Use of antisense oligonucleotides to verify the role of the alpha(1A)-adrenergic receptor in the contractility of the rat uterus post partum

The Use of Medical Expulsive Therapy During Pregnancy: A Worldwide Perspective Among Experts

INTRODUCTION

Medical expulsive therapy (MET) is a pharmacologic approach thought to augment the spontaneous passage of ureteral calculi. The usage of MET pharmacologics for presumed ureteral calculi during pregnancy has not been studied and their safety and utility are unknown. We sought to characterize the worldwide usage of MET in the setting of pregnancy with presumed ureteral calculus (P-MET), as well as factors associated with physician use. Experts in stone management were specifically sought.

MATERIALS AND METHODS

A nine-question survey was delivered through society-administered e-mail. Questions gathered physician's worldwide region, degree of specialization in stone disease, practice type, interval since training, and willingness to use both MET and P-MET. We assessed drugs of choice in those using P-MET and reasons for avoidance in non-P-MET users. Finally, we assessed the impact of physician-perceived medicolegal risk on usage of P-MET.

RESULTS

Five hundred sixty-five responses were recorded. Sixty-three percent were US-based practitioners and the remaining represented a worldwide distribution. Worldwide usage of MET was 97.6%, and tamsulosin was globally preferred by over 90% of urologists. P-MET was endorsed by only 44.3%. 23.6% of European practitioners used this strategy compared with 51.1% of US physicians. Time from training and practice type did not significantly interact with adoption of P-MET; experts were less likely to use P-MET. Physician nonuse of MET during pregnancy was adverse outcome related: 76.7% reported either the fear of legal risk (52.8%) or concerns about safety (23.9%).

CONCLUSION

Respondents report impressive worldwide adoption of MET. P-MET is less trusted, and fears of legal risk and safety far outweigh questions about effectiveness. The effectiveness of drugs during pregnancy-induced ureteral dilation is unknown. Still, 44% of global respondents embrace usage of this drug strategy despite a paucity of evidence supporting either safety or effectiveness during pregnancy.

Calcium influx and release mechanism(s) in histamine-induced myometrial contraction in buffaloes

The present study was undertaken to characterize the presence of histamine H1R using molecular biology tools and unravel the influx and release mechanism(s) involved in calcium signalling cascades in histamine-induced myometrial contraction in buffaloes. The presence of H1R mRNA transcript and immunoreactive membrane protein in buffalo myometrium was confirmed by RT-PCR and Western blot analysis. Further, histamine produced concentration-dependent (1nM-10μM) contraction in buffalo myometrium with a potency of 7.13±0.11. When myometrial strips were pre-incubated either with Ca(2+) free solution or with nifedipine, a L-type Ca(2+) channel blocker, dose response curve (DRC) of histamine was significantly (P<0.05) shifted towards right with decline in maximal contraction (Emax). Reduction in Emax of histamine in the presence of nifedipine (55.75±3.10%) was significantly (P<0.001) greater than that in the presence of ruthenium red (93.61±3.43%), a blocker of IP3-gated and RyR-sensitive Ca(2+) channels. Moreover, histamine produced only 26.87±1.99% of the maximum contraction in the presence of both nifedipine and CPA (blocker of sarco-endoplasmic reticulum Ca(2+)-ATPase). Interestingly, following concurrent exposure to U-73122 (a PL-C inhibitor) and nifedipine, the DRC of histamine was significantly (P<0.05) shifted towards left with increase in maximal contraction (126.30±3.36%). Our findings in buffalo uterus thus suggest that influx of extracellular calcium plays a major role in histamine-induced myometrial contraction, while release of intracellular calcium through calcium-release channels of sarcoplasmic reticulum has a minor role. A possible involvement of non-selective cation channels in histamine-induced myometrial contraction cannot be ruled out, and therefore requires further investigations.

