Progesterone withdrawal effects in the open field test can be predicted by elevated plus maze performance

Allopregnanolone (3alpha-hydroxy-5alpha-pregnane-20-one) is a ring-A-reduced metabolite of progesterone, which is naturally produced during the luteal phase of the menstrual cycle, during pregnancy and by stressful events. The steroid hormone inhibits neural functions through increased chloride ion flux through the GABA(A) receptor. The effects and subsequent withdrawal symptoms are similar to those caused by alcohol, benzodiazepines and barbiturates. This study examined the withdrawal effects of progesterone with regards to the influence of individual baseline exploration and risk taking. Rats were tested on the elevated plus maze (EPM) before hormonal treatment, in order to evaluate differences in risk taking and exploration of open and elevated areas. Treatment consisted of ten consecutive once a day progesterone or vehicle s.c. injections. On the last day of treatment, estradiol was injected in addition to progesterone, followed by a 24-h withdrawal before testing in the open field test (OF). Progesterone-treated rats showed a withdrawal effect of open area avoidance in the OF. The vehicle-treated control rats showed strong correlations between the EPM and OF parameters. This relationship was not found for the progesterone group at withdrawal. Rats with greater numbers of open arm entrance in the EPM pretest showed an increased sensitivity to progesterone withdrawal (PWD) compared to rats with low exploration and risk taking. The results indicate that the effects of PWD relate to individual exploration and risk taking. Furthermore, the possible analogy of PWD and PMS/PMDD in relation to individual traits is discussed.

Tolerance development to Morris water maze test impairments induced by acute allopregnanolone

The progesterone metabolite allopregnanolone, like benzodiazepines, reduces learning and impairs memory in rats. Both substances act as GABA agonists at the GABA-A receptor and impair the performance in the Morris water maze test. Women are during the menstrual cycle, pregnancy, and during hormone replacement therapy exposed to allopregnanolone or allopregnanolone-like substances for extended periods. Long-term benzodiazepine treatment can cause tolerance against benzodiazepine-induced learning impairments. In this study we evaluated whether a corresponding allopregnanolone tolerance develops in rats. Adult male Wistar rats were pretreated for 3 days with i.v. allopregnanolone injections (2 mg/kg) one or two times a day, or for 7 days with allopregnanolone injections 20 mg/kg intraperitoneally, twice a day. Thereafter the rats were tested in the Morris water maze for 5 days and compared with relevant controls. Rats pretreated with allopregnanolone twice a day had decreased escape latency, path length and thigmotaxis compared with the acute allopregnanolone group that was pretreated with vehicle. Pretreatment for 7 days resulted in learning of the platform position. However, the memory of the platform position was in these tolerant rats not as strong as in controls only given vehicle. Allopregnanolone treatment was therefore seen to induce a partial tolerance against acute allopregnanolone effects in the Morris water maze.

Neuroactive steroid effects on cognitive functions with a focus on the serotonin and GABA systems

This article will review neuroactive steroid effects on serotonin and GABA systems, along with the subsequent effects on cognitive functions. Neurosteroids (such as estrogen, progesterone, and allopregnanolone) are synthesized in the central and peripheral nervous system, in addition to other tissues. They are involved in the regulation of mood and memory, in premenstrual syndrome, and mood changes related to hormone replacement therapy, as well as postnatal and major depression, anxiety disorders, and Alzheimer's disease. Estrogen and progesterone have their respective hormone receptors, whereas allopregnanolone acts via the GABA(A) receptor. The action of estrogen and progesterone can be direct genomic, indirect genomic, or non-genomic, also influencing several neurotransmitter systems, such as the serotonin and GABA systems. Estrogen alone, or in combination with antidepressant drugs affecting the serotonin system, has been related to improved mood and well being. In contrast, progesterone can have negative effects on mood and memory. Estrogen alone, or in combination with progesterone, affects the brain serotonin system differently in different parts of the brain, which can at least partly explain the opposite effects on mood of those hormones. Many of the progesterone effects in the brain are mediated by its metabolite allopregnanolone. Allopregnanolone, by changing GABA(A) receptor expression or sensitivity, is involved in premenstrual mood changes; and it also induces cognitive deficits, such as spatial-learning impairment. We have shown that the 3beta-hydroxypregnane steroid UC1011 can inhibit allopregnanolone-induced learning impairment and chloride uptake potentiation in vitro and in vivo. It would be important to find a substance that antagonizes allopregnanolone-induced adverse effects.

