Study On The Role Of The Lateral Parabrachial Nucleus Nesfatin-1 On Feeding And Energy Homeostasis

Objective:(1)To observe the effect of nesfatin-1 injection on nocturnal feeding and drinking behavior in the lateral parabrachial nucleus(LPBN).(2)To observe the effects of nesfatin-1 on the excitability of glucose-sensitive(GS)neurons in the LPBN.(3)To investigate whether LPBN nesfatin-1 affects feeding behavior through the melanocortin system.(4)To observe the effect of long-term nesfatin-1 injection on body weight in the LPBN.(5)To observe the effect of long-term nesfatin-1 injection on fat distribution and the protein expression level of uncoupling protein-1(UCP1)in the LPBN.(6)To investigate whether LPBN nesfatin-1 affects body weight through the melanocortin system.Methods:(1)The effects of LPBN administration of nesfatin-1 on rat feeding and drinking behavior as well as the effect of long-term administration on body weight were observed by the combination of catheter implantation,microinjection and the technique of monitoring feeding behavior.(2)By means of in vivo electrophysiological technique,we detected the firing rate of unit neuron and observed the effect of nesfatin-1 on GS neurons in LPBN.(3)By using molecular biological techniques such as HE staining and Western Blot,we observed the fat morphology,detected the protein expression level of UCP1 to investigate the possible mechanism.Results:(1)In the feeding experiment,compared with the 0.9% Na Cl,50 pmol nesfatin-1 injected into the LPBN significantly decreased nocturnal cumulative food intake in 3,5,6,7,8,9,10,11,12 h time points and the inhibition ratios were 31.8%,25.8%,25.4%,25.6%,20.4%,22.1%,24.3%,21.4%,and 18.6% respectively.The average meal size between 6 to 12 h was reduced(2.83 ± 0.4 vs.1.86 ± 0.7 g/meal,P < 0.05),but the 12 h water consumption,6-12 h average meal number,0-6 h average meal number and size were not significantly different(P > 0.05).During the 10-day long term administration in LPBN,50 pmol nesfatin-1 significantly decreased the body weight gain in day 4,5,6,7,8,9,10,and the inhibition ratios were 59.5%,57.6%,57.8%,50.6%,43.0%,37.3%,42.0% respectively compared with the 0.9% Na Cl.(2)33 GS neurons were recorded in LPBN,24 of them were GI neurons and 9 of them were GE neurons.Compared with 0.9% Na Cl,1.5×10-8 M nesfatin-1 could significantly increase the firing rate of GI neurons(2.46 ± 0.6 Hz to 4.65 ± 0.8 Hz,P < 0.05)and decrease the firing rate of GE neurons(3.26 ± 0.4 Hz to 1.67 ± 0.5 Hz,P < 0.05).(3)Compared with the 0.9% Na Cl,50 pmol nesfatin-1 injected into the LPBN significantly decreased nocturnal cumulative food intake in 4-12 h(4 h,6.53 ± 1.3 vs.3.66 ± 0.7 g,P < 0.05;12 h,18.1 ± 1.7 vs.12.2 ± 1.6 g,P < 0.05).And the effect could be attenuated by SHU9119(P > 0.05).During the 10-day long term administration in LPBN,50 pmol nesfatin-1 could significantly reduce the gain of body weight between day 3 to day 9 compared with 0.9% Na Cl(day 3,9.64 ± 2.5 vs.3.64 ± 1.5 g,P < 0.05;day 9,25.46 ± 2.67 vs.16.28 ± 2.5 g,P < 0.05).And the effect could be attenuated by SHU9119(P > 0.05).(4)During the 10-day long term administration in LPBN,50 pmol nesfatin-1 could significantly darker the brown adipose tissue and increase the cell number(49.7 ± 2.3 vs.63.6 ± 1.3 cells/unit area,P < 0.05)as well as increase the UCP1 expression(1.67 ± 0.3 vs.2.39 ± 0.3,P < 0.05)compared with 0.9% Na Cl.And the effect could be attenuated by SHU9119(P > 0.05).But there was no significant difference in the weight of the inguinal,epididymal,perirenal white fat and interscapular brown adipose tissue.And the protein expression level of UCP1 in white fat was not significantly different as well.Conclusion:(1)Nesfatin-1 administrated into LPBN significantly decreased nocturnal cumulative food intake and 6-12 h average meal size.(2)Long term nesfatin-1 administration lower the body weight gain.(3)Nesfatin-1 mainly increase the firing rate of GI in LPBN.(4)LPBN nesfatin-1 regulates feeding behavior partly through the melanocortin system.(5)LPBN nesfatin-1 promotes the expression of UCP1 in BAT partly through the melanocortin system.The results of this study provided experimental references for the further investigation of the role of LPBN nesfatin-1 in the diseases such as obesity and energy metabolism disorders.