Time-dependent changes in plasma prolactin level and stress controllability in rats

1.Numerous studies have shown the importance of controllability factors in the neurochemical, hormonal and behavioural changes associated with presentation of stress stimuli. 2.Previous work from our laboratory revealed that animals exposed to escapable shock had significantly higher prolactin levels than those treated with inescapable shock. 3.The present experiment examined the time-course of plasma prolactin change as a function of shock controllability. 4.Rats were exposed to intermittant escapable, inescapable or no shock for 5, 10, 30 or 60 min and sacrificed for plasma prolactin determination. Additional groups received 60 min shock condition followed by 30 or 60 min rest period prior to sacrifice. 5.Results showed that subjects exposed to 5, 10 or 30 min of escapable shock exhibited higher prolactin levels than inescapable shock or no-shock treated animals. These findings show that the prolactin response to stress is sensitive to controllability factors and is time-dependent