Related Experiment Videos
Postnatal decrease of sodium current density in rat pituitary melanotropes following the onset of dopaminergic
L F López-Santiago1, J C Gómora, G Cota
1Department of Physiology, Biophysics and Neuroscience, Cinvestav-IPN, AP 14-740 Mexico City, DF 07000, Mexico.
Neuroscience Letters
|November 22, 2001
Summary
Dopamine D2 receptor activation reduces sodium channel function in developing rat melanotropes. This inhibition of sodium channels is reversed by blocking D2 receptors, highlighting their role in synaptic input.
Area of Science:
- Neuroscience
- Cellular Biology
- Endocrinology
Background:
- Peptide secretion from rat melanotropes is regulated by dopaminergic input.
- This input develops postnatally and acts via D2 dopamine receptors.
- The precise mechanism of this inhibition on melanotropes is not fully understood.
Purpose of the Study:
- To investigate the impact of developing dopaminergic innervation on sodium (Na+) currents in rat melanotropes.
- To determine the role of D2 dopamine receptors in modulating Na+ channel activity during postnatal development.
Main Methods:
- Whole-cell patch-clamp recordings of Na+ currents were performed on rat melanotropes.
- Melanotropes were isolated from the pituitary intermediate lobe at various postnatal days (P1-P20).
- Pharmacological manipulation using the D2 antagonist sulpiride was employed.
Main Results:
- A progressive decrease in peak Na+ current density was observed in melanotropes from postnatal day 3 to 14.
- This reduction correlated with the development of dopaminergic innervation.
- Sulpiride treatment restored Na+ channel activity to pre-innervation levels, indicating D2 receptor involvement.
- The decrease in current density was attributed to reduced maximal Na+ conductance, not altered channel gating.
Conclusions:
- Postnatal development of dopaminergic input leads to a reduction in functional Na+ channels in rat melanotropes.
- Activation of D2 dopamine receptors by synaptic input is responsible for this reduction.
- Dopaminergic signaling plays a crucial role in regulating melanotrope excitability through modulation of Na+ channel expression.