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At least 235 records · Page 13Linked to original sources
PubMed1992

Evolutionary precedents for behavioral actions of oxytocin and vasopressin.

It is clear that the behavioral actions of oxytocin and vasopressin in mammals are not newly acquired, but have evolutionary antecedents. Injection studies with fish, amphibians, reptiles, and birds indicate that AVT can activate certain reproductive behaviors. The strongest evidence that AVT acts centrally to control reproductive behaviors comes from research on T. granulosa. In this amphibian, injections of AVT agonists activate courtship behaviors (amplectic clasping) in males and egg-laying behaviors in females, whereas injections of AVT antagonists inhibit the behaviors. Also, in Taricha males, AVT concentrations in specific brain areas are associated with the expression of courtship behaviors. Several conclusions about steroid-peptide interactions can be drawn, based on research with this amphibian. First, gonadal steroid hormones act to maintain the behavioral actions of AVT in both males and females. In Taricha, gonadectomy abolishes and steroid implants restore AVT-induced courtship in males and egg-laying in females. Second, gonadal steroids maintain the behavioral actions of AVT, in part, by modulating AVT receptor numbers on target neurons. In Taricha males and females, gonadectomy reduces AVT receptor concentrations (but not binding affinity) in certain brain areas (amygdala pars lateralis) and not others. Third, the type of gonadal steroid determines whether AVT elicits male-like or female-like reproductive behaviors. Ovariectomized Taricha females respond to AVT injections with egg-laying behaviors when implanted with estradiol and with male-like amplectic clasping when implanted with dihydrotestosterone. Fourth, the masculinization of AVT-induced behaviors in females most likely reflects site-specific actions of androgens on AVT-synthesizing neurons. In Taricha, AVTir concentrations in the optic tectum are sexually dimorphic (higher in males than females) and reach peak levels in males during the breeding season. Fifth, AVT content in specific brain areas increase as a function of performing the behaviors. In Taricha, AVTir concentrations in DPOA, CSF, and ventral infundibulum are higher in males that exhibit courtship behaviors than in males that do not. These conclusions illustrate how steroid-peptide interactions in the control of behaviors entail multiple neuroanatomical sites and neurochemical actions.

Animals↗
PubMed1994

Gonadotropin-releasing hormone and its receptors in rat brain.

Since the chemical identification of gonadotropin-releasing hormone (GnRH) in 1971, significant progress has been made in understanding the mechanisms by which GnRH action is mediated in the anterior pituitary. In contrast, relatively little information is available which identifies the intracerebral sites and mechanisms of action of GnRH in the brain. Early immunohistochemical studies of GnRH distribution in the central nervous system, together with behavioral and electrophysiological experiments, suggested that GnRH functioned as a neurotransmitter and was, possibly, involved in the expression of reproductive behaviors. The subsequent identification and characterization of GnRH receptors in the brain further strengthened the view that GnRH caused specific effects in select regions of the brain known to be involved in the neuroendocrine regulation of the anterior pituitary and in the generation of reproductive behaviors. After the mouse pituitary GnRH receptor was cloned it became possible to identify brain neurons which contained the GnRH receptor mRNA. Comparison of the locations of the GnRH peptide, the GnRH receptor protein, and the neurons which contain the GnRH receptor mRNA suggests that the GnRH neuronal system itself can potentially provide a direct link between the neuroendocrine regulation of anterior pituitary function and the intracerebral regulation of reproductive behaviors; furthermore, it is possible that the GnRH neuronal system takes an active part in intracerebral feedback loop systems between the mediobasal hypothalamus and the septum-diagonal band which regulate GnRH release from the median eminence.

Amino Acid Sequence↗
PubMed1995

Effects of opioid peptides on the electrical activity of preoptic and hypothalamic neurons in the quail brain.

