Involvement of the entorhinal cortex in the stress response to immobilization, but not to insulin-induced hypoglycaemia.
Although the involvement of the limbic system in the neuroendocrine responses to some stressors has been documented, the specific role of the entorhinal cortex has not been elucidated. In this study, we investigated the involvement of the entorhinal cortex in stress responses. Fos immunoreactivity, a widely used marker for neuronal activation, was detected in the entorhinal cortex of rats subjected to immobilization stress, whereas no marked staining was observed in the entorhinal cortex of the control and insulin-induced hypoglycaemia groups. Lesion of the entorhinal cortex produced by ibotenic acid significantly attenuated the adrenocorticotropic hormone (ACTH) release evoked by immobilization; however, no significant change in ACTH release was observed in insulin-induced hypoglycaemia. No significant difference between entorhinal-lesioned rats and control rats was observed in blood glucose concentrations when subjected to either immobilization or to insulin-induced hypoglycaemia. Together, these results indicate that the entorhinal cortex is closely involved in the stress response to immobilization but not to insulin-induced hypoglycaemia.
Umegaki
H
H
Department of Geriatrics, Nagoya University Graduate School of Medicine, Showa-Ku, Nagoya, Aichi, Japan. umegaki@med.nagoya-u.ac.jp
Zhu
W
W
Nakamura
A
A
Suzuki
Y
Y
Takada
M
M
Endo
H
H
Iguchi
A
A
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003714:Denervation; D018728:Entorhinal Cortex / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists; D007003:Hypoglycemia / Q000139:chemically induced / Q000503:physiopathology*; D007004:Hypoglycemic Agents; D007051:Ibotenic Acid; D007150:Immunohistochemistry; D007328:Insulin; D008297:Male; D009474:Neurons / Q000737:chemistry; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000503:physiopathology*
D018690:Excitatory Amino Acid Agonists; D007004:Hypoglycemic Agents; D007328:Insulin; D016760:Proto-Oncogene Proteins c-fos; D007051:Ibotenic Acid; D000324:Adrenocorticotropic Hormone