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1.
1. Changes in plasma corticosterone concentrations according to puncture sites and various challenges including injections of an ACTH agonist (Immediate Synacthen) were investigated in male mule ducks. 2. Lower concentrations were measured in samples drawn by puncture from the occipital sinus than at a wing vein site. 3. Immobilisation and a single intramuscular injection of saline solution (1 ml, 0.9%) had no effect on plasma corticosterone after 15 min. 4. A single intramuscular injection of ACTH (5 microg/kg body weight) produced a rise (P<0.05) in corticosterone. Maximum concentrations were measured after 10 min and, in the absence of further sampling, a return to initial levels was observed by 1 h. 5. On the other hand, repeated bleedings following ACTH challenge maintained higher corticosterone concentrations. 6. A single intramuscular injection of ACTH at doses ranging between 0.625 to 20 microg/kg body weight increased corticosterone concentrations (P<0.05) in a dose-dependent manner, with the responses plateauing at doses of 1.25 microg/kg and higher.  相似文献   

2.
1. The effects of daily injections of ACTH (30 IU/kg) or physiological saline on growth and on adrenal and lymphoid tissues of Rhode Island Red (RIR) and Light Sussex (LS) chickens were compared at 1, 2 and 3 weeks of age. 2. Saline injections retarded skeletal growth in both strains during the 1st week but only affected weight gain in LS birds. 3. Injections of ACTH depressed growth rate, caused adrenal enlargement and deplenished adrenal cholesterol to the same extent in both strains. 4. ACTH caused a greater reduction in bursal size in RIR than in LS birds. Spleen size was reduced by ACTH only in RIR birds. 5. At 2 and 3 weeks the plasma concentrations of corticosterone of RIR birds were greater than those of LS birds. Plasma corticosterone concentrations were within the normal range 24 h after the last injection of ACTH in both strains. 6. Plasma concentrations of growth hormone was unaffected by ACTH treatment in RIR birds, but it was increased in LS birds after 3 weeks of treatment.  相似文献   

3.
The effects of exogenous adrenocorticortrophic hormone (ACTH) on the serum corticosterone and cortisol concentrations were determined in 28 mature Moluccan cockatoos (Cacatua moluccensis), a representative of the psittacine species. Birds were randomly assigned to 4 groups (2 ACTH-treated groups and 2 saline-treated controls). Group I (10 cockatoos [5 males and 5 females] ) was given 15 IU of ACTH after blood samples (base line) were taken at 10:00 AM. Blood samples were taken again at 30 minutes and 2.5 hours after ACTH administration. Group II (10 cockatoos) was given similar treatment, but blood samples were taken at 1 and 4 hours after ACTH was administered. Groups III and IV (each of 4 birds) were given saline solution injections as controls. Blood samples were taken at 30 minutes and 2.5 hours after injection (group III) and at 1 and 4 hours after injection (group IV). All serum samples were analyzed for cortisol and corticosterone. Serum corticosterone concentration increased significantly (P less than 0.01) from base-line levels (26 ng/ml) to 108 ng/ml within 30 minutes after ACTH was administered. The high values were maintained for 3 hours and then decreased to 40 ng/ml at the end of 4 hours. Male birds seemed to respond to the ACTH treatment quickly and maintained increased concentration for a shorter period when compared with the responses seen in female birds. Serum cortisol values remained low throughout the experimental period. These results indicate that serum corticosterone was responsive to ACTH administration, but cortisol was not. In addition, there may be a difference in the responses between male and female members of the species.  相似文献   

4.
The present study was conducted to determine whether corticosteroids influence the inductive effect of growth hormone (GH) on plasma concentrations of insulin-like growth factor I (IGF-I). The first experiment was designed to determine the effects of corticosterone alone on basal concentrations of IGF-I. Rats were treated daily for 4 d with 0, 50, 100, 250, or 500 mg of corticosterone/kg of BW. There was a close positive relationship between the dose of steroid injected and plasma concentrations of corticosterone and a close negative relationship between plasma corticosterone and growth. Plasma concentrations of IGF-I showed a positive relationship to dose and plasma concentrations of corticosterone and a negative relationship to growth rate. In the second experiment, rats were treated daily for 21 d with either porcine growth hormone (10 mg of pGH/kg of BW), pGH plus corticosteroid, or vehicle. The dose of steroid administered was increased every 3 d until the mean weight gain of the group was zero. Animals treated with pGH alone gained significantly more weight than controls. This growth response was not impaired significantly by corticosterone acetate at doses up to 500 mg/kg of BW. The more potent corticosteroid, cortisone, arrested the growth of pGH-treated rats at a dose of 80 mg/kg of BW, however. Plasma concentrations of IGF-I were increased by pGH treatment (57%) and increased further by concurrent cortisone treatment (212%). In summary, corticosteroids increase plasma concentrations of IGF-I and enhance the inductive effect of pGH on this hormone despite their catabolic actions.  相似文献   