Changes in global gene expression in rat myometrium in transition from late pregnancy to parturition

The process of parturition involves the complex interplay of factors that change the excitability and contractile activity of the uterus. We have compared the relative gene expression profile of myometrium from rats before parturition (21 days pregnant) and during delivery, using high-density DNA microarray. Of 8,740 sequences available in the array, a total of 3,782 were detected as present. From the sequences that were significantly altered, 59 genes were upregulated and 82 genes were downregulated. We were able to detect changes in genes described to have altered expression level at term, including connexin 43 and 26, cyclooxygenase 2, and oxytocin receptor, as well as novel genes that have been not previously associated with parturition. Quantitative real-time PCR on selected genes further confirmed the microarray data. Here we report for the first time that aquaporin5 (AQP5), a member of the aquaporin water channel family, was dramatically downregulated during parturition (approximately 100-fold by microarray and approximately 50-fold by real-time PCR). The emerging profile highlights biochemical cascades occurring in a period of approximately 36 h that trigger parturition and the initiation of myometrium reverse remodeling postpartum. The microarray analysis uncovered genes that were previously suspected to play a role in parturition. This regulation involves genes from immune/inflammatory response, steroid/lipid metabolism, calcium homeostasis, cell volume regulation, cell signaling, cell division, and tissue remodeling, suggesting the presence of multiple and redundant mechanisms altered in the process of birth.

EFFECT OF ?1-ADRENOCEPTOR SUBTYPE-SELECTIVE INVERSE AGONISTS ON NON-PREGNANT AND LATE-PREGNANT CERVICAL RESISTANCE IN VITRO IN THE RAT

1. The aim of the present study was to compare and elucidate the effects of alpha(1)-adrenoceptor (alpha(1)-AR) subtype-selective inverse agonists on non-pregnant and late-pregnant rat cervical tone. 2. Cervical resistance was investigated in in vitro stretching tests in the absence or presence of alpha(1)-AR subtype-selective inverse agonists (WB 4101, AH 11110A and BMY 7378; all at 10(-6) mol/L), whereas the mRNA levels and density of the alpha(1)-AR subtypes and the G-protein-activating effects of the inverse agonists were determined by reverse transcription-polymerase chain reaction, western blot and [(35)S]-GTPgammaS binding techniques, respectively. 3. The inverse agonists did not cause any change in resistance in non-pregnant and 18-day-pregnant samples. WB 4101 increased cervical resistance from Day 20, whereas AH 11110A had no effect and BMY 7378 exhibited such an action only on Day 21. Phenylephrine (10(-4) mol/L) had no effect on cervical resistance on Day 22. The mRNA levels and density of all alpha(1)-AR subtypes were increased on Day 18, but no further changes were observed after that. The [(35)S]-GTPgammaS binding studies revealed increased G-protein activation of alpha(1A)-AR and a moderate G-protein activation of alpha(1B)- and alpha(1D)-AR. The effect of WB 4101 to increase [(35)S]-GTPgammaS binding was blocked by pertussis toxin (50 ng/mL). Phenylephrine caused a slight and significant decrease in the amount of activated G-protein on Day 22. 4. The effects of inverse agonists on the alpha(1A)-AR can enhance cervical resistance in the late-pregnant rat in vitro. This action is mediated, at least in part, by a pertussis toxin-sensitive G(i)-protein. This effect of the alpha(1A)-AR inverse agonist WB 4101 may offer a new therapeutic target in the prevention of premature labour.

Synergism between beta 2-adrenoceptor agonists and subtype-selective alpha 1A-adrenoceptor antagonists in the tocolytic effect on pregnant rat uterus in vitro

