Sex differences in rats: effects of chronic stress on sympathetic system and anxiety

RENARD G.M.; SUÁREZ M.M.; LEVIN G.M.; RIVAROLA M.A

PHYSIOLOGY AND BEHAVIOR

ELSEVIER

Año: 2005 vol. 85 p. 363 - 369

0031-9384

ABSTRACT RENARD, G. M., M. M. SUÁREZ, G. M. LEVIN AND M. A. RIVAROLA. Sex differences in rats: effects of chronic stress on sympathetic system and anxiety. PHYSIOL BEHAV.- There is evidence that environmental manipulations during early development can induce permanent alterations in both emotional behavior and the maturation of sympathetic system in rats. In the present investigation we tested whether periodic maternal deprivation (4.5 h daily during the first 3 weeks of life-MD) caused chronic changes in anxiety and medullo adrenal responses to chronic stress in either male or female adult (2,5 months of age) rats, or both. Basal endocrine parameters (epinephrine and norepinephine) were totally opposed between males and females, being significantly higher in males p<0.001. They were also altered in MD-treated and stressed rats in a gender-dependent manner. Whereas basal plasma catecholamine levels did not differ significantly between MD and control groups of either sex, the response to chronic stress exposure was higher in males compared with females p<0.001and also in MD females compared to control (non-maternally deprived-NMD) ones p<0.001. In the elevated plus-maze test, MDtreated males displayed a soft increase in anxiety related behavior compared with NMD rats. This was indicated by a reduction in the time spent on the open arms, whereas females showed less anxiety, which was indicated by an increase of the number of entries, and the time spent on the open arms. After exposure to chronic stress only the females displayed decreased anxietyrelated behavior. Thus, maternal deprivation and chronic variable stress caused long-term alterations in sympathetic response and also gender-dependent changes in the anxiety index of adult rats of both sexes, although to a differing way in males and females.