5.
应用提取的鼠脂肪细胞膜分别免疫羊和鸡 ,所产生的抗血清用于 Wistar大鼠被动免疫。实验 1: 组腹腔注射羊正常血清 , 组腹腔注射羊抗鼠脂肪细胞膜抗血清 ,剂量均为 1m L /只 ,连续注射 4 d。结果表明 ,羊抗鼠脂肪细胞膜抗血清免疫促进了大鼠体增重 ,降低了体脂沉积 ,与对照组相比 ,7周末体重增加 6 .35 % (P<0 .0 5 ) ,饲料摄入增加6 .85 % (P<0 .0 1) ,料重比 (F/G)提高 4 5 .0 0 % (P<0 .0 5 ) ;肾周、附睾、网膜脂肪垫重量分别降低 2 3.92 % (P<0 .0 5 )、34.4 5 % (P<0 .0 5 )、0 .98% ,脂肪总量降低 2 0 .92 %。实验 2 :1组腹腔注射鸡正常血清 ,2组腹腔注射鸡抗鼠脂肪细胞膜抗血清 ,剂量均为 1m L/只 ,连续注射 4 d。结果表明 ,鸡抗鼠脂肪细胞膜抗血清免疫对大鼠的生长发育产生了不利影响 ,7周末 ,免疫大鼠平均体重较对照组减少 4 0 g(P<0 .0 5 ) ,饲料摄入显著降低 (P<0 .0 1) ;对体脂的沉积和血液中 TG和 FFA的影响没有规律 ,且无统计学意义  相似文献   

6.
The effects of administration of estradiol antiserum to pregnant rats on birth weight, subsequent growth velocity, carcass composition, and reproductive performance of their offspring were examined. Treated rats were injected i.p. with a potent antiestradiol serum on d 12 of gestation, whereas control rats received a similar injection of normal sheep serum. The pups from the treated rats were 12.2% heavier at birth than those from control rats (P less than .01) and had a greater postnatal growth rate (P less than .05). Chemical analysis of body composition at 56 d of age revealed that there was a tendency for female offspring from treated rats to exhibit carcass characteristics (such as increased percentage of body fat) that were more similar to those of normal male rats than to those of normal female rats. Neither onset of puberty nor reproductive performance was affected by the treatment. These results indicate that treatment of rats during pregnancy with antiestradiol may have potential as a technique for increasing postnatal growth rates.  相似文献   

7.
Effect of ACTH on plasma corticosterone and cortisol in eagles and condors   总被引：1，自引：0，他引：1  
The effect of ACTH on plasma corticosterone and cortisol was determined in 12 eagles (Haliaeetus leucocephalus) and in 6 Andean condors (Vultur gryphus). In all raptors, the concentration of plasma corticosterone was substantially greater than that of cortisol. After ACTH administration, the eagles had a marked increase (P less than 0.001) in plasma corticosterone concentrations, but not in plasma cortisol. Administration of saline solution did not induce increased plasma corticosterone concentrations in the eagles. The condors had a smaller increase (P less than 0.002) in plasma corticosterone concentrations after ACTH administration, as compared with that of the eagles. However, administration of saline solution in 2 condors resulted in an increase in corticosterone similar to the increase after ACTH administration. In the condor, a stress-related release of endogenous ACTH may have an effect similar to that induced by exogenously administered ACTH. Plasma cortisol concentrations did not increase significantly after administration of ACTH or saline solution in either raptor species.  相似文献   

