Effect Of Pineal Gland And Melatonin On TrkB Expression Of Rat Thymus

Objective To study the effect of pinealectomy (Px )and melatonin(MLT) supplementation on trkB expression in rat thymus, discuss weather MLT prevent massive apoptosis of thymocytes by the role of trkB regulation or not, find out pineal gland and MLT affect trkB expression in thymus through thymocytes directly or through macrophages indirectly, or through both. Consequently enrich the theory of neuroendocrine-immune network.Methods①The pinealectomized rats model were established: 110 clean male rats of 2 months old were divided into five groups: normal control group, sham operation group, pinealectomized group, pinealectomy +7.5 mg·kg-1·day-1 MLT intraperitoneal injection group , pinealectomy +15 mg·kg-1·day-1MLT intraperitoneal injection group , and the thymus was taken out at 4th week and 8th week,rats of M0 group were injected normal sodium in the same volume as other groups.②Semiquantitative reverse transcription- polymerase chain reaction (RT-PCR) and the gel imaging analysis system were applied to observe and analyse the changes of thymic trkBmRNA after Px and MLT supplementation;③Immunohistochemistry(IHC) and the quantitative automatic image analysis soft were used to observe and analyse the changes of trkB positive cell in thymus after Px and MLT supplementation;④Double-immunofluorescent labeling for trkB and ED1 and confocal-laser scanning microscope were used to observe and analyse the changes of double positive cell in thymus after Px and MLT supplementation.Results①Compared to normal and sham group, Semiquantitative RT-PCR of rat thymus showed trkBmRNA expression decreased, which revealed the expression of thymus trkBmRNA weakened after Px, and the expression recovered to normal at 8th week in high dose group after MLT supplementation;②C ompared to normal and sham group, the result of IHC in rat thymus showed that the number of trkB positive cell decreased and positive areas lessened, which revealed that the expression of thymic trkB protein weakened after Px, the result of thymic trkB IHC in Px rats after MLT...