[Sex preselection? Contribution to reproductive behavior in East Germany. Survey of an urban population group].
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Most users (64.1%) of the Counseling Unit for the Young are unmarried girls aged 17 to 24, predominantly students and secondary pupils. Although more frequent in older girls (21-24 years old), pregnancy is highly undesirable both in younger (22.2%) and older (57.1%) ones. Since they are most often nulliparae, the underlying health problems are significant. The girls are considered to be pregnant before their coming to the Counselling Unit, because afterwards 83.0% of them start using contraceptives. The health service for adolescents is encountered with two tasks: (1) to get adolescent girls coming to the Counselling Unit before they experience pregnancy in a negative sense, and (2) to observe and analyse the efficacy and side-effects of contraceptives.
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This study assessed the effects of high doses of anabolic-androgenic steroids (AAS) and their withdrawal on male reproductive behavior and reproductive tissues during development. Prepubertal, peripubertal, and adult male Long Evans rats were divided into 4 groups: 1) Testosterone propionate for 16 weeks (TP), 2) TP for 3 weeks and withdrawn for 13 weeks (TPWL), 3) TP for 16 weeks and withdrawn for 3 weeks (TPWS), 4) propylene glycol (control vehicle) for 16 weeks (PG). As determined by sexual performance and sexual preference tests, administration of high doses of AAS to the peripubertal animals enhanced sexual performance and sexual motivation. There was no significant effect on sexual behavior of the prepubertal animals. High doses of anabolic-androgenic steroids depleted Leydig cell number in the prepubertal and adult rats, but had no effect on the Leydig cell number of the peripubertal animals. After long-term withdrawal from AAS no significant effects on sexual behavior were found. The depletion of Leydig cells that occurred in the prepubertal animals after withdrawal was reversible, while the depletion of the Leydig cells of the adult animals did not return to the control level suggesting a long lasting alteration.
Both acute and chronic psychological and social stresses can impair reproductive hormone secretion in a variety of nonhuman primate species. This impairment can be subtle, consisting of a mild suppression in reproductive hormone secretion, or dramatic, underlying a complete suppression of fertility and reproductive behavior. Although group mean responses to various stresses can be measured, it is clear that there are marked differences in the response of the reproductive axis to these stresses among individual animals. Factors that contribute to the variability in the response of the reproductive axis include the type of stress, the magnitude and duration of stress, the perception of the stress by the individual, the social status of the individual, the concurrent level of aggressive behavior displayed by the individual, seasonal cues, and the prior level of activity within the reproductive axis. During some stresses, activation of the adrenal axis, endogenous opioid pathways, increased prolactin release, and changes in sensitivity to gonadal steroid hormone feedback appear to play a role in mediating the effects of behaviorally induced stresses on the reproductive axis. However, a great deal more work is needed to understand the mechanisms underlying impairment of the reproductive axis by most psychological and social stresses, as well as the mechanisms underlying differences in susceptibility to stress-induced impairment of reproductive function within individuals.
Twenty brother-sister pairs of mice were randomly selected from a genetically heterogeneous population of mice to begin a schedule of inbreeding that lasted for six generations (F = 0 to F = .732). We examined a number of indices of reproductive behavior and found that all declined as a function of inbreeding. Specifically, there was a consistent decline in the number of fertile matings, in the number of offspring that survived to weaning, and in the weight of the pups at the time of weaning (21 days of age). We also examined a number of behaviors with the following results: there was a systematic increase in the number of trials required to learn an active avoidance task and a consistent decrease in the number of trials required to extinguish this habit. We observed a statistically significant difference in the retention of a passive avoidance habit, but these results were quite variable and not consistent across generations of inbreeding. Finally, we observed that inbreeding had little effect on measures of locomotor behavior.
Avoidance learning, open-field, and reproductive behaviors of a genetically heterogeneous stock (derived from a four-way cross of selected lines) were compared with the corresponding behaviors of the parental lines. The heterogeneous stock showed heterosis on the body development, fertility rate, litter size at birth and at weaning, and directional dominance on the avoidance learning and open-field measures.
