Tran Phuong V, Tamura Yui, Pham Cuong V, Elhussiny Mohamed Z, Han Guofeng, Chowdhury Vishwajit S, Furuse Mitsuhiro
Laboratory of Regulation in Metabolism and Behavior, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka 819-0395, Japan.
Laboratory of Stress Physiology and Metabolism, Division of Experimental Natural Science, Faculty of Arts and Science, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka 819-0395, Japan.
Neuropeptides. 2021 Oct;89:102169. doi: 10.1016/j.npep.2021.102169. Epub 2021 Jun 30.
The role of the monoaminergic system in the feeding behavior of neonatal chicks has been reported, but the functional relationship between the metabolism of monoamines and appetite-related neuropeptides is still unclear. This study aimed to investigate the changes in catecholamine and indolamine metabolism in response to the central action of neuropeptide Y (NPY) in different feeding statuses and the underlying mechanisms. In Experiment 1, the diencephalic concentrations of amino acids and monoamines following the intracerebroventricular (ICV) injection of NPY (375 pmol/10 μl/chick), saline solution under ad libitum, and fasting conditions for 30 min were determined. Central NPY significantly decreased L-tyrosine concentration, the precursor of catecholamines under feeding condition, but not under fasting condition. Central NPY significantly increased dopamine metabolites, including 3,4-dihydroxyphenylacetic acid and homovanillic acid (HVA). The concentration of 3-methoxy-4-hydroxyphenylglycol was significantly reduced under feeding condition, but did not change under fasting condition by NPY. However, no effects of NPY on indolamine metabolism were found in either feeding status. Therefore, the mechanism of action of catecholamines with central NPY under feeding condition was elucidated in Experiment 2. Central NPY significantly attenuated diencephalic gene expression of catecholaminergic synthetic enzymes, such as tyrosine hydroxylase, L-aromatic amino acid decarboxylase, and GTP cyclohydrolase I after 30 min of feeding. In Experiment 3, co-injection of α-methyl-L-tyrosine, an inhibitor of tyrosine hydroxylase with NPY, moderately attenuated the orexigenic effect of NPY, accompanied by a significant positive correlation between food intake and HVA levels. In Experiment 4, there was a significant interaction between NPY and clorgyline, an inhibitor of monoamine oxidase A with ICV co-injection which implies that co-existence of NPY and clorgyline enhances the orexigenic effect of NPY. In conclusion, central NPY modifies a part of catecholamine metabolism, which is illustrated by the involvement of dopamine transmission and metabolism under feeding but not fasting conditions.
单胺能系统在新生雏鸡摄食行为中的作用已有报道，但单胺代谢与食欲相关神经肽之间的功能关系仍不清楚。本研究旨在探讨在不同摄食状态下，神经肽Y（NPY）中枢作用引起的儿茶酚胺和吲哚胺代谢变化及其潜在机制。在实验1中，测定了在随意进食、禁食30分钟条件下，经脑室内（ICV）注射NPY（375 pmol/10 μl/只鸡）、生理盐水后，间脑中氨基酸和单胺的浓度。中枢NPY在进食条件下显著降低了儿茶酚胺的前体L-酪氨酸浓度，但在禁食条件下没有。中枢NPY显著增加了多巴胺代谢产物，包括3,4-二羟基苯乙酸和高香草酸（HVA）。在进食条件下，3-甲氧基-4-羟基苯乙二醇的浓度显著降低，但NPY在禁食条件下未使其发生变化。然而，在两种摄食状态下均未发现NPY对吲哚胺代谢有影响。因此，在实验2中阐明了进食条件下儿茶酚胺与中枢NPY的作用机制。进食30分钟后，中枢NPY显著减弱了间脑中儿茶酚胺能合成酶如酪氨酸羟化酶、L-芳香族氨基酸脱羧酶和GTP环化水解酶I的基因表达。在实验3中，将酪氨酸羟化酶抑制剂α-甲基-L-酪氨酸与NPY共同注射，适度减弱了NPY的促食欲作用，同时食物摄入量与HVA水平之间存在显著正相关。在实验4中，NPY与单胺氧化酶A抑制剂氯吉兰经ICV共同注射存在显著相互作用，这意味着NPY与氯吉兰共存增强了NPY的促食欲作用。总之，中枢NPY改变了部分儿茶酚胺代谢，这表现为进食而非禁食条件下多巴胺传递和代谢的参与。
