oxytocin and Ischemia

Topics: Administration, Oral; Adrenocorticotropic Hormone; Angiotensin II; Animals; Estrogens; Female; Fetus; Homeostasis; Humans; Hydrocortisone; Ischemia; Labor, Induced; Labor, Obstetric; Oxytocin; Placenta; Pre-Eclampsia; Pregnancy; Progesterone; Prostaglandins; Renin; Structure-Activity Relationship

Oxytocin treatment in rats induces long-lasting antistress and growth promoting effects. This study investigated whether prolyl-leucyl-glycinamide (PLG) (the c-terminal tripeptide of oxytocin) or tocinoic acid (the ring structure of oxytocin) could induce some of these effects in male rats. For this purpose, PLG (2 or 10 mg/kg, s.c.) or tocinoic acid (1 mg/kg, s.c.) was administered to rats once a day for 3 or 5 days. Blood pressure, heart rate, spontaneous motor activity, nociceptive thresholds, and the survival of ischaemic musculocutaneous flaps were measured. In addition, endogenous oxytocin levels and plasma levels of some hormones known to be influenced by oxytocin were determined. PLG (2 mg/kg, s.c., but not 10 mg/kg, s.c.) decreased diastolic blood pressure (p<0.05) and locomotor activity (p<0.05). PLG (10 mg/kg, s.c.) decreased gastrin (p<0.05) and endogenous oxytocin levels in plasma (p<0.01). Tocinoic acid decreased locomotor activity (p<0.05), but did not affect any of the other parameters measured. In conclusion, this study showed that both PLG and tocinoic acid decrease locomotor activity. In addition, PLG also induced some other effects similar to those induced by oxytocin treatment but when administered in high doses it decreased oxytocin levels.

Topics: Animals; Behavior, Animal; Blood Pressure; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Interactions; Gastrins; Heart Rate; Ischemia; Male; Motor Activity; MSH Release-Inhibiting Hormone; Oxytocin; Pain Threshold; Rats; Rats, Sprague-Dawley; Surgical Flaps

This hypothesis proposes that carcinogens in the breast are generated by the action of superoxide free radicals released when acinal gland distension, under the influence of unopposed prolactin, causes microvessel ischaemia. Inadequate nipple care in the at-risk years leads to ductal obstruction preventing the elimination of carcinogens from the breast. The regular production of oxytocin (OT) from nipple stimulation would cause contraction of the myoepithelial cells, relieving acinal gland distension and aiding the active elimination of carcinogenic fluid from the breast. Mechanical breast pump stimulation causes an increase in plasma OT levels in the luteal but not in the follicular phase of the menstrual cycle. OT production upon nipple stimulation in the luteal phase of premenopausal, non-lactating women may be protective against the high rates of mitotic breast cell division noted at this time via the potential to block the effect of oestrogen. The epidemiology of breast cancer suggests that lengthy lactation time is beneficial. Sexual activity in nulliparous women also protects and OT levels have been shown to rise with orgasm in women and in men. OT systems in the brain are intricately linked to oestrogen and progesterone levels, and it is possible that these hormones may modify the OT secretory response both centrally and through an effect on the sensitivity of the breast. OT production with nipple care and in sex and lactation, and the reduction in cycling ovarian hormones that occurs with pregnancy, may all be important preventative factors in the development of breast cancer both pre- and post-menopausally.

Topics: Breast Neoplasms; Female; Humans; Ischemia; Lactation; Menstrual Cycle; Microcirculation; Models, Biological; Nipples; Oxytocin; Prolactin; Sex; Superoxides

Topics: Amniotic Fluid; Angiotensin II; Animals; Dogs; Female; Humans; Hypotension; Ischemia; Kidney; Nephrectomy; Norepinephrine; Oxytocin; Pre-Eclampsia; Pregnancy; Rabbits; Renin; Sodium; Uterus

Topics: Anesthetics, Local; Blood Pressure; Epinephrine; Felypressin; Hemostasis; Humans; Ischemia; Nausea; Otorhinolaryngologic Diseases; Oxytocin; Pulse; Tachycardia; Vasoconstrictor Agents; Vasopressins

Topics: Abruptio Placentae; Castration; Estradiol; Estrogens; Female; Humans; Ischemia; Kidney; Kidney Cortex Necrosis; Kidney Diseases; Necrosis; Ovary; Oxytocin; Pharmacology; Pregnancy; Pregnancy, Animal; Progesterone; Rats; Research; Toxicology