Early interdisciplinary rehabilitation programme for whiplash associated disorders

PURPOSE

To assess the clinical outcomes of a multidisciplinary rehabilitation programme for early intervention of chronic whiplash associated disorders (WAD). The primary aim of the programme was to increase levels of activity and independence in patients suffering WAD.

METHODS

Ninety subjects with purported chronic symptoms associated with whiplash associated disorder (WAD) were referred to a multi-centre multi-modal 5- and 8-week rehabilitation programme in 1997-1998, during which prospective and retrospective functional and psychological evaluations were conducted, the follow-up was to 6 months.

RESULTS

Subjects indicated they were satisfied with the programme. Retrospective evaluation indicated increased ability to cope with and control pain and, to some extent, psychological aspects. The pain intensity in the neck and upper back were significantly decreased at 6 months follow-up. However, for most of the functional and psychological markers, no significant changes were found.

CONCLUSIONS

A multi-modal rehabilitation programme for the chronic suffering attributed to WAD had positive effects according to several aspects of the retrospective evaluations, but according to most of the aspects evaluated prospectively the programme does not appear to have significant benefits.

Rock matrix diffusivity determinations by in-situ electrical conductivity measurements

A fast method to determine rock matrix diffusion properties directly in the bedrock would be valuable in the investigation of a possible site for disposal of nuclear waste. An "effective diffusivity borehole log" would provide important information on the variability of this entity over the area studied. As opposed to traditional matrix diffusion laboratory experiments, electrical conductivity measurements are fast, inexpensive and also easy to carry out in-situ. In this study, electrical resistivity data from borehole logging, as well as from measurements on the actual core, is evaluated with the purpose of extracting matrix diffusivity data. The influence of migration of ions in the electrical double layer, which can be of great importance in low ionic strength pore water, is also considered in evaluating the in-situ data to accurately determine the effective pore diffusivity. The in-situ data compare fairly well to those measured in the rock core.

Perinatal changes in expression of aquaporin-4 and other water and ion transporters in rat lung

1. At birth, rapid removal of lung liquid from potential airspaces is required to establish pulmonary gas exchange. To investigate the role for water channels, aquaporins (AQP) and ion transporters in this process, the mRNA expression of AQP, Na+,K(+)-ATPase and the amiloride-sensitive Na+ channel (ENaC) were studied in the fetal and postnatal rat lung. 2. The mRNA expression of all transporters studied increased postnatally. 3. The following water channels were expressed in the lung, AQP1, 4 and 5. The most specific perinatal induction pattern was observed for AQP4. A sharp and transient increase of AQP4 mRNA occurred just after birth coinciding with the time course for clearance of lung liquid. This transient induction of AQP4 mRNA at birth was lung-tissue specific. Around birth there was a moderate increase in AQP1 mRNA, which was not transient. AQP5 increased continuously until adulthood. 4. Fetal lung AQP4 mRNA was induced by both beta-adrenergic agonists and glucocorticoid hormone, which are factors that have been suggested to accelerate the clearance of lung liquid. 5. Immunocytochemistry revealed that AQP4 was located in the basolateral membranes of bronchial epithelia in newborn rats, consistent with the view that this is the major site for perinatal lung liquid absorption. 6. The Na+,K(+)-ATPase alpha 1 subunit and ENaC alpha-subunit mRNA also increased around birth, suggesting that they co-operatively facilitate lung liquid clearance at birth. 7. These data indicate that removal of lung liquid at birth is associated with pronounced and well-synchronized changes in the expression of AQP and the ion transporters studied. The transient perinatal induction of AQP4, which could be prenatally induced by beta-adrenergic agonists, and the localization of this water channel strongly suggest that it plays a critical role for removal of lung liquid at the time of birth.

