Corticosteroid receptors in the central nervous system of the rat.

Corticosteroid receptors were demonstrated in the medial hypothalamus, the hippocampus and the parietal cortex of the rat while no such receptors were found in the hypophysis, the amygdala and the anterior hypothalamus. The findings suggest the role of extrahypothalamic regions in the perception of corticosteroid feedback as well as in the regulation of the hypothalamo-hypophysial-adrenal function and do not support the assumption that corticosteroids would inhibit corticotrophin secretion by acting directly on the hypophysis.     

The nature of receptors regulating the formation of cyclic AMP in brain tissue.

Extensive studies of the past seven years have provided fundamental information on the pharmacological properties of receptors controlling formation of cyclic AMP in brain slices and homogenates. Receptors for adenosine, α- and β-adrenergic agonists, dopamine, serotonin, H₁- and H₂-histaminergic agonists, and prostaglandins of the E series have been defined and evidence for a glutamate receptor has been presented. Extrapolation of such pharmacological data to studies with whole animals should provide important information as to the physiological significance of specific cyclic AMP-generating systems to the function of the intact brain.     

Substance P receptors in mammalian central nervous system.

1. Multiple distinct affinity states or sites of substance P (SP) receptors exist in freshly-prepared rat brain membranes. 2. Substance P receptors may couple with islet-activating protein (pertussis toxin) sensitive GTP-binding protein(s). 3. Substance P receptors may be regulated Mg2+ and Na+ in an opposite manner. 4. Some important factor(s), in addition to GTP-binding protein, appear to be involved in SP binding activity. 5. An apparent molecular weight of the SP binding site is approximately 46,000 Da.     

Rapid axonal transport in vitro. Effects of derivatives of cyclic AMP and other agents acting on the cyclic AMP system

The effects of agents known to affect the cyclic AMP (cAMP) system in nervous tissue have been studied on the rapid axonal transport in vitro of [³H]leucine-labeled proteins in the frog sciatic nerve. The transport was inhibited by 3 different cAMP analogues; dibutyryl cAMP (1 mM), zeatin (0.5 mM), and zeatin riboside (0.5 mM), whereas another N⁶-substituted adenine derivative, N⁶-, isopentyl-adenine (DMA) (0.5 mM), and also dibutyryl cyclic GMP (1 mM), lacked effects. Two inhibitors of cAMP phosphodiesterases, papaverine and RO 207222, increased the level of cAMP in the nerve and arrested the transport. Papaverine was very potent and caused a reversible transport block at 0.05 mM. Adenosine (3 mM) increased the cAMP content about 16 times, much more than any of the other drugs tested, but only inhibited the transport by about 50%. Veratridine, a depolarizing agent, irreversibly blocked the transport at a low concentration (0.01 mM), which did not change the cAMP level. Transport inhibitory effects by another depolarizing substance, ouabain, and tricyclic psychotropic agent, chlorpromazine, have been described earlier. Ouabain (0.1 mM), in contrast to chlorpromazine (0.1 mM), caused a small increase in the cAMP content. The present results do not suggest the existence of a close relationship between rapid axonal transport and the cAMP system. Transport inhibitory effects due to disturbed energy metabolism will be discussed.     

Lysophospholipids and their receptors in the central nervous system

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), two of the best-studied lysophospholipids, are known to influence diverse biological events, including organismal development as well as function and pathogenesis within multiple organ systems. These functional roles are due to a family of at least 11 G protein-coupled receptors (GPCRs), named LPA_1–6 and S1P_1–5, which are widely distributed throughout the body and that activate multiple effector pathways initiated by a range of heterotrimeric G proteins including G_i/o, G_12/13, G_q and G_s, with actual activation dependent on receptor subtypes. In the central nervous system (CNS), a major locus for these signaling pathways, LPA and S1P have been shown to influence myriad responses in neurons and glial cell types through their cognate receptors. These receptor-mediated activities can contribute to disease pathogenesis and have therapeutic relevance to human CNS disorders as demonstrated for multiple sclerosis (MS) and possibly others that include congenital hydrocephalus, ischemic stroke, neurotrauma, neuropsychiatric disorders, developmental disorders, seizures, hearing loss, and Sandhoff disease, based upon the experimental literature. In particular, FTY720 (fingolimod, Gilenya, Novartis Pharma, AG) that becomes an analog of S1P upon phosphorylation, was approved by the FDA in 2010 as a first oral treatment for MS, validating this class of receptors as medicinal targets. This review will provide an overview and update on the biological functions of LPA and S1P signaling in the CNS, with a focus on results from studies using genetic null mutants for LPA and S1P receptors. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.     

