Concentration of steroids in bovine peripheral plasma during the oestrous cycle and the effect of betamethasone treatment.

Testosterone, oestradiol and progesterone were measured in peripheral plasma during the oestrous cycle of 6 heifers. Oestradiol and progesterone results confirmed earlier reports. Concentration of testosterone on the day of oestrus was 40+/-3 pg/ml (mean+/-S.E.M.), and two peaks were detected during the cycle, one 7 days before oestrus (1809+/-603 pg/ml) and the other (78+/- 7 pg/ml) on the day before the onset of oestrus. The concentration of progesterone declined in most cases 1 day after the maximum concentration of testosterone. Betamethasone treatment in 5 heifers extended luteal function by an average of 10 days: plasma androstenedione and oestradiol concentrations were unaltered; cortisol values were depressed for at least 16 days after treatment; testosterone concentrations were lowered by 13+/-2-4% during treatment, and except in one heifer the peak on Day -7 was abolished.     

Gas chromatographic determination of unconjugated dehydroepiandrosterone, androstenedione, testosterone, pregnenolone and progesterone in human ovarian tissue.

A gas chromatographic method has been presented for the determination of unconjugated dehydroepiandrosterone, androstenedione, testosterone, pregnenolone and progesterone in human ovarian tissue. The procedure utilized radioactive tracers added to homogenate for correcting methodological loss, preliminary separation of steroids by thinlayer chromatography, acetylation, rechromatography on chromatoplate and gas chromatography on 3% SE-30 or 1% XE-60 columns with flame ionisation detection of steroids by using internal standards. Results of control experiments and representative clinical findings on normal and polycystic ovaries are reported.     

Energy substrates in bovine oviduct and uterine fluid and blood plasma during the oestrous cycle

Up to 40 percent of cattle embryos die within 3 weeks of fertilization but there is little or no published information on the composition of the oviduct and uterine fluids essential for their survival during this time. We have measured the concentrations of the energy substrates, glucose, lactate, and pyruvate in cattle oviduct fluid on Days 0, 2, 4, and 6 and uterine fluid on Days 6, 8, and 14 of the oestrous cycle and corresponding blood samples. Oviduct and uterine fluids were collected in situ. Glucose concentrations in oviduct and uterine fluids were similar on all days and lower than in plasma (P < 0.05). Oviduct lactate concentration was up to eightfold higher than uterine or plasma concentration (P < 0.01). Oviduct pyruvate concentrations were similar on all days and lower than plasma concentrations on Days 0 and 2 (P < 0.005). Pyruvate concentrations were similar in the uterus and in plasma except on Day 14 when the concentration in plasma was higher (P < 0.05). There were no associations between systemic progesterone or oestradiol and glucose, lactate or pyruvate. There was a linear positive relationship (P < 0.001) between oviduct fluid secretion rate and oviduct glucose concentration and a linear negative relationship (P < 0.001) between oviduct fluid secretion rate and oviduct lactate, but no association between uterine fluid secretion rate and energy substrates. The different concentrations and associations between the energy substrates in oviduct and uterine fluids and blood plasma indicate a differential regulation of the secretion of these energy substrates by the oviduct and uterine epithelium.     

Episodic secretion of gonadotrophins and ovarian steroids in jugular and utero-ovarian vein plasma during the follicular phase of the oestrous cycle in gilts

