| PrefaceRecent studies have demonstrated a deleterious impact of the estrogen deficiency on the bone mass and cardiovascular system and the resulting reduction of risk for disease by estrogen replacement therapy (ERT). Effects of ERT on relieving climacteric symptoms, improving genitourinary function , preventing osteoporosis and cardiovascular diseases have also been recognized. More and more postmenopausal women are receiving ERT, some of them may even use it all their lives.How estrogen deficiency and ERT affect various systems of the body is one of the key areas in scientific research. More and more clinical and laboratory studies suggest that the immune system is influenced by estrogen levels in the body. In addition, the existence of special estrogen receptors on glands and cells of the immune system also confirms the correlation of estrogen and immune function. ERT seems not to simply replace the lack of estrogen, but also affects the immune system, which is responsible for reacting to exogenous biological stimuli, by resulting in corresponding immunological changes. It's shown that humoral and cellular responses, natural immunity, and the amount of cytokines secreted inthe body are all influenced by estrogenic levels.Due to different laboratory conditions for testing, there are currently a variety of opinions about the impact of estrogen deficiency and ERT on the immune system. Scientific researchers all over the world are trying to find the answers from different perspectives.Nowadays, there have been many reports done abroad on the effects of estrogen deficiency and ERT on immune system, but domestically speaking, it is a subject that has undergone very little study. Genetically consistent mice C57BL/6 were chosen as objects in this experiment; thymus-body ratio, delayed type hypersensitivity (DTH) and abdominal macrophage phagocytosis are used as experimental indexes. We are trying to elucidate the impact that the use of ERT as treatment for estrogen deficiency in both low and high doses has on the immune system, looking at cellular and natural immunity in specific. We aim to provide more information about the relationship between estrogen deficiency, ERT and the immune system in order that a most safe and reasonable method of using ERT may be found.Materials and MethodsC57BL/6 female mice were divided randomly into 4 groups, one of which was the control group and was undergoing sham operation and vehicle injection subcutaneously ; the other three groups were experimental groups and were undergoing bilateral ovariectomy (OVX)+low dose estradiol, OVX+ high dose estradiol and OVX+ vehicle injection, respectively:Group A: Sham operation +vehicle injectionGroup B: OVX+ low-dose ERTGroup C: OVX+high-dose ERTGroup D: OVX+ vehicle injectionGroup B and C were given S.C. injection of 0.2ug and lOOug oestradiol benzoate respectively, each injected as a solution having been dissolved in O.lml olive oil. Injections were given twice a week, starting on the day of the operation. Group A and D were injected with O.lml olive oil only. One month after the operation, each group was divided into three groups which were to undergo three separate tests including: thymus-body ratio, delayed type hypersensitivity and abdominal macrophage phagocytosis (expressed as phagocytic percentage and phagocytic index) of red blood cells of the chicken.Results1 Thymus -body ratio: Group B showed no significant difference compared with control group A(p>0.05); group C was significantly lower than group A (P<0.01 ) ; group D was significantly higher than group A (P<0.01) .2 DTK reactivity: Comparing with control group A, the ear thickness in group B showed no significant difference after sensitization to DNFB(P>0.05); the ear thickness in group C was significantly lower than group A; (P<0.01); the ear thickness in group D was significantly higher than group B (P<0.05 ) .3 Abdominal macrophage phagocytosis: Comparing with control group A, the phagocyt... |
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