|
KMID : 0360419830190010037
|
|
Korean Journal of Pharmacology
1983 Volume.19 No. 1 p.37 ~ p.60
|
|
|
Experimental Studies on Uterine Catecholamines
|
|
|
|
|
Abstract
|
|
|
The ateras receives adrenergic terminals from the mesenteric ganglia and considerably large amounts of catecholamines have been shown to be contained in this organ. On the other haul, the activities of epinephrine, norepinephrine or adrenergic nerve on uterine motility is so complicated that many controversial results have been reported. Recently, a large number of reports concerning the changes of uterine catecholamines content have appeared, but little is known about the role of uterine catecholamines in their activities on uterine motility. The present experiments ware undertaken to determine the significance of the intrinsic uterine catecholamines in the physiology of uterus.
Female albino rabbits weighing approximately 2 kg were employed in this experiment. Uterine strips were prepared and suspended in a constant temperature bath(38°C) containing 10j ml of Locke´s solution aerated with 95% oxygen and 5% carbon dioxide. Spontaneous motility was recorded on a smoked drum with an isotonic lever. The catecholamines concentration of the uterus was determined according to the procedure described by Shore and Olin (1958). Human uterus obtained from patients was also used to determine the catecholamines content of myometrium.
Followings are summarized results.
1) On the non-pregnant rabbit uterine strips, epinephrine and norepinephrine significantly elevated the tonus and stimulated the spontaneous motility. Pretreatment with dichloroisoproterenol(DCl), an adrenergic beta-receptor blocker, enhanced the stimulatory activity of epinephrine or norepinephrine. On the other hand, pretreatment with dibenamine, an adrenergic alpha-receptor blocker, rendered the uterine muscle to exhibit inhibition after the administration of epinephrine or norepinephrine. Following the treatment with both DCI and dibenamine, epinephrine or norepinephrine produced no appreciable effects on the spontaneous motility of the uterus. These results suggest there exist both alpha and beta-adrenergic receptors in the uterine muscle and the response to epinephrine of the former is predominant over that of latter in the non-pregnant uterus of rabbits.
The total catecholamines concentration of the non-pregnant uterus was 351 mpg/g and
the fractional concentrations of epinephrine and norepinephrine were 1.25 mug/g(35.7%) and 226 mpg/g respectively. It is interesting to note that the catecholamines content of uterus was characterized by a high fractional concentration of epinephrine relative to norepinephrine.
2) On the pregnant rabbit uterine strips, the effects of epinephrine and norepinephrine varied according to the period of pregnancy. The response to epinephrine of adrenergic beta receptor of uterus increased during pregnancy, and the effect of catecholamine was inhibitory in the early pregnancy but became stimulatory as the pregnancy progressed. This stimulating action on the uterine motility was found to occur through the action of norepinepbrine.
The uterine catecholamines concentration was markedly reduced during pregnancy. The catecholamines concentration was started to decrease in the early pregnancy, reached the lowest level in the mid-pregnancy and then started to increase again in the late pregnancy when the total catecholamines content became the highest level of all. This increase of catecholamines in late pregnancy was chiefly due to the increase of norepinephrine. These results suggest that the uterine motility may be related to the catecholamines content, especially norepinephrine content in the uterus.
3) Bilateral oophorectomy of rabbits results in a marked shrink of the uterus in size. The spontaneous motility of the uterine segment of these animals was very weak and irregular. Norepinephrine produced inhibitory effect, whereas epinephrine was stimulatory or inhibitory effect on the uterine segment. The total catecholamines content in whole uterus was markedly reduced. The injection of estrogen into the oophorectomized rabbit increased the weight of uterus to approximately three times of that of oophorectomized animal. The spontaneous motility and the response to epinephrine and norepinephrine of the uterine segment were greatly enhanced. Both epinephrine and norepinephrine produced a marked stimulatory effects of the uterine motility. The uterine content of catecholamines, particularly epinephrine, was markedly increased. The injection of progesterone into the cophorectomized rabbit increased the weight of uterus to approximately 2.5 times of that of oophorectomized animal. The spontaneous motility of the uterine segment was weak and irregular. Epinephrine produced stimulatory effect at high concentrations but norepinephrine always produced inhibitory effect on the uterine segment. The uterine content of catecholamines, particularly of norepinephrine, was markedly reduced.
These results suggested that ovarian hormones play an important role not only on the growth and spontaneous motility of uterus but also on the catecholamines content and response to epinephrine and norepinephrine of the uterus.
4) The intraperitoneal injection of reserpine(3 mg/kg) into the non-pregnant, pregnant and oophorectomized rabbits markedly decreased the uterine content of catecholamines, particularly of the norepinephrine. The stimulatory response to epinephrine and, norepinephrine of the uterine segment of these reserpinized rabbits was markedly reduced whereas the inhibitory response to these catecholamines was enhanced. This finding further support the close relationship between the uterine catecholamines content and uterine response to epinephrine and norepinephrine.
5) In the human uterus, the concentration of epinephrine was actually greater than that of norepinephrine and it was significantly greater during the proliferative phase of the menstrual cycle. In the human pregnant uterus, the concentrations of both epinephrine and ncrepinephrine were markedly reduced and showed about 45 percent reduction after 6-8 weeks of ectopic pregnancy. At full term and during labor, the concentrations of epinephrine arid norepinephrine at placental sites were less than those found in the non-pregnant group. Of interest was the finding that the norepinephrine concentration of uterus uterine segment from toxemic patients was two and half times higher than that of lower of the nontoxemic pregnant individuals. Also the epinephrine concentration was slightly increased.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
Listed journal information
|
|
|
|