The vaginal epithelium of immature rats metabolizes androgens through an aromatase-like reaction: changes during the time of puberty

Testosterone (T) at physiological levels can induce precocious vaginal opening without advancing the time of first ovulation. The present experiments were undertaken to test the hypothesis that the vaginal epithelium has the ability to aromatize androgens to estrogens. Using standardized conditions, we estimated aromatase activity using both 3H2O-release from [1 beta-3H]T and thin-layer chromatographic (TLC) characterization of estrogen formed after incubations with [1,2,6,7-3H] testosterone. Vaginal aromatase-like activity, as measured by the 3H2O-release assay, increased between the juvenile and peripubertal phases of development and remained elevated throughout puberty. In contrast, ovarian aromatase increased markedly during the early proestrus (EP) and late (first) proestrus (LP) phases of puberty but declined after the first ovulation. Vaginal aromatase-like activity was induced in vivo by either stimulation of ovarian steroidogenesis with pregnant mare's serum gonadotropin (PMSG), or by producing EP levels of serum T via testosterone-containing Silastic capsules. 4-Hydroxy androstenedione, a potent aromatase inhibitor, decreased both vaginal and ovarian aromatase activity in vitro in a concentration-dependent manner. Although the principal product of ovarian aromatase derived from [1,2,6,7-3H] T was identified as estradiol (E2), the identity of the vaginal estrogen product could not be firmly established. The vaginal metabolite comigrated with 16-keto-E2 in two TLC systems before and one TLC system after acetylation but failed to recrystallize as 16-keto-E2 diacetate and failed to co-elute with 16-keto-E2 diacetate on high performance liquid chromatography. This vaginal metabolite does not correspond to any of 13 steroids tested, including 2-hydroxy-E2, and it does not represent a 5 alpha-reduced metabolite of T.(ABSTRACT TRUNCATED AT 250 WORDS)     

2-bromo-alpha-ergocryptine mesylate (CB-154) inhibits prolactin and luteinizing hormone secretion in the prepubertal female rat

Treatment of immature female rats with 100 micrograms 2-bromo-alpha-ergocryptine mesylate (CB-154) per ml drinking water beginning on Day 30 of age until vaginal opening delayed puberty by 6 days. Rats treated with CB-154 exhibited vaginal opening at 43.3 +/- 0.6 days whereas controls exhibited vaginal opening at 37.9 +/- 0.8 days. Most interestingly, serum levels of luteinizing hormone (LH) and prolactin (PRL) on Days 31-35, determined by a homologous radioimmunoassay were significantly lower in treated rats than in controls. The ovarian concentrations of progesterone (P) and androstenedione (A) were lower in rats treated with CB-154 than in controls; ovarian estradiol (E2) concentrations were low in both groups. Serum levels of P (but not A and E2) were reduced on Days 31-35 of the treatment period. Cessation of the CB-154 treatment on the morning of Day 35 returned the onset of puberty to normal values; steroid and gonadotropin levels also returned to normal values within 2 days after removal of the CB-154 from the drinking water. Near the time of onset of puberty, serum levels of LH in rats treated with CB-154 returned to control values. These data indicate that in the female rat the delay in puberty induced by CB-154 might be due to a reduction in the secretion of LH, especially since the onset of delayed puberty in rats treated with CB-154 correlates with an increase in the serum level of LH. Further studies are needed to elucidate the specific effects of hypoprolactinemia on ovarian function and the onset of puberty in the rat.     

Development of the sex difference in glandular kallikrein and prolactin levels in the anterior pituitary of the rat

Glandular kallikrein is a major estrogen-induced and dopamine-repressed protein of the rat anterior pituitary that appears to originate from lactotrophs. This study examined the development of glandular kallikrein levels in the anterior pituitary in both female and male rats and compared it to anterior pituitary prolactin. In addition, the development of glandular kallikrein levels in the neurointermediate lobe of the pituitary and the kidney were also examined. During puberty, a dramatic surge in glandular kallikrein occurred in female anterior pituitaries (16- to 20-fold increase) and levels remained elevated thereafter. The dynamics of the increase were biphasic--glandular kallikrein increased between Day 30 and 45, plateaued between Days 45 and 55, and then increased again between Days 55 and 65. Female anterior pituitary prolactin increased 7- to 8-fold during puberty. The rise during puberty was biphasic and was generally synchronized with increases in glandular kallikrein. However, the initial rise was proportionately less than that of glandular kallikrein, and the secondary surge was more dramatic. In contrast to females, anterior pituitary glandular kallikrein remained at low levels in male rats; prolactin levels also remained unchanged through puberty and increased moderately thereafter. Glandular kallikrein in the female neurointermediate lobe remained unchanged through Day 55, almost doubled on Day 60, and returned to prepubertal levels by Day 65; males did not exhibit the transient surge in neurointermediate lobe levels. Starting at age 60 days, renal glandular kallikrein was found to be slightly higher (15-20%) in females than in males.(ABSTRACT TRUNCATED AT 250 WORDS)     

