Influence On The Expression Of C-fos Gene By The Different Intensity Light Stimulation In Hen Tectofugal Pathway

To explore the neuroregulation mechanism of illumination to the production trait of the hens, and to provide theorietical basis to promote further development for the scientific use of light in chicken production, In this study, HRP retrograde markers and the detection of c-fos nucleoprotein by immunohistochemistry was combined to study the reaction to the stimulation of different illumination to the tectofugal pathway of the hens. Birds were the vertebrate that depend on visual system most, their tectofugal pathway was one of the major two parallel visual information processing pathways, it include retina, optic tectum, rotundus and ectostriatum. 120 days old hens were applied and after wearing a blinder for 5 days on the right eyes, HRP was inducted, after 48 h, stimulation of illumination by different intensity was applied for 1~1.5 h. After a dark adaptation for 1.5 h, the brains were removed from the skulls after perfusion, successive frozen sections were made, neuron was marked retrograded, immunohistochemical method was applied to detect the expression,way of appearance, position and quantity analysis of c-fos gene in rotundus,optic tectum and SP/IPS nucleus, detected the pathway and function active area of chick tectofugal pathway to different intensity of optical information, and the effect of the expression of c-fos gene in chick tectofugal pathway, lay a foundation for further exploration.The results showed that the retrograde labelled cells with HRP were round, elliptic or polygonal, the positive cells distributed in stratum griseum centrale (SGC) of left optic tectum and SP/IPS nucleus. If the injection sites of HRP located in the side of ROT, the positive cells gathered in superficial layer of SGC and medial part of SP/IPS nucleus. When the injection sites of HRP located in back pars caudalis of ROT,the positive cells gathered in superficial layer of SGC and lateral part of SP/IPS nucleus. When it situated in central part, the positive cells majored in intermediate layer of SGC and lateral part of SP/IPS nucleus. And it changed in regio abdominis caudalis of ROT, the positive cells majored in deep layer of SGC and lateral part of SP/IPS nucleus. It was detceted that there were a great quantity of Fos like immune response positive neurons in diencephalon and mesencephalon, the nucleus and nuclear membrane were tan or particle deposition, cytoplasm, axon and dendrite was not colored, the boundary of nucleus and cytoplasm was obviously, perikaryon in each nuclear regiment was mainly triangle, orbicular-ovate, fusiform and pear-shaped, which distributed major in left side of chicken brain, included SGC, ROT and SP/IPS. The test team expressed significantly,fewer positive neurons distributed in control group, positive neurons in negative control are did not see. Analyze the cell of HRP retrograde markers and the region, density and overlaying of Fos like immune response positive neurons, investigate the effect of different intensity of illumination to the expression of c-fos gene in chick tectofugal pathway. We found that the level of the expression of c-fos gene is different. Among the total, the expression level in SGC and ROT was higher in group 30 lx, it declined slightly in group 40 lx, group 20 lx and 10 xl were lower. In group 40 lx, it expressed higher in SP/IPS,which lower in group 30 lx, 20 lx and 10 lx.In different position in SGC, SP/IPS and ROT, optical density value was tested in the area of 100μm×100μm, it contrast significantly in group 10 xl and 20 lx, 20 lx and 30 lx, 30lx and 40lx, 10 lx and 30lx, 10 lx and 40 lx, 20 lx and 40lx (P<0.05). It reflected that the expression of Fos like immune response positive neurons in each nuclear regiment concerned with different intensity of light stimulus, and in different depth of SGC, the sensitivity to light stimulus was different, and sensitivity was the weakest in the deep layer of SGC, it reached the peak in the 30 lx. Tracking by HRP, it showed that there were two pathway for neuron in SGC deep layer projecting to ROT, one was projected to regio abdominis caudalis of ROT directly, the other was through SP/IPS. The sensitivity to light stimulus of former was lower than ROT lateral part, central part and back pars caudalis, and the expression of c-fos gene in ROT reached the peak in the 30 lx. SP/IPS was divided into inside and lateral, expression product of c-fos in 40 lx were the most in the two parts, but it was obvious in inside than lateral. SP/IPS-circle nucleus projection was a parts corresponding projection that local region order projection. Comprehensive analysis the expression of c-fos gene in tectofugal pathway induced by light stimulus, it was reliability. Through the retina, light information was transmited to ROT in mesencephalon by tectofugal pathway, meanwhile optic tectum-SP/IPS-ROT passageway played an important role in the conduction of light information.