Effect of abdominal vagotomy of the pregnant rat on LH and progesterone concentrations and fetal resorption

Abdominal vagotomy on Day 8 of pregnancy in rats decreased the number of live fetuses at Day 16 and increased the number of resorbing fetuses. The activity of delta5-3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the corpus luteum and interstitial gland, LH and progesterone values in plasma and progesterone values in ovarian tissue were all lower in vagotomized rats than in sham-operated controls. Ovarian PGF levels were not affected. We suggest that these effects were caused by a direct effect of vagotomy on LH secretion which in turn lowers 3beta-HSD activity and progesterone levels in ovarian tissue and plasma, leading to fetal resorption.     

Hormonal control of Luteal 20alpha-Hydroxy steroid dehydrogenase and delta5-3beta-hydroxy steroid dehydrogenase during luteolysis in the pregnant rat.

Treatment of pregnant rats with human chorionic gonadotrophin, luteotrophin (luteinizing hormone), luteotrophin-releasing hormone, prostaglandin F2alpha, aminoglutethimide, or by foetoplacental removal or hysterectomy achieved a common multiple-response pattern, namely increased activity of luteal 20alpha-hydroxy steroid dehydrogenase with decreased activity of delta5-3beta-hydroxy steriod dehydrogenase and release of delta4-3-oxo steroids in vitro. 2. Similar effects of foetoplacental removal are noted in pregnant mice. 3. Gonadotrophin induced lower activities of 20alpha-hydroxy steroid dehydrogenase, except at the very end of pregnancy, and partly inhibited the induction caused by foetoplacental removal. 4. The results suggest that existence of a placental factor that restrains these changes until the end of normal pregnancy, which is produced in amounts proportional to the number of placentae and is conveyed to the ovary via the blood. 5. This factor was not replaced by prolactin. 6. It is argued that neither placental lactogen nor pituitary luteotrophin participate in the induction of 20alpha-hydroxy steroid dehydrogenase at late pregnancy in the rat. 7. Aminoglutethimide induced 20alpha-hydroxy steroid dehydrogenase only in late pregnancy. This was partly reversed by progesterone, wholly reversed by progesterone plus oestrogen, and did not involve the pituitary.     

Effect of gold on stimulation of reproductive function in immature female albino rats

Significant increase in ovarian and uterine weight and stimulation of ovarian delta5-3beta-hydroxysteroid dehydrogenase (delta5-3beta-HSD) activity and elevation of serum estradiol level were observed following gold chloride (0.2 mg/kg body weight/day), s.c. administration in immature female albino rats. Moreover, normal cyclic changes of estrus were found in vaginal smears of these rats whereas the rats of other groups showed diestrus phase throughout the period of experiment. Histological study of ovary also showed Graafian follicle with ovum in rats treated with 0.2 mg/kg/day of gold proving stimulation of reproductive function, which was not found in the ovarian histological study of other groups including controls. Thus, the results suggest a significant stimulatory effect of gold chloride on female reproductive activity in immature rats. Further, since the above-mentioned changes were evident at a specific dose of gold chloride, the data may have some clinical implications on stimulation and enhancement of fertility in immature female rats.     

Enhanced steroidogenesis in hen ovary after malonate administration.

The activities of glucose-6-phosphate dehydrogenase, delta 5-3 beta-hydroxysteroid dehydrogenase and succinic dehydrogenase have been studied histochemically in the ovary of normal and malonate treated hens. Following malonate treatment, glucose-6-phosphate dehydrogenase and delta 5-3 beta-hydroxysteroid dehydrogenase showed increased activities while succinic dehydrogenase activity was diminished significantly. The significance of the above changes has been discussed. The ascorbic acid and cholesterol contents of the ovary were determined to get additional information about steroidogenesis in the gland under such treatment.     

Influence of maternal dexamethasone treatment on morphometric characteristics of pituitary GH cells and body weight in near-term rat fetuses

Growth hormone (GH) and glucocorticoids have a powerful influence on controlling fetal growth, differentiation and maturation of numerous tissues. In the present study, the effect of maternal dexamethasone (Dx) treatment on GH cells and body weight in 19- and 21-day-old rat fetuses was investigated using immunocytochemical and morphometric methods. Pregnant female rats received daily injections of 1.0-0.5-0.5 mg Dx/kg b.w. on days 16-18 of pregnancy (experimental group), while the control group received an equal volume of saline. Dx treatment of pregnant rats enhanced immunostaining intensity and significantly increased (p<0.05) GH nuclear and cell volume, as well as volume density and number of GH cells per square millimeter in 19-day-old fetuses compared to the controls. In 21-day-old fetuses after maternal Dx administration, immunoreactivity, volume density and number of GH cells remained significantly increased (p<0.05). Dx treatment of pregnant rats resulted in marked body weight reduction of 21-day-old but not 19 days old fetuses in comparison with the corresponding controls. The presented results demonstrate that maternal Dx application has pronounced effect on morphometric parameters of GH cells of 19- and 21-day-old fetuses. Also, in near-term rat fetuses body weight was largely independent of pituitary GH cell activity.     

