Hormonal changes during forced moult induced by progesterone in domestic hen

Forced moulting has been induced in domestic hens by progesterone treatment (5 mg/day) for 25 days. Moult happened between the 11th and 19th day after the first treatment. Endocrine changes were followed during the moult by blood sampling in one week intervals. At the time of the last sampling, new egg laying cycle was initiated in all birds. Plasma progesterone concentration increased significantly in response to the treatment then tended to decrease. Oestrone and testosterone levels were the lowest during the period when feather loss was most intensive and increased in the course of feathering. This increase was significant in the case of oestrone. The level of 17-beta-oestradiol did not vary during moult induced by progesterone treatment. Plasma concentration of thyroxine significantly increased during feather loss, showing a maximum in the second and/or third week after the beginning of the treatment, while it decreased when feather growth had begun. Plasma triiodothyronine as well as corticosterone levels were the highest during the latest phase of moult, at the time of feather outgrowing. It has been supposed that moulting would be initiated in response to the synergistic effect on feather follicles of progesterone and thyroxine, which was stimulated by the progesterone treatment. The atrophic stage of the ovary suggested that progesterone was probably of adrenal origin. It was assumed that triiodothyronine and oestrone were responsible for controlling feather outgrowth.     

Effect of thyroxine on the hemoglobin affinity to oxygen and 2,3-diphosphoglycerate level in rat erythrocytes

Affinity of hemoglobin to oxygen was studied in rat erythrocytes under conditions of intraperitoneal administration of thyroxin in a dose of 0.4 mg per 100 g of animal weight each 24 h for five days. A significant right shift of the oxyhemoglobin dissociation curve is observed only on the 6th day simultaneously with the increase of the 2,3-diphosphoglycerate level in erythrocytes in the period under study. The results obtained from the study of the thyroxin effect on the respiratory function of hemoglobin permit recommending it as an antihypoxant.     

The effect of 17β-estradiol treatment on the mass and the turnover of bone in ovariectomized rats taking a mild dose of thyroxin

We performed the dosing experiment to establish whether estrogen administration has any beneficial effects on the mass and the turnover of bone in ovariectomized rats taking a mild dose of thyroxin. Thirty-five Wistar rats, 28 weeks of age, received ovariectomies (OVX) or sham operations and were divided into five groups. Group I was the sham group, Groups 2–5 were ovariectomized. Group 2 was the OVX-control, Group 3 treated with thyroxin 30 μg/kg/day (T4), Group 4, 17β-estradiol 0.3 mg/kg/week (E2), and Group 5, the combination of T4 and E2. The duration of the experiment was 12 weeks. At the end of the experiment, serum chemistries were measured. Bone minerals in the femur were determined with single photon absorptiometry and bone turnover was assessed histomorphometrically. Alkaline-phosphatase increased in Group 3 (OVX-T4), but it reduced in Groups 4 (OVX-E2) and 5 (OVX-T4 + E2). Bone minerals decreased in Groups 2 (OVX) and 3. In Group 4, it was preserved at the same level as in Group 1. Group 5 showed a significant increase of bone mass compared with Group 1. Eroded surface and osteoid surface increased in Groups 2 and 3 and they were reduced in Groups 4 and 5. Bone volume and mineral apposition rate were at a maximum in Group 5. This study demonstrated that 17β-estradiol was capable of preventing the bone mass decrease by regulating the turnover in ovariectomized rats taking a mild dose of thyroxin. Osteoblast function appeared to be stimulated in combination with 17β-estradiol and thyroxin.     

Influence of different doses of progesterone treatments on ovarian follicle status in beef cows

