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PubMed1976

[Effect of p-chlorophenylalanine on rat reproduction under different conditions of lighting (author's transl)].

Reproduction in female rats kept on artificial cycles of light/darkness, continuous lighting and continuous darkness, has been studied. Three weekly doses of p-chlorophenylalanine (p-CPA), 100 mg/kg, were given to half of the rats in each group during the two preconditioning months before copulation. An evaluation has been made of the insemination, fecundation, number of embryos, ovarian cycle and level of 5-HT in the hypothalamus. The administration of p-CPA had an inhibitory effect on the reproductive behavior, especially pronounced in rats kept under continuous lighting and under continuous darkness. The difference in 5-TH levels were greater among the groups kept on cycles of light/darkness without treatment and with p-CPA (0.05 greater than P greater than 0.01). The importance of 5-HT in the mechanisms of reproductive behavior is emphasized.

Animals↗
PubMed1994

Preoptic projections to Barrington's nucleus and the pericoerulear region: architecture and terminal organization.

The medial preoptic area (MPO), a sexually dimorphic region, plays a pivotal role in neuroendocrine function and reproductive behavior. We recently reported that MPO projects heavily to the midbrain periaqueductal gray (PAG). We also noted that MPO projects to the dorsolateral pontine tegmentum. Here we identified the cells of origin of the MPO-->tegmental projection and delineated the terminal organization of MPO projections to Barrington's nucleus, locus coeruleus (LC), and the rostromedial pericoerulear region (pLCrm). Correlative cyto- and chemoarchitectonic studies were done to define better the nuclear groups of the dorsolateral pontine tegmentum. Retrograde tracing revealed that MPO neurons projecting to the dorsolateral pontine tegmentum are preferentially distributed in distinct subregions of MPO, including the sexually dimorphic medial preoptic nucleus (MPN). Anterograde tracing with wheat germ agglutinin-horseradish peroxidase or Phaseolus vulgaris leucoagglutinin demonstrated considerable target specificity in projections from MPO to the dorsolateral pontine tegmentum. Barrington's nucleus receives a dense focal input along its entire rostrocaudal axis. In addition, pLCrm is heavily targeted by MPO inputs; pLCrm contains a concentrated plexus of extranuclear dendrites of LC neurons. The lateral dorsal tegmental (LDT) nucleus and LC proper receive only sparse input from MPO. MPO projections to Barrington's nucleus could regulate micturition reflexes during reproductive behavior. The MPO-->pLCrm projection could influence noradrenergic LC neurons in relation to reproductive and/or gonadal steroid function. Given the strong established connections from olfactory structures to MPO, it is possible that the MPO-->LC pathway provides an anatomical substrate for olfactory modulation of arousal.

Animals↗
PubMed2002

A temperate reef fish, Tautogolabrus adspersus, (Walbaum) as a potential model species for laboratory studies evaluating reproductive effects of chemical exposure.

In ecotoxicological testing, there are few studies that report on reproductive output (egg production) of marine or estuarine fish. Cunner (Tautogolabrus adspersus) were studied as a potential model species to evaluate the impact of pollutants with estrogenic activity on reproduction in estuarine fish populations. Cunner inhabit marine and estuarine areas where contaminant discharges are likely. Baseline values for cunner gonadosomatic index (GSI), hepatosomatic index (HSI), and plasma vitellogenin (VTG) were determined in a field reference site (April 1999-December 1999). Male and female GSI indicated that cunner spawning is synchronized. Female HSI and VTG increased prior to GSI. From our laboratory observations, cunner are suitable for conducting experiments with reproductive endpoints indicative of both exposure (vitellogenin levels) and effects (egg production). However, cunner are not sexually dimorphic and stripping ripe fish is the only method to distinguish sex. In preparation for laboratory exposure studies with cunner, we designed a laboratory experimental holding system to accommodate cunner's reproductive behavior, a vertical spawning run to the water surface. Cunner were successfully acclimated from overwintering torpor to spawning condition in the laboratory by gradually changing the environmental conditions of fish held at winter conditions (4 degrees C and 9:15-h light:dark photoperiod) to spawning condition (18 degrees C and 15:9-h light:dark photoperiod). Our results show that cunner successfully spawned daily in the laboratory. They produced fertile eggs in our experimental system designed to accommodate cunner's vertical spawning runs, demonstrating that male and female reproductive behavior was synchronized in the laboratory. Our observations indicate that cunner would be a useful model species for evaluating reproductive effects of environmental contaminants in laboratory studies.

