Suppression of fixed-ratio operant behavior by β-endorphin

L. Lichtblau, L. H. Fossom, S. B. Sparber

Research output: Contribution to journalArticlepeer-review


Long-Evans hooded rats maintained on a fixed-ratio (FR15) schedule of food reinforcement were given 0.3, 1.5 or 2.9 nmole (1, 5 or 10 μg) of synthetic camel β-endorphin. This produced a dose-related suppression of FR15 responding during the 30 min behavioral session with an ED50 of 0.7 nmole. On a molar basis, β-endorphin is 21 times more potent than morphine in suppressing fixed-ratio responding.

Original languageEnglish (US)
Pages (from-to)No. 355
Issue number2
StatePublished - Jan 1 1977


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