1. Despite great efforts in recent decades, premature birth is still a leading cause of perinatal morbidity and mortality. beta2-Adrenoceptor agonists are frequently used as tocolytics, although their use is rather controversial. Previous animal studies have revealed that blockade of alpha1A-adrenoceptors results in relaxation of the pregnant rat myometrium. 2. The aim of the present study was to investigate the uterus relaxant effect of the beta2-adrenoceptor agonists (terbutaline, ritodrin) applied together with the subtype-selective alpha1A-adrenoceptor antagonists (WB 4101, 5-methylurapidil) in an in vitro rat model. The main objective of the experiments was to clarify whether there was an additive or a potentiating synergism between the two drug classes. 3. Myometrial rings were taken from female, 22-day pregnant (end-term) Sprague-Dawley rats. Electrical field stimulation (EFS) was used to elicit rhythmical contractions. Non-cumulative concentration-response curves were constructed to the beta2-adrenoceptor agonists and the alpha1A-adrenoceptor antagonists alone and to beta2-adrenoceptor agonists co-administered with the alpha1A-adrenoceptor antagonists. 4. Both groups of drugs inhibited EFS-induced contractions in a dose-dependent way. Administering the beta2-adrenoceptor agonists in combination with the alpha1A-adrenoceptor antagonists resulted in a significant decrease in the EC50 and an increase in the maximal contraction inhibiting effect. 5. The potentiating synergism that has been revealed between beta2-adrenoceptor agonists and alpha1A-adrenoceptor antagonists in the uterus relaxant effect may be of great clinical importance because it could improve the efficacy of therapy of preterm delivery.

Altered levels of mRNA expression and pharmacological reactivity of alpha1-adrenergic receptor subtypes in the late-pregnant rat myometrium

The adrenergic system plays a major role in the regulation of the uterine contractility during pregnancy. Our previous studies have shown the significance of the alpha1-adrenergic receptors (ARs) in the control of pregnant uterine contractility both in vitro and in vivo. Our present aim was to determine the changes in mRNA expression and pharmacological reactivity of the alpha1-ARs on days 18, 20, and 22 of pregnancy. To demonstrate the expressions of alpha1-AR subtype mRNA, we used a reverse transcription-polymerase chain reaction (RT-PCR); the pharmacological reactivity was tested by electric field stimulation (EFS). The expression of alpha1A-AR mRNA increased from day 18 to 22, while no alpha1B-AR mRNA was detectable. We found a small increase in the expression of alpha1D-AR mRNA on day 20, which was not followed by a significant change in pharmacological reactivity. The alpha1D-receptor expression and pharmacological reactivity decreased significantly up to day 22. EFS studies revealed that the alpha1A-AR antagonist 5-methylurapidil had EC50 values (1.9 x 10(-6)-6.3 x 10(-6) M) about one order of magnitude lower than those of the alpha1D-AR antagonist BMY 7378 (4 x 10(-6)-3.6 x 10(-5) M). However, the alpha1B-AR antagonist cyclazosine exerted only a slight effect on the stimulated contractions. Strong correlations were found between the alpha1A-mRNA expression and the EC50 of 5-methylurapidil (r(2) =0.9712), and between the alpha1D-AR mRNA expression and the EC50 of BMY 7378 (r(2) = 0.9937). Our findings suggest that both alpha1A- and alpha1D-ARs are involved in the regulation of the pregnant uterine contractility. The density and pharmacological reactivity indicate that the alpha(1A)-AR seems to play the major role in late-pregnant myometrial contraction.

Antisense inhibition of myoD expression in regenerating rat soleus muscle is followed by an increase in the mRNA levels of myoD, myf-5 and myogenin and by a retarded regeneration

It has been reported that muscles of myoD-/- mice present a lower potential to regenerate, but there are no reports on the effect of acute interference with myoD expression limited in space and time to only a particular regenerating muscle. Here we relied on antisense inhibition of this factor. Four different oligos were tested. The suppression of regeneration indices (the expression of desmin, the formation of myotubes and the initiation of endplates) was the most pronounced, with the oligomer targeting a region encompassing the translation start site of myoD. A mixed backbone phosphorothioate-phosphate diester oligo (200 microl at 20 microM) was still detectable in the muscles 1 h after its administration and reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the level of the targeted 5' end of the myoD mRNA was selectively decreased. The level of myoD protein was also lowered. Four hours after the antisense treatment, when the oligos were no longer detectable, the myoD mRNA level was restored and 24 h later it exceeded controls together with that of myf-5 and myogenin. After 4 weeks, the antisense-treated soleus muscles were similar to the control-treated and the untreated regenerated soleus with respect to fiber types and motor endplates, however, they contained smaller fibers which reflected the asynchronity of regeneration. This shows that successfully targeted simple antisense oligonucleotides can be used as selective tools for inhibition of individual factors in studying the process of muscle regeneration.