Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The increase in blood clotting factor VIII (antihaemophilic factor, F-VIII) and fibrinolytic activity induced by the administration of neurohypophyseal hormone analogues, was assayed in sheep. Peptides with high selectivity for vasopressin V1, V2 or myometrial oxytocin receptors in the dose range of 0.1-10 micrograms/kg body weight were investigated. The main conclusions are as follows. The time-course of the F-VIII plasma levels following the administration of the peptides was biphasic, with one surge at about 20 min, a rebound phase, and another increase with the maximum at 60-90 min. The time-course of the fibrinolytic response, expressed as biological activity of plasminogen activator in the plasma euglobulin fraction, displayed a single maximum within 60 min. The baseline responses were reached within 90-120 min. Responses were expressed as integrals of the time-concentration curves in a predetermined time range (90-120 min). F-VIII and plasminogen activator enhancing effects seemed to be tightly linked to the specific vasopressin V2 receptor activities. [Val4,D-Arg8]Vasopressin displayed higher plasminogen activator activities than the standard substance, deamino[D-Arg8]vasopressin. The vasotocin analogue [Phe2,Orn8]oxytocin, a specific vasopressin V1 receptor agonist, also displayed high antihaemophilic and fibrinolytic potencies, expressed in terms of ED50 values, but did not reach the same maximal response as vasopressin V2 receptor agonists. Oxytocin and its highly selective uterotonic analogue, [Thr4,Gly7]oxytocin, displayed low antihaemophilic, and virtually no plasminogen activating potencies. Surprisingly, vasopressin V2 and V1V2 receptor antagonists studied in our experiments showed both enhanced F-VIII and fibrinolytic responses. Dose-response curves frequently displayed a decrease of the F-VIII, and sometimes also decreased fibrinolytic responses, at higher peptide doses. Strong decreases of the packed cell volume (haematocrit) and somewhat lower decreases of the total plasma protein concentration were observed shortly after administration of the peptides.
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PMID:Effects of neurohypophyseal hormone analogues on blood clotting factor VIII and fibrinolytic activity in sheep. 912 40

Oxytocin (OT) is present in the mammalian testis and has been shown to play a role in the modulation of seminiferous tubule contractility and steroidogenesis. However, stage-specific effects of the peptide have not been previously investigated. In this study, computer-assisted analysis and time-lapse videomicrography were used to investigate basal contractility and the response to OT of seminiferous tubules at specific stages of the spermatogenic cycle. Adult rat testes were placed in fresh oxygenated DMEM F12 medium, decapsulated, and the tubules gently teased apart. Stages were identified by transillumination and a 10 mm section of tubule at each of stages IV-V, VII-VIII and XIII-I was placed in a microslide chamber and perifused with medium. After a control period of 3 h, OT (2 nM) was given for 1 h, followed by another control period of 1 h. The experiment was repeated using tubules from different rats and data were analysed to give arbitrary units of tubule contractility. Contractility was observed in all the tubules studied and the contractile activity was shown to vary depending on the stage of the spermatogenic cycle. Mean basal contractility at stages VII-VIII, the time when sperm are shed from the epithelium, was significantly lower than that at stages IV-V and XIII-I. The response of the tubules to OT was also stage-dependent, with the peptide producing the largest increases in contractile activity at stages VII-VIII and having no effect at stages IV-V. We postulate that these stage-specific differences in basal and OT-stimulated contractility may be important in co-ordinating the movement of developing germ cells towards the lumen of the seminiferous epithelium and in the process of spermiation.
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PMID:Stage-related differences in rat seminiferous tubule contractility in vitro and their response to oxytocin. 965 88

It is accepted that whilst hormones such as oxytocin, vasopressin and prostaglandin F2alpha induce myometrial contractions, essentially via an elevation of intracellular calcium, other ligands, such as beta-adrenoceptor agonists, calcitonin gene-related peptide, and prostaglandin E2, promote uterine quiescence via their ability to increase intracellular cyclic AMP levels. At present, the exact factors initiating human parturition remain unknown, and labour may occur due to a loss of uterine quiescence, an increase in uterine contractility, or a combination of both. Whilst many studies have aimed to understand the mechanisms underlying uterine contractility there is a relative paucity of data regarding myometrial relaxation. We have verified the presence of mRNA encoding adenylyl cyclase (AC) isoforms I, II, III, V, VI, VII, VIII and IX in both non-pregnant and pregnant human myometrium, and in isolated myometrial cells maintained in cell culture. Furthermore, by means of immunoblotting and immunocytochemistry, we have demonstrated the expression of these isoforms as membrane-associated AC proteins, and identified changes in individual AC isoform expression during gestation. These findings illustrate the diversity of potential cAMP generating pathways in human myometrium, and the complexity of the signal transduction systems underlying uterine quiescence. Experimental Physiology (2001) 86.2, 265-272.
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PMID:Uterine quiescence: the role of cyclic AMP. 1142 43