Degree of freezing does not affect efficacy of frozen gloves for prevention of docetaxel-induced nail toxicity in breast cancer patients.

PURPOSE: Frozen gloves (FG) are effective in preventing docetaxel-induced nail toxicity (DNT), but uncomfortable. The preventive effect of FG for DNT was compared using a standard (-25 to -30°C) or more comfortable (-10 to -20°C) preparation. METHODS: Breast cancer patients receiving docetaxel were eligible. Each patient wore an FG (prepared at -10 to -20°C for 90 min) for 60 min without replacement on the right hand. The left hand was protected by standard methods (FG prepared at -25 to -30°C overnight and worn for 90 min with replacement at 45 min). The primary endpoint was DNT occurrence at 5 months. Secondary endpoints included docetaxel exposure [cumulative dose and area under the blood concentration time curve (AUC)] until DNT occurrence and discomfort from FG. The pharmacokinetics of docetaxel was assessed. RESULTS: From 23 patients enrolled between December 2006 and June 2010, seven who received docetaxel for less than 5 months were excluded from evaluation. The median accumulated docetaxel dose was 700 mg/m(2) (340-1430 mg/m(2)). Within 5 months of FG use, none developed protocol-defined DNT in either hand. Two patients (13%) developed DNT at 7.2 and 7.3 months, respectively, both at -10 to -20°C. In the control hand (-25 to -30°C), discomfort occurred in 92% of the cycles, compared to 15% in the experimental hand (-10 to -20°C). Five patients (22%) experienced pain at -25 to -30°C, but none did at -10 to -20°C. The degree of docetaxel exposure was not related to DNT occurrence in our study. CONCLUSION: A convenient preparation of FG at -10 to -20°C is almost as effective as a standard preparation at -25 to -30°C, with significantly less discomfort.

Donor antioxidant strategy prolongs cardiac allograft survival by attenuating tissue dendritic cell immunogenicity(†).

Ischemic reperfusion injury (IRI) enhances allograft immunogenicity, worsens transplantation outcome, and is the primary cause of activation of the recipient innate immune response, resulting in subsequent amplification of the alloimmune adaptive response. Here, we aimed at demonstrating that the link between innate injury and alloimmunity occurs predominantly through activation of allograft-derived dendritic cells (ADDC). Perfusion of MCI-186, a free radical scavenger, into donor cardiac allografts prior to transplantation resulted in prolongation of complete MHC-mismatched allograft survival in the absence of immunosuppression (MST of 8 vs. 26 days). This prolongation was associated with a reduction in trafficking of ADDC to recipient lymphoid tissue as well as a reduction in T cell priming. Depleting ADDC with diphtheria toxin (using DTR-GFP-DC mice as donors) 24 h prior to transplant resulted in abrogation of the prolongation observed with MCI-186 treatment, demonstrating that the beneficial effect of MCI-186 is mediated by ADDC. This donor-specific anti-ischemic regimen was also shown to reduce chronic rejection, which represents the primary obstacle to long-term allograft acceptance. These data for the first time establish a basis for donor anti-ischemic strategies, which in the ever-expanding marginal donor pools, can be instituted to promote engraftment.

Clinically significant micafungin resistance in Candida albicans involves modification of a glucan synthase catalytic subunit GSC1 (FKS1) allele followed by loss of heterozygosity.

OBJECTIVES: To determine the mechanism of intermediate- and high-level echinocandin resistance, resulting from heterozygous and homozygous mutations in GSC1 (FKS1), in both laboratory-generated and clinical isolates of Candida albicans. METHODS: The DNA sequences of the entire open reading frames of GSC1, GSL1 (FKS3) and RHO1, which may contribute to the beta-1,3-glucan synthase of a micafungin-susceptible strain and a resistant clinical isolate, were compared. A spontaneous heterozygous mutant isolated by selection for micafungin resistance, and a panel of laboratory-generated homozygous and heterozygous mutants that possessed combinations of the echinocandin-susceptible and -resistant alleles, or mutants with individual GSC1 alleles deleted, were used to compare levels of echinocandin resistance and inhibition of glucan synthase activity. RESULTS: DNA sequence analysis identified a mutation, S645P, in both alleles of GSC1 from the clinical isolate. GSL1 had two homozygous amino acid changes and five non-synonymous nucleotide polymorphisms due to allelic variation. The predicted amino acid sequence of Rho1p was conserved between strains. Reconstruction of the heterozygous (S645/S645F) and homozygous (S645F/S645F) mutation showed that the homozygous mutation conferred a higher level of micafungin resistance (4 mg/L) than the heterozygous mutation (1 mg/L). Exposure of the heterozygous mutant to micafungin resulted in a loss of heterozygosity. Kinetic analysis of beta-1,3-glucan synthase activity showed that the homozygous and heterozygous mutations gave echinocandin susceptibility profiles that correlated with their MIC values. CONCLUSIONS: A homozygous hot-spot mutation in GSC1, caused by mutation in one allele and then loss of heterozygosity, is required for high-level echinocandin resistance in C. albicans. Both alleles of GSC1 contribute equally and independently to beta-1,3-glucan synthase activity.

