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Biomedical subjects

M Bonnin

Publications and source records attributed to M Bonnin.

At least 55 records · Page 3Linked to original sources
PubMed1985

Seasonal variations in plasma luteinizing hormone and testosterone levels in the European badger Meles meles L.

Although active spermatogenesis occurs throughout the year in the male European badger Meles meles L., seasonal fluctuations of testicular activity were observed. The present study compared the pattern of luteinizing hormone (LH) and testosterone (T) secretions throughout the annual cycle. LH secretion was investigated by means of a heterologous radioimmunoassay using anti-ovine LH beta antiserum and canine reference standard. Seasonal and nycthemeral changes in LH and T secretions were observed. During the year a period of maximal values for both hormones is well correlated with the breeding. Moreover, episodic LH releases occurs during the period of minimal testosterone values, indicating resumption of hypothalamo-pituitary activity well before the breeding period.

Animals↗
PubMed1984

Heterologous radioimmunoassay of fox LH: levels during the reproductive season and the anoestrus of the red fox (Vulpes vulpes L.).

A heterologous radioimmunoassay using ovine LH as the labeled hormone, canine LH as the standard, and an antiovine LH rabbit serum was validated for the measurement of fox LH. Physiological validation of the assay was evidenced by the high concentrations of LH at oestrus and following ovariectomy or the administration of LH-RH. Throughout the year, plasma LH levels demonstrate important variations, being low during and after the luteal phase (1.4 +/- 0.3 ng/ml) (mean +/- SE) and increasing during the second part of anoestrus (5.2 +/- 1.4 ng/ml). This latter increase might be correlated with that of androgens observed at the same period. Several LH rises preceded the preovulatory LH surge.

Androstenedione↗
PubMed1984

C21 steroids and transcortin-type protein during delayed implantation in the European badger Meles meles L.

A high-affinity corticosteroid-binding protein (CBG) roughly resembling a transcortin-type protein is present in badger plasma. Plasma CBG, corticosteroid and progesterone (P) concentrations were measured in relation to delayed implantation, true progestation and gestation. Two significant CBG increases were observed during pregnancy. The first, in the second half of embryonic diapause coincides with an increase in plasma corticosteroid concentration and the second, during true progestation and gestation, with an increase in P concentration. Relationship of CBG increases with pregnancy in badger are discussed.

Adrenal Cortex Hormones↗
PubMed1983

Plasma androgen patterns during delayed implantation in the European badger (Meles meles L.).

Androstenedione and testosterone were measured by radioimmunoassay after chromatography on celite microcolumns throughout the delayed implantation period in the European badger (Meles meles L.). Androstenedione and testosterone concentrations varied from 0.05 to 22 ng/ml, and from 30 pg/ml to 359 pg/ml, respectively. There was a typical biphasic pattern in the fluctuation of these two steroids. Androstenedione levels increased between June and August (X= 7.9 +/- 0.8 ng/ml), decreased from September to November (X = 2.3 +/- 0.3 ng/ml), and then increased again from December to February (X = 6.1 +/- 0.7 ng/ml). The same fluctuations of the testosterone levels were observed throughout the diapause, but the concentrations were lower. The overall correlation between androstenedione and testosterone was highly significant (r = 0.75, P less than 0.001). There was also a similarity between the androgen and progesterone patterns of secretion (r = 0.31), particularly at the end of the delay period (r = 0.73, P less than 0.001). No correlation could be demonstrated between androgens and estrogens.

Androstenedione↗
PubMed1981

[Changes in plasma progesterone levels in the female badger after removal of the pregnant uterus].

In the European badger Meles meles L., the progesterone profile during the gestational phase shows two successive periods. The first, corresponding to implantation could be due to pituitary stimulation and seems not to have any relation with embryos. The second seems to be due to the presence of the placenta. Indeed, after hysterectomy the levels of plasma progesterone are significantly lower.

Animals↗
PubMed1978

Plasma progesterone levels during delayed implantation in the European badger (Meles meles).

There was a biphasic pattern of progesterone secretion during the year. Delayed implantation was characterized by low concentrations from February to June, a significant (P less than 0.001) increase during July, August and September, and a return to low levels in October-November. A second significant increase (P less than 0.001) was observed in December and early January just before the presumed time of implantation.

Animals↗
PubMed1978

Oestrogen and progesterone concentrations in peripheral blood in pregnant red foxes (Vulpes vulpes).

Oestrogen levels were low during most of gestation, but there was a significant increase (P less than 0.05) in oestradiol concentrations at implantation. Early pregnancy was characterized by high levels of progesterone which decreased significantly (P less than 0.001) thereafter, but there was no decline in progesterone or rise in oestrogen levels at parturition. There was no difference in the length of progesterone secretion between pregnant and non-pregnant females.

Animals↗