Serotonin is a neurotransmitter functioning also as a hormone and growth factor. To further investigate the biological role of serotonin during embryo development, we analysed serotonin localization as well as the expression of specific serotonin 5-HT1D receptor mRNA in mouse oocytes and preimplantation embryos. The functional significance of serotonin during the preimplantation period was examined by studying the effects of serotonin on mouse embryo development. Embryo exposure to serotonin (1 μM) highly significantly reduced the mean cell number, whereas lower concentrations of serotonin (0.1 μM and 0.01 μM) had no significant effects on embryo cell numbers. In all serotonin-treated groups a significant increase in the number of embryos with apoptotic and secondary necrotic nuclei was observed. Expression of serotonin 5-HT1D receptor mRNA in mouse oocytes and preimplantation embryos was confirmed by in situ hybridization showing a clearly distinct punctate signal. Immunocytochemistry results revealed the localization of serotonin in oocytes and embryos to the blastocyst stage as diffuse punctate cytoplasmic labelling. It appears that endogenous and/or exogenous serotonin in preimplantation embryos could be involved in complex autocrine/paracrine regulations of embryo development and embryo-maternal interactions.
A. LAUKOVÁ , S. CZIKKOVÁ , Z. VASILKOVÁ , P. JURIŠ AND M. MAREKOVÁ . 1998. The occurrence of enterococci in cattle dung water from the basins of 25 cattle farms of 15 northeastern Slovakia districts was screened as well as bacteriocin production among selective enterococcal isolates. The average total count of enterococci detected reached 5·0 × 10 3 cfu ml −1 . Enterococcus faecium was the predominant species (25%) followed by Ent. casseliflavus (19·2%), Ent. faecalis (9·6%), Ent. avium and Ent. durans (1·9%). The antagonistic activity of isolates showed a mainly antilisterial effect. Enterococcus faecalis V24 strain produced a heat stable, largely hydrophobic antimicrobial substance with best production in the range pH 4 to 7 and with a strong inhibitory effect even against Gram-negative bacteria.
Essential oils are plant secondary metabolites possessing various pharmacological properties, primarily anti-oxidative, antimicrobial or immunomodulative, but they can exhibit toxic and allergic effects as well. The aim of this study was to compare the effects of Rosmarinus officinalis essential oil dietary administration in carrageenan paw oedema and trinitrobenzene sulfonic acid (TNBS) colitis. ICR mice received rosemary essential oil at three concentrations (1 250, 2 500 and 5 000 ppm) in the standard laboratory diet starting two weeks before the experiments. The inflammation of paws induced by carrageenan application was evaluated by measurement of paw swelling, paw weight and myeloperoxidase activity. In the TNBS model the mice were killed by cervical dislocation 3 days after colitis induction and the mortality, changes in the body weight of mice, colon weight : body weight ratio, macroscopical scores and myeloperoxidase activity were analysed. Furthermore, IL-1β and IL-6 cytokine levels in colonic tissue were quantified using ELISA assay. Dietary supplementation with 5 000 ppm of rosemary essential oil initially after 2 h increased but after 24 h suppressed the extent of paw oedema. The same dose in the TNBS model exhibited protective effects on colonic mucosa and significantly decreased macroscopic scores for colonic inflammation. On the other hand, in colon samples from mice fed the diet with 1 250 ppm of rosemary essential oil we detected decreased myeloperoxidase activity and significantly lower levels of IL-6 compared to TNBS control animals.Our results indicate that rosemary essential oil is able to influence several variables of murine experimental inflammatory models depending on the concentration used. We conclude that the anti-inflammatory effects of rosemary essential oil should be interpreted carefully due to its timeand dose-related effects.
Juhás Š., D. Bujňáková, P. Rehák, Š. Čikoš, S. Czikková, J. Veselá, G. Iľková, J. Koppel: Anti-Inflammatory Effects of Thyme Essential Oil in Mice. Acta Vet. Brno 2008, 77: 327-334. Plant essential oils are plant secondary metabolites possessing various pharmacological properties, primarily anti-oxidative, antimicrobial or immunomodulatory ones. The aim of this work was to study the effects of thyme essential oil dietary administration in murine DTH/ CHS reaction, carrageenan paw oedema and TNBS colitis. Thyme essential oil was added to the murine diet at three concentrations (5000, 2500 and 1250 ppm) and fed to Balb/c mice. The extent of ear swelling in DTH/CHS reaction and paw oedema induced by carrageenan application was measured using the Mitutoyo thickness gauge. In the model of TNBS colitis we evaluated the changes in body weight, the colon weight : body weight ratio, bacterial translocation to mesenteric lymph nodes, and macroscopical and histological scores. IL-1 and IL-6 messenger RNA expression in colonic samples of one experimental group were assessed using quantitative real-time reverse transcriptase PCR. Dietary supplementation with 5000 ppm of thyme essential oil significantly decreased paw oedema and ear swelling. This thyme essential oil concentration caused a significant inhibition of total mRNA IL-1 expression in the mouse colon, and markedly decreased the macroscopic and microscopic scores of colitis. On the other hand, the 1250 ppm of thyme essential oil in diet increased ear oedema induced by oxazolone application in mice. Our study indicates that thyme essential oil is able to affect murine experimental inflammatory models depending on the concentration used. It is concluded that the anti-inflammatory effects of thyme essential oil should be interpreted with a caution due to its contradictory, dose-related effects.
Abstract. In our study we investigated the effect of maternal restraint stress on preimplantation embryo development using a mouse model. We exposed hormonally stimulated (superovulated) and unstimulated (i.e. spontaneously ovulating) mouse females to restraint stress for 30 min three times a day during the preimplantation period. The stress exposure caused significant increase in blood plasma corticosterone concentration. Microscopical evaluation of embryos isolated from spontaneously ovulating females showed that maternal stress significantly increased the proportion of embryos with lower cell numbers (≤32 cells) and decreased the proportion of embryos with higher cell numbers (65-96 cells and 97-128 cells). Moreover maternal restraint stress decreased the cell counts per embryo and per blastocyst. After an additional 24 h in vitro culture we did not find any difference in the embryo distribution or in the cell counts per embryo/blastocyst between embryos isolated from stressed and control mothers. The exposure to restraint stress did not affect the incidence of apoptosis in blastocysts isolated from spontaneously ovulated dams. In gonadotropin stimulated dams, the hormonal treatment itself notably changed embryo distribution (increasing the proportion of degenerated embryos) and increased the occurrence of apoptotic cells. Our results indicate that psychical stress exposure in very early pregnancy can significantly influence the developmental capacity of preimplantation embryos.
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