Gamma-aminobutyric acid receptors in the central nervous system

Conclusions Recent research has raised a whole set of new and interesting points concerning the arrangement of GABA receptor sites. The most important of these is the separation of two distinct GABA receptor categories, namely bicuculline-sensitive and bicuculline-insensitive, which control the chloride and calcium conductance of the postsynaptic membrane. Information regarding the membrane and intracellular processes involved in activating GABA_B receptors remains particularly limited as yet. Accordingly, findings from the literature maintain that calcium ions are not the sole transmitter of transmembrane current during activation of this category of receptor, while data from biochemical research suggests that the intracellular activity of cAMP and cGMP is changed when bicuculline-insensitive receptors are activated [15, 38]. It should be added that the physiological role played by these receptors is not yet known.The study of bicuculline-sensitive GABA receptor complexes using benzodiazepines, as well as their antagonists and reversible agonists, also offers considerable interest. Such research is particularly apposite in view of the widely discussed possibility of related endogenous-type substances existing and consequently of hitherto unknown inherent mechanisms controlling inhibitory processes within the CNS.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 273–282, March–April, 1986.     

Benzodiazepine receptors in the mammalian central nervous system

A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 2, pp. 269–279, March–April, 1988.     

Acetylcholine receptors in the central nervous system of Drosophila melanogaster.

Mating between gametes of the biflagellated unicellular green alga Chlamydomonas reinhardi consists of several events culminating in zygote formation. Initially, the cells agglutinate by their flagellar tips. This is followed by pairing, cell wall loss, and cell fusion. Here we report on the relationship between the length of the flagellum, and the cells' ability to agglutinate, undergo cell wall loss (as measured by medium carbohydrate accumulation), and to form zygotes. We found that deflagellated gametes regained the potential for sexual agglutination when the flagella had regenerated to less than 3 μm (compared to the full length flagella of approx. 11 μm), while medium carbohydrate appeared only after the flagella had reached an average length greater than 5 μm. By inhibiting flagellar regeneration with cycloheximide or colchicine, we determined that carbohydrate release is related to the length of the flagellum and not to the time after deflagellation. A flagellar length dependence similar to that of carbohydrate release was also observed when we measured the relationship between the gametes' ability to fuse and flagellar length.     

Characterization of immunofluorescent cyclic GMP-positive fibres in the central nervous system.

The cyclic GMP immunofluorescent fibres in the rat central nervous system have been characterized as processes of fibrous astrocytes, on the basis of distribution and similarity to the localization of glial fibrillary acidic protein. The neuroglial localization of the nucleotide is discussed together with the surprising observation that these cyclic GMP positive fibres are absent from the central nervous system of the adult mouse.     

Bellini, Carpaccio, and receptors in the central nervous system.

With the convergence of science from the fields of neurobiology and immunology, many exciting and challenging surprises have emerged regarding cytokines, neuroendocrine hormones, neuropeptides, excitatory amino acids, and their receptors. For some time neurobiologists have known that subsets of neural cells had different receptors for the same ligand. Those subsets of cells could be as different as neurons and astrocytes and as closely related as astrocytes from different lineages or anatomical areas. The neurobiological puzzle has been to determine the functional meaning of these differences. Immunologists in contrast have long understood the clear cut differences between T and B lymphocytes or T helper/inducer and T cytotoxic/suppressor cells and their response to cytokines. However, it is only very recently that they have discovered preferential use by these cells of different receptors for an identical cytokine ligand. Indeed, identical cytokines in the central nervous system and immune response may induce their pleiotropic responses by utilizing different receptors in these two systems. Immunologic paradigms may help neurobiologists predict the existence of subsets of neural cells and their function. Likewise, neurobiology may enable immunologists to predict roles for receptors in gene families as well as the existence of as yet unidentified receptors.     