High progesterone is related to effective human labor. Study of serum progesterone and 5alpha-pregnane-3,20-dione in normal and abnormal deliveries

BACKGROUND

The role of progesterone levels during human labor is unclear.

OBJECTIVE

To investigate serum concentrations of progesterone and 5alpha-pregnane-3,20-dione in normal and abnormal deliveries.

METHODS

Venous and umbilical cord serum samples were collected from 108 parturient women. In a further 49 deliveries, arterial and venous umbilical cord sera were collected separately. The concentrations of progesterone and 5alpha-pregnane-3,20-dione were determined by radioimmunoassay. The delivery modes studied were: elective cesarean section; oxytocin-resistant dystocia; normal but induced delivery, and normal spontaneous delivery.

RESULTS

Progesterone concentrations in maternal and umbilical serum were higher following normal labor than after dystocia (p<0.005) and elective cesarean section (p<0.005). The maternal and umbilical progesterone concentrations in dystocia and elective cesarean section were between 77-43% of those in normal labor. The concentrations did not vary between gestational weeks 37 and 42, within the different modes of delivery. The 5alpha-pregnane-3,20-dione serum concentration in the fetal compartment was twice that in the maternal compartment (p<0.001); its concentration in venous umbilical serum was higher than in corresponding arterial samples (p<0.001). No distinct differences in the 5alpha-pregnane-3,20-dione serum concentration were found with regard to parity or mode of delivery.

CONCLUSION

High progesterone concentrations during parturition appear to be related to effective labor. The findings support results from in vitro experiments on human term myometrium.

Self-marking in written examination: a way of feedback and learning

A new form of written examination, involving self- and teacher assessment, immediate feedback and discussion time with the course leader has been tried and evaluated at seven undergraduate courses in obstetrics and gynaecology at Umeå University, Sweden. Out of 112 students (59 women, 53 men), 101 (90%) rated this method as a better or far better learning situation than the traditional written examination. Twenty-seven (24%) students regarded the examination to be equal to, and 78 students (70%) thought it better or far better than, the conventional assessment as method to check the knowledge. According to the students, the method of self-marking increases the fairness of the examination and reduces the chances of cheating. No significant differences related to gender, age or test results were found. The examination time required of students was the same as with the traditional method, while the amount of time required of teachers was reduced.

Continuous progesterone exposure associated with high contraction frequency in human term myometrial strips

It has been shown that progesterone slightly reduced the work of human term myometrial strips. In vitro, 5 alpha-pregnane-3,20-dione and 3 alpha-hydroxy-5 alpha-pregnan-20-one, two major extra-hepatic metabolites of progesterone, had only minor effects or none at all. The myometrial strips were stored and superfused in a progestin-free buffer until the onset of contractions when progestin superfusion was commenced. In vivo, the human myometrium is never deprived of the influence of these steroids, either prior to or during labor. In the present investigation we studied whether progesterone and the two named progesterone metabolites would have a different effect when the myometrial strips were not deprived of steroid. Muscle biopsy samples from the lower uterine segment were immediately placed and stored in buffer containing progesterone, 5 alpha-pregnane-3,20-dione, or 3 alpha-hydroxy-5 alpha-pregnan-20-one. The strips were then bisected; one half was superfused with progestin buffer, and the other half with plain buffer to serve for control purposes. In strips continuously exposed to progesterone, the onset of contractions was delayed, compared with their progesterone-depleted controls. This was as expected, according to current opinion regarding progesterone and parturition. Once muscular contractions were established, the contraction frequency was significantly higher, due to a shorter muscular relaxation time, in the progesterone-superfused strips than in the controls and strips treated with progesterone metabolite superfusion. This was unexpected and can be interpreted as if continuous presence of progesterone facilitates human myometrial contraction frequency once contractions have started. Conversely, the 5 alpha-progesterone metabolites showed no effect or minor effects.