Purified eicosapentaenoic acid induces prolonged survival of cardiac allografts and generates regulatory T cells.

Fish oil, which is rich in eicosapentaenoic acid (EPA), has been found to have immunomodulatory effects. We examined whether administration of purified EPA affected survival of fully mismatched murine cardiac allografts. Hearts from C57BL/10 (H-2(b)) mice were transplanted into CBA (H-2(k)) recipients treated with one intraperitoneal dose of purified EPA the day of transplantation. Untreated CBA recipients and recipients given 0.1 g/kg of EPA rejected C57BL/10 hearts (median survival time [MST], 8 and 13 days, respectively). With a 1.0 g/kg dose of EPA, graft survival was markedly prolonged (MST >100 days). To determine whether regulatory cells were generated, naïve mice (secondary recipients) underwent adoptive transfer of splenocytes from EPA-treated primary recipients and cardiac allograft transplantation. Adoptive transfer of whole, CD4(+) and CD4(+)CD25(+) splenocytes from EPA-treated recipients induced indefinite survival in secondary recipients. Flow cytometry showed that the CD4(+)CD25(+) cells were Foxp3(+). In reverse transcriptase-polymerase chain reaction (RT-PCR) studies, the expression of peroxisome proliferator-activated receptor gamma (PPARgamma) mRNA was upregulated by EPA treatment. A PPARgamma antagonist abrogated the prolongation of graft survival induced by EPA treatment (MST, 13 days). Thus, in our model, purified EPA induced prolonged survival of fully mismatched cardiac allografts and generated regulatory T cells dependent on PPARgamma activation.

Induction of Regulatory CD4+ Cells and Prolongation of Fully Major Histocompatibility Complex Mismatched Murine Cardiac Allograft by Shigyakusan.

Shigyakusan (also known as Tsumura Japan [TJ]-35) is composed of peony, bitter orange, licorice, and Bupleuri radix is used for cholecystitis and gastritis as an anti-inflammatory agent. We investigated the effect of TJ-35 on alloimmune response in a murine heart transplantation model. CBA mice that underwent transplantation of a C57BL/6 (B6) heart were assigned to four groups: no treatment, TJ-35-exposed, each component-exposed, or each component missing-exposed. The four groups above each received oral administration of TJ-35, each component, or TJ-35 with each component missing from the day of transplantation until 7 days, respectively. Untreated CBA recipients rejected B6 cardiac grafts acutely (median survival time [MST], 7 days). TJ-35-exposed CBA recipients had significantly prolonged B6 allograft survival (MST, 20.5 days). However, MSTs of CBA recipients that had been administered each component and TJ-35 with each component missing did not reach that of TJ-35-exposed recipients. Adoptive transfer of CD4+ splenocytes from TJ-35-exposed primary allograft recipients resulted in significant prolonged allograft survival in naïve secondary recipients (MST, 63 days). Flow cytometry studies showed that the percentage of CD4+CD25+Foxp3+ cell population was increased in TJ-35-exposed CBA recipients. In conclusion, TJ-35-induced prolongation of fully allogeneic cardiac allografts and may generate regulatory CD4+CD25+Foxp3+ cells in our model. The effect seemed to require all components of TJ-35.

Rikkunshito (TJ-43) Improved Reduction of Food Intake in a Murine Cardiac Transplantation Model.

