ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Considerable progress has been made in the understanding of the formation of gastric erosions by the use of animals.The role of gastric acid secretion in their pathogenesis has been clarified. Gastric erosions are associated with the presence of acid in the stomach and slow gastric contractions. With several different experimental procedures, the animal's body temperature falls; preventing the fall averts erosions. A fall in body temperature or exposure to cold are associated with the secretion of thyrotropin-releasing hormone (TRH), and both increased and decreased concentration of corticotropin-releasing factor (CRH) in discrete regions of rat brains. Thyrotropin-releasing hormone when injected into specific sites in the brain produces gastric erosions and increases acid secretion and slow contractions, whereas CRH has the opposite effects. One of the major sites of interaction of the two peptides is in the dorsal motor complex of the vagus nerve. Thyrotropin-releasing hormone increases serotonin (5-HT) secretion into the stomach. Serotonin counter-regulates acid secretion and slow contractions. Many other peptides injected into discrete brain sites stimulate or inhibit gastric acid secretion.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivePsychoneuroimmunology, which investigates the bidirectional communication between the central nervous system and the immune system, has been greatly advanced by the use of animal models. The objective of this paper is to describe animal models of disease that can or might be utilized to elucidate neural-immune interactions that alter pathogenesis.MethodsThis paper reviews animal studies that have demonstrated a link among the brain, behavior, immunity, and disease, highlighting models in which the potential contribution of CNS-immune interactions has not yet been explored.ResultsAnimal studies allow for careful control of environmental stimuli, genetic background, and immunological challenge. As such, they are an important component of psychoneuroimmunology research. Models in which one might study the role of psychosocial factors in immunologically mediated disease processes, as in the case of other pathophysiologic processes, profit from an ability to manipulate both stressful events and the magnitude of the challenge to the immune system.ConclusionsAnimal studies in psychoneuroimmunology highlight the complexity of the interactions among behavior, the brain, the immune system, and pathogen. The genetic background of the animal (both in terms of central nervous and immune system responses), its previous history, the nature of the stressor, the nature of the pathogen and the type of immune response generated are some of the interacting factors that determine the magnitude and direction of stress-induced changes in disease outcome.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo present evidence on the control of the size of fatty meals in the context of the result of interactions of orosensory positive-feedback and postingestive negative-feedback mechanisms activated by fat stimuli in rodent models of feeding and of obesity.MethodWe examined the effects of orosensory stimuli and postingestive stimuli in Sprague-Dawley rats, and in the genetically obese Zucker (fa/fa) rat. We used the sham feeding rat preparation to isolate the orosensory stimulating and postingestive satiating properties of oils. The negative-feedback satiating properties of fats were elicited by intestinal infusions of fats. The Zucker rat is an animal model of obesity with abnormal control of meal size and increased intake of fats. Using this model we further examined the interaction of orosensory and postingestive stimuli in the control of meal size.ResultsThe orosensory properties of fats are sufficient to drive sham feeding and are not dependent on the postabsorptive metabolic consequences of oils in normal and Zucker rats. The satiating action of fats must act at preabsorptive sites because reduction of intake occurs before absorption of fat. The satiating potency of fats is dependent upon their specific chemical conformation and is mediated by endogenous cholecystokinin and afferent fibers of the abdominal vagus. We have found that oils produce significantly more orosensory positive feedback in obese Zucker rats than in lean rats in experimental tests of preference. This is probably the major abnormal mechanism responsible for the increased preference for fats that is characteristic of obese rats because we have not identified any significant decrease in the postingestive satiating potency of fats in obese Zucker rats.ConclusionsFat intake is controlled by both orosensory and postingestive stimuli in normal and genetically obese rodents. In the Zucker rat the investigation of this model of genetic obesity has produced data that is congruent with the preference for high fat foods in obese people and suggests further experiments directed toward a deeper understanding of the controls of fat intake and how they are disordered.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo describe how an animal model system can be used to explore basic questions about the nature of loss and the effects of early loss on later vulnerability to disease.MethodThe physiological and behavioral responses of infant rats to separation from their mothers are first described and then analyzed experimentally into component mechanisms.ResultsThese studies have revealed an extensive layer of processes underlying the psychological constructs generally used to understand the response to loss. Hidden within the observable interactions of parent and offspring, we found a number of discrete sensorimotor, thermal, and nutrient-based events that have unexpected long-term regulatory effects on specific components of infant physiology and behavior. Release from all of these inhibitory and excitatory regulators together during maternal separation constitutes a novel mechanism by which the experience of loss can be translated into a complex patterned response. Evidence for early regulatory processes has also been found in monkey and human mother-infant interactions. Here they may well constitute the building blocks from which attachment and object representations develop. We and others have found long-term effects of loss, and of selective replacement of regulators, on behavioral development and on later vulnerability to disease.ConclusionsThe results give us a new understanding of early attachment as a developmental force and of human grief as a risk to health.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo review the literature regarding the use of animal models in research addressing psychosomatic aspects of diabetes.MethodWe examine the key findings in animal model vs. human research in the area of stress and diabetes. Previous research has suggested that stress is a potential contributor to chronic hyperglycemia in diabetes. Stress affects metabolic activity via the stimulation of a variety of hormones that can result in elevated blood glucose levels. In patients with diabetes, due to a relative or absolute lack of insulin, stress-induced increases in glucose cannot be properly metabolized. Additionally, regulation of these stress hormones may be abnormal in diabetes.ResultsHuman studies on the role of stress in the onset and course of type II diabetes are few and are limited by the constraints and logistics of examining life stress in humans. However, animal research allows for tight experimental control and the manipulation of factors that may contribute to the development and/or course of diabetes, such as stress, eating behavior, the nutrient content of food, and physical activity. Disease processes can be examined at a mechanistic level in animals which is typically limited in human research.ConclusionsThere is a large body of animal work to support the notion that stress reliably produces hyperglycemia in type II diabetes. Furthermore, there is evidence that the autonomic nervous system plays a role in the pathophysiology of this condition in both animals and humans. Examination of eating behavior and nutrient content of food in animal models of diabetes has shed light on the role of these factors in the development of diabetes, as well as obesity. Finally, genetic research using animal models of diabetes will provide new directions for research in humans to delineate the genetic contribution to the development of diabetes.