[Preventing role of warmth-promotion needling in reducing intracellular Ca2＋ overload of in vitro hippocampal neuronal cells of vascular dementia rats]

Abstract

Objective: To investigate the underlying mechanisms of warming-promotion needling (WPN) for vascular dementia (VD) by observing its effect on the expression of L-type calcium channel current (Ica.L), changes of intracellular [Ca^2＋]i in neurons and pathomorphological changes of brain in VD rats.

Methods: One hundred and eight male SD rats were randomized into normal control, model, medication, WPN, uniform reinforcing-reducing needling (URRN), and needle-twirling groups (n＝18 in each group). The VD model was established by repeated occlusion and reperfusion of the bilateral common carotid arteries. Rats of the medication group were treated by gavage of Nimodipine twice a day for 14 days. For rats of the 3 acupuncture groups, WPN or URRN or needle-twirling was applied to "Dazhui" (GV14), "Baihui"(GV20) and "Shuigou"(GV26) for 30 min, once a day for 14 days. Changes of Ica.L in hippocampal neurons were observed by whole-cell patch clamp technique, and levels of [Ca^2＋]i in neuronal cells of living brain slice of hippocampal CA1 area were observed by laser confocal microscope. Histopathological changes of hippocampal CA1 area were observed under light microscope after H．E. stain.

Results: Compared with the normal control group, the current density of Ica.L, and the intracellular[Ca^2＋]i levels were significantly increased (P<0.05), and the I-V curves of Ica.L was apparently shifted down in the model group. In comparison with the model group, the current density of Ica.L was obviously reduced (P<0.05), the I-V curves of Ica.L shifted up and the intracellular Ca^2＋ content notably decreased in the medication, WPN, URRN and needle-twirling groups (P<0.05). The effect of WPN was significantly superior to those of URRN and needle-twiiling (P<0.05). H．E. stain showed a reduction in the number of hippocampal neurons, dilation of intercellular space, swelling of cell body, karyopyknosis, disordered arrangement and increased number of gliacytes in the model group, which was apparently milder in the medication and 3 acupuncture groups (the WPN group in particular).

Conclusion: The WPN can reduce Ica.L current density and [Ca^2＋]i content of hippocampal neurons in brain slices of VD rats, which may contribute to its effect in relieving VD by suppressing calcium overload.

Keywords: Acupuncture; Hippocampal CA1 region; Intracellular calcium content; L-type calcium channel; Vascular dementia; Warmth-promotion needling; Whole cell patch clamp recording.