ABSTRACT
Objective To explore the protective effect and mechanism of gardenoside on the damage of dopaminergic neurons induced by lipopolysaccharide (LPS). Methods Both neuron-enriched cultures and neuron-astrocyte cultures were pretreated with vehicle or gardenesides ( 10, 20 and 40 mg/L) for 30 min at 37℃. The culture media were subsequently renewed in order to remove gardenesides. LPS was then added into all culture media at a final concentration of 10 mg/L Twenty-four hours later, the culture media was collected to measure TNF-α, NO, IL-6, GDNF and MMP-9; the cells were collected to count the number of cells labeled with an antibody against tyrosine hydroxylase (TH) and to assess the expression of TH mRNA using reverse transcription-polymerase chain reaction. Results Gardeneside didn't promote the survival of dopaminergic neurons in neuron-enriched culture, but significantly increased the survival of dopaminergic neurons in neuron-astrocyte culture, compared with the vehicle group, the survival of dopaminergic neurons increased from 203.0%±17.4% to 256.7%±15.2% ( F = 17.22, P = 0.001 ) in 40 mg/L gardenaside group. The amount of TNF-α, NO and GDNF released from the neuron-astrocyte cultures after 24 h of addition of LPS was not changed significantly, while the expression of IL-6 and MMP-9 was increased significantly. In this study, the gardenoside concentration-dependently attenuated the LPSinduced increase of the expression of IL-6 and MMP-9, compared with the vehicle group, the expression of IL-6 and MMP-9 decreased to 67.2%±6.4% (F= 12.89,P =0.001 ), 77.3%±9.8% (F =8.27,P = 0.001 ) respectively in 40 mg/L gardenoside group. Conclusions Astrocytes play a neuroprotective role on dopaminergic neurons, which is decreased by LPS via inducing the secretion of pro-inflammatory factors. Gardeneside may protect dopaminergic neurons from LPS-induced injury in an astrocyte-dependent manner and it inhibits the production of proinflammatory factors instead of promoting the secretion of GDNF. From the point of view that a very low toxicity of gardenesides has been well documented, this report may reveal a new way of developing therapeutic interventions for inflammation-related diseases such as Parkinson's disease.
ABSTRACT
Objective To investigate the role of astrocyte in the lipopolysaccharide-induced damage of dopaminergic neurons. Methods After lipop01ysaccharide was applied to the third generation of rat astrocytes for 24 hours,supernatants of astrocytes culture were collected.The primary middle-brain dopaminergic neuron-enriched culture systems were obtained by neurobasal and ara-c,eoeulture system of both astrocytes and neurons was established by transwell inserts.The lipopolysaccharide was administered into neuron-enriched systems and coculture systems and the change of dopaminergic neurons was detected.At the same time,the supernatants of astrocytes were administered into the neuron-enriched systems,and the survival of dopaminergic neurons and the expression of tyrosine hydroxylase mRNA were observed. Results Lipopolysaccharide had a negative effect on the survival of dopaminergic neurons in a concentration-dependent manner.Both astrocytes and supernatants promoted the survival of dopaminergie neurons,and the former was better than the latter. In the preoccupation of existence of astrocytes,low-concentration lipopolysaccharide promoted the survival of dopaminergic neurons,while high-concentration,decreased.The change of the expression of tyrosine hydroxylase mRNA was similar to the survival of dopaminergic neurons.Conclusions Astrocytes play a protective role in the damage of dopaminergic neurons induced by lipopolysaccharide,and suitable activation of astrocytes would increase the protective effect while excessive activation of astroeytes would attenuate the effect.