There are sex differences in some brain areas in mammalians. Parkinson's disease (PD), caused by the mesencephalic substantia nigra (SN) dopaminergic neuronal loss, displays sexual difference, i.e., the incidence is higher and the symptoms are more intense in males than that in females. However, it has not been known whether sexual dimorphisms exist in the SN. Sixty adult Sprague-Dawley rats were randomly divided into 5 groups: (1) Female intact group (F-INT group); (2) Male intact group (M-INT group); (3) Ovariectomized group (OVX group); (4) Castration group (CAST group); (5) Ovariectomized + estrogen-replaced group (OVX-E(2) group): The rats received sequentially physiological dose of estrogen for 3 d from the 7th day after ovariectomization. P50 auditory evoked potential (P50) was recorded for 14 d from electrodes inserted in the rat right SN in quiet and awake state. After recording, the brain tissues were dissected and the tyrosine hydroxylase (TH)-expressing neurons in the compact zone of the SN were counted using immunohistochemical method. The results showed that the number of TH-positive (TH(+)) cells in the SN of normal male animals was less than that in normal female rats (P<0.05), and the T/C ratio of P50 in normal males was significantly less than that in normal females (P<0.01), indicating that there exists sexual difference in function and structure in the SN. No differences in the T/C ratio of P50 or the number of TH(+) cells were found between M-INT and CAST groups. The T/C ratio of P50 and the number of TH(+) cells in the SN in OVX group were reduced significantly compared with those in F-INT group (P<0.01). There was no significant difference in the T/C ratio of P50 and the number of TH(+) cells in the SN between OVX- E(2) and F-INT groups 15-20 d after estrogen replacement, suggesting that estrogen can promote the survival and functional recovery of dopaminergic neurons in the SN. The results suggest that there exist sex-specific differences in the dopaminergic neurons in the SN structurally and functionally. The difference of estrogen level in cerebra between male and female animals may account for the sexual differences. Endogenous estrogen plays an important role in maintaining the integrity and modulating the functional activity of dopamine system in the SN.
Animals ; Dopaminergic Neurons ; cytology ; Estrogens ; pharmacology ; Evoked Potentials, Auditory ; Female ; Male ; Orchiectomy ; Ovariectomy ; Rats ; Rats, Sprague-Dawley ; Sex Characteristics ; Substantia Nigra ; cytology

Objective To make a parallel mining the data of expression differences of a crucial gene XPA involved in nucleotide excision repair pathway of human skin microarrays by bioinformatics from the system level.Methods Using the ScanGEO, the data of microarrays which included the significant differences expression level of XPA were screened and analyzed from 59 human skin samples in the GEO database. Results There were 7 samples with the down-regulated expression of XPA: cutaneous malignant melanoma, epidermal injury model, DNA damage and UV radiation, foreskin fibroblast response to Toxoplasma gondii RH type 1 (ROP5) mutant infection, interleukin-20 subfamily cytokines effect on epidermal keratinocytes, Egr-1 overexpression effect on skin fibroblasts in vitro: time course, in vitro model for inflammatory dendritic cells.Present expression down. Conclusion Based on the GEO database and ScanGEO, high-throughput shared data can be screened and analyzed efficiently.