Calcitonin gene-related peptide and its receptor in the thymus

Calcitonin gene-related peptide (CGRP), a 37-amino acid residue neuropeptide, was immunostained in rat thymus at two sites: a subpopulation of thymic epithelial cells, namely subcapsular/perivascular cells, were heavily stained besides some nerve fibers surrounding arteries and arterioles. The administration of nanomolar concentrations of rat -CGRP dose-dependently raised intracellular cyclic adenosine monophosphate (cAMP) levels in isolated rat thymocytes (half-maximum stimulation 1 nM) but not in cultured rat thymic epithelial cells. Peptides structurally related to CGRP (i.e., rat calcitonin or amylin) had no effect. CGRP(8–37), an N-terminally truncated form, acted as an antagonist. Peripheral blood lymphocytes did not respond to CGRP, suggesting that receptors are present only on a subpopulation of thymocytes but not on mature T cells. This was substantiated by visualization of CGRP receptors on single cells by use of CGRP-gold and -biotin conjugates of established biological activity: only a small proportion of isolated thymocytes was surface labeled. In situ, the CGRP conjugates labeled receptors on large thymocytes residing in the outer cortical region of rat thymus pseudolobules. Thus, immunoreactive CGRP is found in subcapsular/perivascular thymic epithelial cells and acts via specific CGRP receptors on thymocytes by raising their intracellular cAMP level. It is suggested that CGRP is a paracrine thymic mediator that might influence the differentiation, maturation, and proliferation of thymocytes.     

Surface characteristics of thymocytes in glucocorticoid treated rats using rosette-formation technique and surface marker analysis.

Glucocorticoid (GC) treatment is known to induce destruction of cortical thymocytes and then their reconstitution. By using the rats treated with GC, we examined the relationship between rosette-formation and surface markers (CD4 and CD8) for clarifying the processes of differentiation and maturation in rat thymocytes. Thymus weight and thymocyte count began to decrease immediately after GC administration and became minimal on 5-7 days, followed gradual recovery. The percentage of rosette-forming thymocytes began to decrease immediately after GC treatment and became minimal on 5 days, followed by recovery to the normal level by the 10th to 14th day after treatment. During the analysis of the changes in the percentage of 4 subsets (CD4-8-, CD4+8+, CD4+8+, CD4-8+) of rat thymocytes after GC treatment, the percentage of CD4+8+ cells was found to change in close relation to the change in the percentage of rosette-forming lymphocytes, suggesting that rosette-forming thymocytes are CD4+8+ cells. These results suggest that the treatment induces destruction of GC-sensitive thymocytes, possibly rosette-forming cells, followed by migration of precursor T cells (CD4-8- cells) in the thymus, and that the precursors change into rosette-forming cells (CD4+8+ cells) in the thymus, followed by differentiation and maturation into non-rosette-forming cells (CD4+8- or CD4-8+ cells).     

In vivo treatment of class II MHC-deficient mice with anti-TCR antibody restores the generation of circulating CD4 T cells and optimal architecture of thymic medulla

TCR ligation by the self-peptide-associated MHC molecules is essential for T cell development in the thymus, so that class II MHC-deficient mice do not generate CD4(+)CD8(-) T cells. The present results show that the administration of anti-TCR mAb into class II MHC-deficient mice restores the generation of CD4(+)CD8(-) T cells in vivo. The CD4 T cells were recovered in the thymus, peripheral blood, and the spleen, indicating that the anti-TCR treatment is sufficient for peripheral supply of newly generated CD4 T cells. Unlike peripheral CD4 T cells that disappeared within 5 wk after the treatment, CD4(+)CD8(-) thymocytes remained undiminished even after 5 wk, suggesting that CD4 T cells in the thymus are maintained separately from circulating CD4 T cells and even without class II MHC molecules. It was also found that the mass of medullary region in the thymus, which was reduced in class II MHC-deficient mice, was restored by the anti-TCR administration, suggesting that the medulla for CD4(+)CD8(-) thymocytes is formed independently of the medulla for CD4(-)CD8(+) thymocytes. These results indicate that in vivo anti-TCR treatment in class II MHC-deficient mice restores the generation of circulating CD4 T cells and optimal formation of the medulla in the thymus, suggesting that anti-TCR Ab may be useful for clinical treatment of class II MHC deficiencies.     