Animals↗
PubMed1993

Endocrine changes associated with spawning behavior in male kokanee salmon (Oncorhynchus nerka) and the effects of anosmia.

This study examines the relationship between social status, behavioral activity, and hormone levels through the spawning cycle in male kokanee salmon (Oncorhynchus nerka). Shortly after arrival at the spawning grounds, male kokanee undergo dramatic changes in morphological and physiological condition: there is an increase in body depth, a bright silvery appearance is replaced by an intense red coloration, and spermiation commences. Males become associated with nesting females which they defend against other males. The androgens, testosterone and 11-ketotestosterone, decline slowly over the spawning period from high levels observed in the silvery males; gonadotropin (GtH II) and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one increase as males approach final maturation. Androgen and GtH levels in males placed in pens with females over the spawning bed were higher than those in males penned without females. Among males competing for females, amounts of milt and plasma concentrations of GtH were higher in those males that were successful in gaining access to nesting females. A marked reduction in milt and plasma hormones following cauterization of the olfactory nares indicates that olfactory stimuli play a role in mediating endocrine and spermiation responses to the nesting females. Anosmic males were less vigorous and persistent in their courtship, suggesting that, either a female pheromone and/or high levels of hormone are necessary to maintain full reproductive behavior in male kokanee. The role of socially induced hormone changes in modulating reproductive behavior is discussed.

Animals↗
PubMed1984

Premature delivery and subsequent reproduction.

To examine the relationship between premature delivery and subsequent reproductive behavior, we attempted to trace 100 mothers four years after the birth of a surviving preterm or term infant. Seventy mothers were successfully traced. Maternal age, ethnicity, gravidity, parity, religion, and socioeconomic status, and the sex, birthweight, gestational age, mode of delivery, and hospital days of the index infant were jointly related to three outcome measures: occurrence of subsequent pregnancy, and, among those who again became pregnant, pregnancy interval and number of subsequent children. Among women who had one or more subsequent births during the follow-up period, those whose index infants were of lower gestational age had fewer subsequent births (r = 0.602, df = 32, p less than 0.011). No other variables, including cesarean birth, were significantly related to later reproductive behavior. These findings indicate that the birth of a premature infant may have a significant effect of decreasing or delaying subsequent reproduction. Through confirmatory studies are needed, awareness of this relationship may help obstetric perinatologists and neonatologists sensitively discuss plans for contraception and further childbearing with women who have experienced the stress of the birth of a premature infant.

Black or African American↗
PubMed1992

Effects of alpha-methyl-para-tyrosine on monoamine levels in the Japanese quail: sex differences and testosterone effects.

Experiments were performed to obtain more information on the regulation by steroids of catecholaminergic systems in the brain of Japanese quail. Dose-response and time-response experiments were first performed to determine optimal conditions for measuring turnover in the quail brain. The norepinephrine and dopamine turnover were then estimated in microdissected brain nuclei of birds that were either sexually mature or gonadectomized or gonadectomized and treated with testosterone. Two major facts that bear direct relationship with the control of masculine reproductive behavior were demonstrated. On one hand, the dopamine turnover in the medial preoptic nucleus, a sexually dimorphic brain structure which is critically implicated in the control of copulatory behavior was much higher in male than in female quail irrespective of the hormonal condition of the birds. On the other hand, norepinephrine concentrations appeared to be higher in several nuclei of the female brain by comparison with males. These sex differences might represent part of the causal factors that underlie the sex dimorphism in reproductive behavior in quail.

Analysis of Variance↗
PubMed1996

Localization of galanin and its binding sites in the quail brain.

