Long-lasting changes in stress-induced corticosterone response and anxiety-like behaviors as a consequence of neonatal maternal separation in Long-Evans rats.
Early neonatal environmental factors appear to have powerful and long-lasting influences on an organism's physiology and behavior. Long-Evans male rats separated from their dam for 3 h daily over the first 2 weeks of life (maternally separated, MS rats) when tested as adults exhibit exaggerated behavioral and neuroendocrine responses to stress compared to 15-min separated (handled, H) animals. The purpose of this study was to compare male and female adult rats that were MS, H or were undisturbed (nonhandled, NH) as neonates in anxiety-like behaviors, in the elevated plus-maze, and in response to startle-inducing auditory stimuli. We confirmed that MS males oversecrete corticosterone (CORT; 2.5-5 times) in response to mild handling stress. MS males and females were less likely to explore open arms of the plus-maze. MS males exhibited 35% higher startle amplitudes compared to controls. Furthermore, MS males were more likely to emit ultrasonic vocalizations in response to startle than were H controls. However, MS and control females did not differ in auditory startle response or in startle-induced ultrasonic vocalizations. Therefore, experiencing maternal separation results in a long-lasting increase in anxiety-like behaviors that occurs in a sex-dependent manner.
Kalinichev
Mikhail
M
Rollins Research Centre, Department of Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Room 5074, Atlanta, GA 30322, USA. mkalini@emory.edu
Easterling
Keith W
KW
Plotsky
Paul M
PM
Holtzman
Stephen G
SG
D000161:Acoustic Stimulation / Q000009:adverse effects; D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000097:blood* / Q000523:psychology; D003345:Corticosterone / Q000097:blood*; D005260:Female; D008297:Male; D008426:Maternal Deprivation; D011247:Pregnancy; D051381:Rats; D020318:Rats, Long-Evans; D013312:Stress, Physiological / Q000097:blood* / Q000523:psychology; D013995:Time; D014828:Vocalization, Animal / Q000502:physiology
D003345:Corticosterone