To determine a dose of progesterone (P4) that allow ovarian follicular wave control, Aberdeen Angus cows were randomly assigned into four groups: T600 (n=5), 600 mg of P4/day; T400 (n=5), 400 mg of P4/day; T200 (n=4), 200mg of P4/day and Control (n=4) (excipient only). Progesterone was injected from day 3 to 9 of estrous cycle. Ultrasonographies and blood sample collections were performed daily from day 2 to 10 and on day 15 of the estrous cycle. Additionally, an ultrasonographic study was conducted on day 13. Progesterone concentrations were different among all groups (P<0.01). The diameter of the dominant follicle was greater for control than for T200, T400 and T600 groups (P<0.01); there was no difference between T200 and T400 (P>0.05), but they had a greater diameter follicle than the T600 group (P<0.01). The growth rate of the dominant follicle between day 3 and 7 of estrous cycle was greater for control group (1.63+/-0.3 mmday(-1)) than for T200 (0.56+/-0.19 mmday(-1), P<0.05), T400 (0.6+/-0.23 mmday(-1), P<0.05) and T600 (0.11+/-0.13 mmday(-1), P<0.01) groups. The mean number of class I follicles (3-4mm) per day for the entire experimental period was less for the control group than for T200 (P<0.05), T400 and T600 (P<0.01) groups (3.7+/-1.3; 5.3+/-1.3; 6.6+/-1.8 and 8.1+/-1.9, respectively). The mean number for the T200 group was less than for T600 (P<0.05) and similar for T400 and T600 groups (P>0.05). The number of class III follicles was greater for control group than for the other groups (P<0.01). T200 and T400 groups had similar numbers of class III follicles (P>0.05) and both had greater numbers of follicles than the T600 group (P<0.05). The diameter of the corpus luteum of the T600 group (15.8+/-1.6 mm) was less than for control (21.0+/-2.5 mm, P<0.01), T200 (19.3+/-2.7 mm, P<0.01) and T400 (20.0+/-2.2 mm) groups (P<0.05). The mean diameter of corpus luteum of T200 was similar to T400 (P>0.05), but different from the control group (P<0.05). In conclusion, the daily intramuscular administration of 200mg or more of progesterone from day 3 to 9 of the estrous cycle indicates that plasma concentrations of progesterone can be used to modify the pattern of follicular development during the follicular wave. From day 5 of the estrous cycle, progesterone concentrations greater than 15 ng/ml (T600 group: 600 mg/day of progesterone from day 3 to 9 of the estrous cycle) inhibit dominant follicle development, increase the class I follicle populations (3-4 mm) and diminish the development of the corpus luteum.     

Control of parturition in the sow using progesterone and prostaglandin

The effect of progesterone and prostaglandin administration on the timing of farrowing was studied in three groups of 25 sows each. Progesterone treatment (100 mg/day) on days 112, 113 and 114 of gestation (group I) significantly prolonged the gestation length to 116.4 +/- 0.4 (mean +/- s.e.) days compared to the control sows (group III; 115.5 +/- 0.2; P less than 0.05). Administration of prostaglandin (200 micrograms Cloprostanol intramuscularly) on day 115 of gestation following progesterone treatment (group II) resulted in a gestation length of 116.0 +/- 0.1 days, with the sows farrowing 25.4 +/- 1.0 h after the prostaglandin injection. 80% of the sows farrowed between 0800 and 1700 h of day 116 of gestation. Plasma progesterone levels were maintained by the exogenous progesterone during treatment. At farrowing, higher levels of progesterone were observed in groups I and II compared to controls. Prostaglandin treatment did not significantly alter withdrawal of progesterone in progesterone treated sows, suggesting that the actions of exogenous prostaglandin is primarily on the myometrium and the cervix. Hormonal treatment in late pregnancy did not have any adverse effects on piglet viability and growth rate, or subsequent reproductive performances of sows. Lactation was initiated normally, and the concentrations of lactose, protein, fat, IgG, Na+, Ca2+ and K+ in colostrum and milk were similar in all groups during the first 5 days of lactation.     

Effect of GnRH administration, combined with the ram effect, on the occurrence of ovulation and pregnancy during the transition period from anoestrus in crossbred ewes

