Soybean isoflavones alter parvalbumin in hippocampus of mid-aged normal female, ovariectomized female, and normal male rats
Abstract
Aim: To investigate the long-term effect of soybean isoflavones on changes in
parvalbumin (PV) immunoreactivity in the hippocampus in normal female, ovariectomized
(OVX) female and normal male rats. Methods: Ten-month-old rats were
assigned to one of 9 groups (n=7 in each group) based on body weight using a
randomized complete-block design. The groups were: control diet-treated females,
OVX females, and males; 0.3 g/kg isoflavone-treated females, OVX females, and
males; and 1.2 g/kg isoflavone-treated females, OVX females, and males. The PV
immunostaining was conducted by using the standard avidin-biotin complex
method. Results: PV immunoreactivity and the number of PV-immunoreactive
neurons in all the groups after isoflavone treatment were significantly changed in
the hippocampal CA1 region and in the dentate gyrus, but not in the hippocampal
CA2/3 region. PV immunoreactivity and the number of PV-immunoreactive neurons
in the control diet OVX females were similar to those in the control diet, and
were greater than those in the control diet normal females. PV immunoreactivity
and the number of PV-immunoreactive neurons in all the isoflavone-treated groups
decreased dose-dependently after isoflavone treatment. Conclusion: Long-term
administration of isoflavones may induce a reduction of PV in interneurons in the
hippocampal CA1 region and in the dentate gyrus. The reduction of PV in these
regions suggests that the long-term administration of isoflavones may cause a
change in calcium homeostasis in the hippocampal CA1 region and in the dentate
gyrus.
Keywords:
parvalbumin (PV) immunoreactivity in the hippocampus in normal female, ovariectomized
(OVX) female and normal male rats. Methods: Ten-month-old rats were
assigned to one of 9 groups (n=7 in each group) based on body weight using a
randomized complete-block design. The groups were: control diet-treated females,
OVX females, and males; 0.3 g/kg isoflavone-treated females, OVX females, and
males; and 1.2 g/kg isoflavone-treated females, OVX females, and males. The PV
immunostaining was conducted by using the standard avidin-biotin complex
method. Results: PV immunoreactivity and the number of PV-immunoreactive
neurons in all the groups after isoflavone treatment were significantly changed in
the hippocampal CA1 region and in the dentate gyrus, but not in the hippocampal
CA2/3 region. PV immunoreactivity and the number of PV-immunoreactive neurons
in the control diet OVX females were similar to those in the control diet, and
were greater than those in the control diet normal females. PV immunoreactivity
and the number of PV-immunoreactive neurons in all the isoflavone-treated groups
decreased dose-dependently after isoflavone treatment. Conclusion: Long-term
administration of isoflavones may induce a reduction of PV in interneurons in the
hippocampal CA1 region and in the dentate gyrus. The reduction of PV in these
regions suggests that the long-term administration of isoflavones may cause a
change in calcium homeostasis in the hippocampal CA1 region and in the dentate
gyrus.