title: Pre-pubertal castration improves spatial learning during mid-adolescence in rats.
abstract: Hippocampus functions, including spatial cognition and stress responses, mature during adolescence. In addition, hippocampus neuronal structures are modified by circulating sex steroids, which dramatically increase during adolescence. Therefore, the effects of castration and the circulating levels of the main sex steroid testosterone on spatial learning and memory were examined across postnatal ages to test whether pre-pubertal castration affected rats' spatial ability in the Morris Water maze (MWM). Male rats were either castrated or sham-castrated at 22d (days of age), or left gonadally intact. They were then trained and tested in the MWM beginning at 28d, 35d, 45d or 60d. We found that all of the intact rats learned the spatial task; however, the males at 22d and 28d required more trials to acquire the task than the males at older ages. The males castrated at 22d and tested at 35d had significantly lower escape latency and traveled distance during training than the sham-castrated males trained at the same age. No differences were observed in mean values of escape latency and traveled distance at 45d even though they had comparable levels of testosterone. We conclude that adult-typical performance for male spatial memory emerges during mid-adolescence and that pre-pubertal castration appears to improve spatial learning during this time.
authors.affiliation: Department of Physiology, faculty of Medical Sciences, Tarbiat Modares University, P O Box: 14115-111, Tehran, Iran. Electronic address: moradpour.farshad@gmail.com.
authors.forename: Farshad
authors.initials: F
authors.lastname: Moradpour
authors.forename: Nasser
authors.initials: N
authors.lastname: Naghdi
authors.forename: Yaghoub
authors.initials: Y
authors.lastname: Fathollahi
authors.forename: Mohamad
authors.initials: M
authors.lastname: Javan
authors.forename: Samira
authors.initials: S
authors.lastname: Choopani
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Gharaylou
mesh_terms: D000367:Age Factors; D000818:Animals; D004924:Escape Reaction / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D009919:Orchiectomy / Q000639:trends; D051381:Rats; D017208:Rats, Wistar; D012741:Sexual Maturation / Q000502:physiology*; D013037:Spatial Behavior / Q000502:physiology*; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone
keywords: Adolescence; Gonads; HFS; LTP; MWM; Morris water maze; N-methy d-aspartic acid; NMDA; PS; Pre-pubertal; Rat; Spatial memory; Testosterone; d; days; fEPSP; field excitatory postsynaptic potential; high frequency stimulation; long term potentiation; population spike