A. Damore et al., EFFECT OF NALOXONE ON THE LONG-TERM BODY-WEIGHT GAIN INDUCED BY REPEATED POSTNATAL STRESS IN MALE-MICE, Behavioural pharmacology, 7(5), 1996, pp. 430-436
Stress during the early postnatal life of laboratory animals can induc
e body weight gain in adulthood. Exposure of mice to repeated postnata
l stress has been shown to increase body weight some weeks after the r
ecording of a hyposensitivity to thermal nociceptive stimulation. Sinc
e the increase in nociceptive threshold after repeated environmental m
anipulations can be interpreted as a behavioral index of stress-induce
d endogenous opioid release, the present experiment was designed to st
udy whether the stress-induced body weight gain could be prevented by
a chronic treatment with the opioid antagonist naloxone. Sixteen litte
rs of CD-1 male mice were used. Treatments took place from day 2 to da
y 19 of postnatal life. As well as body weight we measured spontaneous
motor activity and food and water consumption. Body length and epidid
ymal fat pad weight were also measured, at the end of the experiment.
Stress (i.e. a daily saline injection schedule) increased the rate of
body weight gain and the epididymal fat pad weight; a daily injection
schedule of naloxone did not induce these effects. No significant diff
erences were evident among groups regarding body length, motor activit
y, or food and water intake. The data suggest that repeated postnatal
saline injections may induce long-term modifications in body and epidi
dymal fat weights and that these effects may be mediated by endogenous
opioids.