Rikkunshito (TJ-43), an eight-component traditional Japanese herbal medicine, has been used in clinics for gastritis, vomiting, and appetite loss. We investigated the effects of TJ-43 on the amelioration of appetite loss in the surgical-exposed model of murine cardiac allograft transplantation. CBA mice underwent transplantation of a CBA (syngeneic group) or C57BL/6 heart (allogeneic group) and received oral administration of 2 g/kg/d of TJ-43 from the day of transplantation until 7 days afterward. The amount of food intake (FI) and weight change after operation were recorded from 1 to 28 postoperative days. The allogeneic group had less average amounts of FI for 1 week compared with the syngeneic group (FI was 1.90 ± 0.43 g and 2.66 ± 0.46 g, respectively). Average FIs between the syngeneic and allogeneic groups with TJ-43 for 1 week were 2.36 ± 0.44 g and 2.30 ± 0.13 g, respectively, and those with distilled water were 2.66 ± 0.46 g and 1.90 ± 0.43 g, respectively, suggesting that exposure with TJ-43 tended to ameliorate the reduction of FI. Similarly, the effect on the amelioration of average FI in syngeneic and allogeneic groups exposed for 2 weeks was confirmed. However, exposure to with TJ-43 had no effects on FI after 4 weeks. TJ-43 could prevent reduction of average FI induced by the surgical-exposed model of murine cardiac allograft transplantation.

Graft Protective Effect of HMG-CoA Reductase Inhibitor Pravastatin in Murine Cardiac Allograft Transplantation.

The HMG-CoA reductase inhibitor (statin), which reduces serum cholesterol, has been demonstrated in the control of immune responses and may potentially play an important role in the regulation of acute and chronic rejection in organ transplantations. We investigated the graft-protective effect of a kind of statin, pravastatin, in the survival of fully major histocompatibility complex--mismatched murine cardiac allograft transplantation. Fully vascularized heterotopic hearts from C57BL/6 donors were transplanted into CBA recipients through microsurgical techniques. CBA recipients transplanted with a C57BL/6 heart received oral administration of 40, 120, or 400 µg/kg/day of pravastatin from the day of transplantation to 7 days afterward. Immunohistochemical staining studies were performed to determine whether intimal formation of coronary arteries in the transplanted cardiac allografts was preserved and also to conduct morphometric analysis. Untreated CBA recipients rejected C57BL/6 cardiac grafts acutely (median survival time [MST] 7 days). CBA recipients exposed with 40 and 120 µg/kg/day of pravastatin had a small prolonged allograft survival (MSTs of 10 and 9 days, respectively). However, the MST of CBA recipients exposed to 400 µg/kg/day of pravastatin was significantly effective for allograft survival (MST 50 days). Immunohistochemical staining assessments on 4 weeks after grafting showed suppression of intimal hyperplasia in allograft coronary arteries. Pravastatin could induce the prolongation of fully major histocompatibility complex--mismatched cardiac allograft through the protection of the coronary artery.

More Hippocampal Weight and Cells in Cardiac Allograft Transplanted Mice.

The hippocampus is a brain structure that plays a fundamental role in memory and learning. Many animal studies have demonstrated that the structure of the hippocampus has evolved through exercise and play. However, little is known on the relationship between the brain and immunological reaction. In this study, we investigated the correlation between the weight of the hippocampus and transplant immunology in a murine heart transplant model. Fully vascularized heterotopic hearts from CBA (H2k, allogeneic group) or C57BL/6 (H2b, syngeneic group) donors were transplanted into C57BL/6 recipients by using microsurgical techniques. The weights of the whole brain and hippocampus from syngeneic and allogeneic groups were recorded 1, 2, and 4 weeks after grafting, and histologic assessments were performed. The syngeneic group maintained beating cardiac grafts for over 30 days, but the allogeneic group rejected CBA cardiac allografts acutely within 8 days. The average weight of whole brain from syngeneic and allogeneic group 1, 2, and 4 weeks had no significant differences. However, the average weight of hippocampus at 2 and 4 weeks was considerably increased in the allogeneic group compared with the syngeneic group. Histologic assessments with hematoxylin-eosin and Kluver-Barrera staining of hippocampus from allogeneic group 1 week after grafting demonstrated a greater number of granule and pyramidal cells in the hippocampus. Alloimmune responses in our model increase the weight of hippocampus.

Administration of Thrombomodulin (CD141) Could Improve Cardiac Allograft Survival in Mice.

