The spontaneous firing rates of dopamine-inhibited dorsomedial arcuate neurons exhibit a diurnal rhythm in brain slices obtained from ovariectomized plus estrogen-treated rats

作者：Liang Shu Ling^*; Pan Jenn Tser

来源：Brain Research Bulletin, 2011, 85(3-4): 189-193.

DOI：10.1016/j.brainresbull.2011.03.009

• Dorsomedial arcuate nucleus
• Single-unit extracellular recording
• Diurnal rhythm
• TIDA neuron
• Dopamine receptor

The activity of tuberoinfundibular dopaminergic (TIDA) neurons exhibits a diurnal rhythm in female rats, as determined by neurochemical investigation. Whether the spontaneous firing rates of presumed TIDA neurons in the dorsomedial arcuate nucleus (dmARN) also exhibit a diurnal pattern has yet to be ascertained. Single-unit activities of 131 dmARN neurons were recorded in brain slices prepared from 83 ovariectomized plus estrogen-primed rats, and grouped according to their responses to dopamine and the time at which they were observed. In dopamine-inhibited dmARN neurons, significantly lower firing rates were observed in the afternoon compared to those recorded in the morning (2.51 +/- 0.27 Hz, n = 15, from 1130 to 1330 h vs. 1.08 +/- 0.07 Hz, n = 47, from 1430 to 1630 h). No such change was observed in dopamine-excited or nonresponsive dmARN neurons (1.83 +/- 0.32 Hz, n = 9 vs. 1.46 +/- 0.17 Hz, n = 21). Four dmARN neurons were continuously recorded from 1130 to 1600 h or even longer until 2000 h. The averaged firing rates decreased significantly between 1300 and 1600 h, two neurons were also inhibited by dopamine and a selective D(2) receptor agonist, PHNO, in both normal and low Ca(2+), high Mg(2+) perfusion mediums. This study revealed the existence of diurnal changes in the firing rates of dopamine-inhibited dmARN neurons. These results are strongly correlated with the rhythmic changes observed in TIDA neuronal activity determined through neurochemical methods.

• 出版日期2011-5-30
• 单位长春大学