Effect of casein diet on gonadotropin releasing hormone antagonist induced changes in adrenal gonadal functions in male rats

Adult male rats received daily injections (sc) of gonadotropin releasing hormone antagonist (0.2 mg/kg(-1) x day(-1)) for 21 days when they were sacrificed on day 22, adrenal weight, adrenal A5-3beta (delta 5-3beta) hydroxysteroid dehydrogenase (Delta5-3beta-HSD) activity and serum level of corticosterone were increased significantly while testicular 17beta (17beta) hydroxysteroid dehydrogenase (17beta-HSD) activity and serum level of testosterone and spermatogenesis were decreased in the rats fed on 5% casein diet. GnRH antagonist treated rats fed on 20% casein diet, resulted significant decrease in adrenal weight, serum corticosterone and adrenal A5-3beta-HSD activity while testicular 17beta-HSD activity serum testosterone levels and the weights of sex organs were increased with respect to anti GnRH treated rats fed on 5% casein diet. But the GnRH antagonist treated rats fed on 20% casein diet showed decreased spermatogenesis quantitatively and sperm count appeared similar to anti GnRH treated rats fed on 5% casein diet. These results indicate that high casein diet protects adrenocortical activity and stimulates testosterone synthesis without effecting spermatogenic arrest in GnRH antagonist treated rats. It may be concluded that GnRH antagonist in presence of high milk protein diet may be considered to be a suitable antihormone in the development of an ideal male contraceptive.     

Ovarian development in control and decapitated pig fetuses

Ovarian development was studied in control and decapitated pig fetuses. Fetuses were decapitated at 42 days postcoitum. At 51, 61, 74, 90 and 112 days postcoitum decapitated and control females were collected. Ovarian weight gradually increased during development in control animals. Deprivation of pituitary hormones as a result of fetal decapitation did not cause a decline in ovarian weight increase. Germ cell maturation in control and decapitated fetuses proceeded in a similar fashion, with secondary follicles being the most advanced stage. Enzyme histochemical activity was present in the primary interstitial gland cells and in granulosa cells and was similar in normal and decapitated fetuses. Both NADH diaphorase activity and 3 beta-hydroxysteroid dehydrogenase activity increased from 51 to 74 days and remained relatively constant thereafter. Since fetal decapitation in the pig hardly influences ovarian development, pituitary dependency of the fetal ovary in the pig is unlikely.     

Effect of removal of the ovarian bursa of the rat on infundibular retrieval and subsequent development of ovulated oocytes

The ovarian bursa was peeled from around one ovary of each rat and the rats were killed 1, 2, 3, 4 and 5 weeks later. The proportion of rats that maintained a bursa-free ovary did not change over the 5-week period (80-89%). Ovulation from the peeled ovary occurred in all rats but oocytes (1-4) were found in the ipsilateral oviduct in only 18% of the rats. The presence of oocytes in the oviduct was normally associated with some degree of re-encapsulation of the ovary. In another experiment rats were mated within 1 week of removal of the bursa from around the ovary. Unilateral pregnancy resulted in 92% of the rats. In a third experiment fertilized oocytes from mated donor rats were transferred into the oviduct next to the peeled ovary in 15 mated recipients. Of 85 zygotes transferred, 51 survived to be viable fetuses on Day 20. A single fetus developing from an endogenous oocyte was found in the transfer uterine horn in only one rat. This preparation may be useful in studies which attempt to determine the viability of oocytes that have undergone various manipulations in vivo or in vitro.     

Amelioration of some metabolic effects produced by hyperthyroidism in late pregnant rats and their fetuses. Effects on lipids and proteins.

