Skip to main content
eScholarship
Open Access Publications from the University of California

UC Irvine

UC Irvine Previously Published Works bannerUC Irvine

Neonatal administration of β-endorphin produces “chronic” insensitivity to thermal stimuli

Abstract

Male and female rat pups were injected with β-endorphin, naloxone or a saline control solution during days 2-7 postnatally. At 90 days of age the rats were tested for analgesia with the tail flick test. Testing was conducted during the first 2 hours of the light and the dark cycle. In both sexes and during both phases of the light cycle rats treated with β-endorphin as infants evidenced a significant elevation in threshold for painful thermal stimuli. Early treatment with naloxone also resulted in elevated threshold for thermal stimuli. Administration of naloxone to these rats as adults did not reverse the analgesic effect. It was concluded that early exposure to β-endorphin results in permanent changes in behavior perhaps by altering the interaction of endogenous opiates with their binding sites during a ciritcal period of opiate receptor development. © 1979.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View