ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

This review highlights two emergent themes in stress neurocircuit control of the hypothalamo-pituitary-adrenocortical axis. First, excitation and inhibition of neurons controlling stress hormone release appear to be conveyed by stressor-specific pathways that fall into two loose categories: processive (or neurogenic) stressors, which are the end-product of processing of exteroceptive cues, and systemic stressors, which relay information on disruption of internal homeostasis. Second, a good deal of stress integration may be occurring by way of local hypothalamic circuitry, which may mitigate actions of limbic pathways and even ascending brainstem systems proximal to stress-initiative neurons. The literature suggests that stress integration is a convergent process that is channeled through local hypopthalamic circuits prior to elaboration of a neuroendocrine stress response.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Evidence has accumulated in recent years suggesting that the CRH system can play a significant role in the regulation of energy balance. Both CRH and its related peptide urocortin have been reported to exert anorectic and thermogenic effects. These effects could be mediated through the CRH type 1 receptor, which represents one of the two CRH receptors so far identified. In addition to being part of circuitries involved in the regulation of energy balance and to possessing the capacity for coordinating anorectic and thermogenic effects, the CRH system is also sensitive to the action of hormones capable of signaling the brain about the fluctuations in energy reserves. In this regard, it has recently been demonstrated that the CRH system responds to the action of the adipose tissue-derived hormone leptin. Leptin has been reported to reduce CRH expression in the paraventricular hypothalamic nucleus of leptin-deficient obese rodents, an action with the potential to reduce energy deposition by inhibiting the hyperactivity of the hypothalamic-pituitary adrenal axis. Leptin has also been very recently reported to increase the expression of the CRH type 2α in the ventromedial hypothalamic nucleus, a key structure in the control of insulin secretion and in the regulation of energy balance. Finally, the CRH system appears to demonstrate a plasticity in obesity and in response to food deprivation that is consistent with its action on food intake and thermogenesis. The observations have been made that food deprivation and obesity can blunt the expression of the CRH type 2α receptor in the ventromedial hypothalamic nucleus and can induce the expression of the CRH-binding protein (a CRH-inactivating protein) in brain areas involved in the anorectic and thermogenic actions of CRH.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Angiotensin II (ANG) is an 8 amino acid peptide recognized for its endocrine roles in the regulation of vascular resistance and aldosterone secretion. In addition to theses roles it is now well established that ANG exerts significant control over the autonomic nervous system as a result of specific actions within the central nervous system. Circulating ANG acts at circumventricular organs (specialized CNS sites that lack the normal blood brain barrier) to influence classical behavioral (drinking), endocrine (vasopressin, oxytocin, ACTH secretion), and autonomic functions. Additional recent work has suggested the intriguing possibility that this peptide also plays a neurotransmitter role in neuronal pathways controlling autonomic output.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Perinatal hypothyroidism may result in abnormal development of the central nervous system, or cretinism in man. However, the molecular mechanisms of thyroid hormone (TH) action involved in this process are not yet fully understood. To study such mechanisms, the developing rodent cerebellum during the perinatal period can be an excellent model system. Recently, a mutant mouse,staggerer (sg), which exhibits morphological and neurological abnormalities of the cerebellum similar to those seen in hypothyroid animals, has been shown to result from the homozygous disruption of the orphan nuclear hormone receptor, RORα gene. In this mouse, TH does not alter the abnormal phenotype nor normalizepcp-2gene (TH-regulated) expression, although tissue TH receptor (TR) and serum TH levels are normal. We have recently confirmed the involvement of RORα in TH-mediated regulation of neuronal differentiation. In addition, it has been shown that TH action on cerebellar development may be mediated at least in part by brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), members of the neurotrophic factor family that serve critical roles in neurite growth and synaptogenesis. These findings may provide new insights in the molecular mechanisms of TH action in neuronal development and differentiation.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Much progress has been made during the past year in determining the effects of estrogen in the central nervous system. In addition to its classical action as a transcription factor ligand for the estrogen receptor (ER), there is increasing evidence that estrogen may also act via cross-talk with other signal transduction pathways such as the protein kinase A (PKA) and mitogen activated protein kinase (MAPK) pathways to regulate gene expression in the brain. Another exciting development has been the discovery of a second estrogen receptor, ERβ. Data describing the differential distribution of the estrogen receptors ERα and ERβ in the brain and their varying pharmacological profiles are now being reported. Finally, there is new evidence suggesting that estrogen may have growth factor-like effects or antioxidant activities related to its ability to protect against Alzheimer’s disease. This review will describe the most recent data concerning these diverse actions of estrogen in the central nervous system.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

The development of functional hypothalamic amenorrhea (FHA) is often associated with long term, high intensity exercise training, where it is viewed as an adaptive response to chronic metabolic energy deficiency. When encountered in weight-stable, non-athletic women, FHA has long been thought to be psychogenic in origin. Recent studies have revealed a striking similarity of dietary intake and neuroendocrine/metabolic abnormalities for both conditions. Women with psychogenic and exercise-related FHA display evidence of subclinical eating disorders accompanied by a severe restriction of dietary fat intake and multiple endocrine-metabolic alterations. Among these, reduced levels of T3, glucose, and GHBP, a decrease in the ratio of IGF-I/IGFBP-1, accelerated GH pulse frequency, and elevated interpulse GH levels are indicative of an energy-deficient state. Decreased glucose availability and subsequent glucoregulatory adaptations (decreased insulin/IGF-I action and increased cortisol/CRF action) are potential signals mediating the suppression of GnRH pulse generator activity. Thus, nutritional deficits may represent a common contributing factor in the development and maintenance of multiple neuroendocrine-metabolic aberrations underlying both psychogenic and exercise-related FHA.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

An increase in pulsatile release of luteinizing hormone-releasing hormone (LHRH) is essential for the onset of puberty. The pubertal increase in LHRH release triggers an elevation of gonadotropin secretion which, in turn, controls steroidogenesis and gametogenesis, resulting in puberty. Although LHRH agonists have been used in humans to treat disorders associated with puberty, the mechanism of the increase in LHRH release during puberty is still unclear. This review describes the possible mechanism involved in the pubertal increase in pulsatile LHRH release in primates. That is, the increase in LHRH release is triggered by the reduction of inhibitory γ-aminobutyric acid (GABA) input and a subsequent increase in excitatory glutamatergic input to the LHRH neurosecretory system in the hypothalamus. Other stimulatory signals, such as those from norepinephrine (NE) and neuropeptide Y (NPY) neurons, appear to further contribute to this event.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Major advances in our understanding of the complexities of the perimenopausal process have occurred during the past 5 to 10 years. We now understand that the follicle pool is exhausted at an increasing rate during the last decade of menstrual cyclicity. We are beginning to appreciate that multiple factors, including neuroendocrine changes, may play a role in the perimenopausal period. In addition, it appears that rodents may serve as models for several aspects of menopause.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Fibromyalgia is a chronic disorder of unknown etiology characterized by widespread musculoskeletal pain as well as fatigue, malaise, orthostatic hypotension, gastrointestinal complaints, and disrupted sleep. Individuals with fibromyalgia have increased sensitivity to a variety of painful stimuli, which may be due to alterations in the central nervous system’s processing of pain. Recent studies suggest that alterations in hormone levels, often due to changes in hypothalamic-pituitary function, occur in fibromyalgia. These studies are reviewed and their relevance for the pathophysiology and potential therapy of fibromyalgia are discussed.

ISSN:1068-3097    

出版商:OVID    

年代:1999

数据来源: OVID