Alteration of membrane properties of MGBv neurons and the effect of GABA receptor agonist on them during postnatal development in rats
- VernacularTitle:大鼠生后MGBv神经元主动膜特性的变化及GABA受体激动剂的影响
- Author:
Yao XIAO-HONG
1
;
Wan ZI-BING
;
Xiong YING
Author Information
1. Third Military Medical University
- Keywords:
whole cell recording;
patch clamp;
brain slice;
ventral partition of medial geniculate body;
GABA receptor
- From:
Neuroscience Bulletin
2005;21(3):182-187
- CountryChina
- Language:Chinese
-
Abstract:
Objective To observe membrane properties of ventral partition of the medial geniculate body (MGBv) in Wistar rat and the effect of GABA receptor agonist on them during postnatal development. Methods Whole-cell patch clamp recording was used to record waveform of action potential (AP) and the effect of GABA receptor agonist on them from neurons in the MGBv of rats ( postnatal days 3-30). Results There was a difference in AP firing pattern in rat MGBv neurons of different postnatal day. We only recorded low threshold Ca2+ spikes (LTS) in P3 MGBv neurons, but recorded AP in P6-30 MGBv neurons after depolarizing currents application; AP was recorded at the start phase of pulse and with a long-last after hyperpolarization potential (AHP) in P8, in P20 AP was recorded after a delay and it appeared on depolarizing ramp with a shorter-last AHP compared with P8. The GABAA receptor agonist, muscimol, and the GABAB receptor agonist, baclofen, had effects on responses evoked by depolarizing current in the MGBv neurons in P6 and P15 rats. Muscimol and baclofen reduced AP firing rather than AP amplitude in P6 MGBv neurons, however, in P15 MGBv neurons baclofen had little effect on AP firing while muscimol greatly reduced the size of voltage shift produced by positive or negative current injection. Conclusion The AP waveform of MGBv neurons matures rapidly during first two postnatal weeks. A similar rapid maturation also has been observed in rat neocortical and hippocampal pyramidal neurons as well as in ferret dorsal lateral geniculate nucleus (LGNd) neurons. These results suggest that in the central nervous system of small mammals, AP waveforms mature rapidly in many types of neurons, thus, coordinated activities in neuronal circuits may occur. In early postnatal development, GABA receptor mainly mediates an excitation effect, depolarizes P6 MGBv neurons and dramatically increases the frequency of AP firing. Inhibition of GABA receptor matures slowly along with increment of postnatal days.