We have recently isolated three opioid peptides, i.e., Met- and Leu-enkephalins and Met-enkephalin-Arg6-Phe7, from the avian brain. In the present study, therefore, effects of these endogenous opioid peptides on the electrical activity of preoptic and hypothalamic neurons of the adult male Japanese quail were examined using a brain slice preparation. All of the three opioid peptides inhibited the spontaneous firing activities of subsets of neurons in the preoptic area and the paraventricular nucleus in the hypothalamus. Threshold concentrations for the inhibitory action were between 10(-7) and 10(-6) M in Met- and Leu-enkephalins and approximately 10(-6) M in Met-enkephalin-Arg6-Phe7, respectively. In a few cells in these brain areas, however, Leu-enkephalin rather potentiated the spontaneous activities, resulting in an increase of firing rates or a decrease of interburst intervals. The inhibitory effect of Met-enkephalin was completely blocked by naloxone, an opioid receptor antagonist, but not affected by bicuculline, a gamma-aminobutyric acid A (GABAA) receptor antagonist. These results suggest that there are functional opiate receptors in subsets of preoptic/hypothalamic neurons and that one of their main physiological functions in these areas is an inhibition of neuronal activities. Because these brain regions are considered to be involved with the regulation of a variety of male reproductive behaviors, opioid peptides may regulate some reproductive behavior through the mechanism that provokes such an inhibition.

Action Potentials↗
PubMed1997

Inhibitory role of opioid peptides in the regulation of aggressive and sexual behaviors in male Japanese quails.

We have recently isolated three opioid peptides, i.e., Met- and Leu-enkephalins and Met-enkephalin-Arg6-Phe7, from the avian brain. Furthermore, electrophysiological studies have shown that the dominant effect of these enkephalins on preoptic and hypothalamic neurons is an inhibition of neuronal activities in the male Japanese quail. The hypothalamus and preoptic area are known to be involved in the control of male reproductive behaviors, such as aggressive and sexual behaviors. To determine the functional role of opioid peptides in these reproductive behaviors, therefore, the present study was undertaken using adult males of the Japanese quail. We examined behavioral changes following an injection of naloxone (0.2, 2.0, and 20.0 nmol), a nonselective opioid receptor antagonist, or D-Ala2-Met5-enkephalinamide (DALA; 0.2, 2.0, and 20.0 nmol), a selective delta opioid receptor agonist, into the preoptic and anterior hypothalamic regions. Naloxone treatment showed a significant increase in the frequency of several aggressive actions and the effect was dose dependent. In contrast, DALA treatment significantly decreased the frequency of aggressive actions in a dose-dependent manner. Similar significant effects of these two drugs were observed in the sexual behavior. These findings provide the first evidence for the role of opioid peptides in the reproductive behaviors in the bird and suggest an inhibitory action of opioid to evoke the behaviors.

Aggression↗
PubMed1976

Effects of interactions with older males on behavior and reproductive development in first-year male red-winged blackbirds Agelaius phoeniceus.

Male red-winged blackbirds Agelaius phoeniceus in their first year normally do not establish territories or breed. To investigate the possibility that interactions with older males might inhibit reproductive development of young males, we compared the behavior of first-year males in the presence and absence of older males. For three months during the first half of the breeding season, we studied mixed- and single-age groups of three males in standardized outdoor aviaries: two groups of three first-year males (FFF groups), two groups of one older and two first-year males (AFF groups), and one group of three older males (AAA group). In all groups one male established clear dominance, invariably the older male in AFF groups. The dominant male in FFF groups displaced subordinates less frequently than did the dominant older male in AFF groups early in the season, but equally frequently later. In May the largest testies weights of males in FFF groups were significantly lower than those of dominant older males in AFF groups. First-year males in the absence of direct interactions with older males can achieve levels of aggressive behavior comparable to those of a dominant older male in similar social environments but the seasonal development of their aggressive behavior occurs later and their testes in May are smaller than dominant adults'. This delay in the seasonal development of aggressive behavior in first-year males, independent of the immediate social environment, suggests that the age-dependent territoriality of males in this species is not strongly regulated by effects of older males on the development of younger males.

Age Factors↗
PubMed1993

[Attitudes and behavior for reproductive health].