Avian galanin was first isolated from the chicken intestine, and subsequently we isolated the same peptide from the quail oviduct. Galanin is known to be a multifunctional peptide in the neuroendocrine system in mammals, while little information is available for the galanin action in the central nervous system in birds. In the present study, therefore, we examined the presence and the localization of galanin and its binding sites in the quail brain. The binding of [125I]iodo-avian galanin to brain tissues specifically inhibited as a function of the concentrations of unlabeled avian galanin. In all of the observed brain regions, the number of galanin-binding sites when compared on the basis of unit weight was maximal in the interbrain including the preoptic and hypothalamic regions and minimal in the cerebellum. The Scatchard plot analysis of the galanin binding to the interbrain revealed that the apparent equilibrium constant of dissociation (Kd) was 0.281 (95% confidence interval, 0.234-0.351) nM, suggesting the presence of a single class of high-affinity binding sites. Although galanin-like immunoreactivity was found in several restricted regions throughout the brain, the most intense immunoreaction was present in the diencephalic region. Abundant immunoreactive cell bodies and/or fibers were localized in several preoptic and hypothalamic nuclei, i.e., the nucleus preopticus medialis (POM), the nucleus paraventricularis (PVN), the nucleus periventricularis hypothalami (PHN) and the nucleus infundibuli (IN), that are known to be involved in the control of reproductive behaviors as well as the pituitary hormone secretion. A substantial number of immunoreactive cell bodies and/or fibers was further observed within the septal nuclei in the telencephalon and several mesencephalic nuclei including the nucleus intercollicularis (ICo) involved in the control of vocalizations. These results suggest that avian galanin may act as an important factor to modulate the some reproductive behaviors and/or the pituitary hormone secretion in the bird.

Amino Acid Sequence↗
PubMed1993

Circulating gonadal steroid hormones regulate estrogen receptor mRNA in the male rat forebrain.

In male rats, the conversion of testosterone to estrogen via aromatization is a critical step in a number of androgen-mediated functions, especially reproductive behavior. Within the central nervous system (CNS), locally formed estrogen binds to its cognate estrogen receptor protein. Little is known about what factors regulate the expression of estrogen receptors in the male rat CNS. This study examined whether circulating male gonadal steroid hormones have a role in the regulation of estrogen receptor mRNA in brain regions critical for the expression of male reproductive behavior. Male rats were gonadectomized or sham operated, and 3 days later were sacrificed. Their brains were fixed by perfusion, frozen, and sectioned. Tissue sections were hybridized to an 35S-labeled 850 base cDNA probe, complementary primarily to the steroid binding domain of the estrogen receptor mRNA. Following post-hybridization washes, slides were dipped in photographic emulsion and exposed for 2 weeks. Estrogen receptor mRNA-containing neurons were observed in all brain regions previously shown by steroid hormone autoradiography to concentrate estrogen. Gonadectomy did not alter the number of estrogen receptor mRNA-producing neurons, but did produce a two-fold increase in the relative amount of estrogen receptor mRNA per cell in the medial preoptic nucleus, periventricular preoptic area, and bed nucleus of the stria terminalis. This study shows that circulating gonadal steroids down-regulate steady state levels of estrogen receptor mRNA within specific brain regions, and thereby have the potential to regulate the sensitivity of particular target regions in the CNS to estrogen.

Animals↗
PubMed1999

Sexual behaviors and reproductive health outcomes: associations with wife abuse in India.