The effect of a GnRH analogue (buserelin) combined with the ram effect on the reproductive efficiency of ewes was investigated in 105 cross-bred fat tailed ewes, during the transition period from anoestrus to the natural breeding season. Plasma progesterone concentration was used in the assessment with regard to ovulation and pregnancy. Ewes were maintained on natural pastures composed of medium to low quality forages, and received supplementation (40% alfalfa hay: 60% wheat straw) ad libitum, plus 100–300 g barley grain per head per day. Ewes were isolated from the rams for at least two months and then kept in close proximity of the rams for one week, before the introduction of the rams. The ewes were randomly divided into three equal groups (n = 35 per group). With the introduction of the rams into the flock (day 1) one group was considered as the control and the other two groups were treated with 4.2 μg (low dose) and 8.4 μg (high dose) buserelin on days 5 and 19, respectively. Blood samples were collected on days 5, 12, 26 and 120 after ram introduction for determining the plasma progesterone levels. On day 12 (one week after treatment) the high dose GnRH group recorded significantly lower plasma P4 concentrations (P < 0.05), compared with the control group (1.0 ± 0.1 ng/ml versus 2.4 ± 0.4 ng/ml). On the same day the low GnRH dose group recorded intermediate P4 concentrations, recording no significant differences with the other two groups. The high dose group recorded a significantly (P < 0.05) higher proportion of non-ovulated ewes (61.8%), compared to the control (32.3%) and low dose (31.4%) groups on day 12 of the study. At days 5 and 26 these differences were not significant, but the proportion of non-ovulated ewes was higher in the high dose buserelin treatment group. The percentage of pregnant (plasma P4 > 2.5 ng/ml) and non-pregnant (plasma P4 ≤ 2.5 ng/ml) ewes at day 120 of the study was not statistically different between the treatment groups. The pregnancy rate was highest in the control group (97.1%), when compared to the treated ewes (94.3% and 88.6% in low dose and high dose treatment groups, respectively). Treatment with buserelin combined with the male effect during the breeding season negatively affected the plasma P₄ concentration, reducing the reproductive performance of the ewe treatment groups.     

Effect of in ovo leptin administration on the development of Japanese quail

Potential changes in the activity of endocrine axes related to growth as a result of leptin administration during embryonic development of birds were evaluated in the Japanese quail as a model bird with fast growth and development. On day 5 of incubation, 0.1 microg or 1 microg of recombinant mice leptin in 50 microl of phosphate buffered saline were injected into the albumen of eggs. Animals from each group were killed by decapitation on day 0, 2, 5, 7, 14, 21, 28, 35, 42, 49 and 56 of life. Plasma concentrations of triiodothyronine (T(3)), thyroxin (T(4)), corticosterone, testosterone, total lipids, triacylglycerols, cholesterol, glucose and alkaline phosphatase activity were measured. Quail treated by leptin hatched earlier (5-24 hours) and had a higher body weight than the control group (P<0.05-0.001). Mean body weight across the whole observed period was higher in both treated groups as compared to the control group (P<0.05). Leptin in ovo administration was accompanied by changes of endocrine and metabolic parameters during postembryonic development. The most prominent changes appeared immediately after hatching (T(3), T(4), total lipids, triacylglycerols) and before sexual maturity. It is suggested that leptin acts as a general signal of low energy status to neuroendocrine systems in birds which improves utilization of nutrients.     

Subpopulations of mononuclear leukocytes associated with inhibition of Ehrlich ascites tumor growth by treatment with Bothrops jararaca venom

Snake venoms have been used as antineoplastic substances in several experimental models. We demonstrated in previous studies that Bothrops jararaca venom (BjV) induces inhibition of Ehrlich ascites tumor (EAT) growth accompanied by an increase of mononuclear (MN) leukocytes in all groups inoculated with EAT and/or venom. The objective of the present study was to characterize the subpopulations of MN leukocytes involved in the inhibition of EAT growth by treatment with BjV. Swiss mice were inoculated with 1.0x10(3) EAT cells by the intraperitoneal route and treated with 0.4 mg/kg of BjV by the same route (Group TV). Treatment was started 24 h after tumor cell inoculation and consisted of five intraperitoneal injections performed at 72 h intervals. After 2, 8 and 14 days, groups of animals were sacrificed and the number of B, TCD4 and TCD8 lymphocytes, macrophages and natural killer cells present in the peritoneal cavity was determined by flow cytometry. The control group consisted of animals inoculated with EAT and treated with 0.1 ml of saline under the same conditions as the experimental group (Group T). Two additional control groups consisted of animals not inoculated with EAT and treated with saline or venom. Data were analyzed statistically by the Kruskal-Wallis non-parametric test for independent samples. On the 2nd and 8th day we observed a difference between groups T and TV (group T > group TV) for all cell types, except natural killer cells, that only differed on the 2nd day. However, on the 14th day there was no difference in MN cells among groups. These data suggest that the inhibition of EAT is related to the toxic action of BjV on tumor cells and/or to the proteolytic effect of the venom on the mediators produced by the cells for growth modulation.     

Effect of progesterone on ovarian follicles, emergence of follicular waves and circulating follicle-stimulating hormone in heifers.