Rat thymus reconstitution after thymocyte destruction by glucocorticoid treatment--from the view of endogenous DNA synthesis and soybean lectin responsiveness in thymocytes

The dynamic process in rat thymocyte restoration after their destruction by glucocorticoid (GC) administration was examined. Thymus weight and thymocyte count became minimal 4-5 days after the administration. Then the thymus took a course of recovery. Endogenous DNA synthesis in thymocytes, reflecting their proliferation within thymus, decreased for 4 days but began to increase 6-8 days after GC treatment. Thymocyte responsiveness to soybean lectin (SBL), a possible stimulator for T-cell-precursors, showed elevation 4-5 days after the treatment. A marked decrease of lymphocytes in the cortex and unclearness of cortico-medullary junction were observed 2-3 days after GC treatment. Clusters of small lymphoid cells, which possibly contained SBL-responding cells, were found in the subcapsular area 4 days after the treatment and successively, large lymphocytes became visible in the same area. Thereafter, small lymphocytes in the cortical mid and deep zones increased, and cortico-medullary junction was restored. These histological features are discussed from the view of correspondence with the dynamic changes of endogenous DNA synthesis and SBL responsiveness in the thymocytes after GC administration.     

The acute phase response to inflammation: the role of monokines in changes in liver glycoproteins and enzymes of glycoprotein metabolism

The role of monocyte derived factors in the acute phase response to inflammation is discussed. The kinetics of response of alpha 1-acid glycoprotein, sialyltransferase and albumin to a rat monokine preparation is described. There was an increase in synthesis of alpha 1-acid glycoprotein and sialyltransferase and a decrease in albumin synthesis following administration. However, the kinetics of response of sialyltransferase to the monokine was much slower than was found for the other two proteins. The possibility that sialyltransferase responds to a different monokine compared to the other acute phase proteins is discussed.     

CCR8 on human thymocytes functions as a human immunodeficiency virus type 1 coreceptor

To determine whether human immunodeficiency virus type 1 (HIV-1) coreceptors besides CXCR4 and CCR5 are involved in HIV-1 infection of the thymus, we focused on CCR8, a receptor for the chemokine I-309, because of its high expression in the thymus. Similar levels of CCR8 mRNA were detected in immature and mature primary human thymocytes. Consistent with this, [(125)I]I-309 was shown to bind specifically and with similar affinity to the surface of immature and mature human thymocytes. Fusion of human thymocytes with cells expressing HIV-1 X4 or X4R5 envelope glycoprotein was inhibited by I-309 in a dose-dependent manner. In addition, I-309 partially inhibited productive infection of human thymocytes by X4, R5, and X4R5 HIV-1 strains. Our data provide the first evidence that CCR8 functions as an HIV-1 coreceptor on primary human cells and suggest that CCR8 may contribute to HIV-1-induced thymic pathogenesis.     

Biochemical and immunohistochemical studies with specific polyclonal antibodies directed against bovine myelin/oligodendrocyte glycoprotein

Bovine myelin/oligodendrocyte glycoprotein (MOG) was purified from a Wolfgram protein fraction of brain myelin by molecular sieving and preparative gel electrophoresis. The N-terminal sequence of this wheat germ agglutinin reacting glycoprotein was determined. Antibodies against purified MOG and synthetic N-terminal octapeptide of MOG were produced in rabbits. Respective affinity purified antibody preparations gave identical results on Western blots. Treatment with specific glycosidases indicated that the oligosaccharide chains of MOG are only of N-chain type. This glycoprotein seems to be restricted to mammalian species since it was not detected in other animal species, ranging from fish up to reptiles. Immunohistochemical investigations on rat brain sections revealed that MOG is restricted to myelin sheaths and oligodendrocytes, thus corroborating previous results obtained with the MOG 8-18C5 monoclonal antibody. Decreased staining pattern in Jimpy brain further attested its specific localization in myelin-related structures. The octapeptide site-specific antibodies were not reactive on brain sections which may be attributed to the burying of this N-terminal sequence in the membrane. These MOG polyclonal antibodies appear to be valuable tools for further studies concerning this minor glycoprotein.Abbreviations BSA bovine serum albumin - CNS central nervous system - DM-20 minor myelin proteolipid protein - MAG Myelin-associated glycoprotein - MBP myelin basic proteins - MOG Myelin/oligodendrocyte glycoprotein - OMgp Oligodendrocyte/Myelin glycoprotein - PAGE polyacrylamide gel electrophoresis - PBS phosphate buffered saline - PeptMOG n-terminal octapeptide of MOG - PLP major myelin proteolipid protein - PMSF phenylmethylsulfonylfluoride - SDS sodium dodecylsulphate - TBS Tris buffered saline - WPF Wolfgram protein fraction - WGA Wheat germ agglutinin     