Educational interventions represent an alternative for the reproductive well-being. The objective of this investigation was to identify in a mexican community, attitudes and behaviors related to reproductive health, with the goal of implementing a specific health education program. The study population consisted of women between 12 and 44 years old, living in non-residential areas of the Delegation Miguel Hidalgo, D.F. Variables of interest were analyzed only in women with parity (n = 300). Data were collected through interview. The mean age was 31 +/- 8 years. 93.3% were married or in consensual union. 63% had elementary, junior high or prevocational studies. 89% answered that would visit the doctor before considering a pregnancy (junior high+, p < .05), 99% would seek prenatal care if they were pregnant, and 92.7% would have a hospital delivery (parity < or = 3, p < .003). 69.5% had a preconceptional visit before their last pregnancy and 89.9% received prenatal care (junior high+, p < .008). 92.5% had only hospital deliveries (< or = 30 years, p < .05, junior high+, p < .0001, primigravida p < .002, with institutionalized medical services, p < .001), 1.7% had only out-of-hospital deliveries, and 5.8% both. Agreement between attitudes and behaviors are presented. An educational program consisting of confirmation and support to positive attitudes, values and beliefs, and reinforcement to decision making, will result in a final behavior: early assistance to medical care.

Adolescent↗
PubMed1996

In vivo regulation of central nervous system progesterone receptors: cocaine induces steroid-dependent behavior through dopamine transporter modulation of D5 receptors in rats.

To characterize the membrane pathway by which the cocaine-sensitive dopamine transporter (DAT) modulates progesterone receptor activation, steroid-dependent behavior lordosis was used in estrogen-primed ovariectomized Sprague-Dawley rats with stereotaxic implanted third ventricle cannulas. Lordosis in response to solicitous males was observed in females after intercerebral ventricular administration of DAT antagonists WIN35,428 (80 ng) and cocaine (0.016-1.6 micrograms). Significantly, antisense oligonucleotides (AS) to DAT mRNA also induced reproductive behavior. In contrast, the D1-D2 receptor membrane-repopulation inhibitor N-ethoxycarbonyl-2 ethoxy-1,2-dihydroquinoline and the D1-like antagonist SCH23390 blocked cocaine-inducible behavior. Further, facilitation of behavior by AS to the DAT was suppressed by N-ethoxycarbonyl-2 ethoxy-1,2-dihydroquinoline. Behavior was not dependent on D2 receptors, since animals pretreated with the D2 antagonist sulpride displayed lordosis after cocaine challenge. Antisense oligonucleotides to D5 but not D1 dopamine receptor mRNA suppressed reproductive behavior associated with cocaine. Microinjections of cocaine to the ventromedial nucleus (VMN) but not arcuate nucleus or preoptic area potentiated lordosis, suggesting the functional presence of DAT in the VMN. Finally, cocaine facilitation of behavior was blocked by both antiprogestin RU486 and progesterone receptor AS microinjected into either the third ventricle or the VMN. Collectively, the data provide strong evidence for cocaine modulation of reproductive behavior through presynaptic cocaine-sensitive dopamine transporters and postsynaptic D5 dopamine receptor mediation of progesterone receptor-dependent behavior in rat central nervous system.

Animals↗
PubMed1995

Species differences in estrogen receptor and progesterone receptor-mRNA expression in the brain of sexual and unisexual whiptail lizards.

Circulating concentrations of gonadal steroid hormones and reproductive behavior in female vertebrates vary as a function of ovarian state. Steroids secreted by the ovary, specifically estrogen and progesterone, influence the expression of behaviors associated with reproduction by intracellular sex steroid receptors located in specific regions of the brain. Using in situ hybridization, we analyzed estrogen receptor and progesterone receptor messenger RNA expression in several brain regions of ovariectomized, vitellogenic, and postovulatory individuals from two species of whiptail lizards (Cnemidophorus uniparens and C. inornatus). Although these species are genetically very similar, they differ in two aspects of their reproductive biology: (i) the unisexual C. uniparens alternate between expressing female-typical and male-like pseudosexual behaviors while female C. inornatus normally express only female receptive behavior, and (ii) circulating estradiol concentrations in reproductively active female C. uniparens are approximately five-fold lower than in reproductively active female C. inornatus. We found that the regulation of sex steroid receptor gene expression was region specific, with receptor-mRNA expression being increased, unchanged, or decreased during vitellogenesis depending on the area. Furthermore, several species differences in the amount of sex steroid receptor-mRNA were found that may be relevant to the species differences in circulating estrogen concentrations and sexual behavior.

Animals↗
PubMed1987

Pinealectomy blocks vernal courtship behavior in red-sided garter snakes.

