Some observations on behavior and reproductive organs in blinded chickens.
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Animals↗
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[Electroencephalographic and electrodermographic activity parallel to a time reproduction human behavior].
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Electroencephalography↗
The green anole (Anolis carolinensis): a reptilian model for laboratory studies of reproductive morphology and behavior.
The green anol (Anolis carolinensis) is an excellent reptilian model for studying reproductive behavior and the neural and muscular morphology that supports it. This lizard has been the subject of behavioral and ecological study for more than 100 yr, and a rich literature exists on its natural history. Both courtship and copulatory behaviors reveal sex and seasonal differences, which allow for the study of mechanisms regulation naturally occurring variation in performance at multiple levels within a single animal model. Green anoles are readily obtained due to their abundance in the wild; once in the laboratory, they are easily maintained, bred, and reared. Background on the natural history and husbandry of this lizard is provided, and the authors' research program on the regulation of reproductive anatomy and behavior is reviewed, Discussion includes the similarities and differences in the mechanisms mediating both structure and function compared with more traditional animal models. This type of comparative research will make it possible to identify the fundamental principles governing reproductive biology, thus advancing both basic and applied knowledge.
Animal Husbandry↗
Birth trajectory under changing fertility conditions.
An initially stable population of women is assumed to shift its reproductive behavior to a different level either abruptly or in a prescribed gradual fashion. A closed-form solution which is exact up to about 30 years after the reproductive adjustment is found for the resulting birth trajectory. Exact expressions are also found for the long-time asymptotic behavior of both the birth trajectory and the total population size when the shift in reproductive behavior is to bare replacement level. Accurate approximations to these asymptotic results are then derived and used to illustrate why a growing population continues to grow even after shifting to bare replacement reproductive behavior.
Age Factors↗
Genomic and membrane actions of progesterone: implications for reproductive physiology and behavior.
Progesterone, produced by the ovaries and adrenal glands, regulates reproductive behavior and the surge of luteinizing hormone which precedes ovulation by acting on neurons located in different parts of the hypothalamus. The study of the activation of these reproductive functions in female rats has allowed to explore the different mechanisms of progesterone action in the brain. It has allowed to demonstrate that new actions of the hormone, which have been observed in particular in vitro systems, are also operational in vivo, and may thus be biologically relevant. This mainly concerns the direct actions of progesterone on receptors of neurotransmitters such as oxytocin and GABA. Activation of the progesterone receptor in the absence of ligand by phosphorylation may also play a role.
Animals↗
Reproductive and sexual behavioral problems in dogs.
This paper reviews the influence of genetics on canine sexual behavior, the causes of common sexual and reproductive behavioral problems in dogs as well as treatment approaches, including environmental management, behavior modification, and pharmacological intervention.
Aggression↗
Seasonal variation of steroid hormone levels in an intertidal-nesting fish, the vocal plainfin midshipman.
This study characterized the seasonal variation of the steroid hormones testosterone (T), 11-ketotestosterone (11-KT), 17beta-estradiol (E2), and cortisol (F) as they relate to the gonadal development and reproductive behavior of the plainfin midshipman fish, Porichthys notatus. The plainfin midshipman is a deep-water teleost that seasonally migrates into the shallow intertidal zone where type I, or "singing," males build nests, acoustically court and spawn with females. The gonadosomatic index and plasma steroid levels were measured from adult type I males and females collected over four time periods (non-reproductive, pre-nesting, nesting, and post-nesting) that corresponded to seasonal fluctuations in midshipman reproductive biology and behavior. Among type I males, plasma levels of T and 11-KT were low during the winter non-reproductive period, gradually increased during seasonal recrudescence of the testes in the spring pre-nesting period, and then peaked at the beginning of the summer nesting period. In the latter half of the nesting period and during the fall post-nesting period, plasma levels of T and 11-KT were low or non-detectable. Low, detectable levels of E2 were also found in the plasma of 50% or more type I males during every seasonal period except the winter non-reproductive period. Among females, plasma levels of T and E2 were low throughout the year but briefly peaked in April during the spring pre-nesting period when ovaries underwent seasonal recrudescence. Plasma F levels were correlated with collection depth and were lower in males than females when fish were collected deeper than 120 m. The sex-specific peaks of steroid hormone levels in male and female midshipman may serve differential functions related to the physiology, reproductive behavior, and vocal communication of this species.