Blood samples were collected simultaneously from the jugular and utero-ovarian veins of 13 gilts from Days 11 through 16 of the oestrous cycle. A luteolytic dose (10 mg) of PGF-2 alpha was given on Day 12 to facilitate the natural occurrence of luteolysis and standardize the associated decrease in concentrations of progesterone. The mean interval from PGF to oestrus was 5.5 +/- 0.7 days (mean oestrous cycle length = 17.5 +/- 0.7 days). Mean concentrations, pulse amplitudes and pulse frequencies of oestradiol and progesterone were greater (P less than 0.05) in the utero-ovarian than jugular vein. Secretory profiles of LH and FSH were similar (P greater than 0.05) in plasma collected simultaneously from both veins. Based on these data, temporal relationships among hormonal patterns of FSH and LH in the jugular vein and oestradiol and progesterone in the utero-ovarian vein were examined. Concentrations of progesterone declined (P less than 0.05) between Days 12 and 14, while all secretory variables for oestradiol increased (P less than 0.05) from Day 12 through 16 of the oestrous cycle. The pulsatile secretion of FSH remained relatively constant during the experiment. However, both pulse amplitude and mean concentration tended (P less than 0.2) to be lower on Day 16 compared with Day 12. The episodic secretion of LH shifted from a pattern characterized by high-amplitude, low-frequency pulses to one dominated by numerous pulses of diminishing magnitude between Days 13 and 14. From Days 14 to 16 of the oestrous cycle, 91% of all oestradiol pulses were temporally associated with gonadotrophin pulses composed of both FSH and LH episodes. However, pulses of oestradiol (52%) not associated with an episode of LH and/or FSH were observed on Days 12 and 13. These data demonstrate that during the follicular phase of the pig oestrous cycle substantial oestradiol production occurred coincident with luteolysis and before the shift in the episodic secretion of LH. The pool of follicles which ovulated was probably the source of this early increase in the secretion of oestradiol. Therefore, we propose that factors in addition to FSH and LH are involved in the initial selection of follicles destined to ovulate during the early stages of the follicular phase of the pig oestrous cycle. In contrast, high-frequency, low-amplitude pulses composed of LH and FSH were the predominant endocrine signal associated with oestradiol secretion during the second half of the oestrous cycle.(ABSTRACT TRUNCATED AT 400 WORDS)     

Simultaneous radioimmunoassay of androstenedione, dehydroepiandrosterone and 11-beta-hydroxyandrostenedione in plasma

A simultaneous radioimmunoassay for delta 4-androstenedione (delta 4), dehydroepiandrosterone (DHA) and 11 beta-hydroxyandrostenedione (11 beta OH delta 4) in plasma is described. This involved preparing first an anti-11 beta-hydroxyandrostenedione-3-0-carboxymethyl oxime/BSA antiserum which binds both delta 4 and 11 beta OH delta 4, and an anti-dehydrosterone-7-0-carboxymethyl oxime/BSA antiserum. A chromatographic step using celite minicolumns separates these three steroids. The method was applied to the measurement of the plasma basal values of these three androgens in control subjects. Mean concentrations (ng/ml) of delta 4, DHA and 11 beta OH delta 4 were respecstively 1.35, 6.63 and 3.13 in males; 1.35, 6.65 and 2.59 in premenopausal females; 0.46, 1.53 and 1.38 in post-menopausal females, and 0.39, 0.73 and 1.78 in children 1--6 years of age. Dynamic tests were also carried out: ACTH stimulation was found to increase delta 4, DHA and 11 beta OH delta 4. Dexamethasone had a reverse effect causing a 50% diminution in delta 4 levels, a marked decrease in DHA levels, and a 90% decrease in 11 beta OH delta 4 levels. Metyrapone test was found to produce a 223% increase in delta 4 levels, a 196% increase in DHA levels, and a decrease of more than 90% in the 11 beta OH delta 4 levels. Estroprogestative drug treatment was accompanied by a decrease of not only delta 4, but also of DHA and 11 beta OH delta 4. Preliminary clinical results concerning these steroids show a parallel increase or decrease of delta 4 and 11 beta OH delta 4 in adrenal pathology. In ovarian hyperandrogeny, delta 4 is increased and 11 beta OH delta 4 is unchanged.     

Variations in the concentrations of androstenedione in peripheral plasma of women the day and during the menstrual cycle

The target tissues (e.g., hypothalamus, pituitary, uterus and vagina) of mature female ovariectomized rats show selective uptake of radioactivity in one hour after the injection of 6,7, ³H-estradiol-17β in a dose of 0.1 μg per 100 g body weight. Injection of 100 μg norethindrone or norgestrel per 100 g body weight 15 min before or 15 min after the administration of tritiated estradiol reduced the radioactivity in most target tissues, and also in the non-target tissues to a lesser extent. The uptake of radioactivity in the pituitary and uterus is reduced more by norethindrone than by norgestrel treatment when these Steroids were injected 15 min after estradiol-17β injection. It appears that there exists a competitive inhibition of estradiol-17β by these contraceptive Steroids in the rat. It is speculated that such competition with estradiol-17β may be an inherent property of the 17-substituted 19-nortestosterone group of Steroids.     

