This study was performed to determine the action mode of oxytocin antagonist. In Study 1, the duration of in vivo action of oxytocin antagonist I (AI) was examined. After infusing AI, oxytocin was given and repeated every hour for 5 hr. Uterine activities were monitored with a polygraph. Study 2 determined the effect of AI on uterine oxytocin receptor number (Rn) and binding affinity (Kd). AI treated rats were sacrificed at 0.5 and 4 hr later for receptor assay. In Study 1, the uterine contractile response to oxytocin was significantly inhibited (p>0.05) compared to controls at five min, 1 and 2 hr after injection of AI. No differences in response were detected compared to controls (p>0.05) at later hours. In Study 2, no differences (p>0.05) between the AI and control animals in either oxytocin receptor number or binding affinity was found. These data suggest that the major mode of AI action is via competitive inhibition at the uterine oxytocin receptor and not by altering receptor number or binding affinity. AI is suggested to have the potential of being a potent and specific tocolytic agent for prevention of preterm labor in human.
Animal ; Female ; Oxytocin/pharmacology ; Oxytocin/metabolism ; Oxytocin/antagonists & inhibitors* ; Rats ; Receptors, Oxytocin/metabolism ; Uterus/physiology ; Uterus/drug effects*

This study was performed to determine the action mode of oxytocin antagonist. In Study 1, the duration of in vivo action of oxytocin antagonist I (AI) was examined. After infusing AI, oxytocin was given and repeated every hour for 5 hr. Uterine activities were monitored with a polygraph. Study 2 determined the effect of AI on uterine oxytocin receptor number (Rn) and binding affinity (Kd). AI treated rats were sacrificed at 0.5 and 4 hr later for receptor assay. In Study 1, the uterine contractile response to oxytocin was significantly inhibited (p>0.05) compared to controls at five min, 1 and 2 hr after injection of AI. No differences in response were detected compared to controls (p>0.05) at later hours. In Study 2, no differences (p>0.05) between the AI and control animals in either oxytocin receptor number or binding affinity was found. These data suggest that the major mode of AI action is via competitive inhibition at the uterine oxytocin receptor and not by altering receptor number or binding affinity. AI is suggested to have the potential of being a potent and specific tocolytic agent for prevention of preterm labor in human.
Animal ; Female ; Oxytocin/pharmacology ; Oxytocin/metabolism ; Oxytocin/antagonists & inhibitors* ; Rats ; Receptors, Oxytocin/metabolism ; Uterus/physiology ; Uterus/drug effects*

Recent studies have provided several lines of evidence that peripheral administration of oxytocin induces analgesia in human and rodents. However, the exact underlying mechanism of analgesia still remains elusive. In the present study, we aimed to identify which receptor could mediate the analgesic effect of intraperitoneal injection of oxytocin and its cellular mechanisms in thermal pain behavior. We found that oxytocin-induced analgesia could be reversed by d(CH₂)₅[Tyr(Me)²,Dab⁵] AVP, a vasopressin-1a (V1a) receptor antagonist, but not by desGly-NH₂-d(CH₂)₅[DTyr², Thr⁴]OVT, an oxytocin receptor antagonist. Single cell RT-PCR analysis revealed that V1a receptor, compared to oxytocin, vasopressin-1b and vasopressin-2 receptors, was more profoundly expressed in dorsal root ganglion (DRG) neurons and the expression of V1a receptor was predominant in transient receptor potential vanilloid 1 (TRPV1)-expressing DRG neurons. Fura-2 based calcium imaging experiments showed that capsaicin-induced calcium transient was significantly inhibited by oxytocin and that such inhibition was reversed by V1a receptor antagonist. Additionally, whole cell patch clamp recording demonstrated that oxytocin significantly increased potassium conductance via V1a receptor in DRG neurons. Taken together, our findings suggest that analgesic effects produced by peripheral administration of oxytocin were attributable to the activation of V1a receptor, resulting in reduction of TRPV1 activity and enhancement of potassium conductance in DRG neurons.
Analgesia* ; Calcium ; Diagnosis-Related Groups ; Electrophysiology ; Fura-2 ; Ganglia, Spinal* ; Humans ; Injections, Intraperitoneal ; Neurons ; Oxytocin* ; Potassium* ; Receptors, Oxytocin ; Receptors, Vasopressin ; Rodentia ; Spinal Nerve Roots*

