Melatonin-binding sites in the rat brain and pituitary mapped by in-vitro autoradiography

1989 ◽  
Vol 3 (1) ◽  
pp. 71-75 ◽  
Author(s):  
L. M. Williams
Keyword(s):  
Rat Brain ◽  
Binding Sites ◽  
Area Postrema ◽  
Specific Binding ◽  
Melatonin Receptors ◽  
Pars Tuberalis ◽  
Lower Affinity ◽  
High Affinity ◽  
In Vitro Autoradiography

ABSTRACT Using picomolar concentrations of [125I]iodomelatonin and in-vitro autoradiography, specific melatonin-binding sites have been mapped in the rat brain and pituitary. Using this same technique, high-affinity melatonin receptors had previously been identified in the suprachiasmatic nucleus (SCN) and median eminence regions of the rat hypothalamus. The presence of melatonin binding in the SCN has been confirmed, but the second area of binding has been identified as the pars tuberalis of the pituitary, and a completely novel area of binding is also reported in the area postrema. The existence of lower affinity melatonin receptors in the rat brain was also investigated using in-vitro autoradiography and higher concentrations of [125I]iodomelatonin. No further sites of specific binding were, however, disclosed.

Localization of vasopressin binding sites in rat brain by in vitro autoradiography using a radioiodinated V1 receptor antagonist

Neuroscience ◽  
1988 ◽  
Vol 27 (3) ◽  
pp. 749-761 ◽  
Author(s):  
P.A. Phillips ◽  
J.M. Abrahams ◽  
J. Kelly ◽  
G. Paxinos ◽  
Z. Grzonka ◽  
...  
Keyword(s):  
Receptor Antagonist ◽  
Rat Brain ◽  
Binding Sites ◽  
In Vitro Autoradiography

scholarly journals Influence of age on NMDA receptor complex in rat brain studied by in vitro autoradiography.

1990 ◽  
Vol 38 (12) ◽  
pp. 1725-1731 ◽  
Author(s):  
S Kito ◽  
R Miyoshi ◽  
T Nomoto
Keyword(s):  
Cerebral Cortex ◽  
Nmda Receptor ◽  
Rat Brain ◽  
Binding Sites ◽  
Recognition Site ◽  
Receptor Complex ◽  
In Vitro Autoradiography ◽  
Aged Brain ◽  
Nmda Receptor Complex

N-methyl-D-aspartate (NMDA) receptors are known to play an important role in learning and memory and to be involved in neuron cell death accompanying cerebral ischemia, seizures, and Alzheimer's disease. The NMDA receptor complex has been considered to consist of an L-glutamate recognition site, a strychnine-insensitive glycine modulatory site, and a voltage-dependent cation channel. In the present study, effects of age on an L-glutamate recognition site and a glycine site were examined in rat brain by quantitative in vitro autoradiography with [3H]-CPP and [3H]-glycine. Both [3H]-glycine and [3H]-CPP binding sites were most abundant in the hippocampus and cerebral cortex, and they showed a similar distribution pattern throughout the brain. [3H]-glycine binding sites were severely decreased in the telencephalic regions, including the hippocampus and cerebral cortex, in aged brain. Conversely, [3H]-CPP binding sites were well preserved in these brain areas. In the mid-brain regions and cerebellum, neither [3H]-glycine nor [3H]-CPP binding sites changed in the aged brain. Our results indicate that within the NMDA receptor complex, glycine receptors are primarily affected in the aging process.

scholarly journals The specific binding of the microtubule-associated protein 2 (MAP2) to the outer membrane of rat brain mitochondria

1989 ◽  
Vol 261 (1) ◽  
pp. 167-173 ◽  
Author(s):  
M Lindén ◽  
B D Nelson ◽  
J F Leterrier
Keyword(s):  
Rat Brain ◽  
Outer Membrane ◽  
Binding Sites ◽  
Specific Binding ◽  
Brain Mitochondria ◽  
Microtubule Associated Proteins ◽  
Cross Linkage ◽  
Associated Proteins ◽  
A Site

Purified mitochondria from rat brain contain microtubule-associated proteins (MAPs) bound to the outer membrane. Studies of binding in vitro performed with microtubules and with purified microtubule proteins showed that mitochondria preferentially interact with the high-molecular-mass MAPs (and not with Tau protein). Incubation of intact mitochondria with Taxol-stabilized microtubules resulted in the selective trapping of both MAPs 1 and 2 on mitochondria, indicating that an interaction between the two organelles occurred through a site on the arm-like projection of MAPs. Two MAP-binding sites were located on intact mitochondria. The lower-affinity MAP2-binding site (Kd = 2 x 10(-7) M) was preserved and enriched in the outer-membrane fraction, whereas the higher-affinity site (Kd = 1 x 10(-9) M) was destroyed after removing the outer membrane with digitonin. Detergent fractionation of mitochondrial outer membranes saturated with MAP2 bound in vitro showed that MAPs are associated with membrane fragments which contain the pore-forming protein (porin). MAP2 also partially prevents the solubilization of porin from outer membrane, indicating a MAP-induced change in the membrane environment of porin. These observations demonstrate the presence of specific MAP-binding sites on the outer membrane, suggesting an association between porin and the membrane domain involved in the cross-linkage between microtubules and mitochondria.

