Experimental changes of tyrosine hydroxylase neurons in mesencephalic ventral tegmental area of Parkinson disease rats

Objective To explore the changes of tyrosine hydroxylase neurons in mesencephalic ventral tegmental area (VTA)of Parkinson disease (PD)rats. Methods Stereotaxic injection of 6-OHDA into the left substantia nigra pars compacta (SNC) and ventral tegmental area (VTA) of rats to develop PD rat model, The behavioral changes induced by apomorphine were observed at 4,7,14,21,28 days after the injection of 6-OHDA; neuronal alteration of left mesencephalic VTA were studied adopting Nissl's staining, and the changes of tyrosine hydroxylase neurons were analyzed by tyrosine hydroxylase (TH) immunohistochemistry and image analysis. Results The PD rats showed abnormal rotary behavior, in the rotation, the start time of PD rats shortened gradually, the continuous time lengthened, and the rotary rate speeded by degrees. The rotary behavior became invariable until 2 weeks after 6-OHDA injection; Serious neuronal alteration in left (the injured side)VTA of PD rats were observed by Nissl's staining; The number of tyrosine hydroxylase neurons in left (the injured side)VTA of PD rats, decreased significantly compared to right side throughout the test time. As to the number of tyrosine hydroxylase neurons in left (the injured side)VTA, 2 or 4 weeks after 6-OHDA injection decreased significantly compared to 1 week after 6-OHDA injection in PD group (P0.05). Conclusion The PD rats showed serious neuronal alteration in the injured VTA, tyrosine hydroxylase neurons were lost significantly in the injured VTA of PD rats, Mesencephalic VTA tyrosine hydroxylase neurons take part in the pathologic changes of PD rats.