The hypothesis was tested that greater growth of the dominant follicle of wave 1 (first follicular wave of an interovulatory interval), compared with that of subsequent anovulatory waves, is due to lower circulating concentrations of progesterone during the growing phase of the follicle. Control heifers (n = 6) were compared with heifers (n = 6) treated with a decreasing dose of progesterone from day 0 to day 5 (ovulation = day 0). Maximum diameter (12.7 +/- 0.9 versus 15.3 +/- 0.7 mm) and mean diameter of the dominant follicle of wave 1, averaged over days, were smaller (P < 0.05) in the progesterone-treated than in the control group. Progesterone treatment did not suppress circulating follicle-stimulating hormone (FSH); but the second FSH surge was earlier, resulting in earlier emergence of wave 2 as indicated by a tendency (P < or = 0.1) for group x day interactions attributed to earlier detection of the dominant follicle and an earlier rise in the total number of follicles detected. The stated hypothesis was supported. We also tested the hypothesis that exposure to low circulating concentrations of progesterone at the end of the growing phase of the anovulatory dominant follicle of wave 1 results in continued growth and prolonged maintenance of the dominant follicle. Heifers (n = 6 per group) were given a luteolytic dose of prostaglandin F2 alpha (PGF2 alpha) on day 6 and treated with a low (30 mg day-1), physiological (150 mg day-1), or high (300 mg day-1) dose of progesterone on days 6 to 20. Continued periodic emergence of anovulatory follicular waves occurred (2.1 +/- 0.0 waves, 2.8 +/- 0.2 waves, 3.8 +/- 0.3 waves, respectively; P < 0.05) until treatment was stopped (interovulatory intervals: 26.2 +/- 1.0, 30.8 +/- 0.6 and 40.3 +/- 1.7 days, respectively; P < 0.05). Compared with the physiological dose group, the growth of the dominant follicle was inhibited to a lesser degree in the low-dose group since it grew for longer (P < 0.05) and to a larger diameter (P < 0.05), and persisted for longer (P < 0.05). Prolonged dominance of this oversized (> 20 mm) follicle was associated with delayed emergence of wave 2. The hypothesis was supported. Results also showed that the high dose of progesterone suppressed the dominant follicle more than the physiological dose when given during the growing phase, but not when given after the growing phase.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect on pregnancy and plasma progesterone of exogenous steroid maintenance in ovariectomised pregnant rabbits

Pregnancy was maintained in ovariectomised does with 1 to 4 mg/day of exogenous progesterone with or without 0.2 μg/day of estradiol. Progesterone doses were designed to give similar plasma progesterone levels in treated groups to those found in normal pregnancy, and were measured and compared with normals since this comparison does not appear to have been published previously. In normal pregnancy mean progesterone levels reached 10 ng/ml on day 7 and then plateaued at 14 ng/ml between day 10 and 20 before falling to very low levels at parturition. In treated groups progesterone levels reached 10 ng/ml on day 6 and remained between 10 and 13 ng/ml until day 20 before declining. The difference between treated and control plasma progesterone plateau levels was tested using the t-test and was found not to be significant. The differences in progesterone levels between treated groups with or without estradiol, whether pregnant or not, were also not significant. Mean litter sizes (alive or dead) were not significantly different. However, fetal viability in the group maintained on progesterone alone was significantly lower than in the normal controls.     

Induction of estrus in cows by a new analogue of PGF2α(alfaprostol)

A new analogue of PGFα, alfaprostol, was used to induce estrus in normally cycling and anestrous cows.Five groups of six animals were treated with single injections of different doses of the drug (4, 5, 6, 7 or 8 mg/animal) on day 10–11 of the estrous cycle. Six cows in anestrus, with palpable corpora lutea, were treated i.m. with 8 mg/animal. The luteolytic properties of alfaprostol were assessed by measuring milk progesterone by RIA for 96 h after treatment and by checking for the subsequent signs of estrus. The dose of 4 mg caused a slight fall in progesterone but did not induce heat; the 5 and 6 mg doses induced estrus in animals and the 7 mg dose was effective in animals. The 8 mg dose produced a sharp reduction in milk progesterone within 24 h, followed by estrus in both the normally cycling and the anestrous groups in animals. No clinical signs of drug intolerance were seen. The present results show that alfaprostol might be of great use for both cycle synchronization in normally cycling cows and for treatment of anestrus caused by a persistent corpus luteum.     