Enhancement of [3H]DAGO1 binding to rat brain by low concentrations of monovalent cations

1987 ◽  
Vol 65 (11) ◽  
pp. 2338-2345 ◽  
Author(s):  
Gordon T. Bolger ◽  
Kendall A. Marcus ◽  
Ronald Thibou ◽  
Phil Skolnick ◽  
Ben Avi Weissman
Keyword(s):  
Rat Brain ◽  
Binding Sites ◽  
Divalent Cations ◽  
Opiate Receptors ◽  
Opiate Receptor ◽  
Affinity Binding ◽  
High Affinity ◽  
Regulatory Effects ◽  
In Vitro Effects

The effects of mono- and di-valent cations and the nonhydrolyzable guanyl nucleotide derivative 5′-guanylimidodiphosphate (Gpp(NH)p) on the binding of the selective, high affinity μ-opiate receptor agonist, [3H]DAGO ([3H]Tyr-D-Ala-Gly-Mephe-Gly-ol), to rat brain membranes were studied in a low ionic strength 5 mM Tris–HCl buffer. Na+ and Li+ (50 mM) maximally increased [3H]DAGO binding (EC50 values for Na+,2.9 mM and Li, 6.2 mM) by revealing a population of low affinity binding sites. The density of high affinity [3H]DAGO binding sites was unaffected by Na+ and Li+, but was maximally increased by 50 mM K+ and Rb+ (EC50 values for K+, 8.5 mM and Rb+, 12.9 mM). Divalent cations (Ca2+, Mg2+; 50 mM) inhibited [3H]DAGO binding. Gpp(NH)p decreased the affinity of [3H]DAGO binding, an effect that was enhanced by Na+ but not by K+. The binding of the μ-agonist [3H]dihydromorphine was unaffected by 50 mM Na+ in 5 mM Tris–HCl. In 50 mM Tris–HCl, Na+ (50 mM) inhibited [3H]DAGO binding by decreasing the density of high affinity binding sites and promoting low affinity binding. The effects of Na+ in 5 mM and 50 mM Tris–HCl were also investigated on the binding of other opiate receptor agonists and antagonists. [3H]D-Ala-D-Leu-enkephalin binding was increased and inhibited, [3H]etorphine binding increased and was unchanged, and both [3H]bremazocine and [3H]naloxone binding increased by 50 mM Na+ in 5 mM and 50 mM Tris–HCl, respectively. These findings indicate that the in vitro effects of Na+ at μ- and possibly other opiate receptors in rat brain are dependent on the concentration of Tris–HCl used in the assay buffer, lower concentrations of Tris-HCl revealing novel regulatory effects for Na+ at μ-opiate receptors.

DEMONSTRATION OF MELATONIN-BINDING SITES ON THE PARS TUBERALIS OF THE RAT

1988 ◽  
Vol 119 (1) ◽  
pp. R1-R3 ◽  
Author(s):  
L. M. Williams ◽  
P. J. Morgan
Keyword(s):  
Suprachiasmatic Nucleus ◽  
Median Eminence ◽  
Binding Sites ◽  
Pars Tuberalis ◽  
Rat Hypothalamus ◽  
In Vitro Autoradiography

ABSTRACT Melatonin-binding sites have previously been identified in the suprachiasmatic nucleus (SCN) and median eminence (ME) of the rat. We have further investigated the localization of melatonin-binding sites in the rat hypothalamus and pituitary using the ligand [125I] iodomelatonin and in-vitro autoradiography. The presence of specific melatonin-binding sites in the SCN is confirmed; however the second area of melatonin binding is identified as the pars tuberalis of the pituitary and not the ME as previously described. No other areas which bound melatonin were found in either the pituitary or the hypothalamus.

scholarly journals Contribution of gangliosides to thyroxin binding with plasma membranes

1995 ◽  
Vol 41 (2) ◽  
pp. 28-30
Author(s):  
T. S. Saatov ◽  
F. Ya. Gulyamova ◽  
G. U. Usmanova
Keyword(s):  
Binding Sites ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
Specific Binding ◽  
Brain Cell ◽  
Cell Recognition ◽  
High Affinity ◽  
Specific Binding Sites

Besides intracellular receptors of thyroid hormones, specific binding sites for T3 and T4 were detected on plasma membranes (PM) of some cells and a relationship between membrane reception .and lipid composition of membranes shown. The parameters of 125I-T4 binding to highly purified PM of hepatic and cerebral cells of rats were studied. The hepatic and cerebral cellular membranes were found to contain two sites of hormone binding each, one of these sites being characterized by a high affinity and low capacity, and the other by low affinity and a higher binding capacity. The association constant of highly affine site of hepatocyte membranes was found to be higher than that of brain cell membranes. T4 membranous receptors may be significant in the process of cell “recognition" by the hormone. In vivo and in vitro experiments with 125I-T4 and 14C-labeled thyroxin in ganglioside fractions showed appreciable binding of the hormone to Gm3 fraction, this evidently pointing to participation of this, ganglioside in T4 interaction with membrane receptor. It is possible that gangliosides situated on membranous surface are components of or function as receptors.

