Alcohol Consumption

Alcohol Consumption

Overall: Two days of water, followed by two, 2-day choices of 6% ethanol vs. water, with a position change between days 1-2 and 3-4.

After the cocaine test of Friday, mice are placed by pairs into a new home cage (i.e., bedding change) with a water bottle that has a sipper tube (something that Portland site lacks on routinely used water bottles). They are then moved to the drinking study room (if this room differs from the colony where they have been housed.)

The following Monday AM, starting at approximately 9 AM, two graduated drinking cylinders (hereafter sometimes called bottles or tubes) per cage are filled with tap water, in preparation for placement on the cages. All manipulations in this study are done starting at 10 AM each day, and are performed serially from top left to bottom right, in the same order each day, at as near the same rate as possible.

There is a blank cage at the top left (#1) position, and another at the bottom right (last) position. If two racks are required, then an additional two control cages are used, flanking the experimental mice. (Multiple control tubes allows assessment of evaporation in an instance where the control tube leaks). Starting at 10 AM, mice are placed into individual cages. They are NOT weighed. Each cage has food pellets on the top, distributed around both drinking tubes,

and the same corncob bedding used elsewhere throughout. When all 64 mice are placed in their cages, two water bottles are placed on each cage top, set so the meniscus will align with the graduations on the water bottle. When all mice have two bottles, the experimenter reads the volume to the nearest 0.2 ml by reading the bottom of the meniscus. While the meniscus will be on an angle with respect to the length of the bottle, it is read by adopting a view that parallels the ground (and the cage rack and cage lid). A penlight is placed near the tube to aid in reading the graduation marks. The mice are then left alone until the next day.

Tuesday 10 AM, menisci on both the L and R bottle (from the point of view of the experimenter) are read, and otherwise nothing is done, unless refilling is necessary. Tuesday afternoon, a large enough volume of 6% ethanol (v/v) in tap water is prepared to refill all tubes used throughout the week long study. It is kept tightly sealed and a companion bottle of tap water is kept with it. Both bottles are maintained at room temperature.

Wednesday AM, starting early enough to be ready at 10 AM, two new bottles are prepared for each cage (including control cages). One contains ethanol, the other water. Ethanol bottles are marked with a sharpie on the bottom of the cylinder. At 10 AM, all water bottles on the cages are again read. Starting at the beginning, both bottles are pulled from each cage, and then again starting at the beginning, mice are weighed. Then, one water and one ethanol bottle are placed on each cage. Ethanol bottles are initially placed on the left for all cages. Finally, the two new bottles are read.

Thursday, the bottles are read.

Friday, the bottles are read, then the positions are exchanged (i.e., ethanol on the right), and then the bottles are read again.

Saturday, like Thursday.

Sunday, bottles are read, bottles are pulled, mice are weighed, and replaced into their 2-mouse home cages with a water bottle and food.

On any day, if after reading, the fluid has been depleted so much that the mouse might run out of a particular bottle's fluid (around 15 ml remaining) before the next reading, the bottle is pulled and replenished, then reread (see note 1, below).

Leakers are usually obvious, with a large pile of wet bedding. Small leaks are sometimes dealt with by the mouse by piling up the bedding under the leaking spout to try to cover up. Thus, we use a very thin layer of bedding so that even if it is piled up artfully, it can't reach the spout tip.

Note 1: We replenish solutions using a squeeze bottle to which has been attached a 16 gauge blunt tip needle. We insert the needle into the hole in the actual sipper tube (after picking up the drinking bottle) and squeeze. That way, the sipper tube doesn't have to be taken off of the bottle, and we reduce injury from breaking tubes.

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