Histochemical localization of NADPH-d-positive structures in bovine uterine and ovarian arteries during the oestrous cycle and early pregnancy

The aim of the present study was to histochemically demonstrate nitric oxide synthase-related NADPH-d activity in ovarian and uterine arteries of heifers at different stages of the oestrous cycle and during early pregnancy. Catalytic activity of NADPH-d activity was found in the endothelial lining of all examined vessels, however, staining intensity was higher in the segments ipsilateral to the corpus luteum than in those taken from the contralateral side. Moreover, the reaction was much more intense during the luteal than during the follicular stage of the cycle. Similar differences were observed for NADPH-d activity in the muscular coat. In conclusion, the present results suggest that the endothelial/muscular cells may be the main source of nitric oxide in the studied parts of the bovine arteries, and also that NADPH-d activity may depend on the hormonal status of the organism.     

The effect of ACTH therapy on serum dehydroepiandrosterone, androstenedione, testosterone and 5 alpha-dihydrotestosterone in infants

Serum concentrations of dehydroepiandrosterone (DHEA), androstenedione, testosterone, 5 alpha-dihydrotestosterone and cortisol were measured in 10 infants (age 5-22 months) before, during and after 6-weeks of ACTH therapy for infantile spasms. During therapy, their mean DHEA concentrations increased 2.3-fold, androstenedione 12.3-fold, testosterone 2.7-fold, 5 alpha-dihydrotesterone 2.5-fold and cortisol 2.9-fold compared to pre-therapy values. Serum dehydroepiandrosterone sulphate (DHEA-S) concentrations were also increased during ACTH therapy above the normal prepubertal range. Three days after the cessation of ACTH treatment, all androgens had returned to the pre-therapy level. We conclude: At least in pharmacologic doses ACTH alone stimulates adrenal androgen secretion in infants, excluding the necessity of a separate adrenal androgen stimulating hormone.     

Variations in oxytocin, vasopressin and neurophysin concentrations in the bovine ovary during the oestrous cycle and pregnancy

Bovine ovaries were obtained from the abattoir and corpora lutea were classified as: (1) early luteal phase (approximately Days 1-4); (2) mid-luteal phase (Days 5-10); (3) late luteal phase (Days 11-17); (4) regressing (Days 18-20) and (5) pregnant (Days 90-230). In addition, preovulatory follicles and whole ovaries without luteal tissue were collected. Concentrations of oxytocin, vasopressin, bovine neurophysin I and progesterone were measured in each corpus luteum by radioimmunoassay. Progesterone and neurophysin I levels increased from Stage 1 to Stage 2, plateaued during Stage 3 and declined by Stage 4. Oxytocin and vasopressin concentrations increased from Stage 1 to Stage 2 but declined during Stage 3 and were low (oxytocin) or undetectable (vasopressin) in follicles, whole ovaries and pregnancy corpora lutea. Therefore the concentrations of both peptide hormones were maximal during the first half of the cycle and declined before those of progesterone. The high concentration of oxytocin within the corpus luteum coupled with the presence of bovine neurophysin I suggests that oxytocin is synthesized locally.     

Androstenedione and testosterone concentrations in plasma and milk of the cow throughout pregnancy

Androstenedione concentrations in both plasma and milk were higher than those of testosterone throughout pregnancy. Testosterone concentration increased during pregnancy; the levels in milk were always lower than in plasma. Androstenedione concentrations increased in plasma and milk during pregnancy but the values were twice as high in milk as in plasma after Day 90. This change in androstenedione distribution suggests that the mammary gland could be active in the uptake of androstenedione from plasma to milk or that the mammary gland itself might synthesize this hormone.     

Levels of prostaglandin F (PGF) in bovine endometrium uterine venous, ovarian arterial and jugular plasma during the estrous cycle (38789).

