Effects of Lactobacillus plantarum Postbiotics on Growth Performance, Immune Status, and Intestinal Microflora of Growing Minks

The present experiment was conducted to investigate the effects of Lactobacillus plantarum postbiotics on growth performance, immune status, and intestinal microflora of growing minks. A total of 80 minks (40 males and 40 females) were divided into four groups, each group contained 20 minks (10 males and 10 females). The minks in the four groups were fed a basal diet supplemented with 0, 0.15%, 0.3%, and 0.45% Lactobacillus plantarum postbiotics (PLP), respectively. After one week of adaptation, the experiment ran for eight weeks. The results showed that Lactobacillus plantarum postbiotics tended to have effects on average daily again (ADG) during the first 4 wk of the study (p < 0.1), and had effects on immune status (p < 0.05). Lactobacillus plantarum postbiotics also affected the abundance of intestinal bacteria at genus level (p < 0.05), but had no effects on α diversity of growing minks (p > 0.05). Compared to the minks in the control group, minks in 0.30% PLP group tended to have greater ADG, and IgA and IgM content in serum as well as SIgA content in jejunal mucosa (p < 0.05), and had less jejunal mucosal TNF-α and IL-8 levels, while minks in 0.45% PLP group had less IL-2 (p < 0.05). Compared to the control, Lactobacillus plantarum postbiotics decreased the relative abundances of Bacteroides_vulgatus and Luteimonas_sp. in male minks, and the relative abundances of Streptococcus_halotolerans in female minks (p < 0.05), respectively. Males grew faster and ate more associated with less F/G than females (p < 0.05). Males also had greater serum IgA and IgG content (p < 0.05), and males had less jejunal mucosal IL-1β, IL-8, IL-2, IL-6, IL-12, IL-10, TNF-α, and IFN-γ levels (p < 0.05). These results suggest that dietary supplementation of 0.3% postbiotics harvested from Lactobacillus plantarum could improve growth performance and immune status, and modulated the intestinal bacteria abundance of growing minks.

Tumor suppressor function of BCSC-1 in nasopharyngeal carcinoma

BCSC-1 is dramatically upregulated in CNE-2L2 human nasopharyngeal carcinoma cells with reduced malignancy (AS cells) and is proposed to be a candidate tumor suppressor gene. We therefore examined the effect of BCSC-1 expression on malignant behaviors of CNE-2L2 cells. Growth in vitro and tumorigenesis in nude mice of wild-type CNE-2L2 cells (W cells) were inhibited by ectopic BCSC-1, and those of AS cells were promoted by BCSC-1 suppression. The tumor suppressor function of BCSC-1 was further confirmed by a study showing that intratumor BCSC-1 injection caused growth suppression of the tumor from W cells inoculated in nude mice. Immunohistochemistry exhibited marked reduction of BCSC-1 expression in 11 of 39 human nasopharyngeal carcinoma specimens. Because BCSC-1 expression was as rich as that in normal cells in the rest of the carcinoma specimens and was poor in CNE-2L2 cells, HNE-1 human nasopharyngeal carcinoma cells with rich BCSC-1 expression were used as a control in the study. No effect of BCSC-1 transfection on growth of the cells was observed. The data suggest that BCSC-1 suppression might play roles in tumorigenesis of some nasopharyngeal carcinomas and that BCSC-1 might be a potential gene therapy target in nasopharyngeal carcinomas with poor BCSC-1 expression. Enhanced aggregation of cells together with increased E-cadherin and alpha-catenin expression and reduced Wnt signaling might be involved in the mechanisms of tumor suppressor function of BCSC-1.

Regulation of gonadotropin-releasing hormone (GnRH) gene expression by insulin-like growth factor I in a cultured GnRH-expressing neuronal cell line

A GnRH-expressing neuronal cell line (NLT) was used to determine whether insulin-like growth factor I (IGF-I) regulates GnRH gene expression. A receptor-binding assay demonstrated the expression of IGF-I receptors on NLT cells. Activation of IGF-I receptors induced the Ras/Raf-1/mitogen-activated protein kinase pathway and increased c-fos expression. NLT cells treated with IGF-I underwent cell proliferation and exhibited a growth-independent increase in mouse GnRH mRNA expression. In cells transfected with DNA constructs containing the human GnRH promoter, which includes a consensus AP-1 binding site fused to the luciferase reporter gene, a significant increase in reporter activities was induced by IGF-I, whereas mutation of this AP-1 site significantly reduced IGF-I-induced promoter activation. These results demonstrate that IGF-I serves as an important signal in the regulation of both human and rodent GnRH gene expression.