CONTEXT: Wife abuse has been associated with a variety of health concerns. Associations between abuse and reproductive health in India are not well known. OBJECTIVE: To examine relationships between men's reports of wife abuse and reproductive health issues in northern India. DESIGN: Structured face-to-face interviews were conducted as part of the male reproductive health supplement of the PERFORM System of Indicators Survey, a systematic multistage survey conducted in 1995-1996. SETTING: The northern state of Uttar Pradesh, one of the least developed states in India. PARTICIPANTS: A total of 6632 married men aged 15 to 65 years who lived with their wives and completed all survey questions for the study variables reported here. MAIN MEASURES: Physically and sexually abusive behaviors toward wives, sexual activities outside marriage, sexually transmitted disease (STD) symptoms, contraception use, unplanned pregnancies, and sociodemographic characteristics. RESULTS: Fifty-four percent of men reported not abusing their wives, while 17% reported physically but not sexually abusing their wives, 22% reported sexual abuse without physical force, and 7% reported sexual abuse with physical force. Abuse was more common among men who had extramarital sex (for sexual abuse using force: odds ratio [OR], 6.22; 95% confidence interval [CI], 3.98-9.72). Similarly, men who had STD symptoms were more likely to abuse their wives (with current symptoms: OR, 2.43; 95% CI, 1.73-3.42). Unplanned pregnancies were significantly more common among wives of abusive men, especially sexually abusive men who used force (OR, 2.62; 95% CI, 1.91-3.60). CONCLUSIONS: Wife abuse appears to be fairly common in northern India. Our findings that abusive men were more likely to engage in extramarital sex and have STD symptoms suggest that these men may be acquiring STDs from their extramarital relationships, thereby placing their wives at risk for STD acquisition, sometimes via sexual abuse. These abusive sexual behaviors also may result in an elevated rate of unplanned pregnancies.

Adolescent↗
PubMed1992

Central neural mechanisms of progesterone action: application to the respiratory system.

Around the turn of the century, it was recognized that women hyperventilate during the luteal phase of the menstrual cycle and during pregnancy. Although a causative role for the steroid hormone progesterone in this hyperventilation was suggested as early as the 1940s, there has been no clear indication as to the mechanism by which it produces its respiratory effects. In contrast, much mechanistic information has been obtained over the same period about a different effect of progesterone, i.e., the facilitation of reproductive behaviors. In this case, the bulk of the evidence supports the hypothesis that progesterone acts via a genomic mechanism with characteristics not unlike those predicted by classic models for steroid hormone action. We recently, therefore, undertook a series of experiments to test predictions of those same models with reference to the respiratory effects of progesterone. Here we highlight the results of those studies; as background to and precedent for our experiments, we briefly review previous work in which effects of progesterone on respiration and reproductive behaviors have been studied. Our results indicate that the respiratory response to progesterone is mediated at hypothalamic sites through an estrogen- (E2) dependent progesterone receptor- (PR) mediated mechanism requiring RNA and protein synthesis, i.e., gene expression. The E2 dependence of the respiratory response to progesterone is likely a consequence of the demonstrated induction of PR mRNA and PR in hypothalamic neurons by E2. In short, we found that neural mechanisms underlying the stimulation of respiration by progesterone were similar to those mediating its reproductive effects.

Animals↗
PubMed1999

Thyroid hormone coadministration inhibits the estrogen-stimulated elevation of preproenkephalin mRNA in female rat hypothalamic neurons.

Expression of the enkephalin gene in ventromedial hypothalamus (VMH) of the female rat has been correlated with the performance of lordosis behavior. By antisense DNA evidence, it has been drawn into a causal role as well. Here, we explored whether, parallel to earlier molecular and behavioral results, thyroid hormone coadministration could disrupt the estrogenic induction of preproenkephalin (PPE) mRNA. As expected, estradiol benzoate treatment to ovariectomized rats led to a large and significant increase in PPE gene expression in the VMH. This increase was inhibited by coadministration of thyroid hormone. The thyroid hormone interference in PPE gene expression was specific to the VMH, as there were no significant effects in the central nucleus of the amygdala or in the caudate/putamen. These in situ hybridization histochemical results form a direct parallel both to previous transcriptional measurements and to reproductive behavior assays in which thyroid hormones were able to oppose estrogenic facilitation. Previous evidence supports the notion of competitive DNA binding and protein/protein interactions providing mechanisms for nuclear thyroid hormone receptors to affect estrogen receptor function, but other, additional mechanisms cannot be ruled out. To date, both oxytocin and PPE gene expression represent potential hypothalamic systems by which thyroid hormones could interfere with estrogen-stimulated female rat reproductive behavior.

Amygdala↗
PubMed1999

Sexual dimorphisms in avian and reptilian courtship: two systems that do not play by mammalian rules.