8.
The effect of adrenocorticotropin hormone (ACTH) on plasma cortisol and on gonadotropin releasing hormone (GnRH)-induced release of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone was determined in nine Holstein bulls and 12 Holstein steers. Treatments consisted of animals receiving either GnRH (200 micrograms, Group G), ACTH (.45 IU/kg BW, Group A) or a combination of ACTH followed 2 h later by GnRH (Group AG). Group G steers and bulls had elevated plasma LH and FSH within .5 h after GnRH injection and plasma testosterone was increased by 1 h after GnRH injection in bulls. In Group A, plasma cortisol was elevated by .5 h after ACTH injection in both steers and bulls, but plasma LH and FSH were unaffected. In Group A bulls, testosterone was reduced after ACTH injection. In Group AG, ACTH caused an immediate increase in plasma cortisol in both steers and bulls, but did not affect the increase in either plasma LH or FSH in response to GnRH in steers. In Group AG bulls, ACTH did not prevent an increase in either plasma LH, FSH or testosterone in response to GnRH compared with basal concentrations. However, magnitude of systemic FSH response was reduced compared with response in Group G bulls, but plasma LH and testosterone were not reduced. The results indicate that ACTH caused an increase in plasma cortisol, but did not adversely affect LH or FSH response to GnRH in steers and bulls. Further, while testosterone was decreased after ACTH alone, neither ACTH nor resulting increased plasma cortisol resulted in decreased testosterone production in the bull after GnRH stimulation.  相似文献   

9.
OBJECTIVE: To assess serum 17-alpha-hydroxyprogesterone (17OHP) and corticosterone concentrations in dogs with nonadrenal neoplasia and dogs being screened for hyperadrenocorticism. DESIGN: Prospective study. ANIMALS: 16 clinically normal dogs, 35 dogs with nonadrenal neoplasia, and 127 dogs with suspected hyperadrenocorticism. PROCEDURE: ACTH stimulation tests were performed in all dogs. Baseline serum cortisol and corticosterone concentrations were measured in the healthy dogs; baseline serum cortisol concentration and ACTH-stimulated cortisol, corticosterone, and 17OHP concentrations were measured in all dogs. Endogenous plasma ACTH concentration was also measured before administration of ACTH in dogs with neoplasia. RESULTS: In 35 dogs with neoplasia, 31.4% had high serum 17OHP concentration and 22.9% had high serum corticosterone concentration. Of the 127 dogs with suspected hyperadrenocorticism, 59 (46.5%) had high ACTH-stimulated cortisol concentrations; of those, 42 of 59 (71.2%) and 32 of 53 (60.4%) had high serum 17OHP and corticosterone concentrations, respectively. Of dogs with serum cortisol concentration within reference range after ACTH administration, 9 of 68 (13.2%) and 7 of 67 (10.4%) had high serum 17OHP and corticosterone concentrations, respectively. In the dogs with neoplasia and dogs suspected of having hyperadrenocorticism, post-ACTH serum hormone concentrations were significantly correlated. CONCLUSIONS AND CLINICAL RELEVANCE: Serum concentrations of 17OHP or corticosterone after administration of ACTH may be high in dogs with nonadrenal neoplasia and no evidence of hyperadrenocorticism. Changes in serum 17OHP or corticosterone concentrations after administration of ACTH are proportionate with changes in cortisol concentration.  相似文献   

10.
1. Three‐week‐old Light Sussex (LS) and Rhode Island Red (RIR) chicks were injected with long‐acting corticotrophin (ACTH: 30 IU/kg) and the plasma concentrations of corticosterone, growth hormone (GH) and prolactin were determined over a 6‐h period. Plasma concentrations of corticosterone and growth hormone were also measured after an injection of corticosterone (500 μg/kg).

2. The resting plasma concentration of corticosterone in LS was less than that in RIR birds. The increase elicited by ACTH was smaller in LS but, since it was maintained for longer, the plasma corticosterone response was at least 18% larger than that in RIR birds.

3. Plasma GH concentration was decreased after an injection of ACTH in both strains but the decrease lasted longer in the LS chicks.