Prostaglandins F (PGF) were measured in uterine vein, ovarian artery, and jugular vein plasma and in the endometrial tissues at various times during the bovine estrous cycle, and were compared to peripheral plasma progesterone levels. Four groups of heifers at days 1-5, 10-14, 15-17 and 20-0 of the estrous cycle were studied. Low levels of PGF (48 plus or minus 12 ng/g dry tissue were measured in the endometrium on days 1-14 of the cycle. Higher values (131 plus or minus 9.0) were found at days 15 until the day of estrus (p less than 0.001). Similarly, very low levels of PGF were observed in the uterine vein plasma at days 1-14 (0.162) plus or minus 0.044) ng/mlM plus or minus S.E.), whereas on days 15 until the day of estrus the levels ranged from 1.5 to 3.0 ng/ml. The increases in uterine vein PGF on day 15 occurred even while peripheral plasma progesterone levels were still high. However, PGF was not elevated in either the ovarian artery or the jugular vein at any time during the cycle, even when uterine vein levels were greatly elevated. No differences in PGF content were detected in endometrial tissue from uterine horns adjacent or opposite to the functional corpus luteum.     

Changes in serum leptin, insulin, androstenedione and luteinizing hormone during ovarian cycle in the bat, Taphozous longimanus

Detailed reproductive pattern and associated endocrine characteristics have been documented in only a few species of order Chiroptera. The aim of the present study was to examine the changes in body weight, serum insulin, leptin, androstenedione and luteinizing hormone (LH) concentrations during annual ovarian cycle in the sheath-tailed bat, Taphozous longimanus. Bats were sampled over three years. Leptin, a satiety hormone produced primarily by adipose tissue, provides information to feeding center of the brain about nutritional status, fat mass, appetite and energy expenditure. The circulating concentration of leptin begins to increase from October and attains a peak in December. The peak serum leptin concentration coincides with body weight in November before winter dormancy in December. The serum leptin levels dissociate from body weight during December. The other peaks of serum leptin levels coincide with late stages of the two successive pregnancies. The serum insulin concentration begins to increase from September and attains a peak during December. The insulin concentration remains low from January to August. The circulating androstenedione concentration begins to increase in October, reaching a peak in December. This increase in androstenedione concentration correlated with the period of heavy accumulation of abdominal fat and increase in body weight. There was a sharp decline in androstenedione concentration and body weight in January. The serum LH shows peaks, in November, coinciding with the peaked body weight, the other peaks in January and May, coinciding with ovulation for the two successive pregnancies. The high leptin and insulin levels might be responsible for the maintenance of reproductive response and gonadal function during adverse environmental condition in the winter, while high androstenedione, and associated body weight along with LH might be responsible for maintaining basal gonadal function. We conclude that high leptin, androstenedione and insulin serve, as signal for the reproductive functions in that sufficient body fat are available to meet the caloric demands and maintain normal function during adverse winter conditions.     

Contractility of the ovarian vascular bed during the oestrous cycle and early pregnancy in gilts

The vasoconstrictor activity of the ovarian vascular bed in vitro was investigated during the oestrous cycle and early pregnancy. Gilts were killed during the follicular phase (Days 20 to +1; N = 5) or luteal phase (Days 11 to 13; N = 4) of the oestrous cycle, or on Day 13 of pregnancy (N = 5). Immediately before death, a sample of vena cava blood was obtained for determination of progesterone and oestrogen (oestrone and oestradiol-17 beta) concentrations. One ovary was removed, cannulated, perfused in vitro, and subjected to 10-min infusions of saline (vehicle control) and noradrenaline. Vasoconstriction was provoked by electrical stimulation at the end of each infusion. Ovaries from luteal-phase gilts exhibited greater (P less than 0.01) vasoconstriction than did ovaries from follicular-phase and pregnant gilts at the end of saline and noradrenaline infusions. The oestrogen to progesterone ratio was less (P less than 0.01) for luteal-phase and pregnant than for follicular-phase gilts. Vasoconstriction was negatively correlated (r = -0.99, P less than 0.01) with the oestrogen to progesterone ratio in systemic blood of gilts during the oestrous cycle but not during early pregnancy (r = +0.39, P greater than 0.10), possibly due to an effect of the conceptuses.