Long-lasting changes in behavioural and neuroendocrine indices in the rat following neonatal maternal separation: gender-dependent effects.
Neonatal maternal separation (MS) has been used to model long-term changes in neurochemistry and behaviour associated with exposure to early-life stress. This study characterises changes in behavioural and neuroendocrine parameters following MS. On postnatal days (PND) 3-15, male and female Long-Evans rats underwent 3 h daily MS. Non-handled (NH) control offspring remained with the dams. Starting at PND 90, behaviour was assessed at weekly intervals in the elevated plus-maze, elevated T-maze, and locomotor activity boxes, and body weight monitored throughout. At the end of the study, adrenals were weighed and blood collected for analysis of plasma corticosterone and adrenocorticotropic hormone (ACTH) under basal conditions and following restraint stress. As adults, MS weighed more than NH animals. Activity on the open arms of the plus-maze was similar between MS and NH animals. In the T-maze, MS males had shorter emergence latencies than their NH counterparts. Spontaneous ambulation in a novel environment was significantly higher in MS than in NH animals, and males exhibited overall lower activity than females. Basal plasma corticosterone was lower in MS than in NH females, but no rearing condition difference was observed following restraint stress. Females had higher corticosterone and ACTH levels than males, whereas adrenal glands of MS animals weighed less than those of NH controls. The MS paradigm caused long-term gender dependent effects on behaviour and HPA axis status. The consistent gender differences confirm and expand existing results showing altered anxiety and stress reactivity in male and female rats.
Slotten
Helge A
HA
Institute of Neuroscience, School of Biomedical Sciences, Queen's Medical Centre, University of Nottingham, NG7 2UH, Nottingham, UK. helge.slotten@nottingham.ac.uk
Kalinichev
Mikhail
M
Hagan
Jim J
JJ
Marsden
Charles A
CA
Fone
Kevin C F
KC
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000818:Animals; D000831:Animals, Newborn; D003345:Corticosterone / Q000097:blood*; D005260:Female; D008297:Male; D008426:Maternal Deprivation; D018782:Maze Learning / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D009490:Neurosecretory Systems / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D012727:Sex Characteristics; D013995:Time
D000324:Adrenocorticotropic Hormone; D003345:Corticosterone