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Regardless of various healing potentials demonstrated by the tested cells (different cell composition, growth and organization), their response to melatonin was similar. Moreover, in the two investigated cultures, augmentation of the collagen content by melatonin was reversed by luzindole, which indicates the possibility of melatonin membrane receptor involvement in that process. The present results suggest that the increased melatonin-stimulated deposition of collagen observed in the infarcted heart of rats could be dependent on activation of the melatonin membrane receptors on scar myofibroblasts.

Background. Tissue engineering is a strategy aimed at improving the regeneration of injured tissues.Objectives. The aim of the present study was to determine whether a tri-copolymer composed of crosslinked collagen, chondroitin sulfate and hyaluronic acid (Col + CS + HA) provides a better environment for fibroblast and embryonic nerve cell culture than a collagenous scaffold (Col).Material and methods. The porosity of each of the matrices was characterized with a scanning electron microscope. Fibroblasts were isolated from rat wound granulation tissue (polypropylene net implanted subcutaneously). Embryonic nerve cells were obtained from the brains of rat embryos. The cells were applied to scaffolds and then stained with bisbenzimide to calculate cell entrapment within the material. The metabolic activity of the cells cultured within the scaffolds was tested using the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay.Results. The Col scaffolds had a homogenously porous structure with a pore diameter of 50 μm for 70% of pores. The pore diameter in the tri-copolymer (Col + HA + CS) ranged from 24 to 160 μm (95% of total pore volume). Four times more cells (fibroblasts and embryonic nerve cells) were trapped within the superficial part of the collagenous scaffold than that of the tri-copolymer. On the third day of culture the metabolic activity of the fibroblasts within the 2 tested scaffolds was significantly higher than in the control conditions (cell culture on a laminin-coated surface). Also, the embryonic nerve cells demonstrated increased metabolic activity in Col + CS + HA scaffolds than the Col scaffolds.Conclusions. Both fibroblasts and embryonic nerve cells could be seeded within the 2 tested scaffolds. Both the scaffolds provide good conditions for fibroblast culture. However, the Col + CS + HA tri-copolymer is preferable for embryonic nerve cell engineering.

The inflammatory reaction influences the deposition of collagen within wound granulation tissue. The aim of the present study is to determine whether histamine acting directly on myofibroblasts derived from wound granulation tissue may influence collagen deposition. It also identifies the histamine receptor involved in this process. The experiments were carried out on cells isolated from the granulation tissue of a wound model (a polypropylene net inserted subcutaneously to rats) or intact rat skin. Collagen content was measured following the addition of different concentrations of histamine and treatment with histamine receptor antagonists (ketotifen – H1 inhibitor, ranitidine – H2 inhibitor) and a histamine receptor H1 agonist (2-pyridylethylamine dihydrochloride).The cells were identified as myofibroblasts: alpha-smooth muscle actin, vimentin, and desmin positive in all experimental conditions. Histamine increased the collagen level within both cell cultures, i.e., those isolated from granulation tissue or intact skin. It did not, however, influence the expression of either the collagen type I or III genes within the cultured myofibroblasts. Histamine activity was reduced by ketotifen (the H1 receptor inhibitor) and increased by the H1 receptor agonist, as demonstrated by changes in the levels of collagen in the myofibroblast culture. Histamine increased collagen content within the cultures, acting directly on myofibroblasts via H1 receptor stimulation.

The role of melatonin membrane receptors in melatonin-dependent oxytocin secretion from the rat hypothalamo-neurohypophysial system -an in vitro and in vivo approach Rola błonowych receptorów melatoniny w zależnym od melatoniny uwalnianiu oksytocyny z układu podwzgórze-część nerwowa przysadki szczura -badania in vitro oraz in vivo AbstractIntroduction: Melatonin exerts its biological role acting mainly via G protein-coupled membrane MT 1 and MT 2 receptors. To determine whether a response of oxytocinergic neurons to different concentrations of melatonin is mediated through membrane MT 1 and/or MT 2 receptors, the effect of melatonin receptors antagonists, i.e. luzindole (a non-selective antagonist of both MT 1 and MT 2 receptors) and 4-phenyl-2-propionamidotetralin (4-P-PDOT -a selective antagonist of MT 2 receptor), on melatonin-dependent oxytocin (OT) secretion from the rat hypothalamo-neurohypophysial (H-N) system, has been studied both in vitro and in vivo. Materials and methods: For in vitro experiment, male rats served as donors of the H-N explants, which were placed in 1 ml of normal Krebs-Ringer fluid (nKRF) heated to 37