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PubMed1991

Reproductive behavior and health in consanguineous marriages.

In many regions of Asia and Africa, consanguineous marriages currently account for approximately 20 to 50% of all unions, and preliminary observations indicate that migrants from these areas continue to contract marriages with close relatives when resident in North America and Western Europe. Consanguinity is associated with increased gross fertility, due at least in part to younger maternal age at first livebirth. Morbidity and mortality also may be elevated, resulting in comparable numbers of surviving offspring in consanguineous and nonconsanguineous families. With advances in medicine and public health, genetic disorders will account for an increased proportion of disease worldwide. Predictably, this burden will fall more heavily on countries and communities in which consanguinity is strongly favored, as the result of the expression of deleterious recessive genes. However, studies conducted in such populations indicate that the adverse effects associated with inbreeding are experienced by a minority of families.

Congenital Abnormalities↗
PubMed1979

Facilitation of female reproductive behavior from mesensephalic central gray in the rat.

Electrical stimulation in the mesencephalic central gray (CG) and adjacent subtectum through chronically implanted electrodes in free-moving estrogen-primed ovariectomized female rats elicited a rapid and large facilitation of the lordosis reflex in response to either male mounts or manula cutaneous stimuli. Unilateral stimulation was sufficient for this effect. The facilitation increased in a graded manner to increased stimulus intensity, and was optimally evoked by stimuli delivered at 50--150 Hz. Facilitation disappeared rapidly following the end ot electrical stimulation, and within 15 min, reflex performance returned to the prestimulation level. Lordosis facilitation appeared when no aversive responses occurred; stimulation with comparable parameters at the lateral edge of CG or in the mesencephalic reticular formation often resulted in postural changes or aversive responses but was not able to facilitate lordosis. Lordosis refelx facilitation was probably mediated by projections descending from neurons in and around the CG, and represents stimulation of a functional link between ascending somatosensory and descending motor systems for the control of lordosis behavior.

Animals↗
PubMed1979

Mesencephalic mechanisms for integration of female reproductive behavior in the rat.

Placement of bilateral electrolytic lesions in the mesencephalic central gray (CG) of estrogen-primed ovariectomized female rats produced an immediate decline in performance of the lordosis reflex. Lesions that destroyed the dorsal half of the CG and the adjacent subtectal region were effective. The decrease in individual animals in terms of the lordosis reflex score ranged from 20 to 100% of the prelesion performance. Such lesions abolished the facilitation of lordosis by electrical stimulation of the ventromedial nucleus of the hypothalamus. Similar abrupt losses of lordosis followed bilateral lesions of either a) the area between CG and the cuneiform nucleus of the mesencephalic reticular formation (NCf); or b) the ventrolateral quadrant of the NCf. The difference between these two lesions was that the effect of the latter could be overridden by electrical stimulation of the CG, whereas that of the former could not. We conclude that the CG is an important supraspinal component of the circuit for lordosis behavior, constituting a link between ascending somatosensory and descending motor systems for lordosis. It probably facilitates lordosis when activated by behaviorally relevant peripheral somatosensory and/or ventromedial hypothalamic inputs.

Animals↗
PubMed1988

Presumptive relict reproductive behavior in small parrots.

Recent studies of experimentally elicited egg-care behaviors in three species of small, hole-nesting parrots, and of their evolutionary implications are reviewed. A suite of primarily nonthermal egg-care responses are adaptive for nesting in shallow terrestrial scrapes, rather than in cavities. These responses appear to be relics from times before hole-nesting began; as such, they may provide 'windows' into certain nonthermal aspects of terrestrial-nesting practices during ancestral stages. A suite of primarily thermal egg-care behaviors, elicited when nests are exposed to light and view, progress from mere initial curiosity, inspection, and manipulation of fostered eggs by nonbreeding parents, to more extensive manipulation and episodic concealment of a pair's own eggs by crouching over them, to crouching lengthily over eggs with some incubation but nighttime abandonment, to continuous 24-hour incubation. This progression may retrace certain aspects of major ancestral stages of thermal egg care. Stages of primary oocytes and follicles during ovarian development, and of maturing follicles during breeding cycles of some species, may retrace the phylogenetic progression of sizes of ancestral clutches and ripe follicles. These phenomena and the retention of many of the experimentally elicited egg-care responses are attributed largely to the highly conservative evolution of the central nervous system.