Production and characterization of a bovine T cell-specific monoclonal antibody identifying a mature differentiation antigen

A monoclonal antibody (MAb), BLT-1, with specificity for bovine mature T cells was prepared by somatic cell hybridization of myeloma NS-1 and spleen cells from BALB/c mice hyperimmunized with bovine T lymphocytes. The MAb reacted with over 92% of nylon wool-nonadherent lymphocytes (T cells) but not with nylon wool-adherent EAC-positive lymphocytes (B cells) in the indirect immunofluorescence assay. It is an IgM, with kappa-light chains, which fixed complement well and killed over 95% of mature T cells in complement-mediated cytotoxicity assays. It reacted with the same proportions of peripheral lymphoid cells (peripheral blood, lymph nodes, and spleen) as the polyclonal goat anti-bovine thymocyte serum (GABTS), but only with 25% of GABTS-positive thymocytes. Immunoperoxidase staining of frozen tissue sections showed that the BLT-1-positive cells were located in the medulla of the thymus and in the T lymphocyte areas of lymph nodes. Western immunoblotting assays showed that the BLT-1-reactive membrane antigen is a 22,000 m.w. protein which was inducible in bovine thymocytes with bovine thymic hormones, thymosin fraction 5, thymosin alpha 1, and thymopentin ORF-18150, indicating that it is a mature T lymphocyte differentiation antigen. The thymosin alpha 1 and thymopentin were found to show additive effects on mature T cell antigen expression by bovine thymocytes.     

Cold acclimation and oxygen consumption in the thymus

Mitochondrial uncoupling protein 1 is usually associated with brown adipose tissue but has recently been discovered in rat and mouse thymus. We wished to establish whether there was a thermogenic role for UCP 1 in thymus and thus examined the effect of 5 weeks cold-acclimation on rat thymus tissue abundance, thymocyte oxygen consumption, thymus mitochondrial abundance, uncoupling protein 1 expression and function. We found that thymocytes from cold-acclimated rats had oxygen consumption rates 8 times less than those from rats held at room temperature and that thymocytes from cold-acclimated rats or rats kept at room temperature were noradrenaline insensitive. In addition, we found that thymus tissue or mitochondrial abundance was not increased after cold-acclimation. However uncoupling protein 1 expression per unit mass of mitochondria was increased after cold-acclimation, as determined by immunoblotting (approximately 1.7-fold) and GDP binding (approximately 1.5-fold). Consistent with our protein expression data, we also observed an increased, state 4 (approximately 1.5-fold), GDP-inhibitable (approximately 1.3-fold) and palmitate activatable (approximately 1.6-fold) oxygen consumption rates in isolated thymus mitochondria. However, extrapolation of our data showed that cold-acclimation only increased the amount of UCP 1 per gram of thymus tissue approximately 1.2-fold. Taken together, we conclude that UCP 1 does not have a thermogenic role in thymus.     

Luteinizing hormone-releasing hormone in thymus and hypothalamus of rat fetuses: suppressing effect of antagonist and of antibodies on concanavalin A-induced proliferation of thymocytes

The effect of endogenous luteinizing hormone-releasing hormone (LHRH) on the proliferation induced by concanavalin A (Con A) in rat fetal thymocytes was studied. A selective antagonist (2 microg per fetus) or antibodies to LHRH (20 microl per fetus) were injected in utero into 20-day-old rat fetuses, and this resulted in a two- or fivefold decrease in the Con A-induced proliferation of thymocytes, respectively. In combined culture of the antagonist (10-5-10-6 M) with fetal thymocytes, the proliferative response was not decreased. The concentration of LHRH was determined by radioimmunoassay in tissues of immunocompetent organs and in blood serum of 18- and 21-day-old fetuses, and the hormone was found in the hypothalamus, thymus, and peripheral blood. The initially low level of LHRH in the thymus increased by 65 and 40%, respectively, on the first day after birth and became similar to the level in the hypothalamus. In the fetal blood serum, the LHRH level was significantly higher than in the thymus and hypothalamus of fetuses of the same age. The hormone concentration was greatest in the 18-day-old fetuses, and it decreased twofold by the 21st day. The findings indicate that LHRH is involved in regulation of T-cell immunity even during prenatal ontogenesis.     

