Dihydrotestosterone secretion in pregnant and pseudopregnant rats

The objective of this study was to determine levels of dihydrotestosterone in the peripheral circulation and the source of its secretion throughout pregnancy and pseudopregnancy. Rats were bled from the jugular vein and ovarian or uterine vein from Day 8 through Day 22 of pregnancy and from Day 8 through the end of pseudopregnancy in various types of pseudopregnant rats. Jugular vein samples alone were obtained on the day of parturition and every fourth day thereafter during the lactational period. Our results indicate that the levels of dihydrotestosterone in the peripheral circulation were high throughout pregnancy and pseudopregnancy then declined during the lactational period. The sources of dihydrotestosterone were primarily the ovary in pseudopregnant rats and the ovary plus uterus in pregnant rats.     

Mounting behavior in pregnant and pseudopregnant female rats

Mounting behavior by female rats with regular 4-day estrous cycles was significantly reduced after the induction of pregnancy, pseudopregnancy, or treatment with progesterone. The mounting behavior shown by pseudopregnant female rats was comparable to that shown by ovariectomized females. Pseudopregnant and unmated females showed mounts with pelvic thrusting with the same frequency after treatment with estradiol benzoate (EB). EB stimulated the display of mounts with pelvic thrusting in ovariectomized females, and this behavior was not affected by concurrent progesterone treatment. It is suggested that the reduction of mounting in pregnant and pseudopregnant female rats is due to decreased ovarian estrogen secretion.     

Evidence for hormonal imbalance after methadone treatment in pregnant and pseudopregnant rats

The effects of methadone (METH) on the plasma estriol level and hormonal target tissues' cyclic nucleotides (cAMP and cGMP) were investigated in pregnant and pseudopregnant rats. In the pregnant animals, METH (5 mg/kg/day), given once daily from Days 6 to 15 of gestation, significantly reduced the maternal body weight gain in association with an increase in the number of dams bearing resorptions (56%) and a significant reduction in fetal body weight (33%). An inhibition of the plasma estriol level by METH was observed on Day 9 of gestation. Stimulation of the sympatho-adrenal axis and hypothalamo-pituitary axis by acute METH administration was observed and correlated with a significant increase in the levels of cyclic nucleotides in the uterus and adrenal glands of pregnant rats. However, tolerance to METH effects on cyclic nucleotide levels developed by Day 15 of gestation. METH also depressed the fetal cyclic nucleotide levels on Days 12 and 15 of gestation. These findings suggest that METH had pronounced effects on hormonal secretion during pregnancy, and hormonal transport to or hormonal production by the fetuses. In contrast, METH did not exhibit any adverse effects on the hormonal and cyclic nucleotide levels of pseudopregnant rats with deciduoma formation; a model for the maternal compartment. These latter findings may reflect METH's adverse effects on the fetal compartment, and suggest the use of pseudopregnancy as a model to distinguish adverse drug effects between these compartments.     

Cytosol and nuclear levels of thymic progesterone receptors in pregnant, pseudopregnant and steroid-treated rats

Cytosol and nuclear levels of progesterone receptors in rat thymus and uterus were compared in mature Sprague-Dawley rats under a variety of physiological (non-oestrus, oestrus, pregnancy) and experimental circumstances (pseudopregnancy, oestrogen administration, oestrogen plus progesterone administration). Cytosols and nuclear extracts were charcoal treated to remove endogenous steroids, and incubated overnight at 4 degrees C with the synthetic progestin [3H]R5020 +/- greater than 100-fold R5020, in the presence of greater than 200-fold RU26988 (a highly specific synthetic glucocorticoid) to exclude tracer from glucocorticoid receptors. In the various states examined, levels of progesterone receptors in the uterus were an order of magnitude higher (350-1300 fmol/mg protein) than in the thymus (40-140 fmol/mg protein). In contrast, considerable parallelism between uterus and thymus was seen in terms of the effects of the various manipulations upon tissue levels of progesterone receptors, and of their distribution between cytosol and nuclear compartments.     

Morphometric image analysis of follicular lesions of the thyroid

OBJECTIVE: To determine the role of image morphometry in distinguishing various follicular lesions of the thyroid in cytologic smears. STUDY DESIGN: Archival fine needle aspiration smears of 10 cases each of follicular hyperplasia, follicular adenoma, follicular carcinoma and follicular variant of papillary carcinoma were used for the study. All cases were histopathologically proven. At least 100 random nuclei from each case were subjected to analysis with an image cytometer. Area, convex area, length, width, perimeter, convex perimeter and roundness of nuclei were measured using a 40 x objective (1 pixel = 0.446 micron). RESULTS: ANOVA showed that all the nuclear variables studied were significantly different (P < .05) in follicular hyperplasia as compared to follicular carcinoma and papillary carcinoma. All nuclear variables except roundness were also significantly different (P < .05) between follicular hyperplasia and follicular adenoma. However, between follicular adenoma, follicular carcinoma and papillary carcinoma there was considerable overlap of nuclear morphometric parameters. CONCLUSION: Image morphometry may help to distinguish nonneoplastic follicular lesions (hyperplasia) from neoplastic lesions (adenomas and carcinomas). However, to distinguish benign from malignant follicular lesions, image morphometry might not improve the accuracy of standard cytologic examination.     

Daily changes in peripheral plasma progesterone concentrations in pregnant and pseudopregnant rabbits

Peripheral levels of plasma progesterone were found to be similar in pregnant New Zealand White and Dutch-belted rabbits. In early gestation progesterone concentrations rose rapidly, remained relatively constant and declined slowly during the latter third of pregnancy. Among pseudopregnant rabbits progesterone levels rose rapidly until day 11 and declined rapidly thereafter until day 19 at which time baseline values were obtained.     

