P Cuatrecasas

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The distribution of immunoreactive enkephalin in rat brain and spinal cord was studied by immunoperoxidase staining using antiserum to leucine-enkephalin ([Leu5]-enkephalin) or methionine-enkephalin ([Met5]-enkephalin). Immunoreactive staining for both enkephalins was similarly observed in nerve fibers, terminals and cell bodies in many regions of the(More)
Insulin action may involve the intracellular generation of low molecular weight substances that modulate certain key enzymes. The production of two substances that regulate the activity of adenosine 3',5'-monophosphate phosphodiesterase was evaluated in cultured myocytes by incorporation of radiolabeled precursors. Insulin caused the rapid hydrolysis of a(More)
Analgesic activities of morphiceptin, beta-casomorphins, [D-Ala2, D-Leu5]enkephalin and Sandoz peptide, FK 33-824, were examined by intracerebroventricular administration in rats. Their relative potencies in vivo were compared with their receptors binding activities. The receptors binding affinities were determined from the competition curves against(More)
Neuroblastoma cells were used to study the surface distribution and organization of opiate (enkephalin) receptors and the possible relevance of changes in these variables to biological functions. Opiate receptors readily form clusters that are visible by image-intensifier fluorescent microscopy and are localized on both the cell body and processes. These(More)
The simultaneous addition of [D-Ala2, D-Leu5]-enkephalin and morphiceptin at concentrations at which 98% of enkephalin (delta) and morphine (mu) receptors are occupied only partially inhibits the binding of [3H]diprenorphine to rat brain membranes. These conditions, furthermore, do not affect the curves for displacement of [3H]diprenorphine binding by(More)