Peptides related to β‐lipotropin with opioid activity

Structure-Activity Relationships of Enkephalin-Like Peptides

“…The inhibition of intracellular levels of cAMP (basal, or after PGE1 stimula tion) in neuroblastoma X glioma hybrid cells has been followed using a restricted range of analogues (55,56). In general, the results relate well with those obtained in the MVD assay; the potency of Leu-and Met-enkephalin is high (only the Nle5 analogue is more potent), and the potency of ana logues relates to structure in a similar way in both assays.…”

Endorphins exert opiate‐like action on neuroblastoma X glioma hybrid cells

“…In their influence on the hybrid cells the endorphins are approximately one order of magnitude less potent than the enkephalins. On the other hand it is comparable to that of two other fragments of P-LPH, /_CLPH-[61-691 and@LPH-[61-751 [21]. Thus, it appears that elongation at the carboxyl end of the peptide chain of enkephalin yields peptides of reduced potency.…”

“…Opiates [ 17,181, the enkephalins [ 19,201 and some of their analogues [21,22] have also been demonstrated to act on the opiate-receptors of neuroblastoma X X glioma hybrid cells in culture. These cells exhibit many properties characteristic of neurons [23-251. In the presence of prostaglandin Er (PGEr) the concentration of adenosine 3'5'-cyclic monophosphate (cyclic AMP) is increased in the hybrid cells [26] .…”

Neuroblastoma × Glioma Hybrid Cells Synthesize Enkephalin‐Like Opioid Peptides

“…This is much less than is present in rat brain (Hughes et al, 1977). Met-Enk is equipotent to Leu-Enk in both the cyclic AMP assay (Wahlstrom et al, 1977) and the binding assay (Diekmann et al, 1978).…”