运动与脑中谷氨酸受体及其基因表达

谷氨酸作为中枢神经系统中最重要的兴奋性神经递质。它与相应的细胞膜受体即谷氨酸受体相结合而发挥作用。本文对谷氨酸受体及其基因的结构和功能进行了综述，并在此基础上对运动性中枢疲劳和谷氨酸受体基因之间的可能关系做了初步的探讨和展望。     

Opioids and behavior: genetic aspects

Summary Three animal models, based on genetic differences in endogenous opioid peptides and opioid receptors, are described. Obese mice and rats, whose pituitary opioid content is elevated, may be used to investigate eating disorders. Recombinant inbred strains of mice, which differ in brain opioid receptors and analgesic responsiveness, can be used for study of opioid-and nonopioid-mediated mechanisms of pain inhibition. Individual reactivity to opioids can be examined in C57BL/6 and DBA/2 inbred strains of mice. A model that combines a variety of opioid effects is offered and suggests the existence of a genetically determined dissociation of opioid effects on locomotor activity and pain inhibition. In addition, stimulatory locomotor responses in the C57BL/6 reaction type are linked to a high risk of drug addiction and facilitatory effects on adaptive processes, while high analgesic potency in the DBA/2 reaction type is accompanied by a low proneness to drug abuse and amnesic properties of opioids.     

Sensory basis of bird orientation

Summary Sensory information which may be essential for the complex process of orientation of birds is described in this article. The use of vibrational, visual, chemical, olfactory, magnetic cues and their receptive mechanisms, as far as they are known, are explained. Special reference is given to the behavioral and physiological aspects of magnetic sensitivity.     

Allosteric proteins after thirty years: The binding and state functions of the neuronalα7 nicotinic acetylcholine receptors

A key statement of the 1965 Monod-Wyman-Changeux (MWC) model for allosteric proteins concerns the distinction between the ligand-binding function ( ) and the relevant state function ( ). Sequential models predict overlapping behavior of the two functions. In contrast, a straightforward experimental consequence of the MWC model is that for an oligomeric protein the parameters which characterize the two functions should differ significantly. Two situations, where \bar Y$$ " align="middle" border="0"> and the system ishyper-responsive or where and the system ishypo-responsive, have been encountered. Indeed, the hyper-responsive pattern was first observed for the enzyme aspartate transcarbamoylase, by comparing with monitored by a change in sedimentation. Extensions of the theory to ligand-gated channels led to the suggestion that, on the one hand, hyper-responsive properties also occur with high-affinity mutants. On the other hand, native channels of the acetylcholine neuronal7 receptor and low-affinity mutants of the glycine receptor can be interpreted in terms of the hypo-responsive pattern. For the ligand-gated channels, whereas is detected directly by ion flux, ligand binding has rarely been measured and the formation of desensitized states may complicate the analysis. However, stochastic models incorporating both binding and channel opening for single molecules predict differences that should be measurable with new experimental approaches, particularly fluorescence correlation spectroscopy.     

Role of phospholipids in the binding activity of vasoactive intestinal peptide receptors

Summary Phospholipase digestion of rat intestinal epithelial cell membranes was performed in order to study the influence of membrane phospholipids on the binding activity of VIP receptors. Phospholipases A₂ and C strougly (ED₅₀4×10^–2 and 4×10^–1 g/ml, respectively) and rapidly reduced¹²⁵I-VIP binding to membranes whereas phospholipase D was ineffective. This suggests an important role of both hydrophobic and hydrophilic groups of phospholipids on VIP receptor binding activity.This work was supported by INSERM (CRL 827017) and the Fondation pour la Recherche Médicale Française.     

Lectin receptors in snail proteogalactans. II.Archachatina marginata andAchatina achatina (preliminary report)

Summary The lectin receptor sites on the proteogalactans from the albumin glands of West African land snails,Archachatina marginata andAchatina achatina have been studied by precipitin reactions using the agar-gel double diffusion technique with various lectins. The proteogalactans from both snails have predominantly terminal -D-galactose structures; but they show characteristic differences in the topographical features at the surfaces of the carbohydrate structures presumed to be compatible with the combining site for these lectins.     

Acetylcholine receptors in the gastrulating chick embryo

Summary Muscarinic acetylcholine receptors are present in the gastrulating chick embryo.     

Ethanol influence on insulin secretion from isolated rat islets

Summary This study was done to delineate the role of - and -adrenergic receptors and cyclic AMP in the mechanism of ethanol effects on insulin release from isolated islets. Rats were given an -adrenergic blocker, phentolamine, or a -adrenergic blocker, propranolol. In addition, ethanol 1 g/kg was given intragastrically 1 h prior to sacrifice. Glucose mediated insulin release from isolated islets was enhanced by phentolamine and decreased by propranolol. Ethanol treatment inhibited glucose-induced insulin release from isolated islets of control rats as well as those given phentolamine and/or propranolol. Insulin release from isolated islets in response to dibutyryl-cyclic AMP was attenuated by ethanol. Theophylline enhanced glucose mediated insulin release from control islets but ethanol treatment produced a significant inhibition of insulin response. The data suggest that the site of action of the deleterious effects of ethanol on insulin release from isolated islets in rat does not involve adrenergic system and cyclic AMP.Supported by the U.S. Veterans Administration     

Why do hormone receptors arise?

Conclusions In view of the foregoing considerations, it appears that the receptor-hormone relationship is, by origin, essentially a cell-environment (chemical) relationship which influences cell behavior. With the development of multicellularity, the interests of the single (individual) cell became subordinated to those of the cell population (community), and the cell-environment relationship became modified inasmuch as receptor activity became integrated into the functional program of the entire organism. Accordingly, the open program of the individual cell, which involved continuous dynamic changes of the membrane receptors under the influence of the signal molecules, was superseded by a closed program for the given receptor, which gave rise to a chemical memory of the cell. With multicellularity the cellular functions have become integrated into an almost entirely predetermined program in which the quality and operation of the receptors are encoded to maintain the system of regulation, and impart differentiating features to given types of target cells which distinguish them from others, and delimit the response potentials of the species. A limited openness of the pre-programed system exists in the early stage of ontogenesis, and accounts for certain individual variations within the limited potentials of the species.The answer to the question posed in the title of this paper is therefore the following: the hormone receptors arise because the external environment of the individual cell is transformed at the multicellular level to an internal environment, in which the random variety of environmental molecules is replaced by a predetermined set of ligands (signal molecules). Under these conditions the randomlypresented membrane patterns capable of signal reception are transformed to encoded receptor structures which execute a programed function of the closed system, but nevertheless preserve some primordial traits, which can explain many surprising observations in the field of receptor physiology.The Editors wish to thank Professor G. Csaba for having designed and coordinated this review.     

免疫激活:关于toll样受体与nod样受体的探索

toll样受体和nod受体在天然免疫应答中是重要的家族。激发配体促进受体相互作用的精确检测从而导致多重信号的形成和多级信号转导的触发。这个过程能导致促炎因子的上调、细胞凋亡和调控其他免疫防御。最近,在这些受体家族中识别激活配体和配体的分子基础的检测上有重大进展。理解这些过程,对于新的疫苗佐剂的开发、感染性疾病的治疗、炎症反应和潜在的疾病甚至癌症,都提供了必要的信息。