4. Plasma prolactin concentration was unaffected by ACTH.

5. After intra‐abdominal injection of corticosterone, plasma GH concentration was depressed in both strains. It is concluded that ACTH‐induced depression of plasma GH and growth is mediated by corticosterone.  相似文献   


11.
The effect of intramuscular injection of naloxone, an antagonist of opiatergic actions, on serum concentrations of luteinizing hormone (LH) and ovarian activity in prepuberal ewes was investigated. Naloxone stimulated release of LH over a period of approximately 3 h. Subsequently, serum concentrations of LH did not differ from controls. Serum concentrations of estradiol-17β were elevated 8 h after treatment with naloxone. Ewe lambs did not ovulate. Endogenous opioid peptides may be involved in the regulation of secretion of LH in immature female sheep.  相似文献   

12.
We reported previously that passive immunization against inhibin enhances follicular growth and increases the ovulation rate. However, the ovulation rate was not comparable to the number of follicles. Therefore, the aim of this study was to attempt to increase the ovulation rate by increasing the interval between inhibin immunization and PGF2alpha injection. Five miniature Shiba goats were treated with 10 ml inhibin antiserum (inhibin-AS) developed against [Tyro30]-inhibin alpha (1-30). A control group (n=5) was treated with normal goat serum. All animals were injected intramuscularly with 125 microg PGF2alpha 72 h after treatment to induce estrus and ovulation. Blood samples were collected for hormonal assay and the ovulation rate was determined by laparotomy. In contrast to the control group, there was a significant increase in plasma concentrations of FSH in the immunized group. After luteolysis, plasma concentrations of estradiol-17beta increased markedly to a preovulatory peak about 2 folds higher (P<0.01) than that of controls. In addition, the ovulation rate was greater in the immunized group (14.4 +/- 2.2) than in the control group (2.2 +/- 0.6), and the mean number of follicles > or = 4 mm in diameter was 10.0 +/- 0.8 in the inhibin-AS group compared with 2.4 +/- 0.3 in control group. The present results demonstrate that immunoneutralization of endogenous inhibin increased FSH secretions in miniature shiba goats. The increased FSH secretion enhanced follicular growth and increased the ovulation rate. Additionally, increasing the interval between inhibin-AS and PGF2alpha injections (to 72 h) resulted in a greater ovulation rate compared with the previous protocol (48 h). Therefore, inhibin-AS treatment proved to be an effective alternative to exogenous gonadotropin methods for induction of superovulation in goats.  相似文献   

13.
The effect of selection for high stress response on adrenocortical function was examined by measuring the corticosterone response of adrenocortical cells isolated from random-bred Japanese quail and quail selected for high serum corticosterone response to immobilization (high-stress). Highly enriched adrenocortical cells were incubated with various concentrations of ACTH1-24 (ACTH), 8-bromo-cyclic AMP (8Br-cAMP) and pregnenolone for 2 hr. Corticosterone production was measured by radioimmunoassay. Basal corticosterone production values by cells from random-bred and high-stress birds were not different. In contrast, the average maximal ACTH- and 8Br-cAMP-induced corticosterone production by cells from high-stress quail was 89% greater than that of cells from random-bred quail. However, the average pregnenolone-supported corticosterone production by cells from high-stress birds was 34% less than that of cells from random-bred birds. Thus, the data suggest that although random-bred quail cells had a greater potential capacity for corticosterone production, high-stress quail cells had a greater ability to couple ACTH, ACTH-transmembrane-signaling factors and subsequent second messengers with the available steroidogenic enzyme pool. The magnitude of the differences in function between cells from high-stress and random-bred birds was greater for female cells compared to male cells. In addition to differences in cellular function, there were also differences in adrenal and relative adrenal weights between random-bred and high-stress quail. The average, adrenal and relative (mg/100 g body weight) adrenal weights of high-stress quail were 14-16% greater than those of random-bred quail. It is concluded that the enhanced serum corticosterone response of the high-stress quail line is, in part, due to an increase in relative adrenal weight and an increase in adrenocortical cell responsiveness to ACTH.  相似文献   

14.
In boars and rabbits, administration of adrenocorticotropic hormone (ACTH) results in a testis-dependent, short-term increase in concentrations of testosterone in peripheral plasma. This experiment was designed to assess the short-term effects of a single ACTH injection on plasma concentrations of testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH) and cortisol in stallions. Eight light horse and two pony stallions were paired by age and weight and then one of each pair was randomly assigned to the treatment (ACTH, .2 IU/kg of body weight) or control (vehicle) group. Injection of ACTH increased (P<.01) plasma concentrations of cortisol by approximately twofold in the first 60 minutes; control stallions showed no change (P>.10) in concentrations of cortisol during the blood sampling period. Control stallions exhibited a midday increase (P>.05) in concentrations of testosterone similar to that reported previously; ACTH treatment prevented or delayed this increase such that concentrations of testosterone in treated stallions were lower (P<.05) than in controls 4 to 5 hours after injection of ACTH. Treatment with ACTH had no effect (P<.10) on plasma concentrations of LH or FSH up to 12 hours after injection.  相似文献   

