Effectiveness of cabergoline for termination of pregnancy in silver fox (Vulpes vulpes fulva).

Red foxes (Vulpes vulpes) are a major pest species in Europe and Australia. Traditional methods of control such as hunting or poisoning are no longer sufficient or feasible. As with domestic dogs and cats, prolactin (PRL) in the vixen is an essential luteotropin during the second half of gestation. Hence, PRL inhibitors such as cabergoline have been used to induce abortions. Eighteen mated silver fox vixens (three groups of six foxes each) were treated orally with a placebo of paraffin oil (I), or with 15 microg/kg cabergoline in feed once (11) or twice (III), on day 30 (I and II) or days 30 and 32 (III) post-coitum. Blood samples were taken prior to and after treatments and concentrations of PRL and progesterone (P4) were determined. Normal parturitions were observed in five of six, five of six and two of six vixens in groups I, II and III, respectively. In group III plasma concentrations of PRL and P4 decreased significantly but only temporarily. This drop in hormone concentrations was more pronounced in the vixens that did not carry to term. In conclusion, doses in excess of 15 microg/kg of cabergoline are likely to prevent the development of fetuses to term in pregnant vixens.

Replacement of fetal calf serum in cell cultures by an egg yolk factor with cholecystokinin/gastrin-like immunoreactivity.

The in vitro culture of various cell types is an important scientific tool and is becoming increasingly acceptable as a viable alternative to animal experiments. Fetal calf serum (FCS) is a supplement used in many cell culture media, and provides cells with growth factors and cytokines necessary for successful culture. In view of the animal welfare issues surrounding the production of FCS, an alternative agent allowing the replacement or reduction in the use of FCS is desirable. A yolk extract factor (EYF-X) obtained from chicken eggs is described, which facilitates the in vitro culture of a variety of cell types. When the extract was added to a culture medium used for in vitro fertilisation, the number of successful fertilisations was significantly increased. In a further in vitro model (permanent neuronal cell line N2A), the yolk extract significantly stimulated cell proliferation as well as the growth of cell processes. A set of specific antibodies against different parts of the prepro-cholecystokinin reacted with the extract. The intensity of the reaction depends on the age of the egg (time after the laying date). Analysis by gel chromatography recorded a main protein fraction with an apparent molecular mass of 20-30kDa. This fraction was labelled by Western blot with an antibody with specificity against CCK-octapeptide. These findings suggest that the yolk factor may be a CCK/gastrin-like molecule. Since CCK/gastrin-like molecules have also been detected in the spermatozoa of mammals, the influence on in vitro fertilisation could be explained by the yolk factor replacing the endogenous CCK/gastrin-like molecule destroyed in sperm freezing. The results of this study suggest that it might be possible to replace FCS with EYF-X. The application of the yolk factor to a broad spectrum of cell types remains to be investigated.

New methods for gamete rescue from gonads of nondomestic felids.

Methods for rescuing oocytes and spermatozoa post mortem are described, which were adapted from domestic cat as a model. Ovaries were mechanically processed for large-scale recovery of oocytes. Numbers of intact cumulus-oocyte complexes (COCs) per animal and of preantral follicles per ovary were 18 +/- 2 and 2892 +/- 665 in domestic cats, respectively. Similar results were obtained from 13 individuals of 6 nondomestic felids: 16 +/- 2 COCs and 1867 +/- 1144 follicles. Preantral follicles were cultured for at least 7 days. Intact COCs were maturated for 24 h and fertilized in vitro with homologous or heterologous (from domestic cat) spermatozoa. Spermatozoa were collected from caudae epididymides (n = 11; five nondomestic species) and cryopreserved (n = 8) using a programmed freezer. The reproductive competence of oocytes collected post mortem was demonstrated by development to embryos (> or = 8 cells) in vitro. Spermatogenic efficiency of males was assessed by flow cytometric analysis of mitotic and meiotic testicular cells as well as by estimation of testosterone concentration in testes. The results demonstrate the possibility of retrospective assessment of male and female reproductive capacity. In conclusion, the described methods could be a useful part of gamete rescue programmes for endangered felids.

Investigations of BrdU incorporation in roe deer blastocysts in vitro.

These data provide direct evidence for slow proliferation activity in pre-implantation roe deer trophoblasts and even minor growth of the embryoblast. The blastocyst grows very slowly from August to January. Incorporation of BrdU into the nuclei during a period of 4 h was used to determine the proliferation of the embryonic cells in vitro. The results show for the first time the DNA synthesis in trophoblast cells of roe deer blastocysts from October to December. During the period of October to November the incorporation of BrdU is weak, and in December there is a duplication of DNA metabolism.

[Spectrum of the adverse effects of Cordemcura]. / Untersuchungen zum Nebenwirkungsspektrum von Cordemcura.

Side-effects of Cordemcura were verified in a relatively extensive repertoire of methods. Investigations of blood pressure activity, effect on heart frequency as well as PQ and QT times after continuous infusion, influence on diuresis and antidiuresis and behaviour to achieve results of a possible activity of the central nerve system were given priority. The proved vasodilatory qualities of Cordemcura become also evident in the rat blood pressure reduction due to higher dose as a result of i.v. injection. No hypotensive effect could be observed after oral administration of the drug. Heart frequency as well as PQ and QT times after i.v. infusion of 1 X 10(-4) mol/kg/min Cordemcura over a period of 15 min remained unchanged. Doses going far beyond therapeutically applied doses indicate a reduction of diuresis after oral administration of Cordemcura for rats. Only due to these high doses unspecific changes in the behaviour of rats and mice occurred. No specific central nerve system activity could be observed.