Long-term changes induced by neonatal handling in the nociceptive threshold and body weight in mice

During the first 3 weeks of life, four litters of CD-1 male mice were daily handled (HA group) and four other litters were left undisturbed (UHA group). At 35 days of life, mice underwent the tail flick (TF) and hot plate (HP) tests to measure the baseline reaction to thermal nociceptive stimulation. At the age of 50, 80, and 140 days body weight was measured. At the last time point the epididymal fat pads (EFPs) were also taken and weighed. We found that, 16 days after the suspension of the manipulation, HA mice showed increased latencies to both nociceptive tests and, starting on day 80, they began to develop a significant increment in body weight. An increase was also evident in EFP weight of HA mice.