Expressive variety of choline acetyltransferase in different cerebral regions of rats with fimbria/fornix transection

Zongjun GUO; Liying JIN; Jianjun YIN

ABSTRACT

BACKGROUND:

The choline acetyltransferase (CHAT) is the key synthetic enzyme for acetylcholine, and is the important symbol of the functional activity of the cholinergic system. There was a relationship of the cholinergic neurons damage with the pathogenesis of Alzheimer disease (AD) and the mild cognitive impairment (MCI). Whether or not the fimbria/fornix transection may affect the expressive variety of ChAT in different cerebral regions of rats (cortex, hippocammpi CA1, amygdala, Meynert nucleus) is very important for the recognition of the pathogenesis of AD and MCI and the establishment of experimental animal model of AD.

OBJECTIVE:

To observe the expressive variety of ChAT in different cerebral regions of rats with fimbria/fornix transection and discuss exploratorily the methods of simulative experimental AD.

DESIGN:

A randomized and control study.

SETTING:

Institute of Cerebrovascular Disease, Affiliated Hospital of the Qingdao University Medical College and the Department of Neurology, No. 1People' s Hospital of Jining.MATERIALS The experiment was completed in the Institute of Cerebrovascular Disease, Affiliated Hospital of the Qingdao University Medical College from March to December 2003. Totally 14 adult healthy female Wistar rats aged 5 months were randomly divided into model group and control group with 7 in each group.

METHODS:

① The bilateral fimbria-fornix of brain in model group were transected on the stereotaxic apparatus to set animal model. After opening the skull, at the coordinates, along the bregma posterior 2.2 mm-2.5 mm and lateral 1.0 mm according to the atlas of Paxinos and Watson, and the dorsal fornix, the anterior part of hippocampus and the fimbria were cut off with a double blade under visual inspection. Rats in the control group were not performed with fimbria/fornix transection, and the other procedures were completed as those in the model group. ② On the 28 day after the surgery, all rats were killed under anesthesia to take out the brain tissues and make coronary sections for histochemical observation in a immunohistochemical way. The expressions of the ChAT positive neurons were observed in the cortex, hippocammpi CA1, amygdala, Meynert nucleus, and the brown neurons under microscopy was the ChAT positive neurons.MAIN OUTCOME

MEASURES:

Expressions of ChAT positive neurons in the cortex, hippocammpi CA1, amygdala, Meynert of the basal forebrain in the model group and the control group.

RESULTS:

All the rats entered the final analysis without any loss. The expression of ChAT positive neurons in the cortex, hippocammpi CA1,amygdala, Meynert of the basal forebrain in the model group were distinctly decreased than that in the control group (2.97±1.45, 32.60±7.33, t=10.51,P ＜ 0.01); (6.83±2.41, 50.57±5.85, t=1 8.30, P＜ 0.01); (14.43±6.75, 35.43±10.49,t=4.47, P ＜ 0.01); (5.77±6.62, 48.77±7.10, t=1 1.72, P ＜ 0.01), and the differences were significant.

CONCLUSION:

Finbria/fomix transection can decrease the expression of ChAT positive neurons in many cerebral regions of rats, and can be used in a method of setting the experimental animal model of AD.