Inhibition of morphine analgesia by ascorbate

Area of Science:

• Pharmacology and Toxicology
• Biochemistry

Background:

• Morphine is a potent opioid analgesic.
• Ascorbate (vitamin C) is an antioxidant with potential interactions with opioid receptors.

Purpose of the Study:

• To investigate the in vivo effect of ascorbate on morphine analgesia.
• To determine if ascorbate interferes with morphine's mechanism of action.

Main Methods:

• Mice were administered single oral doses of ascorbate prior to morphine.
• Analgesic effects were measured using the tail-flick test.
• Lethal doses of morphine were used to assess protective effects.

Main Results:

• Ascorbate dose-dependently decreased morphine's analgesic effect.
• Inhibition of analgesia onset rapidly (2 hours) and lasted long (48 hours).
• High ascorbate doses protected mice against lethal morphine doses.

Conclusions:

• Ascorbate interferes with morphine's analgesic and lethal effects in vivo.
• This supports in vitro findings that ascorbate may destroy opioid receptors.
• Further research is needed to elucidate the in vivo mechanism.