The immunoreactivity and activity of adenylate cyclase type I are changed in the hippocampal CA1 region after transient forebrain ischemia in gerbils.
Adenylate cyclase (AC) has a specific sensitivity to Ca2+/calmodulin. AC-I, one of the mediator of learning and memory, plays an important role in signal transduction underlying learning and memory function. In the present study, we found ischemia-related changes of AC-I in the hippocampal CA1 region, but not in the CA2/3 region, after 5 min of transient forebrain ischemia in gerbils. In the sham-operated group, AC-I immunoreactive neurons were detected in pyramidal and non-pyramidal cells in the hippocampus proper. AC-I immunoreactivity was significantly increased at 3 h in the CA1 region after ischemic insult. Thereafter, AC-I immunoreactivity was gradually decreased. Four days after ischemic insult, AC-I-immunoreactive CA1 pyramidal cells in the stratum pyramidale were very few due to delayed neuronal death. The results of Western blot analysis showed that changes of AC-I protein contents were similar to immunohistochemical data after ischemic insult. Gpp(NH)p-dependent AC-I activity in hippocampal CA1 region was not changed in all groups, while Ca2+/calmodulin-dependent AC-I activity in hippocampal CA1 region was significantly decreased 24 h after ischemia-reperfusion. These results suggest that the decrease of AC-I activity may be associated with impairment of neurodevelopment and neuroplasticity including learning and memory although the AC-I immunoreactivity was maintained 24 h postischemic group compared to that of the sham-operated group.
Hwang
In Koo
IK
Department of Anatomy, College of Medicine, Hallym University, and Chunchon Sacred Heart Hospital, South Korea.
Yoo
Ki-Yeon
KY
Kim
Young-Sil
YS
Jung
Boo Kyoung
BK
Li
Hua
H
Kim
Do-Hoon
DH
Kang
Tae-Cheon
TC
Shin
Hyung-Cheul
HC
Won
Moo Ho
MH
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D004195:Disease Models, Animal; D005849:Gerbillinae; D006624:Hippocampus / Q000201:enzymology* / Q000473:pathology; D007150:Immunohistochemistry / Q000379:methods; D002546:Ischemic Attack, Transient / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D009474:Neurons / Q000378:metabolism; D015424:Reperfusion; D013194:Staining and Labeling / Q000379:methods; D013997:Time Factors
D000262:Adenylyl Cyclases