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J. F. SMITH and A. J. ALLISON

The volume of cervical mucus produced in the ewe appears to be controlled by the circulating levels of oestrogen (Vickery & Bennett, 1968), and is greatest during pro-oestrus and oestrus (Grant, 1934). The volume produced is of the order of 20 ml (Restall, 1967) and in spayed ewes is a linear function of the quantity of exogenous oestrogen (Lindsay & Francis, 1968).

It seems, therefore, that the disturbance in the pattern of oestrogen production in the ewe in which oestrus is controlled with progestagen-impregnated sponges (Smith & Robinson, 1970) may be reflected in the production of cervical mucus and that this could account for the changed pattern of transport of spermatozoa following progestagen treatment (Quinlivan & Robinson, 1967, 1969).

Forty-five Merino ewes, aged 5 years, randomized into three progestagen-dose-level groups of fifteen ewes

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L. A. Hinds and M. J. Smith

Summary. Female brush-tailed bettongs, Bettongia penicillata, were housed with either an intact or vasectomized male or isolated from males in the peripartum period. Development of the quiescent corpus luteum formed at the post partum oestrus was initiated by removing the pouch young. Blood samples for analysis of plasma progesterone were collected from the females 2 days before removal of pouch young, daily for 5 or 6 days and then 2·3 times each week until 19 days after removal of pouch young.

Plasma progesterone profiles were similar in pregnant and nonpregnant cycles. There was an early progesterone peak (1206 ± 121 pg ml−1, mean ± sem; n = 16) between days 2 and 5 after removal of pouch young, and a second period of high concentrations (> 800 pg ml−1) before birth on day 17·4 ± 0·2 (n = 16). The interval between the early peak and birth was 14 or 15 days. On five of 34 occasions, no increases in plasma progesterone concentrations occurred after removal of pouch young.

On 12 of 15 occasions for 13 females that had been isolated from males post partum, plasma progesterone concentrations also remained low (< 100 pg ml−1) and did not change after removal of pouch young. Females that showed no increases in plasma progesterone concentration after removal of pouch young had significantly lower (P < 0·001) plasma progesterone concentrations while lactating than those females that did undergo a cycle after removal of pouch young (60 ± 4 pg ml−1, n = 17 and 225 ± 23 pg ml−1, n = 30, respectively). Females isolated from males post partum, and monitored until day 12 after removal of the pouch young, and that showed no increases in progesterone in this period, had ovaries that contained no corpus luteum, only corpora albicantia and numerous atretic or developing follicles.

We conclude that brush-tailed bettongs are induced ovulators, a characteristic described for only one other marsupial, Monodelphis domestica, from South America.

Keywords: pregnancy; oestrous cycle; marsupial; brush-tailed bettong

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R. J. Fairclough, J. F. Smith and A. J. Peterson

Previous studies have suggested that the biological activity of steroid hormones can be neutralized by antibodies raised against steroid–protein hormones. Active (Ferin, Zimmering, Lieberman & Vande Wiele, 1968) or passive (Scaramuzzi, 1975) immunization procedures have been reported. The latter method is particularly useful when studying the physiological role of hormones in the oestrous cycle when hormonal changes occur during a relatively short interval.

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J. F. Smith, R. J. Fairclough and A. J. Peterson

Summary. Plasma concentrations of progesterone and Provera were measured daily in 3 cows during 21 days of treatment with Provera-impregnated intravaginal sponges. Plasma concentrations of oestradiol-17β and 13,14-dihydro-15-keto-prostaglandin F (PGFM) were measured hourly from 5 h before until 62 h after sponge removal. The profile of progesterone concentrations indicated that luteolysis occurred at the expected time (Days 19 to 23 of the cycle), even though plasma Provera concentrations were 150–250 pg/ml. The occurrence of peaks of PGFM after sponge withdrawal suggests that PGF-2α release is stimulated by falling levels of progestagen.

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A. J. Peterson, R. J. Fairclough and J. F. Smith

Summary. Androstenedione and testosterone were measured by radioimmunoassay after chromatography on micro-columns of Lipidex-5000 in jugular plasma samples taken every 2–3 h at the time of luteolysis and oestrus in 3 dairy cows. The concentrations of androstenedione and testosterone varied between 5 and 60 pg/ml and 5 and 80 pg/ml respectively and no consistent pattern in the fluctuations of either steroid was observed.

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J. F. PORTER, A. T. SHENNAN and SANDRA SMITH

Summary.

Kininogen and kinin levels in venous plasma were determined in groups of normal adult men and women and in pregnant women at different periods of gestation and in labour.

Kininogen levels were found to be significantly higher in the pregnant women than in the male and female controls. A significant positive linear correlation was found between period of gestation and plasma kininogen level.

Differences between the mean plasma kinin levels in groups of control adults and pregnant women were in most cases not significant.

No significant linear correlation was found between kinin and kininogen levels in plasma in any of the groups studied and no definite trends were found in the kinin and kininogen levels at delivery.