We have studied the effect of 40-45 days administration of 1 mg/kg thyroxine on protein and lipid metabolism in liver, heart, lungs, kidneys and adrenal glands of virgin and 21-day pregnant rats and their fetuses and placentae. The chronic administration of thyroid hormone produced significant increases in serum T3 and T4 in both groups as well as in organ weights and protein concentrations in virgin rats, but much smaller modifications in pregnant ones. Hyperthyroidism decreased the weight of fetal livers and increased that of placentae; protein content was increased in all fetal organs. Hyperthyroidism induced increases in phospholipid concentrations in all the organs and in total lipids only in liver and heart of adult rats, which were not counteracted by pregnancy. Pregnant rats had increases in total lipids in liver and kidneys and in adrenal phospholipids. In hyperthyroid fetuses there was an increase in hepatic total lipids and no changes in phospholipids. Hepatic lipogenesis (measured by in vivo incorporation of 3H2O into lipids) was increased by hyperthyroidism in virgin and pregnant rats, but the increase was significantly smaller in the pregnant hyperthyroid rats compared with the virgin ones. Fetal lipogenesis in liver and lung was not changed. In addition, an increase was observed in lipogenic enzyme (fatty acid synthetase and glucose-6-phosphate dehydrogenase) activities in hyperthyroid virgin rats which was prevented by pregnancy. In fetuses only pulmonary glucose-6-phosphate dehydrogenase was increased when expressed in terms of tissue weight. Our results indicate that the metabolic effect of hyperthyroidism is attenuated in pregnant rats and their fetuses, when compared with adult virgin rats, in most of the parameters studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Environmental stress alters the developmental pattern of delta 5-3 beta-hydroxysteroid dehydrogenase activity in Leydig cells of fetal rats: a quantitative cytochemical study

Quantitative cytochemistry was used to determine the effect of subjecting pregnant rats to environmental stress on the activity of delta 5-3 beta hydroxysteroid dehydrogenase (3 beta-HSD) in Leydig cells of their fetuses. Enzyme activity was measured by microspectrophotometry in individual Leydig cells in cryostat sections of fetal testes on Days 16-21 postconception. Fetuses of stressed mothers lacked the peak of enzyme activity on Days 18 and 19 of gestation that is characteristic of Leydig cells of normal fetuses at this time. In addition, both before and after these 2 days, 3 beta-HSD activity in Leydig cells of stressed fetuses was significantly higher than normal. The altered developmental pattern of 3 beta-HSD activity in the stressed fetuses largely corresponds to the changes in plasma testosterone found previously in male fetuses of mothers exposed to the same regimen of stress. Thus, in the fetal Leydig cell, the activity of 3 beta-HSD, a key steroidogenic enzyme, can be modified by environmental stress, and provides an index of steroidogenic activity of the fetal testes and of the titers of circulating testosterone.     

Adrenal dehydrogenases in alloxan diabetic rats following continuous exposure to light

The enzymes delta5-3beta-hydroxysteroid dehydrogenase delta5-3beta-HSD) and glucose-6-phosphate dehydrogenase (G-6-PDH) were demonstrated histochemically in the adrenal cortex of female rat. The activities of these enzymes were increased significantly in the alloxan-treated rats kept in LD (light: darkness) cycles of 10:14 h. Continuous light exposure to diabetic animals appeared to decrease delta5-3beta-HSD and g-6-PDH in comparison to the diabetic rats kept in 10 h illumination. The evidence indicates that suppression of adrenal steroidogenesis in diabetic rats after exposure to continuous light is due to the alteration of pentose phosphate pathway.     

The plant metabolite 6-methoxybenzoxazolinone interacts with follicle-stimulating hormone to enhance ovarian growth

6-Methoxybenzoxazolinone (6-MBOA) is a novel plant metabolite that enhances reproductive status in vertebrate consumers while it inhibits insect, fungal, and bacterial infestation of the plant. Ovaries of prepubertal rats show a dose response to increasing amounts of 6-MBOA.administered in Silastic capsule implants. Ovaries increased in size in response to capsules with 0.5-3.0 cm exposed surface area of 6-MBOA, whereas larger capsules (6 cm 6-MBOA) had no effect. Removal of the pituitary in both prepubertal and mature rats eliminated the stimulatory influence of 6-MBOA. In hypophysectomized animals treated with diethylstibestrol implants, 6-MBOA did not affect ovarian weight and no animals ovulated. Administration of follicle-stimulating hormone (FSH) increased ovarian weight and stimulated production of ova, and FSH combined with 6-MBOA resulted in larger ovaries that released more ova. 6-MBOA also enhanced ovarian growth in intact prepubertal animals treated with pregnant mare's serum gonadotropin. These results show that 6-MBOA has the ability to interact with FSH to stimulate follicular development and increase ovulation. Non-steroidal plant compounds may have a significant impact on the reproductive patterns of wild animal populations.     

