Preference for morphine and drug-seeking behavior in morphine dependent rats

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Previous studies established morphine-pretreated rats' preference for morphine-admixed food.
• This research further investigates morphine preference using varied methodologies and conditions.

Purpose of the Study:

• To assess morphine preference in rats using both five and two cup methods.
• To examine the impact of limited feeding time on morphine preference.
• To determine the dose-dependency of morphine preference after stabilization.

Main Methods:

• Utilized five and two cup choice methods to assess food preference in rats.
• Administered morphine through pretreatment and limited feeding schedules.
• Observed preference rates following subcutaneous morphine injections and varying drug concentrations.

Main Results:

• Morphine-pretreated rats showed a consistent preference rate of approximately 60-61% for morphine-admixed food.
• Limited feeding time progressively increased the preference rate for morphine, stabilizing around 60%.
• Subcutaneous morphine administration demonstrated a dose-dependent effect on preference, and concentration changes affected preference in parallel.

Conclusions:

• These findings clearly demonstrate drug-seeking behavior in rats.
• Morphine treatment enhances spontaneous intake of morphine-admixed food, reinforcing drug-seeking patterns.