Dear All,
How do perform Maternal Odor Preference/Homing Behavior in pups? and how many day old pups should be used for this behavior study??
My lab routinely does pup retrieval assays. We prefer pups that are between P0 and P6, although younger is better. Older pups can crawl back into the nest by themselves. To do this we remove the mother from the cage, then remove all the pups from the nest and scatter 4 of the pups into different corners of the cage. The remaining pups stay out of the cage until the mother has retrieved all 4 scattered pups into the nest. We time how long it takes for her to find the pups, and also to bring them back to the nest.
See Fig. 2 of attached paper.
Article Complex Chemosensory Control of Female Reproductive Behaviors
I thought you were asking about a behavioral test of the pup's odor preference, not the mother's. It is possible to test odor preferences in very young pups, but it is tricky, as they have poorly developed motor behavior. Conventional choice tests are more feasible after they are proficient at walking, around 10-12 days. If you are testing pups, take care to avoid litter effects by testing multiple pups from the same litter in the same experimental condition, as though they were statistically independent ( see Holson & Pearce, 1992, Neurotoxicol Teratology 14:221)
Dr Robinson thank you so much your answer, really it will help me.. yes, i was asking about pup's Odor preference behavior test,,
Thanks. The paper that Dr. Unger pointed out is a good introduction to behavioral assays with young mouse pups. Other authors you might look for that have done very good olfactory work with very young (rat) pups include Jeffrey Alberts, Norman Spear, and Regina Sullivan. A lot of that work has been published in Developmental Psychobiology.
I agree with Dr. Unger and would like to further develop it: in order to avoid litter effects, it is important to use one male/female from the same litter per condition. Also, don't forget, pups are much more sensitive to temperature changes than adults which affect their performance during the odor choice test!
An alternative to avoiding litter effects is to test multiple subjects in the litter, but run statistics on litter means, not individual scores.
Yes, pups are sensitive to temperature and should be handled with gloves. The ideal temperature you wish to test them at depends on the behavior of interest and their age. We ran most of our experiments on P1 pups (24-hours after birth); to ensure behavioral activity, we ran in a regulated environment at 34-35°C. Cooler than that and they cannot maintain body temperature and will thermally crash over 20-30 min.
Could an idea would be to calculate Ultrasonic vocalisation prior (e.g. 10 sec) the mother is there and while the mother is close to the pup ? (e.g. having the mother far and then let them walk towards the pup). You will should be able to quantify the number and quality of calls will increase. You will also avoid the pup to move due to his limited motor skill
In neuro-hormonal terms, formation of odour and homing preferences seem to be associated with central release of endogenous opioids in rats pups. For reference, see Nelson & Panksepp (1998) Brain substrates of infant-mother attachment: contributions of opioids, oxytocin and norepihephrine, Neuroscience and Biobehavioral Reviews, 22(3):437-452.:
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