15.
1. Adult White Leghorn hens showing short or long tonic immobility reactions were classified as low-fear (LF) or high-fear (HF) responders, respectively. Following cannulation, their adrenocortical responsiveness to ACTH administration and the effects of chronic frustration induced by thwarting of feeding on plasma corticosterone concentrations and heterophil/lymphocyte (H/L) ratios were measured at regular intervals. 2. ACTH injection elicited significant and similar mean increases in circulating corticosterone concentrations in both the LF and HF groups. 3. Absolute H/L ratios were higher in HF than in LF hens after cannulation, although both groups showed similar proportional increases from pre-operation ratios. 4. Plasma corticosterone concentrations and H/L ratios were significantly increased at 20 h and 44 h respectively after the frustration of feeding regime began. Thus, adrenocortical activation preceded increases in H/L ratios but, whereas the elevated plasma corticosterone concentrations found after 20 h remained virtually constant thereafter, H/L ratios rose progressively throughout the 68 h frustration period. 5. There were no significant differences between groups in their plasma corticosterone and H/L responses to frustration. However, a consistent trend towards greater adrenocortical activation was observed in the HF than in the LF hens.  相似文献   

16.
Effects of exogenous ACTH on plasma corticosterone and cortisol concentrations and the effects of thyroid stimulating hormone (TSH) on plasma triiodothyronine (T3) and thyroxine (T4) were determined in the following 3 species of parrots: red-lored Amazon (group 1), blue-fronted Amazon (group 2), and African gray (group 3). Each bird was given ACTH (0.125 mg/bird) IM, except for 3 to 4 birds in each group, which were given saline solution (controls). Blood samples were collected before and 90 minutes after ACTH stimulation. In group 1 (n = 12), mean plasma corticosterone concentrations increased significantly (P less than 0.001) from 1.06 microgram/dl (before ACTH) to 4.89 micrograms/dl (after ACTH); mean corticosterone concentrations increased in the control birds from 1.06 microgram/dl to 1.84 microgram/dl; and mean cortisol concentrations increased only slightly from 0.228 microgram/dl to 0.266 microgram/dl. In group 2 (n = 12), mean corticosterone concentrations increased significantly (P less than 0.001) from 2.09 micrograms/dl to 10.58 micrograms/dl; control mean corticosterone concentrations decreased slightly from 2.09 micrograms/dl to 1.77 microgram/dl; and mean cortisol concentrations increased from less than or equal to 0.16 microgram/dl to 0.266 microgram/dl. In group 3 (n = 12), mean plasma corticosterone concentrations increased significantly (P less than or equal to 0.001) from 2.33 micrograms/dl to 4.67 micrograms/dl; mean control plasma corticosterone concentrations decreased from 2.33 micrograms/dl to 1.68 microgram/dl; and plasma corticol concentrations were not detectable. Each bird was given TSH, IM (1 U/bird). Blood samples were collected before and 6 hours after TSH administration. Saline solution was not administered as controls.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
胆酸负荷对绵羊和大鼠血浆(血清)甘胆酸浓度的影响   总被引：5，自引：2，他引：3  
湖羊通过颈静脉插管灌注较高剂量的胆酸和大鼠通过尾静脉给予不同剂量的胆酸造成胆酸负荷,研究其对血浆（血清）甘胆酸（ＣＧ）浓度的影响,结果表明：湖羊血浆ＣＧ浓度在灌注胆酸后呈波动性变化,在１８ｈ和１３８ｈ显著高于灌注前。大鼠以中胆酸组血清ＣＧ变动最为显著,灌注４ｈ后开始升高,１８ｈ后达到显著水平,一直持续至１３８ｈ,并在１８,９０,１１４和１３８ｈ显著高于对照组;低胆酸组仅在灌注后１８ｈ血清ＣＧ显著高于对照组,其他时间变化不显著;而高胆酸组在灌注后４２,６６,９０和１１４ｈ显著高于灌注前,但与对照组比较差异均不显著  相似文献   