An alternative gonadotropin-releasing hormone (GnRH) RNA splicing product found in cultured GnRH neurons and mouse hypothalamus

Gonadotropin-releasing hormone (GnRH) is encoded by the proGnRH gene which contains four exons and three introns. In this study, two immortalized GnRH-expressing cell lines (Gn11 and NLT) were characterized. The NLT and Gn11 cells, derived from a same brain tumor in a transgenic mouse, display neuronal morphology and neuron-specific markers. However, NLT cells secrete much higher levels of GnRH than Gn11 cells. To delineate the mechanism underlying this difference, reverse transcriptase-polymerase chain reaction and RNase protection assays were performed to examine proGnRH gene expression. While the mature proGnRH mRNA was predominately expressed in NLT cells, Gn11 cells express an abundant short transcript. Sequence analysis revealed that this short transcript contains exons 1, 3, and 4, but not exon 2, which encodes the GnRH decapeptide. RNase protection assays demonstrated that NLT cells express much higher levels of mature proGnRH mRNA than Gn11 cells. The lower level of GnRH secreting capacity in Gn11 cells is due, in part, to decreased expression of mature proGnRH mRNA. When proGnRH gene expression in the mouse brain was examined, the same short splicing variant was observed in the olfactory area and preoptic area-anterior hypothalamus. But the prevalent transcript in these regions was the mature proGnRH mRNA. In contrast, only the mature proGnRH mRNA was found in the caudal hypothalamus. These results suggest that alternative splicing may be one of the mechanisms regulating proGnRH gene expression in the animal brain.

Phorbol ester regulation of the gonadotropin-releasing hormone (GnRH) gene in GnRH-secreting cell lines: a molecular basis for species differences

Phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) regulation of the GnRH gene was studied in two mouse GnRH neuronal cell lines, Gn11 and NLT. TPA treatment of NLT cells grown in low serum conditions did not alter endogenous mouse GnRH mRNA levels, indicating that the endogenous mouse gene is not regulated by phorbol esters under these conditions. This result is confirmed in transfection studies in which TPA treatment did not change expression of a mouse GnRH-luciferase reporter gene construct. In contrast, TPA treatment stimulated expression of a human GnRH-luciferase reporter construct, correlating with the expression of the protoon-cogenes c-fos and c-jun. TPA stimulation of the human GnRH gene is mediated by a consensus AP-1 site located at -402 to -396 bp, TGACTCA, which specifically binds c-fos and c-jun in Gn11 and NLT cells and recombinant c-jun in gel mobility shift studies. In contrast, the rodent GnRH genes, when aligned for maximum homology, contain a DNA sequence with a 1-bp difference, TGTCTCA from the human gene. In gel mobility shift studies, this DNA sequence does not form a complex with Gn11 or NLT nuclear extract or with recombinant c-jun. This is the first demonstration of species-specific differences in phorbol ester regulation of GnRH gene transcription and could, in part, explain differences in reproductive function among mammals.

The role of norepinephrine in mediating luteinizing hormone release in response to blockade of kappa-opioid receptors in the medial preoptic area

Our previous study [32] indicated that blockade of kappa-opioid receptors with nor-binaltorphimine (nor-BNI) in the medial preoptic area (MPOA) produced two different LH responses during midpregnancy in the rat: an increase in basal pulsatile LH secretion, followed in many cases by a larger and/or sustained increase in LH release. In the present study, two experiments were conducted to examine the role of norepinephrine (NE) in mediating these different LH responses. In experiment 1, the effects of NE synthesis inhibition with FLA-63 on nor-BNI induced LH secretion were examined. In 5 of 9 vehicle pretreated rats, nor-BNI perfusion in the MPOA produced only an increase in basal pulsatile LH secretion. In the remaining 4 animals blockade of MPOA kappa-receptors produced not only an increase in basal LH secretion, but also a large/sustained release of LH. Pretreatment with FLA-63 had no effect on the nor-BNI induced increase in basal pulsatile LH secretion, but completely prevented the occurrence of the large/sustained release of LH. The objective of experiment 2 was to determine whether any change in NE release occurred at the site of nor-BNI perfusion in rats showing this large/sustained increase in plasma LH levels, by measuring in vivo NE release at that site. No significant change in perfusate NE levels was observed during perfusion of the MPOA with nor-BNI alone or in combination with desipramine, a NE reuptake blocker, in rats that showed this type of LH response. These results demonstrate that while NE does not mediate the increase in basal pulsatile LH release produced by nor-BNI perfusion in the MPOA, it is essential for the large/sustained elevation in LH secretion seen in response to blockade of kappa-opioid receptors at this site. This latter type of LH secretory response is not, however, associated with an increase in NE release directly at the site of kappa-opioid receptor blockade in the MPOA in pregnant rats.