Animals↗
THE EVOLUTION OF ASEXUAL FUNGI: Reproduction, Speciation and Classification.
Phylogenetic and population genetic methods that compare nucleic acid variation are being used to identify species and populations of pathogenic fungi and determine how they reproduce in nature. These studies show that asexual or sexual reproductive morphology does not necessarily correlate with clonal or recombining reproductive behavior, and that fungi with all types of reproductive morphologies and behaviors can be accommodated by a phylogenetic species concept. Although approximately one fifth of described fungi have been thought to be asexual and clonal, recent studies have shown that they are also recombining. Whether a particular pathogen reproduces clonally or by recombination depends on factors relating to its biology and its distribution in space and time. Knowing the identity of species and populations and their reproductive modes, while taking a broad view of pathogen behavior in space and time, should enhance the ability of pathologists to control pathogens and even predict their behavior.
Journal Article↗
Seasonality of adult male Japanese macaques (Macaca fuscata): androgens and behavior in a confined troop.
Seasonal variations in levels of serum testosterone, dihydrotestosterone (DHT), reproductive behavior, and social behavior were investigated in 12 adult males (5 to 20+ years of age) of the Oregon troop of Japanese macaques (Macaca fuscata). Blood samples were collected at 2- to 4-month intervals, and behaviors were monitored twice weekly over a 15-month period. Significant seasonal variations in levels of testosterone and DHT, and in frequencies of mount series, ejaculations, number of female partners, displays, courtship, and aggression were observed. Seasonal variations in reproductive and social behaviors did not correlate with seasonal variations in androgen levels because seasonal increases in these behaviors followed seasonal increases in the androgens with a 1- to 2-month delay. However, significant correlations between increased androgen levels and the onset of mating activity occur when mean monthly frequencies of mount series are shifted 1 to 2 months earlier to coincide with the rise in serum androgen levels. The frequency of adult male play and male-male mounting increased significantly when androgen levels were low. We suggest that photoperiod changes may function as a proximate cue in male Japanese macaques which induces a state of biological readiness for mating, and the behavioral consequences (i.e., mating) are then dependent upon the presence of receptive females.
Agonistic Behavior↗
Common regulation of feeding and mating in Aplysia fasciata: pheromones released by mating and by egg cordons increase feeding behavior.
We examined whether pheromones released by reproductive behaviors (mating and egg-laying) affect feeding behavior. A preliminary experiment demonstrated that the quantity of food eaten can be used to measure the effects of pheromones on feeding. Using this measure, we then showed that Aplysia that were prevented from mating, but that were in the same aquarium as mating conspecifics, eat more food than do Aplysia in a medium lacking mating animals. Mating and feeding were not temporally correlated, indicating that pheromones released by mating probably do not initiate feeding, but rather modulate feeding after it has begun. Aplysia that were in the same aquarium as freshly deposited egg cordons also ate more than did animals in a medium lacking eggs.
Animals↗
Social control of cell size: males and females are different.
Successful animals survive because they modify their behavior in response to changes in their physical and social environments. Some responses such as fleeing or fighting, are immediate and can be understood or at least described by their proximate causes. Other modifications occur in animals over a longer time frame because they require tissue growth (or loss), changes in responsiveness to signalling molecules, or other alterations in the regulation of physiological systems. There are numerous examples of the short-term cause-effect relationships which are known in some detail. In contrast, less is known about how long-term changes result from environmental or social signals. Since reproduction is arguably the single most important aspect of an animal's life, reproductive behaviors offer a unique chance to study such change. Reproduction requires exquisite coordination of physiological state and behavioral acts. Many aspects of reproductive behavior occur only under natural conditions so it is imperative to analyze naturally occurring behaviors in real animals, preferably in the natural habitat. We have been studying an African cichlid fish in natural and semi-natural conditions because the connection between physiology and behavior can be easily seen. Moreover, the consequence of social success can be traced directly to changes in the brain, both in the short and long term. In this species, territorial males inhibit sexual maturation of nonterritorial males during development. Even after a male becomes sexually mature and territorial, being defeated causes his gonads to regress rapidly.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Localization and expression of aromatase mRNA in adult zebrafish.