Oxytocin, like vasopressin, has been known to act in the IMCD by the activation of adenylyl cyclase through V2 receptor, but the exact mechanism of its action remains to be elucidated. To prove whether oxytocin is involved in the activation of adenylyl cyclase in the renal collecting duct, we measured the cAMP production and urinary cAMP excretion rate. After single IMCD segments of Sprague-Dawley rats were microdissected and treated with different con- centrations of vasopressin(10pM, 10nM) and oxytocin (10pM, 10nM), cAMP production was measured. Urinary cAMP excretion rate was measured after dehydration and intraperitoneal injection of vasopressin and oxytocin. The results are as follows. 1) cAMP production in single IMCD was significantly increased in vasopressin group(10pM: 48,9+/-4.7(mean+/-SE), 10nM:94.6+/-5.3fmol/mm) and oxy-tocin group(10pM: 11.3+/-2.9, 10nM: 65.7+/-6.1fmol/mm) compared with that in the control(3.2+/-0.2fmol/ mm). 2) Urine volume was significantly decreased in dehydration group(40+/-7Ml/hour) and vasopressin group(420+/-120Ml/hour), but urine volume of oxytocin group(1,480+/-230Ml/hour) was not different from that of control(1,550+/-120Ml/hour). Urine osmolality was significantly increased in all experimental groups(control: 737.0+/-132.6, dehydration group : 2,463.9+/- 412.5, vasopressin group : 1,702+/-412.5, oxytocin group 1,293.4+/-117.9mOsm/kg). Urinary cAMP excretion rate was significantly increased in dehydration group(4,149.5+/-1,072.3pmol/hour) and oxytocin group(4,843.3+/-2,341.8pmol/hour), but not in vasopressin group(1,358.1+/-690.2pmol/hour), compared with that in control(49+/-10.7pmoVhour). These results suggest that oxytacin has anti-diuretic effect by the activation of adenylyl cyclase through V2 receptor.
Adenylyl Cyclases ; Dehydration ; Injections, Intraperitoneal ; Osmolar Concentration ; Oxytocin* ; Rats, Sprague-Dawley ; Receptors, Vasopressin ; Vasopressins

OBJECTIVETo analyze the level of the oxytocin (OT) and the expression of oxytocin receptor (OTR) in males with idiopathic infertility.

METHODSSixty-five infertile males aged 20 -45 years were divided according to their semen parameters into an idiopathic oligozoospermia group (OG, n = 20), an idiopathic asthenozoospermia group (AG, n = 25), and an idiopathic oligoasthenozoospermia group (OAG, n = 20). Another twenty 20-45 years old healthy male volunteers with a natural childbearing history were included in the control group (CG). All the subjects were detected for the contents of luteinizing hormone (LH), follicle stimulating hormone (FSH) , testosterone (T) and OT, and analyzed for the expression of OTR by sequencing the functional region of the OTR promoter (OTRP), OTR-mRNA, and OTR-COOH terminus. The gene sequences were compared using DNASTAR-MegAlign, Western blot values changed into enumeration data, and all the data analyzed by one-way ANOVA and Dunnette's multiple range t-test.

RESULTSA significantly lower content of OT was observed in CG ( [79.30 +/- 3.83] pg/ml) than in OG ([118.53 +/- 7.69] pg/ml, AG ([108.81 +/- 5.66] pg/ml) and OAG ([103.71 +/- 4.54] pg/ml) (F(0.05/2[2,82]) = 8.29, P < 0.01). The content of LH was significantly lower in AG ([4.26 +/- 0.31] IU/L) and OAG ([4.55 +/- 0.40] IU/L) than in OG ([6.77 +/- 0.57] IU/L) and CG ([7.19 +/- 0.50] IU/L) (F(0.05/2 [2,82]) = 11.64, P < 0.01), and so was the content of FSH in AG ( [5.02 + 0.39] IU/L) than in CG ([8.91 +/- 0.91] IU/L), OG ([11.86 +/- 1.76] IU/L) and OAG ([8.82 +/- 1.03] IU/L) (F(0.05/[2,82]) = 7.22, P < 0.01). There were no significant differences in the T content among the four groups (F(0.05/2[2,82] = 0.42, P = 0.739). No evident gene mutation was found in OTRP and OTR-mRNA gene sequencing. Human OTRs in the lymphocytes were monomers and oligomers, mostly tetramers and hexamers. There were obviously more monomers in AG (0.41 +/- 0.03) and OAG (0.13 +/- 0.01) than in OG (0.05 +/- 0.004) and CG (0.05 +/- 0.003) (F(0.05/2[2,82]) = 115.50, P < 0.01), while the number of oligomers was markedly decreased in 20% of the cases in AG.

CONCLUSIONSignificant differences in the content of OT and expression of OTR between fertile and infertile men suggested an association of OT with male infertility. The decreased expression of OTR oligomers and increased expression of monomers may be related to idiopathic asthenozoospermia, which has provided a new insight into the pathogenesis and treatment of male infertility.