18.
The effect of ACTH (16 units) on plasma cortisol and corticosterone concentrations in healthy psittacine birds was evaluated. Plasma corticosterone significantly increased (P less than 0.01) from a mean (+/- SD) basal concentration of 3.25 +/ 3.6 ng/ml to 26.47 +/- 9.25 (one hour after ACTH administration) and 25.69 +/- 13.23 ng/ml (2 hours after ACTH administration). For maximal increase in plasma corticosterone as measured by radioimmunoassay (RIA), heat denaturation was necessary to release corticosteroids from steroid-binding proteins. As measured by RIA, plasma cortisol concentrations did not increase, whether or not the heat denaturation step was included. Addition of cortisol to avian plasma did not prevent accurate quantification of cortisol as measured by RIA. Plasma corticosterone concentrations in cockatoos, macaws, Amazon parrots, conures, and lorikeets before and after ACTH administration indicated that the ACTH stimulation test could be used to evaluate adrenal secretory capacity in psittacine birds.  相似文献   

19.
The objectives of this study were first to show adrenocortical response to a long‐acting adrenocorticotropic hormone preparation (tetracosactide acetate zinc suspension) (ACTH‐Z) and its effect on adrenocortical function in beef cows ( Experiment 1 ) and second to apply the ACTH‐Z challenge in dairy cows based on cortisol concentrations in milk collected at routine milking ( Experiment 2 ). In Experiment 1 , four beef cows in luteal phase were challenged with ACTH‐Z, and plasma cortisol concentrations were determined for 48 h after the injection at 30‐min to 2‐h intervals. A rapid ACTH test was conducted 3 days before and 2 h after the completion of ACTH‐Z injection for 48 h to investigate the effect on adrenocortical function. Plasma cortisol concentrations increased significantly 30 min after ACTH‐Z injection (p < 0.001), and the high cortisol levels were maintained for approximately 10 h after the injection. In Experiment 2 , eight dairy cows were subjected to ACTH‐Z challenge 1–2 weeks and 4–5 weeks post‐partum. Blood and milk samples were taken at morning and afternoon milking. All the cows showed a significant increase in cortisol concentrations in plasma as well as in skim milk 8 h after ACTH‐Z injection 1–2 weeks and 4–5 weeks post‐partum (p < 0.001). There was a significant correlation between plasma and skim milk cortisol concentrations 8 h after ACTH‐Z challenge (r = 0.74, p < 0.001). The results obtained in this study suggest that elevated levels of plasma cortisol are maintained for approximately 10 h after ACTH‐Z treatment without adverse effect on adrenocortical function and a long‐acting ACTH‐Z challenge based on cortisol concentrations in milk, which were collected at the morning and the afternoon milking, can be a useful tool to monitor adrenocortical function in cows.  相似文献   

20.
Antiserum generated in a horse against testosterone conjugated to bovine serum albumin (BSA) was administered to six lighthorse mares (androgen-immunized mares) 1 to 3 d before a prostaglandin-induced estrus and twice again at 2-d intervals. Six control mares were administered antiserum generated against BSA on the same schedule. Relative to testosterone, cross-reactivities of other steroids with the testosterone antiserum were (%): dihydrotestosterone, 52; 5 alpha-androstane-3 alpha,17 beta-diol, 8.6; androst-4-ene-3,17-dione, 1.2; and all others tested less than .1. Tritiated testosterone binding in plasma increased (P less than .01) in androgen-immunized mares within 1 h and remained elevated (P less than .01) relative to controls for greater than 21 d. There was no effect (P greater than .10) of passive immunization against androgen on interval to estrus after prostaglandin injection, duration of estrus, ovarian volume, number of palpable follicles or follicular volume during estrus. In contrast, concentrations of luteinizing hormone (LH) were higher (P less than .05) in androgen-immunized mares than in control mares during estrus and early diestrus. Concentrations of follicle stimulating hormone (FSH) and progesterone at those times were not affected (P greater than .10). From these data, we conclude that androgens in the mare during estrus may be involved with the regulation of LH secretion. In contrast, no involvement with FSH secretion was apparent under these short-term conditions.  相似文献   

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