Rosette formation by human thymocytes

A proportion of lymphocytes in human fetal and post-natal thymus, and in blood, formed rosettes with red blood cells from sheep and pig. The count of rosette-forming cells (RFC) among human thymocytes varied widely, from 2–216 per thousand cells, and was higher in fetal than in post-natal life. The count of RFC among human thymocytes was not reduced by specific rabbit anti-human immunoglobulin sera, indicating that the receptor was not of immunoglobulin character; the reaction was inhibited by antithymocyte serum and metabolic poisons and certain enzymes. The receptor may be equivalent to other “non-specific” glycoprotein hemagglutinins in plants and viruses.The importance of species differences in immunological assays is emphasized. Thus human thymocytes gave high counts of RFC only with red blood cells of sheep and pig; moreover thymus lymphocytes from only man and pig, but not several other species including rodents, were highly reactive with sheep red blood cells. The capacity for rosette formation could be a marker for T cells in human blood.     

Effects of the acute and chronic administration of chlordiazepoxide on the development of spontaneous motility in chick embryos

The effects of the acute and chronic administration of chlordiazepoxide on spontaneous motility and on the reactivity of the generator of embryonic motility were studied in chick embryos from the 4th to the 19th day of incubation. 1. The acute administration of chlordiazepoxide (5 mg/kg e.w.) significantly depressed spontaneous motility from the 13th day of incubation. 2. The chronic administration of chlordiazepoxide (12.2 mg/kg e.w./24 h) from the 4th to the 8th, 12th and 16th day of incubation enhanced the reduction of the spontaneous motility of 17-day-old embryos. 3. The chronic administration of chlordiazepoxide significantly modified the activity of both activators (strychnine, metrazol, bicuculline, picrotoxin) and inhibitors (GABA, chlordiazepoxide) of the spontaneous motility of chick embryos.     

Phenotypic heterogeneity of Gross virus-induced thymic lymphomas in the rat: cellular origins and migratory properties

Neoplastic thymocytes from rat thymic lymphoma-leukemias induced by the rat-adapted Gross leukemia virus (RAGV) were analyzed for a variety of differentiation markers. The neoplasms from individual rats all expressed the antigenic phenotype MP+, W3/13+, Thy-1+, RT-1+, RT-7+, W3/25-. However, approximately two-thirds of the neoplasms were positive for the OX 8 antigen, and one-third were negative. The OX 8- neoplasms only involved the thymus, whereas approximately 40% of the OX 8+ neoplasms involved the spleen as well as the thymus. Virtually all OX 8+ and OX 8- neoplastic cells contained terminal deoxynucleotidyl transferase (TdT), and both OX 8+ and OX 8- lymphomas expressed the lactate dehydrogenase (LDH)-5' isozyme and the primary, but not the secondary, ADA isozyme. This enzymatic phenotype is characteristic of thymocyte precursors, but not thymocytes. Our results therefore indicate that RAGV-induced lymphomas arise from transformed prethymic TdT+ cells which contain the LDH-5' and the primary ADA isozymes. These preleukemic cells presumably migrate to the thymus where they express the RT-7 pan-T-cell antigen and, in some instances, the OX 8 antigen during the development of overt leukemia. The OX 8+ neoplasms, being more differentiated than their OX 8- counterparts, then migrate to peripheral lymphoid tissues.     

A novel T cell-activating molecule (THAM) highly expressed on CD4-CD8- murine thymocytes

Recent studies have focused on the potential role of accessory molecules such as CD2, CD28, Thy-1, or TAP in the delivery of activating signals to thymocytes through antigen-independent pathways. To better understand the molecular interactions involved in the expansion of early thymic immigrants, rat mAb were raised against murine thymocyte-surface molecules and screened for their capacity to trigger thymocyte proliferation. One of these mAb (H194-112, IgG2a) was found to recognize a novel heterodimeric thymocyte-activating molecule (THAM) of Mr = 110,000 to 128,000. Flow cytometric analyses and staining patterns on frozen thymus sections subdivided adult thymocytes in three subsets expressing THAM at either low (10%), moderate (80%), or high (5 to 8%) cell-surface density; these cell groups were found to correspond, respectively, to the medullary, the cortical, and the immature CD4-CD8-, J11d+ thymocytes, in which the T cell precursor pool is included. Moreover, most (90%) day 16 fetal thymocytes were also found to upregulate THAM cell-surface expression. The THAMhigh cells were localized in the subcapsular area of the neonatal thymus and scattered throughout the adult organ. Cross-linked mAb H194-112 induced the proliferation of both immature and mature thymocytes in the presence of either PMA or IL-1 and IL-2. The observation that early thymocytes up-regulate THAM along with the IL-2R suggests that this molecule might be involved in an important activation pathway during thymocyte differentiation.     

