TY - JOUR
T1 - Differential effect of testosterone and repetitive induction on cataleptic and dorsal immobility in mice
AU - Fregoso-Aguilar, Tomás A.
AU - Zamudio, Sergio R.
N1 - Funding Information:
This work was supported by funds from the Instituto Politécnico Nacional (CGPI-IPN, 2005006). TAF and SRZ are fellows of Consejo Nacional de Ciencia y Tecnología (SNI-30882 and SNI-16541 respectively). We wish to thank Dr. Radu Racotta for the revision of manuscript and Dr. Ellis Glazier for the editing of the English-language text.
PY - 2006/6
Y1 - 2006/6
N2 - In nature, many species under conditions of stress (e.g., predator attack, pups carried by the mother, mating) show immobility states called "immobility responses" (IRs), which are characterized by the complete absence of movement and a relative unresponsiveness. These IR states can be induced by several kinds of sensorial stimuli. Many brain neurotransmitters from diverse cerebral areas participate in the expression of IRs. Other factors are also involved in IRs, such as learning and hormones, but at present, there is not enough experimental support about these factors. Our purpose was to investigate whether the IRs are subject to sexual hormone modulation and to examine the possible relation to learning processes. We tested the effects of acute testosterone decanoate (30 mg/kg, s.c.) and repetitive induction of two IRs; cataleptic immobility (CAT) and dorsal immobility (DI). These were tested in mice of both sexes which were either gonadectomized or sham-treated. CAT and DI were measured before and then 1 and 5 h after testosterone injection. The results show a differential effect of the repetitive induction on CAT and DI. CAT was augmented with repetition, and DI was decreased. Sex differences of the effects of the acute testosterone treatment were observed. Sham and castrated male mice showed CAT potentiation; in contrast, DI was reduced albeit only in sham male mice. Sham and ovariectomized female mice were not affected by testosterone. These results support the hypothesis that there are multiple immobility systems that can be differentially modulated by brain regions associated with processes of learning.
AB - In nature, many species under conditions of stress (e.g., predator attack, pups carried by the mother, mating) show immobility states called "immobility responses" (IRs), which are characterized by the complete absence of movement and a relative unresponsiveness. These IR states can be induced by several kinds of sensorial stimuli. Many brain neurotransmitters from diverse cerebral areas participate in the expression of IRs. Other factors are also involved in IRs, such as learning and hormones, but at present, there is not enough experimental support about these factors. Our purpose was to investigate whether the IRs are subject to sexual hormone modulation and to examine the possible relation to learning processes. We tested the effects of acute testosterone decanoate (30 mg/kg, s.c.) and repetitive induction of two IRs; cataleptic immobility (CAT) and dorsal immobility (DI). These were tested in mice of both sexes which were either gonadectomized or sham-treated. CAT and DI were measured before and then 1 and 5 h after testosterone injection. The results show a differential effect of the repetitive induction on CAT and DI. CAT was augmented with repetition, and DI was decreased. Sex differences of the effects of the acute testosterone treatment were observed. Sham and castrated male mice showed CAT potentiation; in contrast, DI was reduced albeit only in sham male mice. Sham and ovariectomized female mice were not affected by testosterone. These results support the hypothesis that there are multiple immobility systems that can be differentially modulated by brain regions associated with processes of learning.
KW - Catalepsy
KW - Dorsal immobility
KW - Immobility responses
KW - Mice
KW - Testosterone
UR - http://www.scopus.com/inward/record.url?scp=33646851247&partnerID=8YFLogxK
U2 - 10.1016/j.yhbeh.2005.12.014
DO - 10.1016/j.yhbeh.2005.12.014
M3 - Artículo
SN - 0018-506X
VL - 50
SP - 27
EP - 32
JO - Hormones and Behavior
JF - Hormones and Behavior
IS - 1
ER -