不同治疗方案对原发免疫性血小板减少症患者外周血调节T细胞水平变化的影响及其意义分析(英文)

目的:探讨原发免疫性血小板减少症(immune thrombocytopenia,ITP)患者治疗前后外周血调节性T细胞(regulatory T cell,Treg)水平变化及其在ITP发病中的作用。方法:选取2010年6月至2013年7月间276例新诊断ITP患者,男114例、女162例,中位年龄40(18-70)岁。按治疗方案随机分为地塞米松组(90例):地塞米松40 mg/d第1~4天口服;泼尼松组(98例):泼尼松1.5 mg·kg-1·d-1口服;2泼尼松组(98例):泼尼松1.5 mg·kg-1·d-1口服;地塞米松+小剂量利妥昔单抗组(88例):地塞米松40 mg/d第1-4天口服,利妥昔单抗100 mg第7、14、21、28天静脉滴注。各组患者于治疗前、治疗后14 d和28 d分别采取外周静脉血,采用流式细胞术检测CD4+CD25+CD127-细胞水平。以60名健康体检者为正常对照组。结果:治疗后第28天,地塞米松组、泼尼松组、地塞米松+小剂量利妥昔单抗组的总有效率分别66.7%、69.4%、79.5%,差异无统计学意义;随访12个月,泼尼松组(37.8%)和地塞米松组(22.7%)之间差异无统计学意义,而与地塞米松+小剂量利妥昔单抗组持续有效率(66.7%),差异有统计学意义(P0.05)。所有ITP患者治疗前外周血CD4+CD25+CD127-细胞表达水平低于健康对照组[(1.66±0.69)%对(4.01±0.38)%,P0.05];地塞米松组、泼尼松组患者治疗后14d CD4+CD25high CD127low细胞水平均高于治疗前[(3.46±0.76)%对(1.68±0.72)%、(3.22±0.77)%对(1.69±0.74)%,P值均0.05];地塞米松+小剂量利妥昔单抗组治疗后14、28d CD4+CD25+CD127-细胞水平[(4.27±1.08)%、(4.43±0.62)%]均高于治疗前[(1.67±0.67)%],差异有统计学意义(P值均0.05);治疗后28 d,泼尼松组、地塞米松组患者CD4+CD25+CD127-细胞水平[(2.68±0.63)%、(2.58±0.66)%]与治疗前比较差异无统计学意义。结论:地塞米松联合小剂量利妥昔单抗在长期疗效及提升T细胞数量方面显著优于地塞米松和泼尼松,值得临床推广。     

Effect of in ovo injection of vitamin C during incubation on hatchability of chickens and ducks

The aim of the investigation was to ascertain the influence of different doses of vitamin C injected at selected dates of incubation into the eggs of broiler breeders and Pekin ducks on hatchability. The injected vitamin C doses were administered into the air cell on the 13th, 15th and 17th days (3 and 6 mg--chickens) and on the 12th and 20th days (4 and 8 mg--ducks) of incubation. In the case of chickens, no significant differences were recorded between the control and experimental groups with regard to hatchability, although the highest value of hatchability from fertilized eggs was determined in the group injected with 6 mg of vitamin C on the 15th day of incubation. On the other hand, in ducks, significant differences were found between the control and experimental groups (4 mg of vitamin C administered on days 12 and 20 and 8 mg of vitamin C injected on day 20 of incubation) regarding hatchability. The value of this trait was higher in the group of eggs injected with ascorbic acid in comparison with the eggs which were not treated. On average, the difference amounted to 32.5 percentage points. Similarly, in the case of the number of dead embryos and unhatched chicks, better results were observed in the above-mentioned experimental groups. In summary, vitamin C injected into chicken eggs failed to influence hatchability. In the case of duck eggs, it was demonstrated that their injection on the 20th day of incubation with selected doses of vitamin C (4 and 8 mg/egg) improved hatchability by decreasing the proportions of dead and unhatched embryos.     