Antitachyphylactic effects of progesterone and oxytocin on term human myometrial contractile activity in vitro

OBJECTIVE

To determine whether progesterone causes any changes in the action of oxytocin on the contractile activity of term human myometrium in vitro.

METHODS

Myometrial biopsies from 13 term pregnant women undergoing cesarean delivery were immediately immersed in Hepes buffer or buffer containing 5 micrograms/mL progesterone. In the laboratory under a stereomicroscope, the specimens were dissected into 1 x 7.5-mm muscle strips. These were mounted into six tissue baths and superfused with Hepes buffer and buffer containing 5 micrograms/mL progesterone, 5 micrograms/mL progesterone plus 10 microU/mL oxytocin, 5 micrograms/mL progesterone plus 100 microU/mL oxytocin, 10 microU/mL oxytocin, and 100 microU/mL oxytocin. Isometric tension was recorded constantly for at least 3 hours.

RESULTS

The frequency of myometrial contractions and tonus increased by superfusion with progesterone, progesterone plus oxytocin, and oxytocin alone compared to buffer. In addition, a gradual decrease in frequency was observed after 60 minutes of contractions with oxytocin alone, whereas progesterone plus oxytocin had no such decrease. The activity area of contractions was greater with 10 microU/mL oxytocin and decreased with progesterone, progesterone plus both concentrations of oxytocin, and 100 microU/mL oxytocin alone, compared to buffer.

CONCLUSIONS

Progesterone stimulated the frequency of contractions and tonus of strips from the lower uterine segment of term human myometrium. A lasting increase in the frequency of contractions was observed with superfusion of progesterone plus oxytocin, suggesting that progesterone counteracted the reaction of tachyphylaxis to oxytocin.

Unexpected stimulatory effect of progesterone on human myometrial contractile activity in vitro

OBJECTIVE

To investigate the effects of continuous exposure of progesterone on contractile activity of term human myometrium in vitro.

METHODS

Myometrial biopsy specimens were obtained from 14 term pregnant women undergoing elective cesarean. The specimens were immediately immersed in Hepes buffer and buffer containing 0.33, 4.1, and 70 micrograms/mL progesterone. Muscle biopsies were dissected along the bundles of smooth muscle under stereomicroscope. These myometrial strips were mounted in tissue baths and superfused with Hepes buffer and buffer containing different concentrations of progesterone.

RESULTS

The progesterone concentration of 0.33 microgram/mL had no significant effect on myometrial contractile activity. The concentrations of 4.1 and 70 micrograms/mL increased the frequency of contractions (P < .01 for each) and tonus (P < .01 for each), decreased the activity area of contractions (P < .01 for each), and delayed the onset of contractions (P < .01 and P < .05, respectively).

CONCLUSION

When the myometrium is not deprived of progesterone, this hormone may have excitatory effects on the frequency of contractions and tonus of the lower uterine segment of term human myometrium.

Some quantitative considerations about DNA adduct enrichment procedures for 32P-postlabelling

The concentrations of 2'-deoxyribonucleoside-3'-monophosphates remaining in calf-thymus DNA digests after nuclease P1 digestion or extraction into 1-butanol, the most commonly used adduct enrichment procedures prior to the application of the 32P-postlabelling assay, were measured using HPLC and 32P-postlabelling methods. When 10 micrograms of DNA digested to mononucleotides was used, the total amount of nucleotides remaining in the samples were approximately 4 and approximately 14 pmol after nuclease P1 treatment or 1-butanol extraction respectively. The influence of various concentrations of normal nucleotides on the labelling efficiency of a 2'-deoxyguanosine-3'-monophosphate adduct of benzo[a]pyrene diol-epoxide was also studied and found to depend upon the ratio of normal nucleotides/adducted nucleotides present in the sample. Also, the ATP/normal nucleotides ratio in the phosphorylation reaction may affect the quantitation of the adducts and thus deserves due consideration.

