Human β-endorphin: Development of tolerance and behavioral activity in rats

Liang fu Tseng, Horace H. Loh, Choh Hao Li

Research output: Contribution to journalArticlepeer-review

92 Scopus citations


Human β-endorphin produced a potent antinociceptive response as estimated by the tail-flick test in rats after intraventricular injection. On a molar basis, the peptide was 21 times more potent than morphine and in addition, the peptide produced morphine-like catatonia and hypothermia. These responses were blocked by naloxone. Repeated injections of the peptide induced tolerance to analgesic response, catatonia and hypothermia. Cross tolerance to morphine was also observed.

Original languageEnglish (US)
Pages (from-to)390-396
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - Jan 24 1977

Bibliographical note

Funding Information:
by the National Institute of Drug (H.H.L.), and NIH Grant GM-2907 Institute of Mental Health Research


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