Alpha-adrenergic receptors in human myometrium: changes during pregnancy

Evaluation of Choroidal Thickness during Pregnancy and Postpartum: A Longitudinal Study

Purpose

To assess the longitudinal changes of choroidal thickness using enhanced depth imaging optical coherence tomography (EDI-OCT) during pregnancy and postpartum.

Methods

The study included 23 eyes of 23 healthy pregnant women and 23 eyes of 23 healthy nonpregnant women. Choroidal thickness was measured manually with EDI-OCT at seven locations: The fovea, 500, 1000, and 1500 μm temporal (T) from the fovea and 500, 1000, and 1500 μm nasal (N) from the fovea. Measurements were obtained at each pregnancy trimester and 6 weeks postpartum and in the follicular phase of the menstrual cycle for the control group.

Results

The mean subfoveal choroidal thickness was 410.2 ± 82.4 μm, 434.8 ± 79.6 μm, 433.5 ± 80.3 μm, and 395.0 ± 71.1 μm in the first, second, and third trimesters and 6 weeks postpartum, respectively. In all seven measured locations, statistically significant changes were noted during pregnancy and postpartum in the choroidal thickness (P < 0.001). Choroidal thickness increased from the first trimester to the second and third trimester, after which it decreased at postpartum. Choroidal thickness was greater in the pregnant group during pregnancy and postpartum compared to the control group (P < 0.001).

Conclusions

This study indicated significant change in choroidal thickness at seven locations measured with EDI-OCT throughout pregnancy and 6 weeks after delivery. We showed that 6 weeks after delivery, choroidal thickness remains significantly higher than nonpregnant subjects.

Changes in Subfoveal Choroidal Thickness During Pregnancy and After Delivery

BACKGROUND AND OBJECTIVE

This study was performed to investigate longitudinal changes in the subfoveal choroidal thickness (SFCT) during pregnancy and after delivery.

PATIENTS AND METHODS

The SFCT was measured in the first and third trimesters, shortly after delivery, and 1 month after delivery in 25 eyes of 25 women. Enhanced depth imaging optical coherence tomography was used for measurement.

RESULTS

The mean SFCT was 347 μm ± 86 μm, 329 μm ± 81 μm, 333 μm ± 81 μm, and 330 μm ± 87 μm in the first and third trimesters, shortly after delivery, and 1 month after delivery, respectively. The SFCT in the first trimester was significantly greater than that in the third trimester, shortly after delivery, and 1 month after delivery.

CONCLUSIONS

This study indicates that the SFCT is greater in the first trimester and decreases in the third trimester of pregnancy. The SFCT does not subsequently change until 1 month after delivery. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:816-821.].

Changes in choroidal thickness during pregnancy detected by enhanced depth imaging optical coherence tomography

AIM

To compare the choroidal thickness measurements of healthy pregnant women obtained in the first trimester with measurements obtained in the third trimester using enhanced depth imaging optical coherence tomography (OCT).

METHODS

54 eyes of 27 healthy pregnant women and 50 eyes of 25 age matched healthy women were enrolled in this observational, cross-sectional study. The pregnant women underwent two OCT scans, one in the first trimester at gestational weeks 6-8, and the other during the third trimester at gestational weeks 32-37; the control group had OCT scanning during the follicular phase of the menstrual cycle, using the enhanced depth imaging mode. Choroidal thicknesses were measured at the fovea, at three locations nasal, and at three locations temporal to the fovea at 500 μm intervals.

RESULTS

The choroidal thickness measurements obtained in the third trimester were significantly decreased in all measured points in both eyes compared to the measurements obtained in the first trimester (p<0.05). At the fovea, the mean (±SD) choroidal thickness measured in the first trimester was 349.22±82.11 μm in the right eyes and 341.30±85.22 μm in the left eyes, which decreased to 333.56±76.61 μm in the right eyes (p=0.014) and 326.93±75.84 μm in the left eyes (p=0.024) in the third trimester. Although not statistically significant, choroidal thicknesses of the control group were less than the choroidal thicknesses of the pregnant women (p>0.05).