Angiostrongylus cantonensis: paralysis due to avermectin B1a and ivermectin

Paralysis due to avermectin B1a and ivermectin of Angiostrongylus cantonensis was compared to that of phenylephrine (an alpha-adrenergic agonist) and strychnine (a cholinergic inhibitor). The paralyzing action of ivermectin (2.5 X 10(-9) g/ml) was inhibited by the single, simultaneous addition of picrotoxin (3 X 10(-5) M), whereas the effect of the drug (2.5 X 10(-7) g/ml) was reversed only when picrotoxin was given with cholinergic spasmogens such as pyrantel and eserine. Bicuculline (3 X 10(-5) M) had a similar antagonistic effect for picrotoxin, but bicuculline was less effective. The paralyzing action of avermectin B1a (3.6 X 10(-14) M, 3.0 X 10(-14) g/ml) was antagonized only when picrotoxin was given with cholinergic spasmogens such as pyrantel, eserine, and N-methylcytisine (N-MC), or alpha-adrenergic antagonists such as phentolamine and dibenamine. On the other hand, the paralyzing action of strychnine (3 X 10(-6) M) or phenylephrine (3 X 10(-5) M) was relatively uninfluenced by picrotoxin, but was antagonized by pyrantel and N-MC or dibenamine. These results suggest that a gabergic mechanism is involved in the paralyzing action of ivermectin, as well as avermectin B1a, in A. cantonensis.     

Cold acclimation and oxygen consumption in the thymus

Mitochondrial uncoupling protein 1 is usually associated with brown adipose tissue but has recently been discovered in rat and mouse thymus. We wished to establish whether there was a thermogenic role for UCP 1 in thymus and thus examined the effect of 5 weeks cold-acclimation on rat thymus tissue abundance, thymocyte oxygen consumption, thymus mitochondrial abundance, uncoupling protein 1 expression and function. We found that thymocytes from cold-acclimated rats had oxygen consumption rates 8 times less than those from rats held at room temperature and that thymocytes from cold-acclimated rats or rats kept at room temperature were noradrenaline insensitive. In addition, we found that thymus tissue or mitochondrial abundance was not increased after cold-acclimation. However uncoupling protein 1 expression per unit mass of mitochondria was increased after cold-acclimation, as determined by immunoblotting (∼ 1.7-fold) and GDP binding (∼ 1.5-fold). Consistent with our protein expression data, we also observed an increased, state 4 (∼ 1.5-fold), GDP-inhibitable (∼ 1.3-fold) and palmitate activatable (∼ 1.6-fold) oxygen consumption rates in isolated thymus mitochondria. However, extrapolation of our data showed that cold-acclimation only increased the amount of UCP 1 per gram of thymus tissue ∼ 1.2-fold. Taken together, we conclude that UCP 1 does not have a thermogenic role in thymus.     

Rat T lymphocyte antigens comparable with mouse Lyt-1 and Lyt-2,3 antigenic systems: characterization by monoclonal antibodies

Rat T lymphocyte antigens were defined by using two distinct monoclonal antibodies (R1-3B3 and R1-10B5). R1-3B3 antibody, when tested for its reactivity with rat lymphoid cells by immunofluorescence, stained almost all of thymus and T cells but not the majority of B cells and bone marrow cells. The antigen defined by R1-3B3 existed more abundantly on medullary thymocytes and peripheral T cells than on cortical thymocytes. Immunochemical data showed that R1-3B3 antibody recognized a single glycoprotein with a m.w. of 67,000, showing marked electric charge heterogeneity with isoelectric points ranging from 5.4 to 7.3. R1-10B5 antibody, on the other hand, had more restricted reactivity with rat T cells and labeled approximately 85% of thymus cells and 30% of the peripheral T cells but neither B cells nor bone marrow cells. These T cells positive for R1-10B5 appeared to be negative for W3/25 antigen, which has been shown to be the marker for the rat T cell subset associated with helper function. R1-10B5 antibody detected a basic glycoprotein complex consisting of sulfhydryl-linked subunits with 30,000 and 34,000 m.w. Although the antigen defined by R1-3B3 was resistant to trypsin digestion, the one detected by R1-10B5 was much more sensitive to trypsin cleavage. All of these data obtained with either R1-3B3 or R1-10B5 are quite comparable to those reported for mouse Lyt-1 or Lyt-2,3 antigens, and thus suggest that the antigens defined by R1-3B3 and R1-10B5 antibodies represent rat homologues of Lyt-1 and Lyt-2,3 antigens in the murine system, respectively.     