Thrombomodulin (TM) is a promising natural anti-coagulant therapeutic protein that is effective in the treatment of disseminated intravascular coagulation. However, the mechanisms by which TM on micro-vessels enable the regulation of intimal hyperplasia remain elusive. We investigated the graft-protective effects of TM in a fully major histocompatibility complex-mismatched murine cardiac allograft transplantation model. CBA recipients transplanted with a C57BL/6 heart received intraperitoneal administration of 0.2, 2.0, and 20.0 µg/day of TM for 8 days. Histological staining was conducted to assess the degree of inflammation and infiltration in the transplanted cardiac grafts. Untreated CBA recipients rejected C57BL/6 cardiac grafts acutely (median survival time [MST] was 7 days). CBA recipients exposed to the above dosages had significantly prolonged allograft survival (MSTs were 16, 21, and 37.5 days, respectively). Histologic assessments from TM-exposed recipients 2 weeks after grafting showed that the myocardium and vessel structure in their allografts were clearly preserved, and that the infiltration of inflammatory cells around coronary arteries was suppressed. TM can induce the prolongation of fully major histocompatibility complex-mismatched cardiac allograft by exerting graft protective effects within the myocardium and coronary arteries.

Seven Japanese Herbals Prolonged Cardiac Allograft Survival.

Japanese herbal medicines have long been used as alternative therapy because of their immunomodulatory effects. In recent years, use herbal medicines is rapidly increasing worldwide. In this study, we investigated the effect of 17 components of traditional Japanese herbal medicines on alloimmune responses in a murine model of cardiac allograft transplantation. Fully vascularized heterotopic hearts from C57BL/6 donors were transplanted into CBA mice by using microsurgical techniques. Artemisiae capillaris herba (Inchinko) was given to CBA recipients at a dosage of 1 g/kg/day from the day of transplantation until 7 days afterward. The other 16 components were given at a dosage of 2 g/kg/day for the same time period. Naïve CBA mice rejected C57BL/6 cardiac grafts acutely (median survival time [MST] of 7 days). CBA transplant recipients given 2 g/kg/day of Glycyrrhizae radix (Kanzou), Poria sclerotium (Bukuryo), Pinellia tuber (Hange), Cnidii rhizome (Senkyu), Paeoniae radix (Shakuyaku), and Scutellariae radix (Ogon) had prolonged C57BL/6 allograft survival significantly (MSTs were 18, 18, 17, 14, 12, and 12 days, respectively). Moreover, CBA transplant recipients given 1g/kg/day of Artemisiae capillaris herba had prolonged C57BL/6 allograft survival (MST >100 days); however, none of other 10 components prolonged allograft survival. In conclusion, administration of 7 components of traditional Japanese herbal medicines might induce prolongation of fully major histocompatibility complex-mismatched cardiac allografts.

Yogurt Feeding Induced the Prolongation of Fully Major Histocompatibility Complex-Mismatched Murine Cardiac Graft Survival by Induction of CD4+Foxp3+ Cells.

Yogurt is a nutrient-rich food and the beneficial effects of yogurt on both health and immunomodulatory effects are well documented. In this pilot study, we investigated the effects of commercially produced yogurt R-1 on alloimmune responses in a murine cardiac transplantation model. The R-1 is produced by Meiji Co., Ltd., and contains live and active lactic acid bacteria (lactobacillus bulgaricus OLL1073R-1) mainly. CBA (H2k) mice underwent transplantation of a C57BL/6 (H2b; B6) heart and received oral administration of 1 mL, 0.1 mL, and 0.01 mL of R-1 from the day of transplantation until 7 days afterward. Additionally, we prepared one group of CBA recipients given 1 mL of R-1 sterilized by microwave for 7 days. Histological and immunohistochemical studies were performed. Naïve CBA mice rejected B6 cardiac graft acutely (median survival time [MST]: 7 days). CBA recipients given of 1 mL of R-1 had significantly prolonged B6 allograft survival (MST, 27 days). However, other doses of 0.1 mL and 0.01 mL of R-1 did not prolonged allograft survival (MSTs, 9 days and 8.5 days, respectively). Also, CBA recipients administered microwaved R-1 had no prolongation of B6 allograft (MST, 9 days). Histological and immunohistochemical studies showed the cardiac allograft from R-1-exposed CBA recipients had preserved graft and vessel structure and the number of infiltrated CD4+, CD8+, and Foxp3+ cells in R-1-exposed CBA recipients increased, respectively. In conclusion, our findings imply that yogurt containing active lactic acid bacteria could change alloimmune responses partially and induce the prolongation of cardiac allograft survival via CD4+Foxp3+ regulatory cells.