Progesterone and estradiol in biodegradable microspheres for control of estrus and ovulation in mares

Progesterone and estradiol 17-beta in poly (DL-lactide) microspheres were used to control estrus and ovulation in mares after luteolysis was induced by prostaglandin F(2)infinity. Mares were given a single intramuscular injection of biodegradable poly (DL-lactide) microspheres, 1 day following prostaglandin treatment, containing no hormones (control), 0.625 g progesterone and 50 mg estradiol (low dose), 1.25 g progesterone and 100 mg estradiol (medium dose), or 1.875 g progesterone and 150 mg estradiol (high dose; n=15 mares per group). Mares treated with the low dose had significantly longer intervals (P<0.05) to estrus and ovulation than the control mares; however, low dose mares had shorter intervals (P<0.05) to estrus than high dose mares and shorter intervals to ovulation than medium and high dose mares. Regression analysis indicated that the medium dose was sufficient for maximizing interval to ovulation while the high dose maximized interval to estrus. All groups of mares exhibited similar (P>0.05) post-treatment estrus lengths. A clinical response scoring system based on synchrony of both estrus and ovulation within a treatment group was also used to measure the effectiveness of treatments on control of estrus and ovulation. Clinical response scores did not differ (P>0.05) among treatment groups. Mares were randomly assigned for insemination at the beginning of the first post-treatment estrus. Rates for embryo recovery performed by uterine lavage 7 days post-ovulation did not differ (P>0.05) among groups. Concentrations of serum progesterone increased in mares receiving progesterone and estradiol microspheres. At 10 to 14 days post-injection of microspheres, progesterone concentrations were higher (P<0.05) and remained above 1 ng/ml in the mares receiving the high dose. Progesterone concentrations were also higher (P<0.05) on Days -3 to -1 (Day 0 = day of post-treatment ovulation) in mares receiving the high dose when compared to control mares. Gonadotropin concentrations were suppressed (P<0.05) in the medium and high dose groups.     

The effects of delaying the start of moult on the duration of moult, primary feather growth rates and feather mass in Common Starlings Sturnus vulgaris

In many species of birds there is a close relationship between the end of breeding and the start of moult. Late-breeding birds therefore often start to moult late, but then moult more rapidly. This is an adaptive mechanism mediated by decreasing day lengths that allows late-breeding birds to complete moult in time. This study asked how these birds complete moult of the primary feathers more rapidly, and the consequences of this on the mass of primary feathers. Common Starlings Sturnus vulgaris were induced to moult rapidly in one of two ways. In the first experiment, one group was exposed to artificially decreasing photoperiods from the start of moult, whereas the control group remained on a constant long photoperiod. The second experiment was a more realistic simulation. Two groups were allowed to moult in an outdoor aviary. One group started to moult at the normal time. In the other, the start of moult was delayed by 3 weeks with an implant of testosterone. The duration of moult was significantly reduced in both the group experiencing artificially decreasing photoperiods and the group in which the start of moult was delayed. The faster moult rate was achieved by moulting more feathers concurrently. The rate of increase in length of each of the primary feathers, and their final length, did not differ between groups. The rate at which total new primary feather mass was accumulated was greater in more rapidly moulting birds, but this was insufficient to compensate for the greater numbers of feathers being grown concurrently. Consequently, the rate of increase in mass of individual feathers, and the final feather mass, were less in the rapidly moulting birds. A 3-week delay in the start of moult is not an unrealistic scenario. That this caused a measurable decrease in feather mass suggests that late-breeding birds are indeed likely to suffer a real decrease in the quality of plumage grown during the subsequent moult.     

Effects of various doses of testosterone propionate on intratesticular and plasma testosterone levels and maintenance of spermatogenesis in adult hypophysectomized rats.

Adult hypophysectomized rats were maintained on different regimens of testosterone propionate (TP) treatment for 27 days (0.2, 0.4, 0.6 and 1 mg/day) and autopsied 16 hours after the last injection. Blood samples were taken, sex organs were weighed and one testis from each animal was fixed in Bouins fluid for histologic analysis. The other testis and blood were used for testosterone (T) determinations. Both testicular and plasma T were below detectable levels in hypophysectomized control rats. The plasma T level showed a dose response relationship with increasing dose of TP but such was not the case for intratesticular T concentrations. Qualitative and quantitative evaluation of testis sections showed that spermatogenesis was incomplete in rats receiving 0.2 mg TP/day characterized by the absence of step 15 to 19 spermatids, degeneration of some pachytene spermatocytes and a significantly lower yield of B type spermatogonia. Analysis of testis sections from animals treated with 0.4 to 1 mg TP/day showed complete maintenance and maturation of pachytene spermatocytes, meiosis and spermiogenesis. However, even with the highest dose of TP (1 mg/day) the total yield of B type spermatogonia was only about 58% of the intact controls. It is concluded that at least 0.4 mg/day of exogenous TP is essential for qualitative maintenance of spermatogenesis in hypophysectomized rats with an intratesticular T concentration of 17 to 18 ng/gm testis.     

