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251.
A synthetic dipeptide, N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide, was shown previously to inhibit the binding of serotonin to a soluble specific serotonin binding protein as well as to alter brain serotonin levels. When injected into rats intraventricularly, the dipeptide caused an increase in pain threshold, lasting for several hours, as determined by either a flinch-jump test or a tail-flick test. This effect was reversed by naloxone. The dipeptide is a very weak inhibitor of the binding of labelled naloxone or dihydromorphine to a membranous opiate receptor preparation. The analgesic activity of the dipeptide was not diminished by p-chlorophenylalanine or the setonergic neurotoxin 5,7-dihydroxytryptamine, which depleted brain serotonin levels. This implies that the analgesic action of the dipeptide is not mediated directly by its effect on serotonin concentration. 相似文献
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Eran Amichai Eran Levin Noga Kronfeld-Schor Uri Roll Yoram Yom-Tov 《Mammalian Biology》2013,78(2):94-103
We used radio-telemetry, observations and physiological measurements to study the basic biology and energetic strategies of Asellia tridens in northern Israel from 2009 to 2010. Between late May and early November, the bats occupied abandoned man-made structures in this area. Parturition occurred between late June and mid-July, and juveniles were independent by late August. A. tridens foraged near the roost in a vegetation-rich, cluttered background environment, catching insects flying close to vegetation. Its diet was diverse, with Coleoptera, Heteroptera, Diptera and Lepidoptera being the main diet components. During summer, males and females differed in their foraging patterns and energetic strategies: Lactating females departed for more frequent foraging bouts than males, and maintained euthermy throughout the day, while males became torpid on a daily basis. 相似文献
254.
Hemopoiesis is a sequence of events initiated by the self-renewal of pluripotent stem cells followed by a series of differentiation steps and completed in the formation of distinct tissue patterns. Differentiation and self-renewal are antagonistic processes. A mechanism that attenuates the differentiation flow is obligatory to prevent the exhaustion of the stem cell pool. We suggest that stromal cells from the bone marrow control stem cell renewal through a mechanism that does not require colony-stimulating factors. The organization of cells within the tissue and their specific localization is suggested to be directed by stromal cell activities other than differentiation inducers. These stromal cell activities restrict differentiation or accumulation of mature cells. They are therefore designated as 'Restrictins'. 相似文献
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Fresh pineal glands are fixed in 10% formalin at room temperature for about 3 days. After washing, dehydrating and clearing they are embedded in paraffin, sectioned and mounted. The tissues are placed in 10% silver nitrate for 24 hours, washed and impregnated in strong silver carbonate. The sections are reduced in 10% formalin, washed and toned in gold chloride, fixed in 5% hyposulfite, counterstained with erythrosin and mounted in Canada balsam. The processes of the pineal parenchymatous cells of the sheep, cow and man have been successfully stained by this method. 相似文献