The reproductive histories of women aged 45-70 years from a homogeneous Berber population of South Morocco were sampled from three contrasting environments: a small town (n = 75), villages in the lowlands (n = 217), and villages in the highlands (n = 128). The main reproductive variables oppose the relatively better conditions of fertile life in the lowlands to the more hostile ones in the highlands. Path analysis confirms this difference through reproductive behaviors and suggests the existence of mechanisms for controlling family size in town and in the rural lowlands, but not in the highlands. The estimates of survival function show significant differences among the three groups, the conditions for survival in the highlands being clearly less favorable. Rank tests of the association of survival data with several covariates indicate the association of survival data with vaccinations and with conditions of delivery. In spite of the lower rate of offspring survival, the highlander group would demonstrate a higher overall number of children reaching reproductive maturity, thanks to an extended reproductive span.
Neuropeptides are supposed to be implicated in the regulation of hormone as well as nonhormone dependent behavioral processes in birds. Previous immunohistochemical studies have suggested that in birds opioid pentapeptides, Met- and Leu-enkephalins, may be present in the brain including the regions that regulate sex hormone dependent behaviors, such as reproductive behaviors. To determine biochemically the presence of opioid peptides in the avian brain, a study was conducted to isolate these peptides from Japanese quails and zebra finches. Acetic acid extracts of the quail and finch brains were respectively forced through disposable C-18 reversed-phase cartridges, and then the retained material was subjected to the cation-exchange and reversed-phase high performance liquid chromatographic (HPLC) purifications. All of the purified substances showed a single peak on the reversed-phase HPLC and these substances enhanced spontaneous contractions of the avian rectum. The purified bioactive substances were further subjected to amino acid sequence analysis and were characterized as peptides with the following sequences: Tyr-Gly-Gly-Phe-Met, Tyr-Gly-Gly-Phe-Leu, and Tyr-Gly-Gly-Phe-Met-Arg-Phe. These three peptides were identical with opioid pentapeptides, Met- and Leu-enkephalins, and a heptapeptide, Met-enkephalin-Arg6-Phe7, which had been previously isolated from mammalian species. This is the first direct demonstration of the presence of opioid peptides in the avian brain and confirms previous immunohistochemical findings suggesting a functional role for the opioid peptide in neural mechanisms of avian reproductive behavior.
The role of gene expression of the estrogen receptor-alpha form (ER alpha) in the regulation of female reproductive behavior was investigated in estrogen receptor knockout (ERKO) mice, deficient specifically for the ER alpha, but not the ER beta, gene. Estrogen- or estrogen- plus progesterone-treated gonadectomized ERKO mice did not show any lordosis response. Detailed behavioral analysis revealed that ERKO females were also deficient in sexual behavioral interactions preceding the lordosis response. They were extremely rejective toward attempted mounts by stud male mice, which could not show any intromissions. During resident-intruder aggression tests, gonadally intact ERKO females were more aggressive toward female intruder mice than wild-type (WT) mice. Gonadectomy did not influence the levels of aggressive behavior, and their genotype differences when mice were tested both before and after gonadectomy. However, when mice were tested after gonadectomy for the first time, very few ERKO mice showed aggression. In contrast to aggression, male-type sexual behavior shown by resident mice toward female intruder mice during aggression tests was not different between ERKO and WT mice and was completely abolished after gonadectomy of the resident mice. Finally, it was also found that ERKO females showed greatly reduced levels of parental behavior toward newborn pups placed in their home cage. These changes in parental behavior were not influenced by gonadectomy. ERKO females retrieved significantly fewer numbers of pups with longer latencies compared with wild-type (WT) or heterozygous (HZ) littermates when they were tested as gonadally intact or 20-65 days after gonadectomy. In addition, during parental behavior tests, a significantly higher percentage of ERKO mice exhibited infanticide compared with WT and HZ mice, which rarely showed infanticide. Taken together, these findings suggest that ER alpha gene expression plays a key role in female mice, not only for sexual behavior but also for other interrelated behaviors, such as parental and aggressive behaviors. In addition, persistence of genotype differences in parental and aggressive behavior after gonadectomy indicates that ER alpha activation during neural developmental processes may also be involved in the regulation of these behaviors.
