Dane Liston

Methyl-β-carboline-induced convulsions are antagonized by Ro 15-1788 and by propyl-β-carboline

Abstract Injected i.v. into baboons, Ro 15-1788 (a benzodiazepine antagonist) and propyl-β-carboline-3-carboxylate did not modify either the behavior or the electroencephalogram at doses up to 2 mg/kg. Methyl-β-carboline-3-carboxylate is a potent convulsant at doses of 20 μg/kg in photosensitive baboons and 100 μg/kg in non-photosensitive baboons. These convulsive doses of methyl-β-carboline-3-carboxylate are effectively antagonized by 0.5 mg/kg of Ro 15-1788 and also by 2 mg/kg of propyl-β-carboline-3-carboxylate.

Characterization of new enkephalin-containing peptides in the adrenal medulla by immunoblotting.

Immunoblotting combined with radioimmunoassays (RIAs) directed specifically towards certain sequences of the proenkephalin molecule has been used to characterize the enkephalin‐containing peptides (ECPs) present in the bovine adrenal medulla. Immunoblotting allowed the simultaneous visualization of all ECPs present in a crude extract of this gland. Combining this technique with RIAs we have been able to characterize a new high molecular mass ECP, a 23.3‐kDa protein which contains the amino‐terminal part of proenkephalin and ends with the sequence of Leu‐enkephalin at its carboxy‐terminus.

Synenkephalin is coreleased with Met-enkephalin from neuronal terminals in vitro.

Synenkephalin, the amino-terminal 1-70 residues of proenkephalin, is released intact from bovine globus pallidus and neurohypophysis following potassium-induced depolarization in vitro via a Ca2+-dependent mechanism. The release of synenkephalin accompanies that of Met-enkephalin in a molar ratio of 1/4. In contrast to Met-enkephalin, which is readily destroyed when released, synenkephalin is not destroyed.

Distribution and characterization of synenkephalin immunoreactivity in the bovine brain and pituitary

The distribution of synenkephalin, the N-terminal fragment of proenkephalin, was studied in various parts of the bovine brain (globus pallidus, caudate nucleus, hypothalamus) and in the posterior pituitary by the use of a radioimmunoassay. The distribution of synenkephalin-immunoreactivity (IR) was compared to the distribution of Met-enkephalin-IR. Gel exclusion chromatography was used to examine the molecular forms of the immunoreactivities present in the tissues. The distribution of synenkephalin-IR was similar to the distribution of Met-enkephalin-IR, with a molar ratio of Met-enkephalin/synenkephalin ranging between 2.7 and 5.9. In all regions tested except the hypothalamus the synenkephalin-IR was present as a single species. However, in the hypothalamus a small amount of IR material (3% of the total synenkephalin-IR) was detected in fractions where larger Met-enkephalin-containing peptides eluted. Based on the concordance between the molar ratio of Met-enkephalin to synenkephalin found in the tissues and the molar ratio present in the sequence of adrenal proenkephalin, it is concluded that the brain and adrenal glands utilize a similar precursor for enkephalin biosynthesis.

Synenkephalin in bovine and human spinal cord.

SummarySynenkephalin, which comprises 70 residues at the aminoterminal of proenkephalin, was studied with immunocytochemical methods in the human and bovine spinal cord. Immunoreactive fibers had the same general distribution as methionine-enkephalin, but not as leucine-enkephalin fibers. They were found in all spinal layers and were most numerous in lamina II (outer zone) and V–VI (lateral portion). Synenkephalin immunoreactivity was overall less dense than that of the enkephalins. These results suggest that proenkephalin is the precursor protein also in enkephalinergic neurons of the human spinal cord.

Characterization of a new 23 kDalton enkephalin-containing protein in the bovine adrenal medulla

Immunoblots combined with specific radioimmunoassays (RIAs) have been used to visualize simultaneously all the enkephalin-containing peptides (ECPs) present in a crude extract of bovine adrenal medulla. They have allowed the characterization of a new high molecular weight ECP which has a molecular weight of 23.3 kDalton, contains the amino-terminal part of proenkephalin and ends with the sequence of Leu-enkephalin at its carboxy-terminus.

Release of synenkephalin from neuronal terminals in vitro

Synenkephalin, the amino-terminal 1-70 residues of proenkephalin is released intact from bovine globus pallidus following potassium-induced depolarization in vitro via a Ca++ dependent mechanism. The release of synenkephalin accompanies that of Met-enkephalin in a molar ratio of 1/4. In contrast to Met-enkephalin which is readily destroyed when released, synenkephalin is not destroyed.