Sexual dimorphisms in the central nervous system exist in numerous vertebrate species, and in many cases these structural differences between males and females parallel differences in the display of reproductive behaviors. Often both the behavioral and anatomical differences are controlled by exposure to gonadal steroid hormones, either during ontogeny or in adulthood. This article reviews some of the evidence supporting the hypothesis that in mammals, testosterone or its metabolites regulate the structure and function of neural and muscle systems involved in the control of masculine sexual behaviors. It then describes data suggesting that the mechanisms regulating sexually dimorphic courtship systems in zebra finches and green anole lizards are not completely parallel to the mammalian systems. Finally, some directions for future study are suggested, with the hope that they will stimulate thought about the nature of comparisons made across vertebrate models when investigators are attempting to determine both which morphological sex differences are important to the control of the reproductive behaviors, and which mechanisms regulating both structure and function are widely employed or are unique.

Animals↗
PubMed1975

Fertility and family planning in Thailand: results from two rounds of a national study.

The Longitudinal Study of Social, Economic, and Demographic Change was undertaken during the late 1960s to provide detailed national information on behavior and attitudes related to fertility and family planning in Thailand. Results from the second round of the study indicate that the practice of family planning increased substantially in both rural and urban areas during the three-year interval between the two rounds. During this period, marital fertility registered a decline in the urban areas. This was a result of a small rise in fertility among Bangkok-Thonburi women combined with a sharp decline in fertility among provincial urban women. Because the National Family Planning Program was officially begun at the time of the first round, its role in the increase in contraceptive use is examined. Although the study shows that the desired number of children is substantially below the actual number of children Thai womenhave by the end of their reproductive years, the desired number of children is still well above the number usually considered ideal in developed countries. Nonetheless, changes in reproductive behavior appear to reflect the impact of modernization on Thai society. In urban areas, marital fertility is only moderately high and a substantial proportion of couples practice family planning. Of particular importance over the remainder of the decade will be the reproductive behavior of rural women, who constitute an extremely high proportion of the Thai female population.

Adolescent↗
PubMed1989

Expression and estrogen regulation of progesterone receptor mRNA in neurons of the mediobasal hypothalamus: an in situ hybridization study.

Diverse effects of steroid hormones on different tissues result from the tissue-specific regulation of target gene expression by steroid hormone receptors. These receptors belong to a family of transacting factors that regulate transcriptional activation of target genes by binding to DNA recognition sequences located in the 5'-flanking region of the target gene. In the brain, receptors for the gonadal steroid hormones estrogen (E) and progesterone (P) are present in discrete neuronal populations. These steroid hormone receptor-containing neurons mediate the effects of the gonadal steroids on a number of neural processes, including reproductive behavior. Using in situ hybridization we have found progesterone receptor (PR) mRNA-containing neurons present in specific hypothalamic nuclei and in the amygdala. E regulates PR mRNA levels in specific neuronal cell groups which express both ER and PR (in basomedial hypothalamus), but not in others (medial amygdala). The E-induced increase in P-responsive neurons in ventromedial hypothalamus can account for the permissive influence of E on P-facilitated reproductive behavior. This is the first demonstration that synthesis of a transcription factor (PR) can be related to a mammalian behavior.

Animals↗
PubMedDate not supplied

Comparative effects of maternal prenatal and postnatal exposures to astemizole on reproductive parameters of rats.