Mammary gland growth in the hypophysectomized pregnant rat (38522).

Sprague-Dawley-Rolfsmeyer rats were hypophysectomized on days 11, 12 or 15 of pregnancy and sacrificed on day 20 to determine the extent of mammary development, as assessed by determination of nucleic acid content. The DNA of six abdominal-inguinal glands in the hypophysectomized groups was not significantly different from that in the sham-operated pregnant or intact pregnant control groups. All groups maintaining pregnancy had significantly higher DNA contents in mammary glands than virgin control or hypophysectomized aborted groups. In order to determine the minimal numbers of placental-fetal units required to maintain pregnancy and mammary gland growth, fetuses and placentas were removed on day 12 of pregnancy in addition to the pituitary so that only one fetus and one placenta remained in the uterus of a group of 6 rats with other groups having 2, 3, 4, 5 remaining. Pregnancy was maintained with only one placental-fetal unit, but mammary gland proliferation was significantly lower than the control group on day 20 of pregnancy. Three to five conceptuses supported mammary proliferation during the latter half of pregnancy at a level not significantly different from intact or sham-operated control groups. Removal of placental units on day 12 in rats having pituitaries intact resulted in no mammary DNA change when 1-5 units remained. Removal of pitutaries on day 12 and placental-fetal units on day 14 also resulted in no change in mammary DNA with as little as two placentas (minus all fetuses),while only one placenta remaining resulted in a significantly lower mammary DNA than in groups wtih 2 or more placentas.     

Influence of endogenous growth hormone-releasing factor (GRF) on the secretion of GH during the perinatal period in the rat

Passive immunization of pregnant rats with a specific antiserum to rat GRF (GRF-AS) is followed by a decrease in fetal serum GH on the 19th day of gestation. A significant reduction in serum GH is still observed in older fetuses and newborn rats. Pituitary GH content increases in 19- and 20-day-old fetuses after GRF-AS administration to their mothers. These results suggest that endogenous fetal hypothalamic GRF (or placenta GRF) play a physiological role in the secretion of pituitary GH as early as the 19th day of fetal life and may be responsible for the peak of GH release that occurs in fetuses at the end of gestation.     

Ovarian contents of immunoreactive beta-endorphin and alpha-N-acetylated opioid peptides in rats

beta-Endorphin was measured by radioimmunoassay in homogenates of ovaries from immature Sprague-Dawley rats (21-29 days of age) and found to be present at levels of about 0.6-0.7 ng/ovary. After administration of PMSG there was approximately a 4-fold increase (2-3 ng/ovary) in total ovarian immunoreactive (ir) beta-endorphin 48 h after injection. Analysis of follicular fluid from similarly treated rats indicated about the same amount of ovarian ir-beta-endorphin (2-3 ng/ovary) as in ovarian homogenates, suggesting that most of the ir-beta-endorphin is localized in follicular fluid of PMSG-primed immature rats. Immature rats were made pseudopregnant by administration of hCG 48 h after PMSG, and at 24 h after injection of hCG there was a slight, but significant and reproducible, increase in the ovarian content of ir-beta-endorphin. The serum concentration of ir-beta-endorphin was in the range of 1-3 ng/ml and was unaffected by PMSG and PMSG/hCG; likewise, the pituitary content of ir-beta-endorphin did not change following administration of gonadotrophins to immature rats. In mature cyclic animals, levels of 2-4 ng ir-beta-endorphin/ovary were found, comparable to those in the ovaries of PMSG-primed immature rats, and there were only small changes during the oestrous cycle. In addition to ir-beta-endorphin, we also obtained evidence for the presence of alpha-N-acetylated opioid peptides (endorphins or enkephalins) in the ovaries of PMSG-primed immature and mature rats. The physiological role of the opioid peptides in reproductive tissue is unknown, but they are presumably acting in an autocrine or paracrine fashion.     

Effect of lithium chloride on spermatogenesis and testicular delta 5-3 beta, 17 beta-hydroxysteroid dehydrogenase activities in the 'antiserum to luteinizing hormone' treated toad (Bufo melanostictus)

Activities of delta 5-3 beta- and 17 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD and 17 beta-HSD), Leydig cell nuclear area (LCNA) and spermatogenesis in the testis were observed after injection of lithium chloride in the 'antiserum to luteinizing hormone (LH)' treated toad. A significant decrease in the activities of steroidogenic enzymes, LCNA and spermatogenesis were noticed after the injections of 'antiserum to LH' to toads. Further decrease in the activities of the above parameters was observed in the lithium chloride--'antiserum to LH' treated toad. It is suggested that lithium chloride may inhibits testicular function without modulating the pituitary activity.     