Plasma insulin response and food intake in pseudopregnant rats

1. Plasma insulin response to an intravenous glucose injection was measured in anaesthetised pseudopregnant and non-pregnant rats. Food intakes and body composition were also compared in pseudopregnant and non-pregnant animals. 2. The insulin responses and food intakes were greater in the pseudopregnant group. 3. Pseudopregnancy increased the fat-free dry weight of the animals and there was a tendency for the proportion of fat to be increased. 4. The results provide further evidence to indicate that in the rat progesterone plays a significant part in increasing insulin secretion during pregnancy.     

In vivo levels of prostaglandin F2 alpha, E2 and prostacyclin in the corpus luteum of pregnant and pseudopregnant rats

Prostaglandin F2 alpha (PGF2 alpha) is a well-known luteolytic factor in the rat corpus luteum. To investigate a possible luteal origin of PGF2 alpha, measurements of this prostaglandin were performed in different luteal tissues in vivo. Prostaglandin E2 (PGE2) and the stable metabolite of prostacyclin, 6-keto-PGF1 alpha, were assayed simultaneously. Corpora lutea of different ages from 57 pregnant and pseudopregnant rats (mated with sterile males) were rapidly excised, dissected in 0 degree C indomethacin solution, homogenized, and extracted for prostaglandins with solid-phase extraction cartridges. Prostaglandins were determined by radioimmunoassay. Plasma levels of progesterone and 20 alpha-dihydroprogesterone were also monitored. In the adult pseudopregnant rat model, luteolysis occurs at Day 13 +/- 1, and maximal levels of all three prostaglandins were detected on Day 13 of pseudopregnancy: 0.40 +/- 0.02, 2.6 +/- 0.29, and 1.76 +/- 0.24 pmol/mg protein (mean +/- SEM, n=7) for PGF2 alpha, PGE2, and 6-keto-PGF1 alpha respectively. In pregnant rats, on the corresponding day, levels were considerably lower: 0.15 +/- 0.02, 0.90 +/- 0.13, and 0.50 +/- 0.06 pmol/mg protein (mean +/- SEM, n=9, p less than 0.0001), respectively. Luteal levels in pregnant rats showed a continuous decline on Days 13 and 19 for all prostaglandins measured, whereas in pseudopregnant rats an increment of PGF2 alpha was noted between Days 7 and 13 and remained high on Day 19. PGE2 closely followed levels of PGF2 alpha, but at a 5- to 10-fold higher level. The coefficient of correlation between PGF2 alpha and PGE2 in the luteal compartment of both models was 0.87 (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dihydrotestosterone on progesterone secretion in pseudopregnant rats

To determine if the administration of dihydrotestosterone (DHT) suppresses serum progesterone concentrations in pseudopregnant rats and if so what role the decidua play in mediating this effect, two pellets (8 mg) of DHT were inserted under each ovarian bursa on Day 9 of pseudopregnancy in hysterectomized or intact rats with or without the decidua. The treatment induced within 24 hr a 50% decline in serum progesterone concentrations in decidua-bearing rats only; a further reduction was observed on Days 11 and 12. To further determine if the effect of DHT on serum progesterone concentrations is due to its effect on luteal luteinizing hormone (LH)-receptor content, rats were similarly treated on Day 9 and the capacity of corpora lutea to bind 125I-labeled human chorionic gonadotropin (hCG) on Day 12 in all three groups of rats was examined. DHT treatment had no effect on luteal LH-receptor content in any group. These results suggest that DHT is luteolytic in pseudopregnant rats only in the presence of the decidua and it is speculated that this effect is mediated by suppressing the decidual luteotropin.     

Morphometric analysis of the degree of aggregation of follicular cells in the diagnosis of malignant thyroid tumors

OBJECTIVE: To develop a system of decision criteria based on a set of features of the degree of thyrocyte aggregation with assessment of their weighting coefficient in the diagnosis of malignant and benign thyroid pathology. STUDY DESIGN: Autopsy, operative and aspiration biopsy material were the object of the study. Light microscopic morphometry was performed with semiautomated computer analysis of images. RESULTS: Of all the sets of features of the degree of thyrocyte aggregation, 10 were chosen that provided the least overlap between the groups of malignant and benign pathology. Boundary values of these features to discriminate between malignant and benign pathology were assembled into a set of diagnostic decision criteria for thyroid carcinoma diagnosis. Based on results from trials, an equation for the calculation of a weighting coefficient for each feature was derived. A diagnostic index was determined by the sum of values of weighting coefficients of the features within the range of values listed in the set of diagnostic decision criteria. CONCLUSION: A set of diagnostic decision criteria was developed for thyroid carcinoma diagnosis that is based on morphometric features reflecting the regularities of changes in the structure of thyrocyte aggregates with malignant and benign pathology. Weighting coefficients of features were assessed, making it possible to perform a probabilistic carcinoma diagnosis.     

Erythrocytic parameters as indicators for differentiating between the pregnant and pseudopregnant bitches in Nigeria

The erythrocytic parameters during pregnancy and pseudopregnancy in bitches were studied and compared in 8 bitches aged 2 -3 years and weighing 10-12 kg. Blood samples were collected from the bitches before mating, during the three trimesters of pregnancy and the post partum period. The packed cell volume (PCV %), haemoglobin concentration (Hb gm/dl), red blood cell count(x106/μl) were determined using standard methods. The mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC) were then calculated. Six of the bitches were pregnant and 2 were pseudopregnant. The results showed that in pregnant bitches, the PCV decreased significantly from the premating values of 51.37+0.94% to 34.00+8.04% during the third trimester of pregnancy (P.