Lack of catecholamine involvement in the increased luteinizing hormone release due to blockade of kappa-opioid receptors in the medial basal hypothalamus during midpregnancy in the rat

Blockade of kappa-opioid receptors in the medial basal hypothalamus (MBH) with nor-binaltorphimine (nor-BNI) stimulates luteinizing hormone (LH) release during midpregnancy in the rat [48]. The objective of this study was to determine whether norepinephrine (NE) or dopamine (DA) mediates the LH response to blockade of MBH kappa-opioid receptors on days 13-17 of pregnancy in the rat. Two experiments were conducted. In the first, push-pull perfusion in conjunction with HPLC was used to monitor in vivo NE release in the MBH occurring in response to (a) artificial CSF followed by CSF containing nor-BNI (40 micrograms/h), (b) desipramine (DMI, a NE reuptake blocker, 10 microM) in CSF followed by DMI, and (c) DMI followed by DMI+nor-BNI. Blood samples were taken at 12 min intervals concurrent with push-pull perfusate samples. Plasma LH levels were determined by RIA. Nor-BNI significantly increased LH release compared to CSF alone, but perfusate NE was undetectable in either perfusion period. However, perfusion with CSF containing 100 mM K+ in these rats markedly increased perfusate NE levels, indicating noradrenergic nerve terminals were present at the perfusion sites in the MBH. Addition of DMI to the CSF significantly increased perfusate NE levels, but produced no change in LH release. Nor-BNI+DMI perfusion increased LH secretion similar to nor-BNI alone, but produced no additional increase in MBH perfusate NE levels compared to perfusion with DMI alone.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of blockade of kappa-opioid receptors in the medial basal hypothalamus and medial preoptic area on luteinizing hormone release during midpregnancy in the rat

The objective of this study was to determine if kappa-opioid receptors present in the medial preoptic area (MPOA) and medial basal hypothalamus (MBH) are involved in opioid peptide suppression of LH secretion during midpregnancy (day 13-16) in the rat. Nor-binaltorphimine (nor-BNI), a selective antagonist of brain kappa-opioid receptors, was applied directly to the MPOA or MBH for 3.5 h by means of push-pull perfusion. Nor-BNI perfusion in the MBH produced a dose-dependent increase in LH pulse frequency as well as increases in blood LH level. The effect on amplitude could not be determined, since too few pulses occurred in cerebrospinal fluid-treated control rats. Nor-BNI perfusion in the MPOA also increased LH pulse frequency. Moreover, in the majority (62%) of rats perfused with nor-BNI in the MPOA, the final 1.5 h of perfusion were unexpectedly characterized by an increase in LH that was of greater magnitude and more prolonged than an LH pulse and produced an elevation in blood LH levels. This delayed LH response did not occur in any rat perfused in the MBH. Perfusion with nor-BNI in the diagonal band of Broca had no significant effect on LH secretion. The LH responses observed during nor-BNI perfusion in the MPOA or MBH were not due to spread to the third ventricle and subsequent diffusion via the cerebrospinal fluid to another brain site, since perfusion with nor-BNI in an area of the ventral thalamus close to the third ventricle had no effect on LH release. These results provide support for the involvement of kappa-opioid receptor-mediated mechanisms in both the MPOA and MBH in the suppression of LH secretion during midgestation in the rat.

Assessment of topical therapy of the burn wound with silver sulphadiazine after its use for 15 years in a burn unit

A comparative study of patients receiving or not receiving topical applications of 1 per cent silver sulphadiazine cream as treatment for burn wounds has shown that the drug is still effective in significantly reducing the amount of bacterial contamination of burn wounds, even after 15 years of use in our Burn Unit. Consequently the overall mortality due to burn wound sepsis has been decreased in this Burn Unit.