To study the expression, regulation, and function of matrix metalloproteinase-2 and its major activator "membrane type 1-matrix metalloproteinase" (MT1-MMP), as well as its inhibitor TIMP-1 in sympathetic neurons under conditions of electrical stimulation.
Moreover, the molecular mechanisms of the beneficial effect of losartan was analysed, an "angiotensin II type I receptor" (AT-1) blocking agent, since angiotensin receptor blockers have been shown to decrease the recurrence of atrial fibrillation independently from blood pressure reduction.
In a previous study (see Saygili et al. 2010) the authors have shown that electrical field stimulation of sympathetic neurons induced nerve sprouting by upregulation of nerve growth factor. There is increasing evidence that matrix metalloproteinase-2 is not only involved in extracellular matrix turnover but may also exert beneficial effects during neuronal growth.
Primary cultures of superior cervical ganglia were performed from postnatal day 1-3 Sprague-Dawley rats.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
5 Hz
Modulation type:
pulsed
Exposure duration:
continuous for 48 hr
|
|
|
Exposure 2:
50 Hz
Modulation type:
pulsed
Exposure duration:
continuous for 48 hr
|
|
| Frequency | 5 Hz |
|---|---|
| Type | |
| Exposure duration | continuous for 48 hr |
| Modulation type | pulsed |
|---|---|
| Pulse width | 1 ms |
| Pulse type | biphasic |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 2 V/cm | - | - | - | - |
| Frequency | 50 Hz |
|---|---|
| Type | |
| Exposure duration | continuous for 48 hr |
| Modulation type | pulsed |
|---|---|
| Pulse width | 1 ms |
| Pulse type | biphasic |
| Exposure source |
|
|---|
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 2 V/cm | - | - | - | - |
The electrical stimulation increased matrix metalloproteinase-2 and MT1-MMP gene expression and protein expression, whereas TIMP-1 expression remained unchanged.
Specific pharmacological matrix metalloproteinase-2 inhibition contributed to an increase in pro-NGF amount in the cell culture supernatant and significantly reduced electrical field-induced neurite outgrowth.
Losartan abolished electrical field-induced nerve sprouting in a significant manner by preventing electrical field-induced NGF, matrix metalloproteinase-2, and MT1-MMP upregulation.
To investigate whether electrical stimulation induced matrix metalloproteinase-2 secretion and activation depended on NGF signaling, loss of function experiments with NGF-neutralizing antibodies were performed: NGF neutralizing did not reduce electric field-induced matrix metalloproteinase-2 secretion and activation.
The major findings of this study are: a) superior cervical ganglia express and secrete matrix metalloproteinase-2 and MT1-MMP to control nerve sprouting via pro-NGF conversion under electrical stimulation; b) electric field-induced sympathic nerve sprouting can be prevented by losartan or matrix metalloproteinase-2 inhibition via two different mechanisms; c) matrix metalloproteinase-2 activation due to electrical stimulation did not depend on NGF signaling.
In summary, specific matrix metalloproteinase-2 blockade prevents sympathetic nerve sprouting by inhibition of pro-NGF conversion while losartan abolishes electrical field-induced sympathetic nerve sprouting by reducing total NGF, matrix metalloproteinase-2 and MT1-MMP expression.
This website uses cookies to provide you the best browsing experience. By continuing to use this website you accept our use of cookies.
