香料物質對嗅覺神經細胞與人體血漿中神經胜肽酪氨酸（NPY）表現之影響

Abstract

NPY為神經胜肽酪氨酸 (neuropeptide tyrosine) 之簡稱，由36個胺基酸所組成，廣泛地分布在中樞神經與周邊神經系統，是一種能促進食慾之胜肽。在2005年Shen等人發現葡萄柚精油及其組成分檸檬油烯(limonene) 能抑制動物之食慾，而薰衣草精油及其主成分沈香醛(linanool) 則增加動物之食慾，故推測香氣成分能刺激或抑制嗅覺神經分泌NPY，進而影響攝食行為。 本實驗室之前的研究發現，以檸檬油烯及沈香酫處理培養兩天之大鼠嗅覺細胞株 Rolf B1. T cells 10分鐘，可以作為抑制及刺NPY mRNA 表現的篩選平台。本研究則以此篩選平台篩選出具有潛在刺激NPY mRNA 表現之香料物質，並進一步藉由人體試驗驗證之。實驗結果發現，篩選之十三種香料物質中，蘑菇醇(octenol) 、蒎烯 (pinene) 及 methyl phenylactetate 均顯著地刺激嗅覺細胞表現 NPY mRNA，故挑選蘑菇醇與蒎烯作人體實驗之驗證。人體實驗則分別以下列香氣刺激人類嗅覺 5、10、15 min，並測其血漿內NPY 含量之變化。另外，由脂肪細胞所分泌的leptin能與NPY作用相互拮抗，當leptin大量分泌時會抑制NPY促進攝食的作用。因此，本研究亦分析血漿內leptin之含量。本研究以水作為控制組，檸檬油烯作為負控制組，正控制組為沈香醛，試驗樣品為蘑菇醇及蒎烯。實驗結果發現，予以檸檬油烯之負控制組中血漿內NPY含量之變化在10 min時下降最多(-11.54%)，顯示其具有抑制食慾之潛力。正控制組中，予以受試者沈香醛5及10 min均可增加血漿內NPY之含量(22.92%, 5.71%)；蘑菇醇之組別亦在5、10及15 min之刺激下均可增加血液內NPY之含量(13.67%, 3.29%,5.21%)；但蒎烯之組別，血漿內NPY含量之變化較不明顯。至於，血漿內leptin之變化，由於其易受多種生理因子影響，故實驗結果缺乏一致性。另外，在受試 5、10及15分鐘後，受試者之血壓及耳溫均無顯著改變。在問卷方面，從受試者對於問卷之回應結果難以看出其與血漿內NPY及leptin含量變化之關係性。

Neuropeptide tyrosine (NPY), a 36-amino acid peptide, is widely present in the central and peripheral nervous system, especially abundant in the brain. NPY is the most important stimulator of food intake. On the other hand, essences such as limonene and linalool, which are respectively the major components of grapefruit oil and lavender oil, have been verified to influence (decrease/increase) appetite in rats. Therefore, we propose that appetite regulation effect of spices might be connected with the secretion of NPY. In a previous study, we had established a NPY expression screening model by culturing olfactory nerve cells Rolf B1.T for 2 days and treating cells with limonene and linalool for 10 min. Thus, in this study, we used this model to screen thirteen spices and expected to find potential spices that could stimulate NPY mRNA expression of Rolf B1.T cells. Furthermore, a clinical trial was implemented to study the effects of these spices on the human physiological indicators, including ear temperature, blood pressure, and plasma NPY secretion. Furthermore, leptin is synthesised by adipocytes in proportion to the levels of stored triglycerides, and is a key hormone in the regulation of food intake and energy expenditure. This research also analyzed the leptin content in plasma. In addition, personal’s questionnaire was used to further investigate the relationship between food intake and aroma components. In NPY expression screening model, our result indicated that octenol, pinene, and methyl phenylacetate significantly increased NPY mRNA levels in the Rolf B1.T cells. Moreover, the results of clinical trial were as follows: 1) when the experimental period was 10 min, limonene (negative control) decreased plasma NPY level, indicating that it might inhibit appetite, 2) when the experimental periods were 5, 10 min, linalool (positive control) increased plasma NPY level, indicating that it might stimulate appetite, 3) when the experimental periods were 5, 10 and 15 min, octenol could increase plasma NPY level, revealing that it might be a potent stimulator of food intake, 4) the plasma NPY level in the pinene group had no obviously changes at any experimental time. However, the results of plasma leptin concentrations were inconclusive. We suspected that it was influenced by other physiological factors. Blood pressure and ear temperature were not significantly changed at any experimental time.