Inability of progestogen pretreatment to prevent premature luteolysis of induced corpora lutea in the anestrous bitch

Fourteen mature anestrous bitches were used to determine the effectiveness of pretreatment with an orally active progestogen to prevent premature luteolysis of induced corpora lutea (CL) in the anestrous bitch. In Group 1, seven bitches were treated orally with megestrol acetate (Ovaban((R))) at the rate of 2.2 mg/kg body weight for eight days. Three days later, the bitches were treated daily with pregnant mare's serum gonadotropin (PMSG) (44 IU/kg body weight) administered intramuscularly for nine consecutive days, and each bitch was given 500 IU human chorionic gonadotropin (HCG) on day 10, or on the first day of induced estrus if the bitches exhibited estrus while being treated with PMSG. A control group (Group 2) of seven bitches was not treated with Ovaban((R)) but was similarly given PMSG and HCG. Estrus was detected twice daily using a vasectomized male dog and verified by vaginal cytology. Blood samples were obtained on the first day of induced estrus (day 0) and every other day until day 90 post-estrus. Plasma progesterone (P(4)) concentrations were determined by a non-extraction solid phase radioimmunoassay (RIA), and data were analyzed by Student's t-test. There was no significant difference between the progesterone profiles of both groups of bitches. In addition, P(4) values were less than 1 ng/ml by day 50 post-estrus. Results of this study suggested that pretreatment with an orally active progestogen was not effective in preventing premature luteolysis of induced CL in the anestrous bitch.     

Plasma gonadotropins and prolactin in pseudopregnancy in the rat

Radioimmunoassay presented a method of measuring plasma levels of FSH,LH and prolactin in pseudopregnant rats. Plasma prolactin levels doubled 15 minutes following cervical probing (p .01) on the day of estrus. Plasma LH levels were not significantly elevated. Due to the use of ether anesthesia at blood collecting 3 hr before and 15 minutes after stimulation, only 1 of 16 rats developed pseudopregnancy. On Day 4 of pseudopregnancy in rats mated with vasectomized males; plasma LH was lower (p .05) than in normal rats on the first day of diestrus, perhaps due to the suppressive action of ovarian progesterone and some estrogen. FSH was higher than in normal rats (p .05) perhaps due to the lesser sensitivity of FSH to the inhibitory effect of progesterone. Large decidoumata developed by Day 9 in uterine horns traumatized on Day 4 (153 plus or minus 8 mg uterus weight compared to 1510 plus or minus 204 mg). Thus, the corpora remain functional after LH and prolactin are at normal and subnormal levels. On Day 9 plasma prolactin was lower than at Day 1 of diestrus (p .001). Plasma FSH was elevated (p .01). Plasma LH was unchanged. The degree of rise of LH levels 5 days following ovariectomy on Day 4 of psuedopregnancy or on the first day of diestrus was greater in the former group (p .02), perhaps due to rebound of LH from suppression by ovarian steroids. FSH rose equally in both groups. Prolactin remain about the same. Increased prolactin release by the adenohypophysis was briefer than expected.     

Action of GnRH on steroid secretion by luteal cells of cyclic and early pregnant sows in vitro

The effect of GnRH was studied on progesterone (P4), oestradiol-17 beta (E2) and testosterone (T) secretion by porcine luteal cells from the 13th day of the oestrous cycle and the 18th day of pregnancy. Trypsin-dispersed luteal cells (5 X 10(4) cells/ml) were incubated in medium 199 with 10% calf serum with or without GnRH in doses of 0.1, 1, 10 and 100 mg/ml and with 1 microgram LH and 50 U/ml hCG. The concentration of P4, E2 and T in the medium was estimated by radioimmunological method after 6 hours of incubation. The results showed that GnRH had no effect on the secretion of the investigated steroid hormones by luteal cells from cyclic sows. GnRH at a dose of 10 g inhibited E2 secretion and at a dose of 1 ng T secretion by cells from pregnant sows. LH and hCG stimulated release of P4 by luteal cells in both physiological stages. The conclusion drawn was that GnRH does not act directly on luteal cells of cyclic sows but may inhibit E2 and T secretion by cells of pregnant sows.