Adult ; Case-Control Studies ; Humans ; Infertility, Male ; metabolism ; pathology ; Male ; Middle Aged ; Neuropeptides ; metabolism ; Oxytocin ; metabolism ; Receptors, Oxytocin ; metabolism ; Young Adult

OBJECTIVETo probe the mechanism of acupuncture in treatment of dysmenorrhea.

METHODSAdult mice with no pregnancy were randomly divided into a normal group, a model group, an acupuncture group and a medication group. The model group, the acupuncture group and the medication group were modeled by Diethylstilbestrol and Ocytocin. For the acupuncture group, at the 7th day of modeling, acupuncture was given at "Sanyinjiao" (SP 6), "Diji" (SP 8), once a day, for 5 days; and at the 7th day of modeling, Yimucao Gao 0.6 mg/g was given intragastrically to the medication group for 5 days. The stretching latent period and the number of stretching within 30 min were observed, and mRNA levels of ocytocin receptor (OctR) and vasopressin receptor (VasR) in the uterus tissue were detected with RT-PCR method.

RESULTSCompared with the model group, the stretching latent period extended (P < 0.05) and the number of stretching within 30 min significantly decreased (P < 0.05); and there were significant differences in the mRNA levels of ocytocin receptor and vasopressin receptor in the uterus tissue in the model group as compared with those in other 3 groups (P < 0.05, P < 0.01).

CONCLUSIONAcupuncture can improve the dysmenorrheal symptom to a certain extent, and the mechanism is possibly related to regulative effects of acupuncture on hormones-mediating receptors in mice.

Acupuncture Therapy ; Animals ; Dysmenorrhea ; metabolism ; therapy ; Female ; Mice ; RNA, Messenger ; analysis ; Receptors, Oxytocin ; genetics ; Receptors, Vasopressin ; genetics

OBJECTIVE: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairment in social skills and communication with repetitive behaviors. Etiology is still unclear although it is thought to develop with interaction of genes and environmental factors. Oxytocin has extensive effects on intrauterine brain development. Vitamin D, affects neural development and differentiation and contributes to the regulation of around 900 genes including oxytocin receptor gene. In the present study, the contribution of D vitamin receptor and oxytocin receptor gene polymorphisms in the development of ASD in Turkish community was investigated. To our knowledge, this is the first study examining these two associated genes together in the literature. METHODS: Eighty-five patients diagnosed with ASD according to DSM-5 who were referred to outpatient clinics of Child and Adolescent Psychiatry of Başkent University and Mersin University and 52 healthy, age and gender-matched controls were included in the present study. Vitamin D receptor gene rs731236 (Taq1), rs2228570 (Fok1), rs1544410 (Bsm1), rs7975232 (Apa1) polymorphisms and oxytocin receptor gene rs1042778 and rs2268493 polymorphisms were investigated using real time polymerase chain reaction method. RESULTS: No significant difference between groups in terms of distribution of genotype and alleles in each of polymorphisms for these genes could be found. CONCLUSION: Knowledge of genes and polymorphisms associated with the development of ASD may be beneficial for early diagnosis and future treatment. Further studies with larger populations are required to demonstrate molecular pathways which may play part in the development of ASD in Turkey.
Adolescent ; Adolescent Psychiatry ; Alleles ; Ambulatory Care Facilities ; Autism Spectrum Disorder ; Brain ; Child* ; Early Diagnosis ; Genotype ; Humans ; Methods ; Neurodevelopmental Disorders ; Oxytocin* ; Polymorphism, Genetic ; Real-Time Polymerase Chain Reaction ; Receptors, Calcitriol ; Receptors, Oxytocin* ; Social Skills ; Turkey ; Vitamin D* ; Vitamins*