Animals↗
PubMed1982

Luteinizing hormone-releasing hormone involvement in the reproductive behavior of a male amphibian.

The present study demonstrates that an intracerebroventricular injection of luteinizing hormone-releasing hormone (LHRH) activates sexual behaviors and elevates the plasma androgen concentrations in rough-skinned newts (Taricha granulosa). The stimulatory effect of LHRH on male behavior may be a seasonal phenomenon, because LHRH stimulation of sexual behavior was only observed during the early part of the breeding season (November and December). When an active LHRH antagonist was injected into male newts, sexual behavior was suppressed. These studies indicate that endogenous LHRH is involved in regulating sexual behavior in this amphibian.

Animals↗
PubMed1976

Early sex education in relationship to later coital and reproductive behavior: evidence from Jamaican women.

In a group of 150 working-class Jamaican women, lack of information from their mothers about sex coupled with chronic resentment was associated with having had more sexual partners, impregnators, and children. In contrast to age at first coitus, age at first pregnancy did not seem related to the early availability of information about sex, and it was less significantly correlated with overall education.

Adolescent↗
PubMed1978

Hormonal control of male reproductive behavior in the lizard, Anolis carolinensis: role of testosterone, dihydrotestosterone, and estradiol.

The androgen aromatization hypothesis was examined in the male lizard, Anolis carolinensis. After castration, sc silastic implants of testosterone (T) restored both challenge and courtship behavior, while dihydrotestosterone (DHT) or 17beta-estradiol (E) had no effect on male behaviors. Both T and DHT, but not E, stimulated hypertrophy and colloid production by the renal sex segment, a secondary sexual characteristic of male lizards. In two separate studies, castrates received DHT in combination with E. In each replicate, half of the castrates responded with increases in courtship behavior after hormone treatment. Epithelial cell height of the sex segment of all DHT and E-treated castrates was comparable to T- or DHT-treated castrates, but colloid production was not stimulated. These experiments indicate that in this species, treatment with T stimulates both sexual behavior and secondary sex character development, whereas treatment with E alone is without effect centrally or peripherally.

Animals↗
PubMed1976

Habitat and reproductive behavior of Trichinella spiralis.

The normal niche of Trichinella spiralis adults was found to be in the epithelial layer of the mucosa of the small intestine of its host. Most worms were found in the epithelium at the base of the villi and in the glandular crypts. Copulation and insemination occurred between 30 and 32 hr postinfection, all although these acts were never observed, it was concluded that copulation and insemination took place in the epithelial layer of the mucosa. A majority of the adults were found to be completely embedded in the epithelium during the deposition of the motile larvae. Motile larvae were deposited in this location and from there migrated through the stroma to venules and lymphatic vessels. Male T. spiralis were found to be capable of inseminating at least 4 females.

Animals↗
PubMed1991

Testosterone effects on staining density and autoradiographic investigations of the alpha 2-adrenergic receptor in the medial preoptic nucleus of the Japanese quail: relationship to the activation of reproductive behavior.

The effects of gonadectomy combined or not with testosterone (T) therapy on the sexual behavior, cloacal gland area, staining density and alpha 2-adrenergic receptors in the medial preoptic nucleus (POM) were studied in male and female Japanese quail. In castrated males, T increased the cloacal gland size and activated copulatory behavior. In agreement with previous reports, these effects were sexually differentiated: under the influence of T, cloacal gland growth was smaller and this treatment did not activate masculine sexual behavior in females. The optical density of the medial preoptic nucleus stained with thionein blue (Nissl stain) was decreased by castration and increased by T in both males and females. This suggests that T has a profound effect on the synthesis of proteins in the POM and, since POM is a critical site in the activation by T of masculine sexual behavior, these induced proteins are, in all probability, a part of the causal chain of biochemical events giving rise to copulatory behavior. The treatment with T had, by contrast, no clear effect on the number of binding sites and on the affinity of the alpha 2-adrenergic receptors in the POM. Therefore, if the noradrenergic transmission is involved in the induction by T of copulatory behavior, it is probably acting either through the alteration of another adrenergic receptor subtype or through the modulation of the baseline levels or turnover of the transmitter itself.

Animals↗