CONCLUSIONS

Choroidal thickness was found to be significantly decreased in healthy pregnant women during the third trimester compared to the first trimester. This finding can provide valuable information when interpreting pregnancy related ocular disorders.

Sensitivity of myometrium to CGRP varies during mouse estrous cycle and in response to progesterone

Calcitonin gene-related peptide (CGRP) inhibits contractions of the myometrium. Isometric force measurements on myometrial strips were carried out to monitor the inhibitory capacity of CGRP in the myometrium during the estrous cycle and in response to estrogen and progesterone in ovariectomized mice. CGRP inhibition of KCl-induced contractions was lowest at estrus and significantly increased during metestrus and diestrus. Progesterone treatment of ovariectomized mice resulted in a significant increase in the responsiveness of the myometrium to CGRP. Expression of CGRP-receptor component protein (CGRP-RCP), a marker of CGRP-receptor expression, was quantitated by Western and Northern blot analyses. The levels of inhibition exerted by CGRP during the various stages of the estrous cycle and in response to steroid hormone treatment correlated with the protein levels of CGRP-RCP. The mRNA levels did not change significantly during the estrous cycle or in response to hormone treatment, indicating that the regulation of CGRP-RCP protein does not occur at the transcriptional level. CGRP had an inhibitory effect both when applied before the stimulus for contraction and when applied during a sustained contracture induced by KCl. This suggests that CGRP-induced generation of second messengers can influence late events in electro-/chemomechanical coupling and/or the contractile machinery directly.

Effects of menstrual cycle and race on peripheral vascular alpha-adrenergic responsiveness

Gender differences in the incidence of many cardiovascular diseases may be due to the effects of sex hormones. Both alpha(1)- and alpha(2)-adrenergic receptors produce vasoconstriction in peripheral blood vessels and have demonstrated gender effects in previous studies. In addition, race has been shown to influence the effects of some alpha-adrenergic stimuli. We therefore sought to determine the effects of the menstrual cycle and race on peripheral blood flow responses to the intra-arterial infusion of phenylephrine (alpha(1)-agonist) and clonidine (alpha(2)-agonist). Ten white and 8 black women were studied during the early luteal phase and the follicular phase; these phases were verified in each woman through measurements of plasma estradiol and progesterone. Plasma norepinephrine was measured with HPLC. During phenylephrine infusion, there was significantly greater vasoconstriction in the luteal phase versus the follicular phase (P<0.05). There were no differences (P>0.8) between white and black women. During clonidine infusion, white women showed significantly more vasoconstriction in the follicular phase than during the luteal phase (P<0.006). For black women, the responses for both phases did not differ (P>0.9). Blood pressures were significantly higher in the black women (diastolic P<0.005, systolic P<0.05). The luteal-phase elevation of alpha(1)-adrenergic responses may be due to elevated levels of estradiol, progesterone, or both. The lack of luteal-phase reduction in alpha(2)-adrenergic vasoconstriction in black women may contribute to their increased pressor responses to adrenergic stimuli.

Heterogeneity of alpha 2-adrenoceptors in human and rat myometrium and differential expression during pregnancy

