| Summary: | 碩士 === 國立中興大學 === 畜產學系 === 90 === Neutrophils play an important role in immune system. To against infection, numerous neutrophils migrate from blood to tissues. Apoptosis may accompany the activation of neutrophils. The present study used dairy goat as an model animal, to evaluate the change of morphology、apoptotic percent and function of neutrophils transmigrate from blood to mammary in different stage of lactation. Also, to explore the effect of different heat treatment on neutrophils.
Neutrophils isolated from blood and milk were about 10-15 μm in diameter and multilobed nucleus. The lobular nucleus of blood neutrophils were almost two or three lobes and some band cells were found. Cyoplasm of blood neutrophils was full of abundant pink granules. Apoptosis was characterized by nuclear pyknosis、cellular shrinkage、reduction in cell volume and apoptotic bodies. The results show milk neutrophils have more apoptosis with extension of lactation and heat treatment can increase apoptosis. In addition, using flow cytometry to analyse apoptosis according to the less SSC-Height（granules） and FSC-Height（cell size）also obtain the same consequence.
Measure the lipid peroxidation of neutrophil by TBARs（thiobarbituric acid reative substance）. There were no significant（P＞0.05）changes between blood neutrophil and milk neutrophils. Also no significant（P＞0.05）changes were observed after neutrophils treated with heat.
The release gelatinase of neutrophils increase significantly stimulated with PMA（phorbol 12-myristate 13-acetate）and heat treatment for 1 hr. There were no significant difference between milk neutrophils and blood neutrophils.
The respiratory burst of blood neutrophils and neutrophils measured by luminal-catalyze chemiluminescence. In the presence of PMA, both the respiratory burst of milk neutrophils and blood neutrophils increased. In different lactation period, the value of late lactation was highest. The values of blood neutrophils were the double of milk neutrophil and increased earlier and higher. However, the respiratory burst of milk and blood neutrophils decreased treated with heat.
Apoptosis of neutrophils were detected by fluorscent microscope and flow cytometric analysis double stained with Annexin V and PI. The results show neutrophils treated with heat have more fluorescent（apoptosis）cell than control. Furthermore, apoptotic percentage of milk neutrophils are higher than blood neutrophils, and increase with extension of lactation.
In conclusion, milk neutrophils were in a more advanced stage of differentiation than their counterparts in blood. With lactation extend, milk neutrophils apoptosis increased and their function decreased significantly, but there was no significant change in lipid peroxidation. Heat treatment induced neutrophils apoptosis and decreased their function but also no effect on lipid peroxidation. So the decrease of function may be caused by aging、apoptosis or other parameter but not oxidative stress.
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