Age-dependent effects of acute and chronic intermittent stresses on serum metallothionein

Prepuberal and adult male rats were chronically stressed for a month with several acute stressors in a random schedule. Some of the animals were killed approximately 20 hours after the last stress session without any additional stress. Other animals from both control and chronic stress groups were subjected to an acute restraint stress for 15 min before being killed. While chronic stress did not alter hepatic metallothionein (MT) either in prepuberal or in adult rats, this treatment significantly increased serum MT levels in young but not in adult rats. Likewise, 15 min of restraint stress increased serum MT levels in young rats only, regardless of whether they were control or chronically stressed rats. The present data indicate that acute and chronic stressors may alter serum MT in an age-dependent fashion.