Yang Hy

Regional distribution of leu and met enkephalin in rat brain

Abstract The regional distribution of leu- and met-enkephalin in the brain of rats killed with a microwave beam focused on the skull was studied using a radioimmunoassay. The enkephalin content varied significantly in the seven regions of rat brain studied: the highest concentration was found in striatum and the lowest in cerebellum and hippocampus. In every brain region studied, the content of met- was higher than that of leuenkephalin. In the brain of rats killed with focused microwave, the content of enkephalins is higher than in brains of rats killed by decapitation. It seems unlikely that this difference is due to an artifact caused by microwave radiation.

On the locaticn of methicnine enkephalin neurons in rat striatum

Abstract Various types of brain lesions were performed in an attempt to elucidate the cell location of met-enkephalin present in the striatum. After hemitransection, at a level between striatun and substantia nigra, there was no decrease of met-enkephalin content in the striatun. This suggests that enkephalinergic neurons do not project from mesencephalon to striatum. Ten days after intrastriatal injection of kainic acid (1 μg), met-enkephalin content in the striatum decreases more than 50% in the injected side. This evidence suggests that neostriatum may contain a considerable number of met-enkephalin intemeurons or that the cell bodies of enkephalinergic neurons of striatum may be located in globus pallidus.

Secretion of enkephalin-like peptides from canine adrenal gland following splanchnic nerve stimulation

Plasma obtained from dogs implanted with an indwelling catheter in the left adrenal lumbar vein contains a greater amount of (met5)-enkephalin-like peptides than does plasma sampled from jugular and femoral veins or femoral artery. Stimulation of the splanchnic nerve ipsilateral to the cannulated vein results in a voltage dependent rise in blood pressure and an increase in the content of (met5)-enkephalin-like peptides in the lumbar vein plasma. Gel filtration reveals that this increase can be accounted by a greater amount of the low molecular weight enkephalin-like peptide(s). Analysis of the material present in this chromatographic peak by high voltage paper electrophoresis followed by chromatography reveals two peptides, one of them having a migration distance and Rf similar to that for the (met5)-enkephalin standard. This study shows the (met5)-enkephalin-like peptides can be released into the circulation following splanchnic nerve stimulation of the adrenal gland.

Detection of two endorphin-like peptides in nucleus caudatus.

Abstract Two endorphin-like peptides with molecular weight larger than [met5]-enkephaiin were detected in bovine caudate. They were separated from [met5]-enkephal in by Biogel P-2 column chromatography and detected with a [met5]-enkephaiin antibody which possesses some affinity for endorphins larger than [met5]-enkephaiin but smaller than β-endorphin. Our antibody has some affinity for α-endorphin but we can exclude that the two new peptides are α, β-endorphin or β-lipotropin. It is suggested that in nucleus caudatus the two endorphin-like peptides we have detected may function as precursors of [met5]-enkephalin.

Elevation of met5-enkephalin and β-endorphin hypothalamic content in rats receiving anorectic drugs: Differences between d-fenfluramine and d-amphetamine

D-Fenfluramine, an anorectic that releases serotonin (5-HT), repeatedly injected in rats (15 mg/kg per day) enhanced the met5-enkephalin and beta-endorphin content of the hyhpothalamus. The onset of this effect was slow, reaching a peak at 5 days; the increase in beta-endorphin gradually declined toward control level while the drug was still being administered although that of met-enkephalin persisted for 15 days. The elevation of the opioid peptide content of the hypothalamus was temporally associated with a slowing in the rate of body weight increase. A transient, small, increase in striatal met-enkephalin content was also induced by repeated D-fenfluramine injections; however the met-enkephalin content of frontal cortex, hippocampus and brainstem was not affected. A modification of the beta-endorphin content of hypothalamus was not seen after acute injection of D-fenfluramine or D-amphetamine but an increase was observed during repeated treatment with D-fenfluramine. Repeated injections of D-amphetamine for 5 days (4.5 mg/kg per day) failed to increase either the met-enkephalin or the beta-endorphin content of the hypothalamus. These data suggest that the anorexia elicited by repeated injections of D-fenfluramine but not that elicited by D-amphetamine, includes a participation by hypothalamic and beta-endorphin stores.