The prenatal and postnatal effects of administration of a nonsedative antihistamine H1, astemizole (ATZ), were compared. ATZ (10 mg/kg) was injected daily into female Wistar rats throughout pregnancy (prenatal treatment) or during the first 6 days of lactation (postnatal treatment). Neither treatment modified dam body weight. Prenatal exposure reduced offspring body weight and lead to a latter expression of the vaginal opening of female offspring. In addition, a long-term disruption of male reproductive behavior was observed, while female sexual behavior was not modified. The sexual activity index and the intromission frequency were increased in prenatally treated animals. Testes wet weight was reduced, but no modifications were detected in vas deferens or seminal vesicles. Postnatal treatment did not alter offspring body weight, open-field activity, sexual behavior and organ weight as well as did not delay testes descent but reduced the time until vaginal opening. Hypothalamic serotonin (5-HT), dopamine (DA) and noradrenaline (NA) as well as DA and NA metabolites were not modified by both prenatal and postnatal treatments. Increased striatal 3,4-dihydroxyphenylacetic acid (DOPAC) levels were observed after prenatal and postnatal treatments, while only postnatal 5-HT levels were increased. We propose that the present results indicate that prenatal ATZ exposure can have long-lasting organizational effects on reproductive behavior of male rats, while postnatal exposure to this drug did not alter mating behavior. In relation to female rats, prenatal and postnatal exposures to ATZ accelerated puberty but did not alter sexual behavior. Neurochemical data show that both treatments increased striatal dopaminergic system activity, suggesting a central ATZ effect after perinatal exposure.

Animals↗
PubMed1994

Arginine vasotocin facilitation of advertisement calling and call phonotaxis in bullfrogs.

Although the neuropeptide arginine vasotocin (AVT) is found in several auditory and vocalization regions of the bullfrog (Rana catesbeiana) brain, its functions in these areas are unknown. We examined the effects of AVT injection on two auditory-evoked reproductive behaviors: advertisement calling in male bullfrogs and call phonotaxis in female bullfrogs. AVT (500 micrograms; intraperitoneal) significantly increased advertisement call frequency and decreased calling latency in male bullfrogs, compared to saline injection. This dose of AVT also significantly decreased the time required for female bullfrogs to reach a call source as well as the latency of females to leave the starting position during call playback. In both males and females, these effects were significant at 0.5 hr and persisted until at least 2 hr after injection. AVT thus facilitated display of two sexually-dimorphic reproductive behaviors in bullfrogs. These effects may be due to direct effects of AVT on auditory processing regions in the bullfrog brain.

Animals↗
PubMedDate not supplied

Maternal age as a factor in determining the reproductive and behavioral outcome of rats prenatally exposed to ethanol.

Nulliparous Long-Evans rats were bred at one of four different ages and assigned to one of three treatment groups within each age condition. Maternal ages were 9, 18, 32, and 36 weeks. Treatment groups were ethanol (E), administered by gavage as 8 g/kg in two divided doses on days 10-14 of gestation, pair-fed (PF) controls, administered as an isocaloric sucrose solution by gavage on days 10-14 of gestation, and ad lib fed controls (C). All offspring were surrogate fostered shortly after delivery to untreated recently parturient dams. Litter sizes were standardized to 8 on the day of birth. Offspring were assessed longitudinally for growth, mortality, and behavior (olfaction, locomotor activity, maze learning, avoidance acquisition and startle). Approximately 85% of the 36 week old dams did not produce viable litters. In the remaining maternal age conditions, ethanol delayed offspring olfactory orientation and increased locomotor activity, the latter dissipating after 50-60 days of age. These ethanol-related effects occurred independent of maternal age condition. Maternal age, independent of ethanol, was a factor which reduced litter size and offspring weight up to 50 days, but produced few effects on behavior. The combination of maternal age and prenatal ethanol interacted to increase pregnancy loss (oldest maternal age), reduce offspring weight up to day 99 (oldest and middle maternal age), alter olfactory orientation performance (oldest and middle maternal age), reverse the typical ethanol-induced increase in activity for males in the figure-8 test (oldest maternal age group), shift the pattern of open-field activity, and change errors in a complex water maze. Not all of these interactions turned out to be specific to the ethanol X old maternal age condition. Several of the interactions occurred in both the old and middle maternal age conditions. The only effect of old maternal age that interacted strongly with ethanol was in their combined effects on reproduction. Here the combination of the two factors increased maternal mortality, the number of early pregnancy losses, and the number of litters where all members were dead or resorbed. It was concluded that short-term prenatal ethanol combined with advanced maternal age produces additive interactions on pregnancy success without affecting longer-term outcomes, while young maternal age showed no clear detrimental effects compared to the middle maternal age reference group.

Aging↗