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Biomedical subjects

M Meunier

Publications and source records attributed to M Meunier.

At least 73 records · Page 4Linked to original sources
PubMed1987

Comparative study of preimplantation development and embryonic loss in two rabbit strains.

The prolificacy of two rabbit strains (Californian and New Zealand) has been studied in parallel with ovulation rate and embryonic development. The number of mean ovulations was 11.6 in Californians and only 9.6 in New Zealand. In spite of the higher rate in the former, the number of young born was about 8 in both strains. Californian and New Zealand blastocysts were transferred at 96 h post-coitum by injecting them into the uterus of recipient does of the same strain or of the other strain (crossed transfer). The percentage of unfertilized and delayed eggs was significantly higher (20% vs 12%) in Californians. The size of blastocysts recovered at 96 h p.c. was significantly higher in New Zealand than in Californian does (370 vs 319 micron). The difference was due to the larger proportion of small Californian blastocysts and of large New Zealand blastocysts. The larger blastocysts were placed in the right horn of recipients and the small ones in the left horn. Number of foetuses at D27 showed that the survival percentage was always higher when large blastocysts were transferred. However the survival difference with small transferred blastocysts was not significant. When transfer was within the same strain or crossed the results were not different. Since the New Zealand blastocysts were larger at D4 p.c. (one day after they arrived in the uterus), it could not be determined if this improved development was due to the conditions in the fallopian tubes or to the quality of the uterine secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Blockade of the final phase of ovulation has no effect on the post-ovulatory surge of serum FSH in the rabbit.

Mating induces a surge of both LH and FSH in the blood of female rabbits, followed 10-12 h later by a surge of FSH only, which begins at the time of ovulation. We have studied the effect of suppression of ovulation on the post-ovulatory surge of FSH. In the first experiment, follicular fluid and oocytes were withdrawn from the largest follicles 8 h after coitus. In the second experiment, ovulation was inhibited by injecting the rabbits with 25 mg indomethacin/kg body weight 7.5 h after mating. Levels of serum FSH and LH were measured for 24-48 h after mating. Control rabbits ovulated normally in both experiments. The treatments did not significantly affect the levels of serum FSH in either experiment, although the second surge of FSH was slightly higher after fluid had been aspirated from the preovulatory follicles. These observations show that the post-ovulatory surge of serum FSH is not dependent upon the completion of ovulation and that it is programmed before 7.5-8 h post coitum.

Animals↗
PubMed1986

Seasonal variations in the pituitary response to LHRH in the brown hare (Lepus europaeus).

In the brown hare, fertile mating takes place from the beginning of December to September. Pituitary and ovarian response to a monthly i.v. injection of 5 micrograms LHRH was studied from September 1983 to October 1984 in 2 groups of 6 hares. The basal concentrations of LH remained undetectable until the end of January, rose from 0.23 +/- 0.14 ng/ml from February to a maximum of 1.44 +/- 0.57 ng/ml in July. LHRH injection was always followed by a release of LH. Between September and December, the LH value peaked 15 min after injection and returned to basal concentrations 2 h later. From January, this pattern altered and a second peak of LH appeared 2 h after injection. Peak levels 15 min after LHRH were around 10 ng/ml between September and December, increased from 47.0 +/- 8.0 ng/ml in January to 106 +/- 33 ng/ml in July and decreased in August (69.4 +/- 10.6 ng/ml). The values of the second peak rose from 11.0 +/- 2.2 ng/ml in January to 90.6 +/- 12.4 ng/ml between March and July and decreased in August (24.5 +/- 5.1 ng/ml). The LH surge induced by LHRH was always followed by a transient rise in progesterone. During the breeding season, this progesterone secretion increased considerably. Ovulation was possible between January and August and the number of ovulating females was maximum between March and July. The amount and duration of progesterone secretion during the resulting pseudopregnancies increased during the breeding season.

Animals↗
PubMed1986

[Paradoxical transitory facilitation of performance in the Hebb-Williams labyrinth after lesion of the cingulate cortex in mice].