Dysgenesic rat ovaries subjected to gonadotrope stimulation]

Dysgenesia of the ovaries was produced by the destruction of the germinal cells during the foetal life by injecting the pregnant rat with Misulban. In the absence of ovocytes, follicular organization did not take place and cordal structure were observed in the ovary. The post-puberal evolution of these gonads led to polymorphous structures according to age and individual cases. Study of dysgenesic ovaries of rats treated by stilboestrol before puberty, showed mainly that the ovarian stroma was affected in response to the inhibition of the pituitary gonadotropic activity. It is concluded that the development of these ovaries is under the control of the hypothalamo=pituitary axis.     

Histochemical study on adrenal delta 5-3 beta-hydroxysteroid dehydrogenase activity in cadmium treated toad (Bufo melanostictus).

Effect of a single subcutaneous injection of cadmium chloride at the dose of 0.5 mg/toad on adrenal delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD) was observed after 7 days. The activity of delta 5-3 beta-HSD was measured histochemically. The experiments indicate that cadmium chloride resulted in a significant decrease in the activity of adrenal delta 5-3 beta-HSD in toad during breeding season (June-July).     

Distribution of cadmium in ovaries, adrenals and pituitary gland after chronic administration in rats.

Wistar rats were given 0.25, 0.5 or 1.0 mg/kg/week CdCl2 for 14, 18 or 22 weeks and the body weight, Cd content of ovaries, adrenals, pituitary gland, furthermore the progesterone and oestradiol-17 beta secretion of ovary were checked. Cd treatment caused a slight decrease in the body weight, but failed to alter the weight of endocrine organs. CdCl2 in a dose of 0.25 mg/kg/week resulted in almost the same Cd content in all the three organs. Rising the amount of Cd administered the pituitary gland accumulated more Cd than the adrenals, and the lowest levels were found in the ovary. CdCl2 even in the dose of 1.0 mg/kg/week failed to alter the ovarian cycle, progesterone and oestradiol-17 beta production of ovary. The data point also to a developing tolerance to Cd as the cumulative dose of CdCl2 lies close to the LD50 levels.     

Effects of lithium chloride on testicular steroidogenic and gametogenic functions in mature male albino rats

The present study was undertaken to evaluate the effects of lithium, an antimanic drug, on steroidogenic and gametogenic functions of testis in the laboratory rat. Adult male rats of Wistar strain maintained under standard laboratory conditions (L:D, 14h:10h), were injected (S.C) with lithium chloride at the dose of 0.1 mg, 0.2 mg and 0.4 mg/100 g body weight/day for 21 days. All the treated animals along with the vehicle treated controls were sacrificed 24 hours after the last injections. Testicular steroidogenic activity was evaluated by measuring the activities of two steroidogenic key enzymes, delta 5-3 beta hydroxysteroid dehydrogenase (delta 5-3 beta-HSD) and 17 beta hydroxysteroid dehydrogenase (17 beta-HSD). Gametogenic capacity was determined by counting the number of germ cells at stage VII of seminiferous cycle. Plasma levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL) and testosterone (T) were measured by radioimmunoassay (RIA). Administration of lithium chloride at a dose of 0.1 mg/100 g body wt. for 21 days led to insignificant changes of plasma FSH, LH, PRL and T along with unaltered activities of testicular delta 5-3 beta-HSD, 17 beta-HSD activities and gametogenesis. In contrast, 0.2 mg of lithium treatment for 21 days causes a significant reduction of plasma FSH (P less than 0.01), LH (P less than 0.001), PRL (P less than 0.001) and T (P less than 0.001) along with inhibition of testicular delta 5-3 beta-HSD activity (P less than 0.01) and 17 beta-HSD activity (P less than 0.001). Gametogenic activity does not exhibits any significant reduction in the number of preleptotene spermatocytes (PLSc) and midpachytene spermatocytes (mPSC) while significant reduction in the number of spermatogonia A (Asg) (P less than 0.01) and Step 7 spermatids (7Sd) (P less than 0.001) were observed at stage VII of seminiferous cycle when compared to control. The degree of detrimental effects of lithium on testicular activity became more prominent at the dose of 0.4 mg/100 g body wt. The results of our experiments suggest that lithium administration might be associated with significant adverse effects on testicular activities. Furthermore, since hormonal changes and altered gametogenic activities were evident when plasma lithium concentration was below or within the therapeutic range, our data may have some potential clinical implications.