A diabetic-like condition of turkey embryos maintained in shell-less culture

Serum insulin concentration and pancreatic insulin content were determined for turkey embryos incubated in ovo and in long-term shell-less culture (ex ovo). Insulin was undetectable (less than 10 pg) in serum from 87% of the ex ovo embryos compared with their in ovo counterparts. This was evident at all incubation ages, although insulin was detectable in more of the ex ovo embryos on Day 24. Insulin increased in the embryos incubated in ovo from 122 (Day 15) to levels exceeding 2000 pg/ml at hatching. Total pancreatic insulin content was greater in the cultured embryos on Days 15, 17, and 22 compared with their in ovo counterparts. Serum glucose was significantly greater (P less than 0.05) in the ex ovo embryos at all ages. In response to an infusion of L-arginine, serum insulin increased from 566 to 1256 pg/ml in the in ovo embryos, whereas no change was evident in the ex ovo embryos (233 vs 257 pg/ml). When embryos incubated in ovo were injected with insulin, a significant (P less than 0.05) reduction of serum glucose was observed at 60 min after injection. Serum glucose concentrations remained elevated in the embryos incubated ex ovo despite the insulin injection. Liver glucose 6-phosphatase activity, assessed on Days 15 and 22 of incubation, was found to be significantly (P less than 0.05) lower in the ex ovo embryos. Turkey embryos incubated in shell-less culture exhibited chronic hyperglycemia in concert with extremely low circulating levels of insulin. The pancreatic beta cells of these embryos were not responsive to arginine or elevated glucose. Taken together these findings suggest the occurrence of a diabetic-like condition in the ex ovo embryos. This defect in insulin secretion may, in part, be responsible for some of the developmental abnormalities characteristic of the turkey embryo cultured ex ovo.     

Bioactive follicle-stimulating hormone levels in serum and urine of male and female rats from birth to prepubertal period

Using a sensitive in vitro granulosa cell aromatase bioassay (GAB), we determined serum and urinary levels of bioactive follicle-stimulating hormone (bio-FSH) in male and female rats from birth to Day 40 of age. In addition, serum immunoreactive FSH (immuno-FSH) was measured by radioimmunoassay to determine the bio- to immuno-(B/I) ratio of FSH. During the neonatal period (Days 1-7 of age), both sexes had detectable serum bio-FSH levels. In the infantile period (Days 7-21), serum bio-FSH levels initially decreased at Day 10 for both sexes, and then rose steadily, reaching maximum concentrations at Day 14 (males: 68.7 ng/ml; females: 114.6 ng/ml). Subsequently, FSH levels in the females decreased from Day 16 throughout the juvenile (Days 21-35) and prepubertal (Days 35-40) periods. In contrast, FSH levels in the males fluctuated during these periods. In the males, immuno-FSH reflected the bioactive profiles, with a B/I ratio of 2.2 +/- 0.2. In the females, the B/I ratio was approximately 2.5 during the neonatal and infantile periods but declined to approximately 1.0 during the juvenile and prepubertal periods, consistent with earlier observations of heterogeneous forms of pituitary FSH in immature female rats. Morning urine samples were also collected daily and bio-FSH concentrations were determined. In both sexes, urinary bio-FSH profiles were highly correlated (r = 0.93) with serum FSH throughout development. However, the urine concentrations were about 50-fold higher than serum.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ovulation induction in anestrous bitches by pulsatile administration of gonadotropin-releasing hormone

