Study type: Medical/biological study (experimental study)

Sympathetic neurons express and secrete MMP-2 and MT1-MMP to control nerve sprouting via pro-NGF conversion. med./bio.

Published in: Cell Mol Neurobiol 2011; 31 (1): 17-25

Aim of study (acc. to author)

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.

Background/further details

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.

Endpoint

Exposure

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

Exposure 1

Main characteristics
Frequency 5 Hz
Type
Exposure duration continuous for 48 hr
Modulation
Modulation type pulsed
Pulse width 1 ms
Pulse type biphasic
Exposure setup
Exposure source
  • C-PaceEP external pacing system
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 2 V/cm - - - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 48 hr
Modulation
Modulation type pulsed
Pulse width 1 ms
Pulse type biphasic
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 2 V/cm - - - -

Reference articles

  • Saygili E et al. (2010): Electrical stimulation of sympathetic neurons induces autocrine/paracrine effects of NGF mediated by TrkA.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

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.

Study character:

Study funded by

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