Distinct ethanol drinking microstructures in two replicate lines of mice selected for drinking to intoxication.

Area of Science:

• Neuroscience and Behavior
• Genetics and Animal Models
• Alcohol Research

Background:

• The High Drinking in the Dark (HDID) mouse model was selectively bred for high voluntary ethanol consumption.
• Previous studies showed HDID-1 mice consume larger, not longer, ethanol drinking bouts compared to controls.
• Understanding drinking microstructure is crucial for elucidating mechanisms of high alcohol intake.

Purpose of the Study:

• To investigate drinking microstructure in HDID mice during binge-like ethanol intake.
• To determine if selection for high ethanol consumption has induced distinct drinking patterns.
• To compare drinking microstructure across different fluid types (ethanol, saccharin) and access conditions.

Main Methods:

• Utilized the limited access Drinking in the Dark (DID) test with a lickometer system.
• Assessed drinking microstructure in HDID-1, HDID-2, and control HS/Npt mice.
• Employed a continuously recording BioDAQ system for detailed analysis of drinking bouts and lick volumes.

Main Results:

• HDID-1 mice exhibited larger ethanol bout sizes, attributed to increased lick volume, compared to HS mice.
• HDID-2 mice displayed a different microstructure characterized by more frequent drinking bouts.
• These distinct microstructures in HDID-1 and HDID-2 mice both resulted in high ethanol intake and blood ethanol concentrations (BECs).

Conclusions:

• Selection for high ethanol intake has generated at least two distinct drinking microstructures.
• HDID-1 mice show a large bout size phenotype specific to alcohol, while HDID-2 mice exhibit high bout frequency across fluid types.
• These findings highlight the complex behavioral adaptations underlying voluntary alcohol consumption and intoxication.