Формирование творческой речевой активности дошкольников с функциональными нарушениями зрения

Рассматриваются основные этапы формирования навыков творческого рассказывания у дошкольников с функциональными нарушениями зрения, перечисляются эффективные приемы стимулирования творческой речевой активности дошкольников с ослабленным зрение

Effect of vasopressin 1b receptor blockade on the hypothalamic-pituitary-adrenal response of chronically stressed rats to a heterotypic stressor

Exposure to chronic restraint (CR) modifies the hypothalamic–pituitary–adrenal (HPA) axis response to subsequent acute stressors with adaptation of the response to a homotypic and sensitization of the response to a heterotypic stressor. Since vasopressin (AVP) activity has been reported to change during chronic stress, we investigated whether this was an important factor in HPA facilitation. We therefore tested whether vasopressin 1b receptor (AVPR1B) blockade altered the ACTH and corticosterone response to heterotypic stressors following CR stress. Adult male rats were exposed to CR, single restraint, or were left undisturbed in the home cage. Twenty-four hours after the last restraint, rats were injected with either a AVPR1B antagonist (Org, 30 mg/kg, s.c.) or vehicle (5% mulgofen in saline, 0.2/kg, s.c.) and then exposed to either restraint, lipopolysaccharide (LPS) or white noise. CR resulted in the adaptation of the ACTH and corticosterone response to restraint and this effect was not prevented by pretreatment with Org. Although we found no effect of CR on LPS-induced ACTH and corticosterone secretion, both repeated and single episodes of restraint induced the sensitization of the ACTH, but not corticosterone response to acute noise. Pretreatment with Org reduced the exaggerated ACTH response to noise after both single and repeated exposure to restraint

Circadian and Ultradian Rhythms of Free Glucocorticoid Hormone Are Highly Synchronized between the Blood, the Subcutaneous Tissue, and the Brain

Total glucocorticoid hormone levels in plasma of various species, including humans, follow a circadian rhythm that is made up from an underlying series of hormone pulses. In blood most of the glucocorticoid is bound to corticosteroid-binding globulin and albumin, resulting in low levels of free hormone. Although only the free fraction is biologically active, surprisingly little is known about the rhythms of free glucocorticoid hormones. We used single-probe microdialysis to measure directly the free corticosterone levels in the blood of freely behaving rats. Free corticosterone in the blood shows a distinct circadian and ultradian rhythm with a pulse frequency of approximately one pulse per hour together with an increase in hormone levels and pulse height toward the active phase of the light/dark cycle. Similar rhythms were also evident in the subcutaneous tissue, demonstrating that free corticosterone rhythms are transferred from the blood into peripheral target tissues. Furthermore, in a dual-probe microdialysis study, we demonstrated that the circadian and ultradian rhythms of free corticosterone in the blood and the subcutaneous tissue were highly synchronized. Moreover, free corticosterone rhythms were also synchronous between the blood and the hippocampus. These data demonstrate for the first time an ultradian rhythm of free corticosterone in the blood that translates into synchronized rhythms of free glucocorticoid hormone in peripheral and central tissues. The maintenance of ultradian rhythms across tissue barriers in both the periphery and the brain has important implications for research into aberrant biological rhythms in disease and for the development of improved protocols for glucocorticoid therapy

Cortisol pulsatility and its role in stress regulation and health

commentaryOne of the classic characteristics of the human stress response is the wide inter-individual variation. Although there is much current interest in the genetic and environmental contributions to these differences, studies on human subject have been sparse and characterised by methodological problems. The major factor that is rarely taken into account is the intrinsic rhythmicity of hypothalamo–pituitary–adrenal activity, not simply the classic diurnal variation but also the endogenous pulsatility which is similar to, but much less well recognized than, the rhythms found within the reproductive and growth hormone axes. In this review we propose some novel ideas relating to the importance of pulsatility both for the design of human stress-response studies and for their interpretation as well as implications for our understanding of disease.NIMH MH50030 NIMH MH52724Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49484/2/cortisolpulseLightman.pd

Characterizing Dynamic Interactions between Ultradian Glucocorticoid Rhythmicity and Acute Stress Using the Phase Response Curve

The hypothalamic-pituitary-adrenal (HPA) axis is a dynamic oscillatory hormone signalling system that regulates the pulsatile secretion of glucocorticoids from the adrenal glands. In addition to regulation of basal levels of glucocorticoids, the HPA axis provides a rapid hormonal response to stress that is vitally important for homeostasis. Recently it has become clear that glucocorticoid pulses encode an important biological signal that regulates receptor signalling both in the central nervous system and in peripheral tissues. It is therefore important to understand how stressful stimuli disrupt the pulsatile dynamics of this system. Using a computational model that incorporates the crucial feed-forward and feedback components of the axis, we provide novel insight into experimental observations that the size of the stress-induced hormonal response is critically dependent on the timing of the stress. Further, we employ the theory of Phase Response Curves to show that an acute stressor acts as a phase-resetting mechanism for the ultradian rhythm of glucocorticoid secretion. Using our model, we demonstrate that the magnitude of an acute stress is a critical factor in determining whether the system resets via a Type 1 or Type 0 mechanism. By fitting our model to our in vivo stress-response data, we show that the glucocorticoid response to an acute noise stress in rats is governed by a Type 0 phase-resetting curve. Our results provide additional evidence for the concept of a deterministic sub-hypothalamic oscillator regulating the ultradian glucocorticoid rhythm, which constitutes a highly responsive peripheral hormone system that interacts dynamically with hypothalamic inputs to regulate the overall hormonal response to stress