Effects of testosterone and growth hormone on long-term retention and extinction of a passive avoidance response in young and aged rats.
Wistar rats were divided into two blocks: young and aged. Each block was then randomly divided into the following groups: (1) Control (saline solution), (2) Growth Hormone (GH), (3) Testosterone enanthate, and (4) GH plus testosterone enanthate. Animals were trained on a one-trial passive avoidance conditioning and tested for retention 24 h after training and thereafter twice a week until the extinction response occurred. Results showed that GH, testosterone, and GH plus testosterone improved long-term memory in young rats. Both GH and testosterone delayed the extinction process in young and aged rats. The GH-testosterone interaction delayed the extinction only in young rats.
Schneider-Rivas
S
S
Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, D.F., México. srivas@servidor.unam.mx
Paredes-Carbajal
C
C
Mascher
D
D
Angoa-Pérez
M
M
Jaramillo-Gonzaléz
E
E
Borgonio-Pérez
G
G
Rivas-Arancibia
S
S
D000375:Aging / Q000502:physiology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology; D005108:Extinction, Psychological / Q000187:drug effects* / Q000502:physiology; D013006:Growth Hormone / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012153:Retention, Psychology / Q000187:drug effects* / Q000502:physiology; D013739:Testosterone / Q000031:analogs & derivatives* / Q000494:pharmacology
D013739:Testosterone; C004648:testosterone enanthate; D013006:Growth Hormone