Preliminary studies in anestrous Beagle bitches demonstrated that a single injection of gonadotropin-releasing hormone (150 micrograms) produced a rapid, physiological rise in serum estradiol lasting 1-3 days while progesterone remained below 1 ng/ml, whereas serial injections of FSH rapidly produced greater elevations in estradiol and a rapid rise in progesterone over 2 ng/ml. Consequently, attempts to induce fertile ovulation by means of pulsatile intravenous administration of GnRH (1 pulse/1.5 hours for 6-12 days; 0.04-0.43 micrograms/kg body weight/pulse) were conducted in eight anestrous bitches. Willingness to mate, serum progesterone levels and results of mating were monitored. In six of the eight bitches, vulval and vaginal signs of proestrus occurred by Day 2-4 after initiation of treatment (Day 0); but, two bitches showed negligible responses. In five of the six bitches in which proestrus was induced, behavioral (n = 4) and vaginal (n = 5) correlates of early estrus occurred by Day 5-7 of treatment and breedings occurred over a period of 4-12 days. Following onset of estrus, four of the five bitches had increases in serum progesterone levels between Days 14 and 18 after initiation of treatment (and 4-11 days after cessation of treatment); three of them became pregnant and whelped normal litters (ranging from 9 to 11 pups). The fifth bitch did not have elevated progesterone during the induced estrus, and upon return to estrus one month later was successfully bred and whelped a normal litter of 10 pups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of gonadotropin-releasing hormone treatment on ovarian steroid production during midpregnancy

During the second half of pregnancy, ovarian testosterone (T) through its conversion to estradiol (E) promotes progesterone (P) synthesis by the ovary which maintains the pregnancy. To determine if the administration of gonadotropin-releasing hormone (GnRH) disrupts pregnancy by suppressing ovarian production of T or its conversion to E, rats were treated from Day 11 through Day 18 of pregnancy with 50 or 100 micrograms/day of GnRH or 1, 5, or 10 micrograms/day of a GnRH agonist (GnRH-Ag; WY-40972) using an osmotic minipump. Rats were bled daily from the jugular vein under light ether anesthesia and on Days 14 or 18 of pregnancy both jugular and ovarian blood samples were obtained. While the GnRH-Ag treatment at the dose of 5 or 10 micrograms/day terminated pregnancy within 48 hr as indicated by vaginal bleeding, 1 microgram/day terminated pregnancy more slowly. Neither dose of GnRH was effective in terminating pregnancy through Day 18. By Day 14, peripheral levels of plasma P in rats treated with 0, 1, 5, or 10 micrograms of GnRH-Ag were 97 +/- 9, 24 +/- 1, 13 +/- 3, and 8 +/- 1, respectively. In the same groups, levels in the ovarian vein were 3205 +/- 633, 1317 +/- 273, 360 +/- 113, and 228 +/- 73 ng/ml. By Day 18, serum P levels in the peripheral circulation and in the ovarian vein were declining even more dramatically. Daily administration of P (4 mg) and E (0.5 micrograms) simultaneously with GnRH-Ag at the dose of 5 micrograms/day from Days 11 through 14 reversed the abortifacient effect of GnRH-Ag and maintained pregnancy indicating that the GnRH-Ag effect is not directly on the uterus. Ovarian vein levels of T on Days 14 or 18 of pregnancy were either not different from controls at 1407 +/- 163 or 1476 +/- 122 pg/ml, respectively, or increased dramatically in certain groups. Ovarian vein levels of E were either not different from controls at 292 +/- 13 pg/ml on Day 14 or increased significantly in rats treated at the dose of 1 microgram/day of GnRH-Ag. However by Day 18, treatment with GnRH-Ag at all doses suppressed ovarian secretion of E. These results suggest that while the GnRH-Ag induces abortion in rats by suppressing ovarian production of P, this abortifacient effect is not due to a fall in ovarian T levels nor to its aromatization to E in the ovary.     

Oxytocin and bovine parturition: a steep rise in endometrial oxytocin receptors precedes onset of labor.

