热应激诱导大鼠延髓内脏带神经元Fos蛋白的表达

为了探讨不同温度下,大鼠的行为表现及大鼠延髓内脏带内神经元Fos蛋白的表达情况,本研究将成年SD大鼠置于不同温度(24℃、34℃、38.5℃、42℃),相对湿度60%的实验仓内60min,观察大鼠的行为表现。应用免疫组化法,观察大鼠延髓内脏带内Fos和酪氨酸羟化酶(TH)阳性神经元的形态、分布和数量的变化。行为学结果显示:(1)24℃时,大鼠无异常表现,直肠温度为36℃左右;(2)34℃时大鼠直肠温度升高至38℃左右,但动物行为亦无明显变化;(3)在38.5℃和42℃时,大鼠直肠温度升高至39℃以上,且大鼠的行为最初表现为精神萎靡,而随后转为兴奋状态。免疫组化染色结果显示:(1)24℃时,延髓内脏带的孤束核与延髓腹外侧区内Fos阳性胞核较少;(2)34℃时,上述部位内Fos阳性胞核的数量增加;(3)38.5℃时,Fos阳性胞核的数量达到峰值;Fos/TH双标神经元的比率分别占TH或Fos单标神经元的69%和43%;(4)42℃时,Fos阳性胞核又降低,并观察到三种Fos阳性细胞:胞核为Fos阳性,胞浆为Fos阳性,以及胞浆、胞核均为Fos阳性。以上结果提示:延髓内脏带参与了热应激过程,Fos蛋白的表达随温度的升高而发生明显的变化,且TH阳性神经元可能参与了这种作用的调节。

HEAT STRESS INDUCED THE EXPRESSION OF FOS PROTEIN IN THE MEDULLARY VISCERAL ZONE OF RAT

To investigate the expression of Fos protein in medullary visceral zone (MVZ) of rats treated with different temperature, the adult rats were located within the experimental incubator, the temperature within the incubator was regulated to 24℃, 34℃, 38.5℃, 42℃, respectively and the relatively humidity was 60%, for 60 minutes,and observe the rats’behavior. Immunohistochemical method was used to observe the shape, distribution and number of Fos-or/and tyrosine hydroxylase(TH)-positive neurons in MVZ. The behaviors results showed: (1) At 24℃, the rats’behavior was normal and the rectal temperature was about 36℃; (2) At 34℃, the rectal temperature raised to 38℃, but rats’behavior was found no change; (3) At 38.5℃ and 42℃, the rectal temperature raised to over 39℃, the rats depressed at first and then came into emotional state. The immunohistochemical staining result showed: (1)At 24℃, Fos-positive neurons were rare in nucleus of tractus solitarius (NTS) and ventrolateral medulla (VLM) in MVZ; (2) Fos-positive neurons in the above regions increased at 34℃; (3) number of Fos-positive neurons peaked at 38.5℃ and the proportion of double Fos/TH-labeled neurons compared to single TH-and Fos-positive cells were 69% and 43%, respectively; (4) Fos-positive neurons decreased at 42℃ and three different types of Fos-positive neurons were found in MVZ: Fos protein only expressed in the nucleus; Fos protein only appeared within the cytoplasm; Fos protein can be found both in the nucleus and the cytoplasm. The present results suggest that MVZ participates in the heat stress. The expression of Fos protein changed markedly following the ambient temperature rised, and TH-immunoreactive neurons were involved in the modulation of the heat stress reaction.