Male red-sided garter snakes (Thamnophis sirtalis parietalis) court only on emergence from winter dormancy. The salient proximate factor responsible for the initiation of courtship behavior appears to be warm ambient temperatures subsequent to sustained exposure to cold temperatures. In the present study, autumn-captured garter snakes were pinealectomized or sham-pinealectomized 1-2 weeks prior to hibernation. After 17 weeks of maintenance in several ambient lighting and temperature conditions, all males were tested for the presence of courtship behavior. No pinealectomized animals exhibited any indications of reproductive behavior, whereas 53% of sham-pinealectomized males actively courted females. Photoperiod did not influence the prevalence of mating behavior. These results suggest that the pineal gland mediates non-photoperiodic seasonal information in the garter snake. This is the first demonstration, in any vertebrate species, that the pineal gland can directly influence reproductive behavior.

Animals↗
PubMed1992

Differential projections of the anterior and posterior regions of the medial amygdaloid nucleus in the Syrian hamster.

The medial nucleus of the amygdala is important for the neural control of reproductive behavior in the adult male Syrian hamster. Two types of signals are essential for this behavior, chemosensory stimuli and gonadal steroids; these signals appear to be received in different parts of the medial nucleus. The anterior region receives input from olfactory and vomeronasal systems, both of which are required for this behavior, whereas the posterior region receives gonadal hormone inputs. Behavioral studies have also suggested a functional differentiation of these two areas; electrolytic lesions of the anterior, but not the posterior, part eliminates normal sexual behavior. In this study, the efferent projections of the anterior and posterior divisions of the medial nucleus of the amygdala in the Syrian hamster were analyzed throughout the forebrain after injections of the anterograde neuronal tracer, Phaseolus vulgaris-leucoagglutinin. Neurons of the anterior, but not the posterior, medial nucleus, were found to project to numerous olfactory bulb projection areas and to the ventral striatopallidal complex. Within areas of the chemosensory circuitry that control reproductive behavior, the anterior region of the medial nucleus projects to the intermediate part of the posterior bed nucleus of the stria terminalis and the lateral part of the medial preoptic area, whereas the posterior region of the medial nucleus projects to the medial parts of these areas. Differences in targets were also observed in the ventromedial nucleus of the hypothalamus where the anterior region projects to the core while the posterior part projects to the shell of this nucleus. Furthermore, reciprocal projections between the anterior and posterior regions of the medial nucleus were observed. Taken together, these studies support the hypothesis that the anterior and posterior regions of the medial amygdaloid nucleus provide substantially different contributions to the control of reproductive behaviors.

Amygdala↗
PubMed1984

Prostaglandin induction of spawning behavior in Cichlasoma bimaculatum (Pisces cichlidae).

Prostaglandin (PG) stimulates female spawning behavior in goldfish and in some other teleosts in which female reproductive behaviors consist of postovulatory oviposition acts. This study examined the effects of PG on female sexual behavior in a teleost fish, Cichlasoma bimaculatum, in which female reproductive behaviors involve both preovulatory courtship and substrate cleaning behaviors, and post-ovulatory oviposition behavior. In females of established pairs, PGF2 alpha injection (5 micrograms, im) at any stage of the spawning cycle, or in the parental phase, rapidly induced substrate cleaning which soon merged into oviposition behavior (without egg release). These results support a role for PG in oviposition behavior of Cichlasoma. However, indomethacin (1 mg, ip), a PG synthesis inhibitor, did not block oviposition in ovulated females which had begun to spawn. Indomethacin may not have lowered PG levels sufficiently. Alternatively, as shown by J.J. Polder (1971, Neth. J. Zool. 21, 265), oviposition behavior may be induced or maintained by other factors associated with the spawning situation.

Animals↗
PubMed1991

Daily variation of multiple behaviors in Aplysia fasciata: integration of feeding, reproduction, and locomotion.