Progesterone concentrations in maternal and fetal serum are lower during functional dystocia than in normal labor

Concentrations of progesterone and estradiol (E2) were measured in parturient serum and in fetal cord serum during normal labor and in women with functional dystocia. In the study group, there were no cases of cephalopelvic disproportion. In oxytocin-resistant dystocia, the course of labor could not be corrected with oxytocin. To ascertain the effect of oxytocin, we included a number of women whose labor had been induced with oxytocin, followed by normal cervical dilatation and descent of the fetus. All the parturients were grouped retrospectively into those with normal labor and those with dystocia, based on previous definitions. The serum concentrations of progesterone in both the fetal cord and maternal vein were found to be significantly lower in the oxytocin-resistant dystocia group than in women in spontaneous normal labor and those with oxytocin-induced labor and normal progression (P less than .05-.005). Oxytocin had no evident effect on the serum concentration of either progesterone or E2, nor did concentrations vary following epidural blockade. Serum E2 concentrations in the maternal vein were similar in all delivery groups. Fetal cord E2 serum concentrations were similar in all vaginal deliveries. Women with the most severe oxytocin-resistant dystocia, delivered by cesarean, had significantly lower serum concentrations of E2 in fetal cord serum compared with the vaginally delivered women (P less than .001).

Relation between lightscanning and the histologic and mammographic appearance of malignant breast tumors

The relation between real-time transillumination (lightscanning) and the histologic appearance of 243 breast carcinomas was evaluated. Lightscanning mainly failed in identifying ductal and lobular carcinomas in situ. The result of lightscanning was also poor regarding small, invasive carcinomas. The absorption patterns in elastosis and scar tissue associated with carcinoma played no important role in the ability of lightscanning to identify a cancer. The relation between the lightscanning and mammographic appearance of 85 breast cancers from the same material was also evaluated. Lightscanning performed poorly in identifying tumors characterized by classifications as compared to tumors with other mammographic appearances. However, the difference was not significant.

Effects in vitro of progesterone and two 5 alpha-reduced progestins, 5 alpha-pregnane-3,20-dione and 5 alpha-pregnane-3 alpha-ol-20-one, on contracting human myometrium at term

Progesterone is known to prevent labour at term in domestic animals, but its effect in primates is uncertain. 5 alpha-reduced progesterone metabolites are more potent central nervous system depressants than progesterone is itself. Progesterone and its 5 alpha-reduced metabolites also relax pregnant rat myometrium in vitro. The serum concentration of the initial 5 alpha-reduced metabolite, 5 alpha-pregnane-3,20-dione, is high during pregnancy, but decreases significantly prior to parturition. The next metabolite, 5 alpha-pregnane-3 alpha-ol-20-one, has anaesthetic properties in human beings. The purpose of this study was to ascertain whether these progesterone metabolites also suppress contracting human uterine muscle at term. An in vitro model was devised. Strips of human myometrial muscle were mounted in organ chambers and after regular contractions had become established, the strips were superfused with progestin solutions. The progestins were dissolved in the buffer using an ultrasound bath. Progesterone, used as reference substance, slightly reduced the measured amount of muscular work performed per contraction, recordable after 18 min of exposure (p less than 0.05). Similar results have been reported previously in the literature; 5 alpha-pregnane-3 alpha-ol-20-one showed the same tendency though not significant at the 5% level. 5 alpha-pregnane-3,20-dione evidently reduced the contraction frequency after 10 min of exposure (p less than 0.05). None of the substances affected the duration of the contraction. These 5 alpha-reduced progesterone metabolites are thus not potent inhibitors of contracting human term myometrium in vitro.