The effects of lesions of the anterior (Ant) or posterior (Post) regions of the cingulate cortex were tested using the closed-field maze tests of Hebb-Williams. Subjects were male BALB/c mice which had received restricted bilateral electrolytic lesions of the Ant or Post cingulate cortex. Their performances in acquisition or retention were compared to those of sham operated mice at different time intervals after the lesion. In a first series of experiments, naive animals were lesioned. The effects of lesions on acquisition were then tested at different time intervals (up to 45 days) after surgery. In a second series of experiments, the animals were lesioned only after prior complete acquisition of the maze tests and tested in a retention paradigm. The results show a differential effect of Ant versus Post cingulate lesions. Ant lesions had no significant effects whereas Post lesions induced a facilitation of performance at time intervals between 19 and 33 days (acquisition paradigm) or 11 and 25 days (retention paradigm). Conversely a reversal (impairment) of the effect was observed when Post animals were tested 28 days (acquisition) or 48 days (retention) after surgery. Taking into consideration the changing nature of the behavioral paradigm used, we suggest that the paradoxical and transitory facilitatory effects of the Post cingulate lesions may indicate that lesioned mice exhibited a greater degree of adaptability in each new learning situation. However, we can also postulate that these facilitatory effects resulted from a difficulty of lesioned mice in addressing long-term memory stores. This would therefore paradoxically protect them from interference generated by the high degree of familiarity in the behavioural testing apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The Hebb-Williams test to assess recovery of learning after limbic lesions in mice.

A scaled-down Hebb-Williams closed-field maze was constructed and adapted for use with mice. In a first experiment, the acquisition performance of the original 12 Hebb-Williams mazes by BALB/c mice was studied in order to re-group the mazes into 3 main groups of difficulty (low, moderate and high). In a second experiment different problems from each class of difficulty were presented at 3 times intervals (between 3 and 7 weeks after surgery) to mice with lesions of the cingulate cortex. The rate of acquisition in lesioned mice was observed to be facilitated between 3 and 5 weeks after surgery for the most difficult mazes. This effect was reversed (impairment) at 7 weeks post-lesion. The observed biphasic behavioral modifications constitute evidence that our present protocol provides a useful tool to evaluate the time-course of changes in learning performance following brain injury.

Animals↗
PubMed1983

A comparison of ovulatory gonadotropic surge in two rabbit strains: no evidence for a relationship between LH or FSH surge and factors of prolificacy.

Plasma levels of LH and FSH before and after ovulation were measured in two rabbit strains (New Zealand A 1077 and Californian A 1066) having a different number of ovulations and rate of embryonic loss. Maximal concentrations and total secreted amounts before ovulation were slightly higher in New Zealand, but the difference was not significant. No relationship between the number of ovulations and the increase in plasma LH or FSH level was found in either strain. In most cases, there was no relationship between gonadotropic surge and early embryonic loss.

Animals↗
PubMed1976

[Immunoglobulins in the CSF during meningitis (author's transl)].

Cerebrospinal fluid and serum immunoglobulins were studied in 76 patients with acute meningitis of various aetiologies. This comparative study showed that the increase of CSF immunoglobulin levels was related to important modifications of the permeability of the blood-brain barrier (especially in case of bacterial meningitis) or to a local in situ production (particularly in case of "viral" meningitis). Results obtained allow us to draw a different biochemical pattern in purulent meningitis and acute lymphocytic meningitis.

Adolescent↗
PubMed1975

Plasma and pituitary levels of LH in field voles, Microtus arvalis, reared under two different photoperiods.

10 Plasma LH levels were measured in voles reared under long (15 L: 9 D) or short (10 L: 14 D) light photoperiods by radioimmunoassay from a Rat LH-Anti Ovine LH system. 20 The number of animals exhibiting a detectable LH level (i.e. greater than 1 ng per ml) and the mean plasma LH values were higher for long days than for short days in spite of a very large variability between animals. 30 The sensitivity of the hypophysis towards LH. RH increased after gonadectomy, but is not controlled by the daily length of the light photoperiod even in the castrated animals.

Animals↗