Biomedical subjects

K T Hayashi

Publications and source records attributed to K T Hayashi.

3 recordsLinked to original sources

PubMed1990

Influence of the hypothalamic-pituitary-adrenal axis on the menstrual cycle and the pituitary responsiveness to estradiol in the female rhesus monkey (Macaca mulatta).

In order to examine the effect of glucocorticoids on the menstrual cycle of rhesus monkeys, cortisol was injected twice daily during the follicular phase. This cortisol treatment did not alter basal gonadotropin secretion but blocked the normal follicular rise of estrogens, the gonadotropin surge and the luteal rise of progesterone, and delayed the onset of the next cycle. In a second study, estradiol benzoate (E2B) was injected on the sixth day following the start of menstrual bleeding either with or without concurrent adrenocorticotropic hormone (ACTH) treatment. E2B injection was able to stimulate surges of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) whether or not the animals had been treated with ACTH. These data suggest that, the action of cortisol, the final mediating step in the hypothalamic-pituitary-adrenal axis, occurs at the level of the gonads versus the pituitary in the rhesus monkey. While the pituitary response to endogenous gonadotropin-releasing hormone or exogenous E2B stimulation appears to remain unaffected, normal folliculogenesis is disrupted, preventing the follicular secretion of estrogens and the subsequent gonadotropin surges. The effects of corticosteroids are temporary, with normal cycling returning when plasma corticosteroids return to basal concentrations, albeit after a delay.

Adrenocorticotropic Hormone↗

PubMed1990

Influence of maternal proximity on behavioral and physiological responses to separation in infant rhesus monkeys (Macaca mulatta).

The effects of maternal proximity on the behavioral and physiological responses of infant rhesus macaques during 4 days of total or adjacent separations from the mother were studied. The 6 infants tested showed behavioral responses that differentiated the two separation conditions. Major differences were found in the quantity and quality of vocalizations, the occurrence of cage-biting and cage-shaking behavior, object exploration, and hunched and freezing postures. In particular, the structure of coo vocalizations clearly discriminated between the presence or the absence of the mother during separation. Cerebrospinal fluid (CSF) concentrations of dopamine and serotonin metabolites did not discriminate between the two separation conditions but showed a transient elevation at 24 hr after separation and were not different from baseline by 96 hr after separation. In contrast, both the plasma cortisol and the CSF norepinephrine metabolite responses tended to be greater and to persist for a longer period of time when infants were totally isolated. The results are discussed within the context of attachment and coping theories.

Animals↗

PubMed1987

Primate vocalization: a psychobiological approach.

Scientific inquiry, for the most part, can be described as parochial. Not only are there clear demarcations between broad disciplinary categories (i.e., anatomy, physiology, psychology), but subspecialties are common within disciplines. Modern technology has made possible a trend toward greater and greater specialization. In fact, there are now areas of scientific investigation that did not exist a few years ago. This increasing specialization and its concomitant reductionism is not without its pitfalls and problems. There is a tendency to move away from the basic evolutionary concept of living organisms as organized systems functioning and adapting within an ecosystem. The laboratory scientist often ignores the inherent organization of living systems in favor of an intense pursuit of his or her particular chosen bit of the biological puzzle. However, there are still disciplines that not only subscribe to the notion of living organisms as organized systems but have made a valiant attempt to bring this concept under laboratory scrutiny. Often, in order to identify these endeavors, a technique is used to combine two or three words into one. Thus, we have several flourishing disciplines described as psychoneuroimmunology, psychoneuroendocrinology, neurochemistry, physiosociology, and so on. For the investigator who attempts a more integrated approach to the broad biological and psychological universe, the demands are heavy. He or she is faced with the need to maintain credibility in several disciplines, each of which is advancing at an accelerated pace. However, we feel that the value of an integrated approach that crosses traditional disciplinary lines will be illustrated in a small way by this article and, we hope, by the series of articles presented in this symposium section of Child Development.

Animals↗