Estradiol plays a key role in the control of many behavioral and physiological aspects of reproduction therefore the expression of cytochrome P450 aromatase (CYP19), the enzyme responsible for the conversion of androgens to estrogens, is of vital interest. The zebrafish, and many other teleosts, have two aromatase genes (CYP19A1 and CYP19A2) that are expressed predominantly in the ovary and brain, respectively, however, the physiological impact of extra-gonadal aromatase has been poorly described. In this study, in situ hybridizations of whole-mount and paraffin sections of adult zebrafish brains, pituitaries, and ovarian follicles showed that CYP19A2 was strongly expressed in the olfactory bulb (OB), ventral telencephalon (TEL), preoptic area (POA), and ventral/caudal hypothalamic zone (HT) of the brain, and in the anterior and posterior lobes of the pituitary. The regional distribution of the CYP19A2 mRNA did not vary with sex however transcript abundance varied within (male "high expressers" had much higher expression in the OB, TEL, and HT than in "low expressers") and between sexes (higher in OB, TEL, and HT of males than in females). In situ hybridizations of CYP19A1 failed to develop a signal in the brain or pituitary but were detectable by RT-PCR. CYP19A1 was highly expressed in Stage III B follicles (>500 nm) with significantly lower levels in the Stage IV follicles (>680 nm), Stage III A follicles (>350 nm), and Stage I and II follicles (350 microm) which were embedded in connective tissues. The differential expression of the aromatase genes, particularly CYP19A2 in the brain, suggests that the two aromatase genes play different roles in the reproductive behavior and/or physiology of bony fish.
Animals↗
Regulation of neuropeptide Y mRNA and peptide concentrations by copper in rat olfactory bulb.
Neuropeptide Y is highly abundant in both the peripheral and central nervous systems and is known to have diverse functions including regulation of feeding behavior, blood pressure, circadian rhythms, reproductive behavior and the response to stress. Northern analysis showed that copper deficiency increased brain NPY mRNA abundance particularly in the olfactory bulb (OB). These increases were not accompanied by alterations in food intake or blood pressure. After 4 weeks of a copper-restricted diet, OB copper concentrations decreased to 44% of control and NPY mRNA increased 1.5-fold. Addition of a copper chelator to the restricted diet, resulted in a two-fold increase in OB NPY mRNA over copper adequate controls. These results were confirmed in primary cultures of OB neurons suggesting that the regulation of NPY mRNA is at the level of the bulb rather than by a hormonal or other copper-regulated factor external to the OB. Immunoreactive NPY (IR-NPY) levels were not, however, increased following the 4 weeks of copper deficiency. Addition of the chelator resulted in a 1.4-fold increase in IR-NPY that, while statistically significant, was not proportional to the two-fold increase in NPY mRNA in the same study. This may suggest that copper deficiency inhibits the translational mechanisms responsible for the synthesis of NPY or that NPY is exported from the bulb in copper deficiency.
Animals↗
Neural gonadal steroid actions.
Neurons sensitive to gonadal steroids are located strategically within neural circuits that mediate behaviors broadly related to the reproductive process. Some neuronal events and properties are regulated by these hormones. Variability in the occurrence and distribution of particular neural hormonal sensitivities across species may be related to variations in the hormonal requirements for sexual differentiation and for activation of reproductive behaviors.
Androgens↗
Androgen effects on tyrosine hydroxylase cells in the northern leopard frog, Rana pipiens.
