The ontogeny of nipple-shifting behavior in albino rats: Mechanisms of control and possible significance
✍ Scribed by Catherine P. Cramer; Dr. Elliott M. Blass; Warren G. Hall
- Publisher
- John Wiley and Sons
- Year
- 1980
- Tongue
- English
- Weight
- 959 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0012-1630
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Nipple‐shifting behavior was studied in rats 3–‐30 days old in 4 experimental paradigms. The incidence of nipple‐shifting of rats tested in groups of 3 on their nonlactating, anesthetized mother was age‐related. Rats 12 days of age and younger did not leave the nipple first suckled during the 2‐hr test period. Starting by Day 15, however, nipple‐shifting increased and reached its maximum in 24‐day‐old rats. This behavior's incidence was directly related to maternal (and, therefore, nutrient and water) deprivation (Experiment I). Milk letdown reduced the incidence of nipple‐shifting behavior at all ages studied and synchronized its occurrence, as almost all shifts occurred immediately after letdown and almost none during the 15‐min interval between successive milk letdowns (Experiment II). Testing rats individually on the nonlactating, anesthetized mother produced age‐related effects. Shifting was virtually eliminated in 15‐day‐old rats, markedly reduced in 21‐day‐old rats, and not affected in 27‐day‐old rats tested individually (Experiment III). Rats 27 and 30 days of age, upon leaving a nipple, ate and did not return to suckle. Rats 15 days old never ate and always returned to suckle (Experiment IV). Twenty‐one‐day‐old rats suckled, and many ate in the mother's presence. The significance of these findings relates to maximizing milk intake and facilitating the process of weaning.