Proton pump inhibitor after endoscopic resection for esophageal squamous cell cancer: multicenter prospective randomized controlled trial.

BACKGROUND: Whether proton pump inhibitors (PPIs) relieve heartburn or precordial pain after endoscopic resection (ER) for esophageal squamous cell carcinoma (ESCC) remains unclear. The aim of this study was to investigate the efficacy of PPI therapy for these symptoms after ER for ESCC. METHODS: We conducted a multicenter prospective randomized controlled trial among 15 hospitals in Japan. In total, 229 patients with cT1a ESCC were randomly assigned to receive PPI therapy for 5 weeks after ER (the PPI group, n = 115) or follow-up without PPI therapy (the non-PPI group, n = 114). The primary end point was the incidence of gastroesophageal reflux disease (GERD)-like symptoms after ER from a self-reported questionnaire (Frequency Scale for Symptoms of GERD). Secondary end points were ulcer healing rate at 5 weeks, incidence of pain, improvement rate of symptoms in those who started PPI therapy because of GERD-like symptoms in the non-PPI group, and adverse events. RESULTS: No significant difference was observed in the incidence of GERD-like symptoms after ER between the non-PPI and PPI groups (30 % vs 34 %, respectively). No significant differences were observed in the ulcer healing rate at 5 weeks (84 % vs 85 %) and incidence of pain within 1 week (36 % vs 45 %). In nine of ten patients (90 %) who started PPI therapy because of GERD-like symptoms in the non-PPI group, PPI administration relieved GERD-like symptoms. No adverse events related to PPI administration were observed. CONCLUSION: PPI therapy is not efficacious in reducing symptoms and did not promote healing of ulcers in patients undergoing ER for ESCC.

Various costimulatory pathways are essential for induction of regulatory cells by intratracheal delivery of alloantigen.

BACKGROUND: We previously reported that intratracheal delivery of alloantigen induced regulatory cells in a mouse heart transplantation model. We investigated the roles of costimulatory pathways in the induction of regulatory cells by intratracheal delivery of alloantigen. METHODS: CBA (H-2k) mice were pretreated with intratracheal delivery of splenocytes (1 x 10(7)) from C57BL/10 (H-2b) mice and administration of monoclonal antibodies (mAb) specific for programmed death (PD)-1 and its ligands, programmed death-ligand (PD-L)1 and PD-L2, CD70, CD134 ligand (CD134L), CD153, CD137L, or receptor activator of nuclear factor-kappaB (NF-kappaB) (RANK). Seven days later, naive CBA mice underwent adoptive transfer of splenocytes (5 x 10(7)) from the pretreated CBA mice and transplantation of C57BL/10 heart. RESULTS: Adoptive transfer of splenocytes from CBA mice that had been pretreated with intratracheal delivery of C57BL/10 splenocytes significantly prolonged the survival of C57BL/10 allograft (median survival time [MST], 68 days) as compared with adoptive transfer from untreated CBA mice (MST, 12 days). Concomitant administration of control immunoglobulin (Ig)G, anti-PD-L2 mAb, or anti-CD137L along with intratracheal delivery did not significantly affect the prolongation (MST, 72, 68, and 65 days, respectively). In contrast, anti-PD-1, anti-PD-L1, anti-CD70, anti-CD134L, anti-CD153, or anti-RANK mAb abrogated the prolongation induced by adoptive transfer from the pretreated mice with intratracheal delivery (MST, 18, 17, 16, 14, 10, and 18 days, respectively). CONCLUSION: The PD-1/PD-L1, CD27/CD70, CD134/CD134L, CD30/CD153, and tumor necrosis factor (TNF)-related activation-induced cytokine (TRANCE)/RANK interactions are independently required for generation of regulatory cells by intratracheal delivery of alloantigen.

Food Restriction Prolongs Murine Cardiac Grafts.