The development of melatonin-binding sites in the ovine fetus

1994 ◽  
Vol 142 (3) ◽  
pp. 475-484 ◽  
Author(s):  
R J A Helliwell ◽  
L M Williams
Keyword(s):  
G Protein ◽  
Binding Sites ◽  
Early Stage ◽  
Specific Binding ◽  
Melatonin Receptors ◽  
Pars Tuberalis ◽  
Dependent Manner ◽  
Pars Distalis ◽  
Specific Expression ◽  
Fetal Sheep

Abstract The pineal hormone, melatonin, is important in the timing of seasonal reproduction in the sheep. Melatonin of maternal origin readily crosses the placenta; its function in the fetal sheep is, however, unclear. To gain an insight into the role of melatonin in ovine development we have identified specific melatonin receptors throughout gestation using 2-[125I]iodomelatonin and quantitative in vitro autoradiography. Specific binding was found at the earliest time studied at 30 days of gestation, over the developing thyroid (term=145 days). At 31 days of gestation specific labelling was found over the thyroid and pituitary glands, the spinal nerves, nasal cavity and developing bronchi. This binding was diminished by over 50% in the presence of 10−4 m GTPγS (an analogue of guanosine triphosphate) indicating that the 2-[125I]iodomelatonin binding at this early stage of gestation represents a receptor coupled to a regulatory G-protein. By 40 days of gestation specific binding was found over the nasal epithelium, cochlear epithelium, regions of the brain, especially the hind brain and the vestibulocochlear and glossopharyngeal nerves, and both the pars distalis and pars tuberalis of the pituitary. As gestation proceeded, labelling over the pars distalis appeared to become more scattered in nature while that on the pars tuberalis remained consistent. Saturation studies of both the neuronal and pituitary binding sites at 121 days of gestation and in the newborn lamb revealed a single class of high-affinity binding sites with Kd values in the picomolar range. Also at 121 days of gestation, binding over the fetal pars tuberalis was diminished in a dose-dependent manner by GTPγS, again confirming that specific binding is indicative of a receptor coupled to a regulatory G-protein. These data demonstrate a potential for sensitivity to melatonin from early in gestation, as well as the developmentally specific expression of the melatonin receptor in certain tissues, and suggest a wider role for melatonin in ovine fetal development than previously considered. Journal of Endocrinology (1994) 142, 475–484

Localization of binding sites for calcitonin gene-related peptide in rat brain by in vitro autoradiography

Neuroscience ◽  
1986 ◽  
Vol 19 (4) ◽  
pp. 1235-1245 ◽  
Author(s):  
P.M. Sexton ◽  
J.S. McKenzie ◽  
R.T. Mason ◽  
J.M. moseley ◽  
T.J. Martin ◽  
...  
Keyword(s):  
Rat Brain ◽  
Binding Sites ◽  
Calcitonin Gene Related Peptide ◽  
In Vitro Autoradiography ◽  
Related Peptide ◽  
Calcitonin Gene

Aldosterone binding in isolated tubules I. Biochemical determination in proximal and distal parts of the rabbit nephron

1982 ◽  
Vol 242 (1) ◽  
pp. F63-F68 ◽  
Author(s):  
N. Farman ◽  
A. Vandewalle ◽  
J. P. Bonvalet
Keyword(s):  
Binding Sites ◽  
Specific Binding ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Nuclear Fraction ◽  
Lower Affinity ◽  
High Affinity ◽  
Specific Binding Sites ◽  
Collecting Tubules ◽  
Binding Curve

Microbiochemical methods were applied to proximal tubules (PCT) and a mixture of distal and cortical collecting tubules (D + C) of rabbit kidney in order to define aldosterone binding sites. For each experiment, after incubation of kidney pyramids with [3H]aldosterone ([3H]A), either alone or in the presence of an excess unlabeled A, 100-150 mm of both categories of tubules were microdissected using collagenase. Specific binding was determined on the nuclear fraction of each sample. Aldosterone concentrations ranged from 2 X 10(-9) to 4.5 X 10(-8) M. No specific binding was detectable in PCT. Specific binding in D + C increased rapidly as a function of [3H]A concentration up to 5 X 10(-9) M and then more slowly. No plateau was reached. Both the absence of saturation of the binding curve and the curvilinear aspect of the Scatchard plot suggested the presence of two binding sites, one of high affinity, presumably a mineralocorticoid site, and the other of lower affinity, possibly a glucocorticoid site. These experiments suggest that the distal structures of the nephron, located in the cortex, are the main sites of binding of aldosterone and contain a high number of specific binding sites for this hormone.

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