Distribution Of Insulin-like Growth Factor-1 In The Brain Of Rat And The Effects Of Fasting And Taste Appetite On The Expression Of It In The Liver And Brain

Insulin-like growth factor-1 (IGF-1) take important role in the metabolism, immunity adjustment, growth, retraining cell from languishing and brain damage protection. It has broad theory meanings and practice meanings to investigate the regulation of IGF-1 production. Circulating IGF-1 root in the liver, and enter the brain through the blood-brain barrier . The brain can synthesize IGF-I itself. In the state of physiology, mRNA of IGF-1 and mRNA of IGF-1 receptor express abroad in the central nervous system. Nutrition state is the primary factor to adjust the production of IGF-1. On the other hand, the taste appetite always change obviously accompany with the alteration of nutrition state. Taste stimulus also induce to product some biology active substances, so that has important influence on the nutrition metabolism. But it is not clearly that if the taste stimulus and the change of taste appetite can affect IGF-1 synthesis or not. In this research , adult male SD rats were study objects and immunohistochemacal staining technique was used to. Firstly, we observed systemically the distribution of IGF-1 immunoreactive cells in the brain, then observed the effects of fasting and taste appetite on the expression of it in the liver and brain, discussed the influence of taste stimulus and taste appetite on adjusting IGF-1 synthesis.This research was composed of three parts: in the first part, we observe the distribution of IGF-1 in the normal rat brain and the changes of IGF-1 expression in the brain in the condition of fasting and without water for 24 h, fasting for 72 h, and taking food after fasting for 24 h; in the second part, the influences of different taste stimulus(sucrose solution, saccharin solution and water) on the expression of IGF-1 in the liver and brain were observed; in the third part, the effects of conditioned taste aversion(CTA) on the expression of IGF-1 in the brain were observed.The results were:1, The IGF-1 immunoreactive cells were distributed extensively in the olfactory bulb, telencephalon, cerebellar cortex, hypothalamus, midbrain, spinal cord and so on .2, In fasting rats, the level of expression of IGF-1 had been lower in lateral mammillary nucleus and perirhinal cortex, but higher in subiculum and occipital cortex than control group. There was no significant difference in the expression of IGF-1 in brains between fasting for 24 h group and for 72 h group.3, For rats without food and water for 24 h, refed could restore the expression of IGF-1 in the brain.4, For rats without food and water for 24 h, the expression of IGF-1 in the liver was depressed; there was no difference between the appetite ratio of sucrose solutions and the appetite ratio of saccharin solution for rats. After rats were forbidden to take food and water, taking sucrose could restore the expression of IGF-1 in the liver, whereas taking saccharin or water could not do that.5, For rats without food and water, the change of the expression of IGF-1 in some regions could restore completely or partly through taking sucrose, saccharin or water.6, CTA could weaken the expression of IGF-1 in the brain, and the effect is special in different areas. In CTA of saccharin group, the expression levels of IGF-1 in CMC and LM fell. In the same way, CTA of sucrose depressed the expression levels of IGF-1 in LM, MP and S.Above results suggest:1, IGF-1 in brain perhaps regulate a lot of actions of neural function.2, Fasting induce the synthesis of IGF-1 in liver to reduce, but the effects of fasting on the expression of it in brain is special in different areas: the influence is stimulative in some areas(S,OC), while is repressive in other areas(LM,PRh).Even in some parts, fasting can not affect the expression of IGF-1 at all.3, In liver, the influences of protein and sugar on the expression of IGf-1 are much larger than the influences of taste stimulus.4, In brain, the nutrition factor, the taste stimulus and taste appetite all affect the expression of IGF-1.5, IGF-1 in brain may take part in the process of the taste identification and CTA.