Overeating and obesity lead to cardiovascular disease, diabetes, and eventually premature death, whereas food or energy restriction reduces risk factors for cardiovascular disease and diabetes and expands the life span. The aim of this study was to investigate the effect of food restriction (FR) in a murine heart transplant model. CBA male recipients (H2(k)) that underwent transplantation of C57BL/6 (H2(b)) hearts were assigned to free access group or FR groups with food intake at 60% (40% FR), 50% (50% FR), or 40% (60% FR) of the average food intake for 1 week after transplantation, and each median survival time was measured. We also performed cell proliferation, cytokine production, and flow cytometry assessments. The 60% FR CBA recipients showed prolongation of allograft survival (median survival time, 24 days). Cell proliferation and interferon-γ were suppressed in the 60% FR CBA recipients. Flow cytometry studies showed a lower CD4(+)CD25(+)Foxp3(+) cell population in splenocytes from the 60% FR CBA recipients. In conclusion, the findings suggest that the prolongation of cardiac allograft resulted from not regulation of alloimmune responses, but partial impairment of alloimmune responses, linking energy restriction to low generation of splenic CD4(+)CD25(+)Foxp3(+) regulatory T cells.

Macroconidial development and germination in Trichophyton mentagrophytes.

Trichophyton Mentagrophytes was investigated for macroconidial development with particular emphasis on the conidial ageing by light and scanning electron microscopy. Macroconidial germination was also studied under various conditions. Sabouraud glucose agar supplemented with 3% NaCl was used to enhance production of macroconidia. After a long-term cultivation macroconidial compartments changed to spherical thick-walled structure. Some 12-month-old macroconidia were still capable of germination. A wide range of temperature (15-37 degrees C), and inoculum of less than 1 X 10(5) conidia per ml of rich media were appropriate for macroconidial germination. The germination process of macroconidia was highly tolerant to NaCl. A small fraction of the conidia were able to germinate even in distilled water without activation. Effect of freeze-thaw or ultraviolet irradiation on macroconidial germination was determined.

Differential gene expression of growth hormone (GH)-releasing hormone (GRH) and GRH receptor in various rat tissues.

Growth hormone (GH)-releasing hormone (GRH) acts on specific receptors in the anterior pituitary to stimulate the synthesis and release of GH. Recent reports suggest that GRH is also synthesized in extrahypothalamic tissues. To evaluate the potential roles of extrahypothalamic GRH, we studied the gene expression of GRH and GRH receptors in various rat tissues by reverse transcribed (RT)-polymerase chain reaction (PCR). Total RNA was extracted from twenty-three rat organs and RT-PCR was performed with GRH and GRH receptor primers. Highly-sensitive RT-PCR-Southern blotting showed that GRH and GRH receptor mRNA coexist in the widespread tissues (14 of 25 tissues). GRH mRNA was relatively abundant in the cerebral cortex, brain stem, testis, and placenta, while GRH receptor mRNA was abundant in renal medulla and renal pelvis. Northern blot hybridization using poly A+ RNA indicated that the transcript of GRH receptor gene found in the renal medulla was similar to the longer transcript (about 4 Kb) of pituitary GRH receptor in the size. These results suggest that GRH plays a potential role not only in the neuroendocrine axis, but also in the autocrine and paracrine systems in extrahypothalamic tissues.

Physiological role of growth hormone (GH)-releasing factor and somatostatin in the dynamics of GH secretion in adult male rat.

To investigate the physiological role of GRF and somatostatin (SRIF) in GH secretion in adult male rats, we prepared in vitro models using the perifusion system of cultured rat anterior pituitary cells exposed to various combinations of human GRF-(1-44)NH2 (hGRF) and SRIF. We studied the following three models on GRF secretion: 1) pulsatile GRF secreted at 1-h intervals, 2) pulsatile GRF secreted at 3-h intervals, and 3) GRF continuously secreted. When 5-min pulses of 20 nM GRF were delivered at 1-h intervals, the responses to GRF gradually declined. The addition of continuous 20 nM SRIF with short pauses prevented this attenuated response and produced high peaks of GH at 3-h intervals. When 5-min pulses of 20 nM GRF were delivered at 3-h intervals, three high peaks of GH were observed regardless of the addition of SRIF. Pretreatment with GRF pulses enhanced the peaks of GH during SRIF pauses. When 20 nM GRF was continuously delivered, a rapid attenuated response to GRF was observed. Although the addition of continuous 20 nM SRIF with short pauses produced three small peaks of GH, these results were caused by the post-SRIF rebound release. These observations suggest that preexposure to prolonged SRIF can prevent an attenuated response to repeated GRF pulses, and that pretreatment with GRF pulses enhances post-SRIF rebound release.