Oxytocin receptors were measured in myometrium and intercaruncular endometrium of cows during pregnancy and parturition. Concentrations of estradiol-17 beta, estrone, and progesterone in peripheral blood were also measured. Receptor concentrations in the endometrium rose almost 200-fold from Day 20 to term (p < 0.0001, ANOVA), from 40 +/- 11 to 7300 +/- 1430 fmol/mg protein. Myometrial receptor concentrations increased 10-fold from 180 +/- 36 fmol/mg on Day 20 to 1850 +/- 360 fmol/mg protein at term (p < 0.0001, ANOVA). During labor, endometrial receptors (6600 +/- 1300 fmol/mg) remained at prelabor values, whereas myometrial receptor concentrations had decreased to 1190 +/- 316 fmol/mg (not significant) and declined further postpartum. Plasma concentrations of progesterone declined from 4-5 ng/ml to about 2 ng/ml between Days 250 and 282 and dropped to < 0.2 ng/ml shortly before delivery. Plasma concentrations of estrone and estradiol-17 beta were below 10-20 pg/ml until Day 230. Estrone concentrations were significantly (p < 0.05) increased by Day 250 and estradiol-17 beta by Day 270, and then both rose rapidly. During labor, plasma estrone was 1135 +/- 245 pg/ml and plasma estradiol-17 beta was 226 +/- 131 pg/ml. The molar ratio of estrone and estradiol-17 beta to progesterone rose from less than 0.01 to 4.4 during labor, and was correlated with oxytocin receptor concentrations in endometrium (r = 0.5160, p < 0.001), but not those in myometrium (r = 0.0122). The regulation of oxytocin receptors by ovarian hormones in the two tissues may therefore differ.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circulating immunoreactive inhibin, gonadotropin, and prolactin levels during pregnancy, lactation, and postweaning estrous cycle in the rat

Serum inhibin levels were measured by heterologous RIA during pregnancy, lactation, and the post-weaning estrous cycle in the rat and correlated with changes in serum FSH and LH and prolactin. Blood was serially collected by cardiac puncture under light ether anesthesia from adult Sprague-Dawley rats on alternate days throughout the experimental period. For the first 8 days of pregnancy, immunoreactive inhibin levels remained high, then gradually decreased to reach a nadir at Day 16, and subsequently rose steeply until parturition. The pattern of serum immunoreactive inhibin levels during early pregnancy does not support a corpus luteum source and the dramatic rise from Day 16 to Day 22 correlates with the recommencement of follicular development in the ovary. Inhibin levels decreased rapidly on the day after birth and were suppressed until Day 8 of lactation, slowly increasing thereafter to reach a plateau from Day 14 until weaning (Day 22.5 of lactation). These changes in inhibin levels positively correlated with LH and FSH and negatively with prolactin, and are consistent with an ovarian source for inhibin associated with the recommencement of follicular development resulting from the diminution of the suckling stimulus. Immediately after weaning, serum immunoreactive inhibin levels showed a 4-day cyclic pattern corresponding to the estrous cycle identified by vaginal smear. Inhibin levels peaked on the day of proestrus, reached a nadir on the day of estrus, and rose slowly during metestrus and diestrus to a new peak at proestrus. Serum FSH levels showed an inverse correlation to inhibin levels consistent with a feedback relationship with inhibin.     

Influence of suckling status and type of birth on serum hormone profiles and return to estrus in early-postpartum spring-lambing ewes

Twenty-three mature, spring-lambing, fine-wool ewes of Debouillet × Rambouillet breeding were allotted at parturition to one of four treatments which were arranged in a 2 × 2 factorial design with groups representing number of lambs born (i.e., one or two) and suckling intensity (i.e., lambs were weaned at 2 d of age or lambs remained with dams). Beginning at 0900 h on Day 2, 9, 16, 23, and 30 post partum (PP), jugular blood samples were collected from each dam at hourly intervals for the ensuing 6 h. Additional jugular blood samples were collected daily (Days 2 through 30). Animals were observed twice daily for signs of estrus using vasectomized rams. Interval from parturition to estrus (mean ± SEM) was similar (P > 0.15) in ewes nursing their offspring (117 ± 6 d) and those that had their lambs removed (124 ± 6 d). Dams producing single lambs returned to estrus in 126 ± 5 d compared with 116 ± 5 d (P > 0.15) for ewes producing twins. Serum luteinizing hormone and progesterone were low (< 1.7 and 0.5 ng/ml, respectively) in all ewes during the first 30 d PP. Serum insulin did not differ (P > 0.10) between suckled dams and those that had their lambs removed, but ewes giving birth to single offspring had higher (P < 0.05) insulin levels on Days 16 and 30 PP (543 ± 73 and 578 ± 57 pg/ml, respectively) than did dams producing twin lambs (324 ± 73 and 361 ± 57 pg/ml, respectively). Serum growth hormone (GH) did not differ (P > 0.40) between suckling intensity groups on Day 2 PP; however, by Days 16, 23, and 30, ewes in the suckled group had more (P < 0.05) GH than did those producing single offspring (5.4 and 3.6 ± 0.4 ng/ml, respectively). Early removal of lambs in spring-lambing ewes did not shorten the interval from parturition to estrus.     