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J. M. DAVIDSON, ERLA R. SMITH and D. A. DAMASSA

Summary.

Following suppression of plasma LH titres in castrated male rats by various doses of testosterone propionate, a more rapid return to pretreatment levels was seen when a period of 8 (or 5) weeks intervened between castration and onset of treatment. This effect was not related to differential retention of testosterone in the circulation.

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T. A. Parkening, T. J. Collins and E. R. Smith

Summary. Circulating plasma concentrations of LH from young mature (3–4 months old), middle-aged (15–18 months old) and aged (31–32 months old) male C57BL/6 mice, Syrian hamsters (3–4, 19–20 and 24–25 months old), Fischer 344 rats (3–4, 18–19 and 28–29 months old), Chinese hamsters (3–4, 19–20 and 29–30 months old) and Mongolian gerbils (3–4 and 19–22 months old) were analysed using a radioimmunoassay (RIA) and a radioreceptor assay (RRA). Male rats exhibited the greatest changes with advancing age: the oldest rats had an almost undetectable quantity of plasma LH, as measured by both assays. In contrast, the oldest male Syrian hamsters had significantly higher levels of LH than did younger animals. A significant decrease occurred in the amounts of LH detectable by RRA in middle-aged Chinese hamsters which was not evident with the RIA. There were no statistically significant differences in LH levels of C57BL/6 mice and gerbils with increasing age. The mean RRA:RIA ratios indicated that age-related differences in LH concentrations resulted from physiological changes in the secretion or the metabolic clearance of LH and not from changes in the biological potency of LH.

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T. A. Parkening, T. J. Collins and E. R. Smith

Summary. Plasma and pituitary concentrations of LH, FSH and prolactin were determined by radioimmunoassay in 2-month-old (young) and 16–20-month-old (old) C57BL/6 mice. There were no statistical differences in hormonal levels between aged females in oestrus (those exhibiting a copulatory plug) and those in constant dioestrus. In the old females plasma levels of LH (P < 0·002) and FSH (P < 0·001) were significantly elevated, while levels of prolactin (P < 0·001) were significantly depressed when compared with those from young animals. Pituitary homogenates from old females also contained more gonadotrophins (P < 0·001) and less prolactin (P < 0·001) than those of the young females. A radioreceptor assay utilizing a plasma membrane of luteinized rat or mouse ovaries indicated that LH from 2-month-old animals bound better to ovarian receptors (P < 0·05) than did LH from old mice, although radioimmunoassay of the same samples gave higher ( P < 0·01) plasma LH levels for the old mice. Since the radioreceptor assay is considered to be a more sensitive test for biologically active LH, the results from these two types of assays suggest that there may be an alteration in the mouse LH molecule with age.

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J. L. Juengel, G. W. Smith, M. F. Smith, R. S. Youngquist and H. A. Garverick

Although the decrease of progesterone in serum and in luteal tissue during luteal regression is well characterized, relatively little is known about changes in proteins produced by the corpus luteum during this time. The first objective was to examine changes in patterns of protein secretion that might be associated with functional and structural luteal regression. The second objective was to characterize the expression of two major secretory products of regressing corpora lutea. Thirty normally cyclic heifers were randomly assigned at day 15–16 of the oestrous cycle (oestrus = day 0) to be ovariectomized at 0 h (no PGF; n = 5) or at 4, 8, 12, 24 or 48 h after PGF-induced luteal regression (n = 5 per time point). Total cellular RNA was isolated from tissue frozen at the time of ovariectomy. Thin slices (< 1 mm) of tissue were placed in methionine-deficient minimum essential media with [35S]methionine and placed in a humidified CO2 incubator at 38°C. Media and tissues were collected 6 h later. Changes in profiles of secreted proteins were analysed by one-dimensional SDS-PAGE. A number of proteins (relative molecular mass ranging from 14 300 to 200 000) were produced by luteal tissue at each time point (0–48 h). The major secretory proteins had relative molecular masses of approximately 21 500, 28 200, 43 700 and 46 000. Secretion of the relative molecular mass 46 000 protein(s) increased (P < 0.05) between 4 and 24 h after PGF injection compared with the 0 h group. Western blot analyses with either tissue inhibitor of metalloproteinase-1 or tissue inhibitor of metalloproteinase-2 antisera detected immunoreactive proteins of relative molecular mass 28 200 and 21 500, respectively. Concentrations of mRNA encoding tissue inhibitor of metalloproteinases-1 increased (P < 0.01) by 8 h after PGF injection, remained stable (P > 0.20) through 24 h and decreased (P < 0.05) by 48 h after PGF. Concentrations of tissue inhibitor of metalloproteinases-2 mRNA were highest (P < 0.05) at 8 h after PGF injection and lowest (P < 0.05) 48 h following induction of luteolysis. In summary, the profile of luteal protein production changed during luteolysis and two secretory products (tissue inhibitor of metalloproteinases-1 and -2) were identified. Metalloproteinase inhibitors may have an important role in tissue remodelling during structural luteolysis.