Suppression of episodic growth hormone secretion in streptozotocin-induced diabetic mice: time-course studies on the hypothalamic pituitary axis.

To elucidate the roles of the hypothalamic peptides, GH-releasing hormone (GRH) and somatostatin (SRIH), potentially responsible for altered GH dynamics in diabetes, we studied the time courses of their changes in level associated with altered GH secretion in streptozotocin (STZ)-induced diabetic mice. Diabetic mice were used at 4, 7, and 14 days after STZ injection for analyses of 1) GH secretion in vivo, 2) hypothalamic GRH and SRIH messenger RNA (mRNA) levels, 3) pituitary GH mRNA and protein contents, and 4) pituitary GH response to GRH in vitro. GH secretion was completely suppressed 7 and 14 days after STZ injection. The hypothalamic GRH mRNA level was reduced to 59.8%, 61.2%, and 48.5% of control values at 4, 7, and 14 days, respectively. In contrast, the hypothalamic SRIH mRNA level was not altered at all of these time points. Pituitary GH mRNA and protein contents were significantly reduced to 70.2% and 61.5% of those in controls, respectively, only at 14 days. Pituitary GH responses to GRH at three doses (10, 50, and 250 nM) in vitro were remarkably increased at 4, 7, and 14 days. These findings indicate that the diabetic state rapidly and primarily inhibits hypothalamic GRH gene expression without affecting SRIH. A persistent decrease in hypothalamic GRH tone has been suggested to result in inhibition of GH synthesis in the pituitary. Enhancement of GH responsiveness to GRH may be due to the up-regulation of GRH receptors in the pituitary.

Inhibitory effects of interleukin-1 on growth hormone secretion in conscious male rats.

Although various pathophysiological effects of interleukin (IL) on the CRF-ACTH-adrenal axis and gonadotropin secretion have been studied extensively, the effects of IL on GH secretion still remain to be elucidated. We investigated the possible effects of IL on GH secretion in six groups of conscious rats. In four groups, IL was administered by continuous iv infusion and in the other two, by intracerebroventricular injection. Saline-treated rats served as controls for these groups. Sequential blood sampling was performed every 20 min in all groups, and the plasma GH concentration was determined by RIA. The expression of hypothalamic c-fos protein in a separate group was examined by immunohistochemistry. Continuous infusion of both IL-1 alpha and IL-1 beta (10 ng/min) significantly inhibited GH surges. The plasma IL-1 level was elevated to 2-3 ng/ml. Continuous iv infusion of IL-2 and IL-6 had no effect on GH secretion. The intracerebroventricular injection of both IL-1 alpha and IL-1 beta significantly inhibited GH surges, and the inhibitory effect was much greater for IL-1 beta than for IL-1 alpha. Continuous iv infusion of IL-1 beta markedly stimulated c-fos expression in specific hypothalamic nuclei, particularly in the paraventricular nucleus. These findings suggest that, in the rat, IL-1 inhibits GH secretion through its peripheral and central actions.

Immunosuppressant agent FK506 stimulates growth hormone (GH) secretion and gene expression of hypothalamic GH-releasing hormone in the rat.

Immunosuppressant agent FK506 has been reported to stimulate ACTH release from pituitary cells. We examined the effects of FK506 on GH release from the rat anterior pituitary cells and the effects of FK506 on hypothalamic GH- releasing hormone (GRH) and somatostatin (SS) gene expression in conscious male rats. In vitro experiments, the monolayer pituitary culture and reverse hemolytic plaque assay were employed to examine the GH release from the rat anterior pituitary cells. In in vivo experiments, the FK506 was administered for 7 days and then sequential blood sampling was performed every 20 min during 6 h in conscious rats. The hypothalamus was removed, and total RNA was extracted for Northern blot analysis. The FK506 significantly stimulated GH release from the rat anterior pituitary cells in a dose-dependent manner in vitro. In in vivo experiments, the area under the curve of GH surges was significantly increased in FK506-treated rats, although the peak height and the trough level of GH surges were not altered. Pituitary GH messenger RNA (mRNA) levels were significantly increased by the FK506 treatment. Hypothalamic GRH mRNA levels were significantly increased in FK506- treated rats, whereas hypothalamic SS mRNA levels were not altered. These findings indicate that FK506 stimulates GH secretion and gene expression of hypothalamic GRH in the rat.