Chronic systemic exposure of Lewis rats to rotenone produced many features of Parkinson's disease (PD), including nigrostriatal dopamine (DA) neurodegeneration and the formation of cytoplasmic inclusions in nigral DA neurons. We also reported that chronic oral administration of rotenone at 30 mg/kg for 28 d caused specific nigrostriatal DA neurodegeneration in C57BL/6 mice. To establish a PD model more suitable for evaluating nigrostriatal DA neurodegeneration, the present study has been designed to assess the neurotoxicity of rotenone after daily oral administration at 30 or 100 mg/kg for 56 d in C57BL/6 mice. The survival rate of rotenone-treated mice at 30 mg/kg did not change from 28 to 56 d, although the survival rate of rotenone-treated mice at 30 mg/kg was decreased to about 70% within one week. The survival rate of the rotenone-treated mice at 100 mg/kg was suddenly decreased after 28 d, and finally to about 15% at 56 d. Rotenone at 30 mg/kg, but not 100 mg/kg, for 28 d caused a significant loss of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. Rotenone at 100 mg/kg caused a highly variable loss of TH-positive neurons among individual mice. Rotenone at 30 mg/kg for 56 d caused a significant loss of TH-positive neurons and behavioral impairment. In addition, α-synuclein immunoreactivity was increased in surviving TH-positive neurons in a time-dependent manner. Thus, this protocol for chronic administration of rotenone at 30 mg/kg for 56 d is more useful for understanding the mechanism of DA neurodegeneration.

Neuron/glial 2 (NG2)-expressing cells are often referred to as oligodendrocyte precursor cells. NG2-expressing cells have also been identified as multipotent progenitor cells. However, microglia-like NG2 glial cells have not been fully examined in neurodegenerative disorders such as Parkinson's disease (PD). In the present study, we chose two rat models of PD, i.e., intranigral or intrastriatal injection of 6-hydroxydopamine (6-OHDA), since the cell bodies of dopamine (DA) neurons, which form a nigrostriatal pathway, are in the substantia nigra pars compacta (SNpc) while their nerve terminals are in the striatum. In the nigral 6-OHDA-injected model, activated NG2-positive cells were detected in the SNpc but not in the striatum. In contrast, in the striatal 6-OHDA-injected model, these cells were detected in both the SNpc and the striatum. In both models, activated NG2-positive cells were located close to surviving tyrosine hydroxylase (TH)-positive neurons in the SNpc. In addition, activated NG2-positive cells in the SNpc coexpressed ionized calcium-binding adaptor molecule 1 (Iba1), a microglia/macrophage marker. Interestingly, these double-positive glial cells coexpressed glial cell line-derived neurotrophic factor (GDNF). These results suggest that microglia-like NG2 glial cells may help protect DA neurons and may lead to new therapeutic targets in PD.

Abstract. L-Dihydroxyphenylalanine (L-DOPA) is considered the gold standard for the treatment of Parkinson's disease (PD). However, long-term administration of L-DOPA can induce abnormal side effects. On the other hand, selective serotonin reuptake inhibitors (SSRIs) including fluoxetine have gained tremendous popularity in the treatment of depression in PD. SSRIs are thought to influence motor function in PD via pharmacological modification of interactions between serotonergic and dopaminergic networks, which are complex and not yet fully understand. In this study, intranigral injection of 6-hydroxydopamine (6-OHDA) in rats caused a significant loss of tyrosine hydroxylase immunoreactivity in the striatum and substantia nigra. However, tryptophan hydroxylase immunoreactivity of the striatum and raphe nucleus was unaffected by 6-OHDA. Immunohistochemical analysis reveal that the serotonergic system was unaffected by the injection of 6-OHDA. We demonstrated also that pre-treatment with fluoxetine significantly suppressed L-DOPA-induced rotational behavior. Additionally, fluoxetine suppressed L-DOPAinduced ERK1/2 and histone H3 phosphorylation. These effects of fluoxetine were abolished by pre-treatment with WAY 100135, a 5-HT 1A antagonist. These results suggest that fluoxetine may influence motor function in PD via pharmacological modification of interactions between serotonergic and dopaminergic neuronal networks.

Bisphosphonates are widely used for the treatment and prevention of bone diseases, including Paget disease, hypercalcemia of malignancy, and postmenopausal osteoporosis. In this study, we developed a novel transdermal patch of alendronate, a nitrogencontaining bisphosphonate, for the treatment of bone diseases. The maximum permeation fluxes of alendronate through rat and human skin after application of this patch were 1.9 and 0.3 mg/cm 2 per hour, respectively. The bioavailability (BA) of alendronate in rats was approximately 8.3% after the application of alendronate patch and approximately 1.7% after oral administration. These results indicated that the transdermal permeation of alendronate using this patch system was sufficient for the treatment of bone diseases. The plasma calcium level was effectively reduced after application of the alendronate patch in 1a-hydroxyvitamin D 3 -induced hypercalcemia model rats. The alendronate patch also effectively suppressed the decrease in bone mass in model rats with osteoporosis. Modest alendronateinduced erythema of rat skin was observed after application of the alendronate patch. Incorporation of butylhydroxytoluene in the alendronate patch almost completely suppressed this alendronate-induced skin damage while maintaining the transdermal permeation and pharmacologic effects of alendronate. These findings indicate that our novel transdermal delivery system for alendronate is a promising approach to improve compliance and quality of life of patients in the treatment of bone diseases. ß

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