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveResearch on the relationship between physiological responses to stressful stimulation and the onset of psychosomatic illnesses has been an area of intense interest for many years. Studies using animal models have contributed significantly to this field of inquiry by taking several complementary approaches.MethodThree specific research strategies taken in our laboratory will be highlighted here. Each involves studies in conscious, freely behaving animals.ResultsGenetically selected animals have been exposed to acute stressors to unmask neuroendocrine and autonomic abnormalities related to disease susceptibility. In addition, studies of aged animals suggest that exaggerated physiological responses to acute stress may underlie some age-related pathologies. Finally, a series of studies has revealed that exposure of laboratory animals to stressful stimulation may exert long-lasting influences on the ways in which these subjects respond in the future to the same or novel stressors.ConclusionsThese findings illustrate how studies with laboratory animals have the potential for refining the questions that are posed in research with clinical populations and for providing insight into the underlying physiological mechanisms of individual variability in disease susceptibility and the development of appropriate therapeutic interventions.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivePremenopausal women, compared with men, are relatively spared from coronary heart disease and the underlying atherosclerosis. Our purpose has been to elucidate the reason for this difference and to explore the role of behavioral factors in this phenomenon.MethodsStudies employed socially housed cynomolgus macaques (Macaca fascicularis) fed an atherogenic diet and subjected to behavioral observations. Ovariectomy, with or without hormone replacement, was used to test specific hypotheses about estrogen's role in the protection of females from atherosclerosis and coronary heart disease.ResultsFemale macaques, like women, are resistant to atherosclerosis. However, this resistance is modified by social status--dominant monkeys develop little atherosclerosis, whereas subordinates resemble males in the amount of lesion that occurs. Subordinate females also are characterized by hypercortisolemia, behavioral dysfunction, and impaired ovarian function; the resulting low concentrations of circulating estrogen perhaps explain their accelerated atherosclerosis. Notably, atherosclerosis is exacerbated in ovariectomized monkeys but is suppressed in association with pregnancy, a hyperestrogenic state. Moreover, exogenous estrogen (an oral contraceptive) inhibits atherosclerosis in premenopausal social subordinates.ConclusionsTo the extent that our results apply to women, they highlight the potential importance of behavioral stressors and their effects on estrogen activity in the premenopausal development of atherosclerosis. The triad of hypercortisolism, ovarian impairment, and psychiatric morbidity found in monkeys also occurs in women and may represent a high-risk state for disorders of the cardiovascular system and, perhaps, other estrogen-sensitive tissues.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveVulnerability to psychosomatic diseases is influenced by events early in life. The objective of this article is to discuss animal research that demonstrates relationships between feeding experiences and growth in infancy and risk of hypertension in adulthood.MethodSubjects were spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto progenitors. Initial experiments involved observations of the behaviors of rat mothers and their infants and follow-up measurements of blood pressures. Further studies focused on measurements of infant blood pressure during feeding, and recent investigations manipulated weight gain and sex hormones early in life.ResultsInfant rats whose mothers were seen nursing more often had increased blood pressure as adults. Each time rat mothers delivered milk to their young, the nursing pups' blood pressures rose dramatically. These feeding-induced increases in blood pressure have been observed in the young of many species including humans. They are mediated by autonomic nervous system activity and are larger in SHR pups. Finally, animals that gain weight rapidly as infants as a consequence of being reared in small litters had higher adult blood pressure; but, this effect is seen only in intact males.ConclusionsAdult physiologic traits can be influenced by the joint actions of genetic predisposition and essential psychosocial interactions during early development. Animal models can stimulate new ideas, provide important confirmations and elaborations of hypotheses from human investigations, and afford experimental approaches for identifying mechanisms underlying the transduction of behavioral experience to disease susceptibility.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveProgress in the use of genetically altered animals for psychosomatic research is reviewed.MethodAnalysis of the strengths and weaknesses of these models, particularly from a developmental and behavioral prospective is used to assess the validity of these models.ResultsGenetically altered animals can be used to create models of the estimated 5000 human diseases in which genetic predispositions play a role, as well as models for diseases that do not involve gene defects, such as human immunodeficiency virus (HIV) infection. In addition, these models have already contributed immensely to our understanding of basic biology and the biology of behavior. Replication of human gene defects in mice has provided direct models of human disease, but there are various factors that sometimes prevent the gene defect from producing the human disease in mice. However, even in this case, the models can contribute to understanding the basic biology of the disease.ConclusionsWhile genetically altered animals have revolutionized the understanding of single gene disorders, their promise has not yet been fulfilled for multigenic behavioral disorders. Newer techniques to allow control of the tissue and stage of development at which a gene is expressed are likely to enhance the usefulness of these models for psychosomatic research. New models of disease for testing psychological impacts on illness and specific ways of altering neurotransmitter function will be discovered. While these models will be extremely useful to psychosomatic medicine, the nature of this discipline of necessity involves emphasis on individual experience, and thus will never be amenable to exclusively genetic analysis.

ISSN:0033-3174    

出版商:OVID    

年代:1996

数据来源: OVID