BACKGROUND: The aquaporin-2 (AQP2) water channel is mainly located in the apical plasma membrane of epithelial cells in the connecting tubule and collecting ducts, but there has been some evidence of a moderate amount of basolateral localization of AQP2 in these nephron segments. Previous in vitro microperfusion studies showed that oxytocin has an antidiuretic action most likely mediated by the vasopressin V2 receptor (V2R) in rat inner medullary collecting duct. METHODS: By using ultrastructural preembedding immunocytochemistry with 1 nm immunogold in male Sprague-Dawley rat kidneys, we investigated the acute (60 min) effect of oxytocin (10 U) on the subcellular localization of AQP2 and tested whether the effect of oxytocin is prevented by a V2R antagonist, OPC-31260 (OPC). RESULTS: In control rat kidneys, AQP2 was mainly expressed in the apical plasma membrane and subapical vesicles in the connecting tubule (CNT) cells, principal cells of cortical (CCD), outer medullary collecting duct (OMCD) and initial part of inner medullary collecting duct (IMCD), and IMCD cells of terminal part of IMCD. Basolateral AQP2 labeling was observed in the CNT cells and IMCD cells. In contrast, there was little basolateral AQP2 labeling in the CCD and OMCD principal cells. Oxytocin treatment induced apical immunolabeling of AQP2 and caused an increase of AQP2 immunolabeling in the basal part including basolateral plasma membrane in the CNT cells, principal cells of CCD, OMCD and initial part of IMCD, and IMCD cells of terminal part of IMCD. Pretreatment of rats with a V2R antagonist OPC before oxytocin treatment caused translocation of AQP2 from the apical plasma membrane to the subapical vesicles. However, AQP2 labeling of basolateral plasma membrane was unchanged or slightly increased. CONCLUSION: Oxytocin induces an increase of AQP2 expression not only in the apical plasma membrane but also in the basolateral plasma membrane. Pretreatment with a V2R antagonist blocked redistribution of apical AQP2 immunolabeling, but did not cause retrieval of AQP2 from the basolateral plasma membrane. These results suggest that apical and basal targeting of AQP2 are regulated by different mechanisms.
Animals ; Aquaporin 2* ; Cell Membrane ; Epithelial Cells ; Humans ; Immunohistochemistry ; Kidney* ; Male ; Microscopy, Electron ; Nephrons ; Oxytocin* ; Rats* ; Rats, Sprague-Dawley ; Receptors, Vasopressin ; Water

Radioiodinated oxytocin prepared by the lactoperoxidase method exhibited a substantial biologic activity in uterotonic assay of the rat uterus. 125I-oxytocin was bound to the uterine membrane particulate fraction, but the unlabelled oxytocin did not inhibit the binding of 125I oxytocin to the membrane fraction of rat uterus. Cold iodinated oxytocin, however, inhibited the 125I-oxytocin binding to the membrane fraction of rat uterus in proportion to its concentration. These results suggest that 125I-oxytocin is not a suitable radioligand for oxytocin receptor binding study.
Animal ; Binding Sites ; Cell Membrane/metabolism ; Female ; Iodine Radioisotopes/metabolism* ; Oxytocin/metabolism* ; Radioligand Assay ; Rats ; Receptors, Cell Surface/analysis* ; Uterus/metabolism*

OBJECTIVETo observe the influence of silencing Connexin43 (Cx43) expression of partial acupoints on acupuncture effect, so as to probe into the mechanism of acupuncture treatment for primary dysmenorrhea.

METHODSThe primary dysmenorrheal rat model made by oxytocin and RNA interference (RNAi) technology was used to silence the expression of Cx43 in acupoints. Fifty SD female rats were divided into five groups, a normal group (N), a model group (M), an acupuncture group (A), an acupuncture plus interference group (A+I), an acupuncture plus interference control group (A+IC). RT-PCR method was used to observe the oxytocin receptor (OTR) and vasopressin receptor (VPR) mRNA expressions in the uterus in each group. Plasma prostaglandin E2 (PGE2) and PGF2alpha levels were detected by radioimmunoassay and ELISA, respectively.

RESULTS(1) The times of writhing body (9.43 +/- 3.87 and 10.28 +/- 4.23) were significantly lower and the latency period of writhing body (12.43 +/- 3.46, 11.00 +/- 3.65) were longer in the group A and the group A+IC as compared with (15.43 +/- 5.13, 17.00 +/- 3.87) and (7.57 +/- 1.99, 8.43 +/- 2.57) in the group M and group A+I (P < 0.05), respectively. (2) The levels of Cx43 mR NA level and protein expression of acupoint in the group A+I were significantly lower than those of the group N (P < 0.05). (3) OTR and VPR mRNA in the uterus in the group A and the group A+IC were significantly lower than those in the group M and the group A+I (P < 0.05), with no significant difference between the group M and the group A+I (P > 0.05). (4) As compared with the group M, PGE2 level increased and PGF2alpha level decreased in the group A and the group A+IC (P < 0.05).

CONCLUSIONSilencing Cx43 expression of partial acupoint can inhibit effectively the effect of acupuncture through decreasing OTR and VPR in endometrium of the dysmenorrheal rat and adjusting the prostaglandins (PGs) synthesis system, which possibly is one of the mechanisms of acupuncture for treatment of primary dysmenorrhea.

Acupuncture Points ; Acupuncture Therapy ; Animals ; Connexin 43 ; genetics ; metabolism ; Dinoprost ; blood ; Dinoprostone ; blood ; Dysmenorrhea ; genetics ; metabolism ; therapy ; Female ; Gene Expression ; Humans ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Oxytocin ; genetics ; metabolism ; Receptors, Vasopressin ; genetics ; metabolism ; Uterus ; metabolism