Effect of postnatal treatment with a gonadotropin-releasing hormone antagonist on sexual maturation of male rats

The role of postnatal pituitary-testicular activity in sexual maturation at puberty was studied in male rats. Rats were injected twice daily with a potent gonadotropin-releasing hormone antagonist (N-Ac-4-Cl-D-Phe1, 4-Cl-D-Phe2, D-Trp3, D-Phe6, D-Ala10-NH2-GnRH) (GnRH-Ant.), 2 mg/kg, on Days 1-15 of life, and killed on Day 48, 56 or 90 of life. The treatment delayed the onset of puberty (monitored by balano-preputial separation) by 8 days (from the age of 48 to 56 days). The weights of testes, seminal vesicles and ventral prostates were reduced by 50-60% on days 48 and 56 of life, but only the testis weights remained suppressed by Day 90. Levels of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH), but not those of prolactin (Prl), were elevated 2-to-4-fold in the treated animals at the three ages studied. Serum and testicular testosterone (T) and the receptors for LH and Prl were suppressed in the peripubertal animals (48 and 56 days), but serum T was elevated and the receptor levels were normal in the 90-day group. The testicular FSH receptors were 50% suppressed at all ages studied. Only minor changes were observed in testicular histology when studied at 48 and 56 days. The 85-day-old animals treated with GnRH-Ant. were infertile when mated with females.(ABSTRACT TRUNCATED AT 250 WORDS)     

Further observations on estrus and ovulation in woodchucks (Marmota monax) in captivity.

The woodchuck is a seasonally breeding sciurid rodent. Female woodchucks are monoestrous and, when isolated from males, remain in a prolonged period of estrus characterized by a clear predominance of cornified cells in the vaginal smear. This study was designed to characterize relationships between the degree of vaginal cornification and sexual receptivity, and to study ovulation and related phenomena of this species in captivity. Fourteen individually caged adult females, maintained under standard laboratory conditions for 9-23 mo, were used in this investigation. Females exhibiting predominantly (67-97%) cornified smears were always receptive, regardless of the time interval from the onset of estrus, and mated within 24 h of pairing. Mated females allowed to complete pregnancy gave birth to live pups 30-32 days later. Litter size ranged from 3-7 pups. Serum progesterone (P) levels increased to approximately 2 ng/ml during the first week of pregnancy and greater than 5 ng/ml during the second and third weeks of pregnancy. Serum estradiol (E2) levels were elevated during the first week of pregnancy and began to decline thereafter. Examination of ovarian serial sections revealed that ovulation took place between 20 and 32 h after copulation. Serum levels increased significantly (4-fold) after ovulation (1.2 +/- 0.3 vs. 0.3 +/- 0.01 ng/ml). However, the circulating levels of E2 remained unchanged between the periods before (53 +/- 1 pg/ml) and after ovulation (60 +/- 3 pg/ml). Ovulation was not simultaneous in all mature follicles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hormonal changes during luteal regression in farmed fallow deer, Dama dama

Concentrations of progesterone, oxytocin and PGFM (pulmonary metabolite of PGF-2 alpha) were measured in plasma from peripheral blood samples collected from 5 fallow does every hour or 2 h for 12-h periods on Days 15-20 inclusive of the oestrous cycle (i.e. luteolysis). For 3 does that exhibited oestrus on Day 21, plasma progesterone concentrations fluctuated between 3 and 10 ng/ml on Days 15-18 inclusive. Thereafter, values declined progressively to attain minimum concentrations of less than 0.05 ng/ml on Day 20. Basal concentrations of plasma oxytocin and PGFM fluctuated between 5 and 20 pg/ml and 10 and 100 pg/ml respectively. Episodic pulses of plasma oxytocin (greater than 300 pg/ml) occurred on Days 15 and 16, whereas pulses of plasma PGFM (greater than 400 pg/ml) occurred on Days 19 and 20. There was little apparent correlation between episodic pulses of the two hormones. For 2 does that exhibited oestrus on Day 22, plasma progesterone concentrations declined to minimum values of 1.0-1.5 ng/ml by Day 20. One of these does showed very high levels of oxytocin secretion throughout the sampling period while the other showed an apparent paucity of oxytocin secretory periods. Two does hysterectomized on Day 13 of their second oestrous cycle failed to exhibit further oestrous cycles. Continual elevation of plasma progesterone concentrations (2-6 ng/ml) for an 8-month period indicated persistence of the corpus luteum after hysterectomy. It is concluded that luteolysis in fallow deer involves episodic secretion of both oxytocin and PGF-2 alpha.     