Behaviors that activate the hypothalamic-pituitary-adrenal (HPA) axis or suppress the hypothalamic-pituitary-thyroidal (HPT) axis can disrupt the hypothalamic-pituitary-gonadal (HPG) axis in women and men. Individuals with functional hypothalamic hypogonadism typically display a combination of behaviors that serve as psychogenic stressors and metabolic challenges. Complete recovery of gonadal function depends upon restoration of the HPA and HPT axes. Hormone replacement strategies have limited benefit, because they do not achieve this objective and they mask deficits that accrue from altered HPA and HPT function. Although fertility can be restored with exogenous administration of gonadotropins or pulsatile gonadoropin-releasing hormone (GnRH), fertility management alone will not permit the HPA and HPT axes to recover. Thus, for complete recovery to ensue, biopsychosocial interventions that address the individual's unique set of psychogenic factors and metabolic challenges must be devised.
Sodium L-aspartate (ASP) was administered to neonatal mice according to an increasing dose schedule from Days 2--11 after birth. Adult ASP-treated animals showed large increases in body weight over controls along with stunted body length. The ASP group also showed decreases in locomotor and exploratory behavior. Reproductive dysfunction occurred in both female and male ASP-treated animals. Among treated animals, females had fewer pregnancies and smaller litters while males showed reduced fertility. Evidence of multiple endocrine dysfunction in ASP-treated animals was reflected by decreased pituitary, thyroid, ovaries and tested weights, along with delayed onset of puberty in females. These results demonstrate that sodium L-aspartate produces a syndrome similar to that seen following the administration of monosodium L-glutamate.
A complete motivated or goal-oriented behavioral act can be viewed as consisting of initiation, procurement, and consummatory phases. In order to gain some insight into the organizing principles of neural circuitry that underlies the expression of motivated behavior, certain basic pathways thought to play an important role in two specific classes of such behavior, hypovolemic thirst and reproductive behavior, are reviewed. In both cases, humoral factors participate in the initiation phase, and their sites of action have been rather clearly defined. Circuitry underlying the procurement phase, which involves foraging behavior, is much more complex, but can be thought of as involving two fundamentally different systems, one concerned with the processing of specific sensory information and the production of refined motor responses, and the other concerned with modulating behavioral state. The former is associated primarily with the thalamocortical-lateral forebrain system whereas the latter is associated primarily with the medial forebrain system. Finally, evidence favoring the hypothesis that "biochemical switching" may take place in fixed neuroanatomical circuitry associated with ingestive and reproductive behaviors is reviewed.
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The sexual behaviour of farm animals was followed up both at loose-pasture raising and under industrial conditions. It was studied in estrus, in the search for a sexual partner, with regard to the tolerance of the female animals for the males in the sexual act, with regard to the herd hierarchy, the intraspecies relationships, and the condition of dominance, aggressiveness, and subordination. The role is stated of the presence of male animals in the herd for the regular course of the sexual cycle, and the shortening and synchronization of the estrus. Discussed is also the importance of the artificial visual, sound, olfactory, tactile and other stimuli of the behaviour of the male breeding animals in substantiating the coitus and the proper semen production. It was found that the reproductive process is largely dependent on on the sexual reactions of the animals, which requires a proper knowledge with regard to the substantiation of each sexual cycle. Thus, it is stated, higher conception and fertility rates are to be expected. It was also established that under the conditions of industrial technologies of raising the number of behavioural reactions in their use was strongly reduced because of the lowered contact between the individual groups, while the practice of artificial insemination thoroughly rules out the contact between the male and female animals.