: Belontiidae).

The effects of castration on male spawning behavior, nestbuilding and fertility were measured in a five day spawning trial with an intact female. Spawning and fertility decreased one week following castration while nestbuilding was unaffected. Sham operated males showed normal spawning and fertility. Two weeks postoperatively, fertility and spawning were increased paralleling partial regeneration of the testes. The antigonadotropin methallibure blocked testes regeneration and recovery of spawning in castrated males but it had no effect on reproductive functions of intact males. Spawning did not decrease in one-week castrated males which were administered testosterone enathanate. The results suggest that gonadal androgen facilitates sexual behavior in Macropodus.

Animals