1. The aim of this study was first, to characterize alpha 2-adrenoceptor subtypes in human and rat pregnant myometrium and second, to investigate the possibility of a differential expression of the putative subtypes according to the stage of pregnancy. 2. In both species, specific [3H]-rauwolscine binding was inhibited by five different compounds with an order of affinity characteristic of the one described for alpha 2-adrenoceptors (yohimbine > or = clonidine > noradrenaline > phenylephrine > propranolol). Binding affinities (pKi) for the compounds tested were, in human and rat, respectively: 7.63 and 8.93 for yohimbine, 6.91 and 8.71 for clonidine, 6.23 and 6.09 for noradrenaline, 5.37 and 5.73 for phenylephrine, 4.64 and 4.72 for propranolol. 3. By use of non-linear iterative curve fitting procedures and by fitting the data to a two-site model, analysis of [3H]-rauwolscine inhibition binding curves performed in the presence of oxymetazoline (alpha 2A-selective), ARC239, prazosin or chlorpromazine (alpha 2B- and alpha 2C-selective) indicated that pregnant human and rat myometrium contain at least two pharmacologically distinct alpha 2-adrenoceptor subtypes (alpha 2A, alpha 2B and/or alpha 2C). RNA blot analysis with probes specific for each cloned human and rat alpha 2-adrenoceptor subtype demonstrated that alpha 2A- and alpha 2B-subtypes were present in both species but alpha 2C seems to be expressed only in human tissues. 4. In the pregnant rat myometrium, subtype selective compounds competition curves revealed a predominant expression of alpha 2A-adrenoceptors at mid-pregnancy whereas, at term, alpha 2A- and alpha 2B-subtypes density reached approximately the same level (alpha 2A:alpha 2B ratio = 73:27 at mid-pregnancy and = 43:57 at term). In addition, quantification of alpha 2A- and alpha 2B-transcripts by densitometry, following data normalization with an oligo(dT)12-18 probe, showed a pattern of expression comparable to the one characterized by pharmacological studies. 5. In conclusion, these data demonstrate heterogeneity of alpha 2-adrenoceptors in pregnant human and rat myometria and an alteration of the alpha 2A-/alpha 2B-subtypes expression pattern during rat pregnancy. Such observations lead us to suggest a multiple role for alpha 2-adrenoceptors in regulating specific functions of myometrium throughout the time course of pregnancy.

Longitudinal study of beta- and alpha-adrenergic receptor properties during human pregnancy

OBJECTIVE

Our goal was to ascertain whether alterations in beta- and alpha-adrenergic receptor number and function (cyclic adenosine monophosphate production) occur during and after pregnancy. Because the actions of beta- and alpha2-adrenergic receptors tend to oppose each other, we hypothesized that there might be progressive, possibly reciprocal changes in these receptors during and after pregnancy.

STUDY DESIGN

Blood was obtained from 21 women at 10, 20, 30, and 37 weeks of pregnancy and 3 to 4 months post partum. Lymphocyte beta- and platelet alpha2-adrenergic receptor number and affinity were quantified by radioligand binding studies, and receptor function was assessed by cyclic adenosine monophosphate generation assays.

RESULTS

Although there were suggestions of progressive alterations in some of the variables studied, beta- and alpha2-adrenergic receptor number, affinity, and function did not manifest any statistically significant changes.

CONCLUSION

Pregnancy did not produce marked alterations in beta-adrenergic receptor or alpha2-adrenergic receptor properties.

Effect of cesarean delivery on perioperative regulation of the beta-adrenergic receptor system of human lymphocytes

We studied the perioperative regulation of the beta-adrenergic receptor (beta AR) system in lymphocytes obtained before and after surgery from 12 patients undergoing cesarean delivery with spinal anesthesia. Receptor number (Bmax) and binding affinity (KD) were determined by Scatchard analysis of [125I]iodopindolol saturation binding curves. Receptor function was assessed by measuring cyclic adenosine 3',5'-monophosphate (cAMP) production in the unstimulated state and in response to stimulation by isoproterenol, forskolin, and prostaglandin E1. Basal cAMP production increased 48% postoperatively (P < 0.05), while stimulated cAMP production and Bmax and KD were not significantly changed after surgery. The response to surgery of the beta AR system on these patients differed from that of patients undergoing cardiothoracic and abdominal surgery in whom we previously found postoperative down-regulation and desensitization of the beta AR system. It is possible that this difference in response is due to amelioration of the stress response to surgery by regional anesthesia, and/or alterations in beta AR status by pregnancy. We conclude that pregnancy and regional anesthesia, but not changes in lymphocyte subset distribution, contributed to the lack of effect of surgery on the beta AR system in the patients studied.