Mild Stress Treatment Research Articles

Effects of maternal stress during different gestational periods on the serotonergic system in adult rat offspring

Pregnant Sprague-Dawley rats were exposed to mild stress treatments during different gestational periods and the offspring were investigated at 60 days of age. In the first study, stress from embryonic day (ED) 11 to ED 20 produced effects similar to those reported following stress throughout pregnancy; increased numbers of 5-HT 2 binding sites in cerebral cortex and a reduced intensity of the behavioral syndrome produced by injections of the 5-HT agonist 5-methoxy-N, N-dimethyltryptamine (5-MeODMT). In the second study, stress from ED 3 to ED 14 had no significant effect on the intensity of the 5-MeODMT-elicited 5-HT syndrome while stress from ED 15 to ED 20 had a similar effect as stress throughout pregnancy. These data provide evidence that the critical period for prenatal stress-induced changes in brain 5-HT neurons is between ED 15 and birth. This suggests that the mechanism involves an interaction with developmental events occuring within this time span such as the growth of nerve axons and the formation of synaptic contacts. Our findings also provide further evidence that stress during the final trimester of pregnancy may have serious adverse effects on fetal brain development.

Controlled Moisture Stress to Improve Cold Hardiness and Morphology of Douglas-fir Seedlings

Abstract Nursery-grown seedlings of Douglas-fir (Pseudotsuga menziesii) were subjected to three levels of moisture stress between late July and the end of August. Measurements in October and December showed that mild stress of -5 to -10 bars significantly improved cold hardiness. In a second experiment, the effectiveness of the mild stress treatment decreased as the onset of the stress was delayed from mid-July until September 1. Furthermore, the earlier onset of stress decreased the height and shoot/root ratio, but increased the root weight and nitrogen content of the needles. For seedlings lifted in October, mild stress also decreased mortality from cold storage. Forest Sci. 25:576-582.