Role of luteinizing hormone-releasing factor (LH-RF) and LH on maintenance of early gestation in rats.

The role of luteinizing hormone (LH) and LH-releasing hormone (LH-RH) in the maintenance of early pregnancy in rats was studied. Serum levels of progesterone (P) and LH were measured daily in untreated pregnant rats from Day 4 through parturition. Serum levels of P and LH were determined on Days 11 and 15 of pregnancy in animals treated with antisera to LH (LH-A/S) and to LH-RH (LH-RH-A/S) on Days 8-10. Serum levels of P peaked on Days 7 and 16 in untreated animals, after which they declined sharply just before delivery. Serum LH fluctuated between 30-160 ng/ml during pregnancy but did not exhibit any distinctive peaks. Treatment with .2 ml LH-A/S on Days 8-10 reduced serum P to virtually undetectable levels on Day 11, and only a slight recovery was evident on Day 15. Lower doses of LH-A/S had no effect. Administration of 1.3 ml LH-RH-A/S had no effect on serum levels of P or LH, and did not impede fetal development. The results indicate that LH is essential to the luteotropic complex of early pregnancy in the rat, and also that LH-RH-A/S can maintain to some extent basal levels of P and LH during early pregnancy.     

Characterization of the epidermal growth factor receptor in preimplantation pig conceptuses.

Embryos recovered from sows on Days 9-13 of pregnancy (Day 0 = first day of estrus) exhibited saturable and time-dependent specific binding of 125I-epidermal growth factor (EGF). The specific binding (pg/mg protein) was greater (P less than 0.001) for Day 13 elongated conceptuses than for conceptuses of earlier stages. Scatchard analyses showed two classes of binding sites (Kd = 7.0 +/- 2.6 x 10(-11) M, Bmax = 6.2 +/- 1.4 fmol/mg protein and Kd = 3.4 +/- 0.2 x 10(-8) M, Bmax = 420 +/- 80 fmol/mg protein). The EGF receptor in Day 13 conceptus membranes is a 170-kDa protein and was phosphorylated in the presence of EGF and adenosine triphosphate. EGF stimulated protein tyrosine kinase activity about 1.6-fold over basal levels. The results show that the preimplantation pig conceptus possesses EGF-binding sites with the properties of functional EGF-receptors.     

Effects of corpus luteum removal on progesterone, estradiol-17 beta and LH in early pregnancy of the tammar wallaby, Macropus eugenii

The quiescent corpus luteum of female tammars was reactivated by removal of the pouch young (RPY). The reactivated corpus luteum was ablated 3 days after RPY. Plasma progesterone and oestradiol concentrations were measured by radioimmunoassay in these and in sham-operated controls. Excision of the CL abolished the rise in progesterone seen at Day 5-6 in the sham-operated animals (130.7 +/- 56.6 vs 452.4 +/- 176.0 pg/ml, mean +/- s.d.). By contrast, oestradiol-17 beta values increased within 6-16 h of CL excision to 16.3 +/- 6.9 pg/ml and remained high for 1-3 days while in the sham-operated animals there were less sustained and more variable peaks of 10-20 pg/ml between Days 3 and 5 (mean 12.0 +/- 3.6 pg/ml at Day 4-5). We conclude that the early transient increase in peripheral plasma of progesterone is of luteal origin but the source of the oestradiol remains unknown.     

