alpha(1B) adrenergic receptors in gonadotrophin-releasing hormone neurones: relation to Transport-P.
British Journal of Pharmacology
336 - 344.
1. Peptidergic neurones accumulate amines via an unusual uptake process, designated Transport-P. [(3)H]-prazosin binds to alpha(1) adrenoceptors on these cells and is displaceable by unlabelled prazosin in concentrations up to 10(-7) M. However, at greater concentrations of prazosin, there is a paradoxical accumulation of [(3)H]-prazosin which we have attributed to Transport-P. Uptake of prazosin via Transport-P is detectable at 10(-10) M prazosin concentration, is linear up to 10(- 7) M and at greater concentrations becomes non-linear. In contrast, in noradrenergic neurones, noradrenaline uptake is linear and saturates above 10(-7) M. In noradrenergic neurones and in non-neuronal cells, there is no uptake of prazosin in concentrations up to 10(-6) M, suggesting that Transport-P is a specialised function of peptidergic neurones. 2. Using a mouse peptidergic (gonadotrophin-releasing hormone, GnRH) neuronal cell line which possesses Transport-P, we have studied the interaction of alpha(1) adrenoceptors with Transport-P. Polymerase chain reactions and DNA sequencing of the products demonstrated that only the alpha(1B) sub-type of adrenoceptors is present in GnRH cells. 3. In COS cells transfected with alpha(1b) adrenoceptor cDNA and in DDT(1) MF-2 cells which express native alpha(1B) adrenoceptors, [(3)H]-prazosin was displaced by unlabelled prazosin in a normal equilibrium process, with no prazosin paradox in concentrations up to 10(-6) M. In DDT(1) MF-2 cells, [(3)H]-prazosin was displaced likewise by a series of alpha(1) adrenergic agonists, none of which increased the binding of [(3)H]-prazosin. Hence, the prazosin paradox is not due to some function of alpha(1) adrenoceptors, such as internalization of ligand-receptor complexes. 4. In neurones which possess Transport-P, transfection with alpha(1b) adrenoceptor cDNA resulted in over-expression of alpha(1B) adrenoceptors, but the prazosin paradox was unaltered. Thus, alpha(1) adrenoceptors and Transport-P mediate distinct functions in peptidergic neurones
|Title:||alpha(1B) adrenergic receptors in gonadotrophin-releasing hormone neurones: relation to Transport-P|
|Additional information:||UI - 21068363 LA - eng RN - 0 (Adrenergic alpha-Antagonists) RN - 0 (Carrier Proteins) RN - 0 (RNA, Messenger) RN - 0 (Receptors, Adrenergic, alpha-1) RN - 19216-56-9 (Prazosin) RN - 33515-09-2 (Gonadorelin) RN - 51-41-2 (Norepinephrine) RN - 9007-49-2 (DNA) PT - Journal Article DA - 20010126 IS - 0007-1188 SB - IM CY - England|
|Keywords:||ACCUMULATION, adrenergic receptors, agonist, agonists, Al, ALPHA, ALPHA-1-ADRENERGIC RECEPTOR, As, BINDING, BINDS, Biological Transport, cDNA, cell, Cell Line, CELL-LINE, CELLS, CHAIN, CHAIN-REACTION, CO, COMPLEX, COMPLEXES, Concentration, COS Cells, DISTINCT, DNA, English, equilibrium, expression, FEMALE RAT, function, gonadotrophin-releasing hormone, hormone, Hypothalamus, interaction, Internalization, LINE, LINEAR, M, MEDIATE, MESSENGER- RNA, MOLECULAR-CLONING, mouse, nature, neuronal cells, Neurones, non-linear, nonlinear, NORADRENALINE, OVEREXPRESSION, PARADOX, PEPTIDERGIC NEURONS, polymerase, Polymerase Chain Reaction, POLYMERASE-CHAIN-REACTION, POSTSYNAPTIC NEURONS, PRAZOSIN, Preoptic Area, process, processes, product, PRODUCTS, Publishing, Receptor, receptors, RIBONUCLEIC-ACID, sequencing, SERIES, SUBTYPE, Transfection, uptake, Adrenergic alpha-Antagonists, Animal, biosynthesis, Carrier Proteins, Cells, Cultured, drug effects, genetics, Gonadorelin, IM, LA, MESSENGER, metabolism, neurons, non-neuronal, Norepinephrine, pharmacology, physiology, PROTEIN, Proteins, Receptors, Adrenergic, alpha-1, Rna, RNA, Messenger|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Medicine (Division of)|
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