Amine sulfate formation in the central nervous system

The sulfates of norepinephrine, dopamine (DA), and serotonin (5-hydroxytryptamine [5HT]) are present in the cerebrospinal fluid (CSF) of laboratory animals and humans. The amounts of sulfated amines in human CSF always greatly exceed the amounts of the free amines. The enzyme responsible for sulfation, phenol sulfotransferase (PST) (EC 2.8.2.1), has been detected in the brain tissue of several species, including humans. PST in the human brain has a high affinity for the amines but it is a low-capacity enzyme. Accordingly, sulfation appears to be of greater significance in the economy of the amines under quiescent conditions than during conditions of increased release of transmitter. Recent evidence suggests that a fraction of the conjugated amines in CSF enters from plasma because in the African green monkey, DA sulfate and 5HT sulfate cross the blood-CSF barrier after i.v. injection. In addition, in humans there are no increases in the concentration of amine sulfates from lumbar to ventricular CSF that would also be compatible with a partly peripheral origin for the amine sulfates. However, it appears that at least a portion of the amine sulfates in CSF originate in the central nervous system because the ratios of [CSF amine sulfates]/[plasma sulfates] are never as high after i.v. injection as under basal conditions.     

NMDA受体与中枢神经系统的发育

离子型谷氨酸受体分为NMDA型和非NMDA型两类,其中NMDA型受体与中枢神经系统发育关系密切。本文综述了NMDA受体的分子特性及NMDA受体五种亚单位NR1、NR2A、NR2B、NR2C和NR2D在动物出生后脑内的时空表达;NMDA受体亚单位在发育中的作用以及NMDA受体活性的胞内调节机制。     

Neurotransmitter-controlled steroid hormone receptors in the central nervous system

Results are discussed indicating that neurotransmitters affect steroid hormone activity not only by controlling via neuroendocrine events the hypophysial-gonadal and hypophysial-adrenal axes, but also by modulating cell responsiveness to steroids in target cells. Hyper- or hypoactivity of pineal nerves result in enhancement or impairment of estradiol and testosterone effects on pineal metabolism in vivo and in vitro. Pineal cytoplasmic and nuclear estrogen and androgen receptors are modulated by norepinephrine released from nerve endings at the pinealocyte level. Neural activity affects the cycle of depletion-replenishment of pineal estrogen receptors following estradiol administration. Another site of modulation of steroid effects on the pinealocytes is the intracellular metabolism of testosterone and progesterone; nerve activity has a positive effect on testosterone aromatization and a negative effect on testosterone and progesterone 5α-reduction. NE activity on the pineal cells is mediated via β-adrenoceptors and cAMP. In the central nervous system information on the neurotransmitter modulation of steroid hormone action includes the following observations: (a) hypothalamic deafferentation depresses estrogen receptor levels in rat medial basal hypothalamus; (b) changes in noradrenergic transmission affect, via α-adrenoceptors, the estradiol-induced increase of cytosol progestin receptor concentration in guinea pig hypothalamus; (c) cAMP increases testosterone aromatization in cultured neurons from turtle brain; (d) electrical stimulation of dorsal hippocampus augments, and reserpine or 6-hydroxydopamine treatment decrease, corticoid binding in cat hypothalamus. In the adenohypophysis changes in dopaminergic input after median eminence lesions or bromocriptine treatment of rats result in opposite modifications of pituitary estrogen receptor levels. Therefore all these observations support the view that neurotransmitters can modulate the attachment of steroid hormones to their receptors in target cells.