Abnormal morphology of the penis in male rats exposed neonatally to diethylstilbestrol is associated with altered profile of estrogen receptor-alpha protein, but not of androgen receptor protein: a developmental and immunocytochemical study

Objectives of the study were to determine developmental changes in morphology and expression of androgen receptor (AR) and estrogen receptor (ER)alpha in the body of the rat penis exposed neonatally to diethylstilbestrol (DES). Male pups received DES at a dose of 10 microg per rat on alternate days from Postnatal Day 2 to Postnatal Day 12. Controls received olive oil vehicle only. Tissue samples were collected on Days 18 (prepuberty), 41 (puberty), and 120 (adult) of age. DES-induced abnormalities were evident at 18 days of age and included smaller, lighter, and thinner penis, loss of cavernous spaces and associated smooth muscle cells, and increased deposition of fat cells in the corpora cavernosa penis. Fat cells virtually filled the entire area of the corpora cavernosa at puberty and adulthood. Plasma testosterone (T) was reduced to an undetectable level, while LH was unaltered in all treated groups. AR-positive cells were ubiquitous and their profile (incidence and staining intensity) did not differ between control and treated rats of the respective age groups. Conversely, ERalpha-positive cells were limited to the stroma of corpus spongiosus in all age groups of both control and treated rats, but the expression in treated rats at 18 days was up-regulated in stromal cells of corpora cavernosa, coincident with the presence of morphological abnormalities. Hence, this study reports for the first time DES-induced developmental, morphological abnormalities in the body of the penis and suggests that these abnormalities may have resulted from decreased T and/or overexpression of ERalpha.     

Circulating progesterone, progesterone-binding proteins and oestradiol-17 beta concentrations in the pregnant Cape porcupine, Hystrix africaeaustralis

Circulating concentrations of progesterone, progesterone-binding plasma proteins (PBPP) and oestradiol-17 beta in pregnant porcupines remained relatively low until Days 25-30 post coitum. Progesterone values peaked (102-180 ng/ml; N = 3) 42-60 days post coitum and the rapid increase in oestradiol-17 beta concentrations approximated that of progesterone with peak values (170-210 pg/ml) being attained 60-85 days post coitum. The pattern of PBPP synthesis, as suggested by circulating concentrations, was closely related to that of plasma progesterone, with values remaining low (less than 20 pmol/ml) until Day 31 post coitum, reaching peak levels at Days 50-56 and Days 73-77 post coitum. The production of PBPP during pregnancy is, as in related New World hystricomorph species, considered to be a mechanism which facilitates a reduction in the rate of progesterone metabolism during pregnancy.     

Peripheral changes in estrone sulfate concentration during the first trimester of gestation in cattle: comparison with unconjugated estrogens and relationship to fetal number

Estrone sulfate originates mainly in the conceptus during gestation in cattle. Its concentration in maternal body fluids is a useful indicator of placental function. The objective of this study was to determine the profiles of estrone sulfate during early gestation in singleton and twin bearing cows using a newly developed extraction method. One or two blastocysts produced in vitro were nonsurgically transferred to regularly cycling Holstein cows on Day 7 (Day 0 was defined as the first day of standing estrus). Pregnancy was diagnosed on Days 30, 45 and 60 by transrectal ultrasonography and finally confirmed at parturition. Six cows with singleton and six with twin pregnancies were used in the experiment. Blood was collected every other morning by jugular venipuncture from the day after transfer to Day 100. Harvested plasma was applied to reversed-phase C18 cartridges. Estrone sulfate and unconjugated estrogens (estrone and estradiol-17beta) retained in the cartridge were eluted separately by methanol stepwise gradient and each measured by validated radioimmunoassay. On average, estrone sulfate concentrations fluctuated between 2 and 6 pg/ml until Day 50 in both groups and then gradually increased. However, the levels of estrone and estradiol- 17beta remained low (1-5 pg/ml) until Day 80. The concentration of estrone sulfate after Day 50 was significantly affected by the day of gestation (P < 0.0001) and the number of fetuses (P < 0.01). After Day 80. estrone sulfate increased drastically, followed by increases in estrone and estradiol-17beta concentrations. The rate of increase in estrone sulfate during Days 80-100 was the greatest among all estrogens (P < 0.05). The rates of increase in estrone sulfate during Days 50-80 and 80-100 were 1.7 times greater in twin pregnancies than in cows having one fetus. These results suggest that the concentration of estrone sulfate in bovine peripheral blood plasma during early gestation has potential application in monitoring embryonic growth as well as fetoplacental development.