The interaction between gonadal steroids and dopamine neurons has been examined extensively in rodent model systems. However, there have been few investigations examining the functional relation between gonadal steroids and dopaminergic systems in nonmammalian taxa, and none in amphibians. We examined the effects of testosterone (T) and dihydrotestosterone (DHT) on changes in tyrosine hydroxylase immunoreactive (TH-ir) neuron number in the fore- and midbrain of male Rana pipiens, the Northern leopard frog, using a whole-mount immunohistochemical procedure. Gonadectomized males had significantly fewer TH-ir neurons in the medial preoptic area (POA), suprachiasmatic nucleus (SCN), and the caudal hypothalamus/posterior tubercular region (HY/TP) compared with T-implanted males. A follow-up study demonstrated that T- and DHT-implanted males had similar numbers of TH-ir neurons in these three regions compared with intact males and that all three of these groups possessed significantly more TH-ir neurons compared with gonadectomized males. These results suggest that circulating sex steroids have a significant impact on the activity of dopaminergic neurons in male R. pipiens. Although the function of these specific dopaminergic neurons is not yet known, the POA, SCN, and TP/DH are known to be integral brain regions underlying the neural control of reproductive behavior in frogs. These results suggest that dopamine may be important in controlling the behavior or neuroendocrine mechanisms of reproduction in these animals and that dopaminergic activity in these areas is regulated by gonadal steroids.
Animals↗
The redemption of thalidomide: standardizing the risk of birth defects.
In this paper we examine how a standardized drug distribution system contributed to a therapeutic and symbolic make-over of thalidomide. In the 1960s, thalidomide was seen as a horror drug that caused severe birth defects among over 10,000 babies who were exposed to it in utero. Currently, thalidomide is viewed as a potentially life-saving drug which is being distributed in the USA. We discuss this transformation from a social worlds perspective, showing how the standardized drug distribution system normalized the risk of foetal birth defects, while preserving the autonomy of health care professionals. The distribution system accomplished this transformation by focusing on the risk associated with female reproductive behavior, and by providing close reproductive surveillance of female patients. This standardized system solidified social inequalities and professional power relationships, revealing assumptions about trust, responsibility and risk.
Abnormalities, Drug-Induced↗
Reproductive functioning in the prenatally stressed female rat.
The reproductive behavior and physiology of female offspring of rats stressed during pregnancy were assessed. Mothers were restrained and placed under bright, hot lights from Day 14 through 21 of gestation. This treatment, which is known to disrupt the sexual behavior of male offspring, did not alter reproductive functioning in the female offspring. The females showed evidence of normal cyclicity, sexual behavior, pregnancy, parturition, pup survival, and maternal behavior when tested beginning at 70 or at 140 days of age.
Animals↗
Aromatization mediates aggressive behavior in quail.
Although testosterone (T) stimulates aggressive and reproductive behaviors in males of many vertebrate species, it is now known that the full expression of T action in the brain requires aromatization to estradiol (E2) and subsequent interaction of locally formed E2 with nuclear estrogen receptors. In experiments reported here, we used a behavioral test which quantifies the response of an individual male Japanese quail (Coturnix coturnix japonica) to the visual stimulus of a conspecific. We have called this behavior aggression because it shares many features in common with traditional measures of aggression, e.g., predicting dominance and subordinance. Nevertheless, the behavior probably also combines a complex steroid-sensitive masculine behavior. The advantage of this test is that it allows the discrimination of individual differences in masculine behavior but avoids fighting and sexual encounters per se, thereby reducing effects of learning, a problem with previous tests of avian aggression. In addition, this test has been applied usefully to identify neuroendocrine correlates to male behavior. Using this test, the arousal of reproductively inactive males (hereafter referred to as aggression) is activated by administration of T or estradiol benzoate (EB), but not by 5 alpha-dihydrotestosterone (DHT). T-induced aggression was blocked by the aromatase inhibitor 4-hydroxyandrostenedione (OHA), an effect partially reversed by treatment with EB. In addition, OHA or the estrogen receptor blocker CI-628 reduced aggressiveness of reproductively active males whereas the androgen receptor blocker flutamide had no effect. Results with the 5 alpha-reductase inhibitor N,N-diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 alpha-carboxyamide (4-MA) were equivocal. Additionally, treatment of reproductively inactive quail with T or E2 but not DHT increased aromatase activity in the hypothalamus-preoptic area (HPOA). We conclude, therefore, that T to E2 conversion is essential for the activation of aggressiveness in this species. Although locally formed estrogen exerts its effects on aggression in part by increasing activity of aromatase per se, analysis of the time course of behavioral induction or suppression by the various treatments suggests that the response has multiple components, including both short latency, receptor-independent and long latency, receptor-dependent events.
5-alpha Reductase Inhibitors↗