Thymus dependency of neonatal tolerance induction in the absence of detectable suppressor cells

Neonatal thymectomy prevents tolerance induction with bovine serum albumin (BSA) in Wistar Furth (WF) rats whose thymus-derived (T) cell deficit is reconstituted with adult nonadherent peripheral blood lymphocytes (PBL). Sham-thymectomized (STx) rats given PBL become tolerant. To establish whether the adult T cells become tolerant in STx rats, their carrier-reactivity was studied in a cooperative immune response following challenge with methylated BSA (mBSA). The results indicate that carrier-reactive cells, derived from PBL, do become tolerant of BSA in the presence, but not in the absence, of the thymus. To determine whether thymic function during tolerance induction is mediated by suppressor T cells, attempts were made to replace the thymus with various populations of thymocytes or lymphoid cells from neonatal or adult normal rats or neonatal BSA-injected rats. No cell population tried could substitute for the thymus during tolerance induction. In addition, it was found that BSA-tolerant rats with intact thymi do not contain either nonspecific suppressor cells whose activity can be boosted with mBSA or specific suppressor activity demonstrable on transfer to normal rats. Timed thymectomy experiments showed that the thymus is required for more than 2, but less than 5 to 7 days after tolerogen injection for significant tolerance induction. These results imply that the thymus itself is necessary for tolerance induction in a peripheral T-cell population and that its effect is not mediated by suppressor cells. It is suggested that peripheral T helper cells may periodically recirculate through the thymus, at least in young rats, and become tolerant of antigen complexed with Ia antigens in the thymic epithelium. Such a mechanism may be of great importance in the development of self-recognition.     

Histochemical and biochemical studies on esterase activity in the rat ovary

A correlative histochemical and biochemical study has been made of the changes in esterase positive sites in immature (10-, 20- and 30-days old), mature normal cycling (3-, 5- and 8-months-old), pregnant and lactating rat ovaries. The typical perivascular esterase-positive sites localized in the hilar portion, branch along the blood vessels and traverse into medullary and cortical portions of the ovary. The stromal vascularity surrounding the normal developing follicles, corpora lutea, atretic follicles and interstitial gland tissue showed rich activity of this enzyme system. On semiquantitative basis the number, intensity and quantity of esterase-positive sites vary with the maturation and reproductive states of the rat. The administration of estradiol-17 beta increased the fine perifollicular and theca externa perivascular esterase-positive sites, whereas atropine and reserpine affected severely both the large and fine meshwork of esterase-positive sites. Biochemical estimates of acetylcholine esterase activity endorse these histochemical observations. The possible roles of AChE activity in varied ovarian functions are discussed.     

松果体及其褪黑素对大鼠胸腺细胞凋亡的影响

目的探讨松果体及其褪黑素对胸腺细胞凋亡的影响以及Caspase-3的表达。方法选用清洁级SD大鼠,分为正常对照组、假手术对照组、松果体摘除组、松果体摘除 褪黑素腹腔注射7.5mg/kg/d组和松果体摘除 褪黑素腹腔注射15mg/kg/d组。术后4、8周取材。运用TUNEL法检测胸腺细胞的凋亡程度,用ABC法染胸腺Caspase-3阳性细胞,计算机图像分析仪测量阳性细胞面积及其染色强度。以RT-PCR法检测褪黑素干预原代培养胸腺细胞Caspase-3的表达。结果松果体摘除后8周时胸腺细胞凋亡显著增加,补充褪黑素则能明显减少胸腺细胞的凋亡。Caspase-3阳性细胞主要见于胸腺皮质,松果体摘除后胸腺皮质Caspase-3阳性细胞面积增加明显,补充褪黑素则使其下降。褪黑素能上调培养胸腺细胞Caspase-3的表达水平。结论松果体能调控大鼠胸腺细胞的凋亡,松果体摘除促进胸腺细胞的凋亡,补充褪黑素能缓解相关影响。