Daily variations in feeding, reproductive behaviors, and activity level were examined under three conditions: (1) animals had access to food and mates; (2) there was access only to food; (3) neither food nor mates were present. Behaviors differed in amplitude of variations from their daily mean value. Egg-laying had the strongest tendency to be clustered. Amplitude of variations in courtship and swimming was larger than those of immobility, crawling, and feeding, while moving in place was the least clustered behavior. Changes in state affected the tendency to be clustered. When food and mates were present, amplitude of variations became progressively larger for immobility, moving in place, crawling, and swimming. Behaviors differed in the degree to which variations were patterned as a 1/day oscillation. Relatively little of the variability in crawling, moving in place, courtship, and egg-laying was due to a 1/day oscillation under any condition. By contrast, a large proportion of the variability of immobility, swimming, mating, and eating was modulated by a 1/day oscillation in at least one condition. The contribution of a 1/day oscillation to variability differed in the conditions examined. For immobility and swimming, when food and mates were present, the 1/day component of variability became smaller. By contrast, presence of mates led to an increase in the 1/day component of variability modulating feeding. Daily peaks of swimming and feeding were in phase with one another, and out of phase with mating and feeding. The ratio of locomotion to inactivity is constant, independent of change in external conditions. However, this ratio varied throughout the day. When food and mates were absent, variations of immobility and swimming were strongly related to variations in the inactivity ratio. When food and mates were added, this tendency decreased. The data suggest that daily variations in occurrence of behaviors can be accounted for by interactions between oscillators affecting Aplysia behavior and motivational variables. A 1/day oscillator has strong effects on mating, swimming, and immobility. The effect of the oscillator is modified by changes in motivational state.

Animals↗
PubMed1996

Thyroid hormone and estrogen interact to regulate behavior.

Environmental perturbations that increase plasma thyroid hormone (T3) concentrations also profoundly affect female reproductive behavior and physiology. We explored whether these effects were mediated by interactions between T3 receptor (TR) and estrogen receptor (ER). This hypothesis was of interest because the half-site of a consensus T3 response element DNA sequence is identical to an ER response element (ERE), and TRs bind to a consensus ERE. Molecular data presented in the accompanying paper [Zhu, Y.-S., Yen, P.M., Chin, W.W.& Pfaff, D.W. (1996) Proc. Natl. Acad. Sci. USA 93, 12587-12592] demonstrate that TRs and ERs are both present in rat hypothalamic nuclear extracts and that both can bind to the promoter the hypothalamic gene preproenkephalin and that interations between liganded TRs and ERs affect preproenkephalin transcription. In this paper, we show that molecular interactions between TRs and ERs are sufficient to mediate environmental effects on estrogen-controlled reproductive behavior. Ovariectomized (OVX) rats treated with high doses of T3 showed significantly lower levels of lordosis behavior in response to estradiol benzoate (EB) compared with OVX females treated with EB alone. Conversely, thyroidectomized/OVX females treated with EB showed significantly greater levels of lordosis behavior compared with OVX females treated with EB, showing the effect of endogenous T3. Thyroid hormone interference with EB-induced behavior could not be explained by a reduction in plasma E2 concentrations or by a general reduction in responsiveness of EB-sensitive tissues. Moreover, numbers of hypothalamic ER-immunoreactive cells increased dramatically following T3 treatment. These data suggest that T3 may reduce EB-dependent sexual behavior through interactions between TR and ER in the nuclei of behaviorally relevant hypothalamic neurons, envisioning for the first time a functional consequence of interactions between two nuclear hormone receptors in brain. These results also open up the possibility of molecular interactions on DNA encoding environmental signals, a new field for the study of neuronal integration.

Animals↗
PubMed1994

Thermal constraints on maternal behavior during reproduction in dwarf hamsters (Phodopus).

The chronic hyperthermia of lactating dwarf hamster (Phodopus) dams may constrain maternal behavior if contact with the litter further increases their body temperature, forcing the termination of nest bouts to dissipate the heat load. Changes in female body temperature and nest attendance in two species of dwarf hamster (P. campbelli and P. sungorus) were recorded each minute over the reproductive cycle. As the pups develop from naked poikilotherms to well-insulated thermoregulators, they function as heat sinks and heat sources. This role of pup development in maternal thermoregulation interacts with the dam's activity, primarily nocturnal wheel running, to produce a complex pattern of heating and cooling in each species. Contact with the pups is more constrained by maternal temperature during the inactive phase (day), and more constrained in P. campbelli than in P. sungorus. The interspecific difference in pup development or maternal thermoregulation is consistent with predictions based on biparental care, and a thermoregulatory role for the male in P. campbelli, but not in P. sungorus. These data suggest that environmental temperature and water availability are ecological variables that affect maternal thermoregulation, reproductive success, and the need for biparental care.

Acclimatization↗