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Biomedical subjects

F Döcke

Publications and source records attributed to F Döcke.

At least 73 records · Page 4Linked to original sources
PubMed1977

Maturation of the oestrogen-dependent LH-stimulating activity of the mediocortical amygdala in female rats.

Immature female Wistar rats were unilaterally implanted with oestradiol benzoate (OB) into the anterior (AMAN) or posterior part (PMAN) of the medial amygdaloid nucleus, or into the central part of the cortical amygdaloid nucleus (CCAN) at different ages. Autopsy was performed 56h after implantation, and the LH concentration in the plasma was estimated by radioimmunoassay. A significant rise of the LH level resulted from implantation of OB: into the PMAN at 21, 26 and 32 days of age, into the AMAN at 32 and into the CCAN at 26 and 36, but not at 32 days of age. The conclusion was drawn that the medial amygdaloid nucleus may be involved in the maturation of the positive oestrogen feedback mechanism. The prepuberal change in the oestrogen-dependent LH-controlling activity of the cortical amygdaloid nucleus indicates that this nucleus may participate in the control of the onset of puberty.

Amygdala↗
PubMed1976

Studies on the puberty-controlling function of the mediocortical amygdala in the immature female rat.

The puberty-controlling function of the mediocortical amygdala in immature female rats was investigated by lesioning this region at different ages and by studying the effects on the onset of spontaneous and experimentally-induced precocious puberty. At 21 days of age, bilateral lesions in the anterior mediocortical amygdala (AMCA) caused precocious puberty and enhanced the puberty-accelerating effect of bilateral lesions produced simultaneously in the medial preoptic area (MPA). Similar lesions, ineffective on day 26, delayed the onset of puberty when produced on day 32 in otherwise untreated rats. Lesions in the posterior mediocortical amygdala (PMCA) at 26 or 32 days of age postponed puberty in untreated rats and inhibited the advancement of their 1st pubertal ovulation that resulted from damage to the ventromedial-arcuate region (VAH) or daily administration of 0.05 mug estradiol benzoate (EB) per 100 g b.w. The results confirm earlier findings of different gonadotropin-controlling activities of the AMCA and PMCA in immature female rats and suggest maturational changes in the function of both areas. The gonadotropin-inhibiting action exerted by the AMCA at 3 weeks of age is lost when puberty approaches; a gonadotropin-stimulating activity seems to develop in both the AMCA and PMCA.

Age Factors↗
PubMed1976

[Relationship between the limbic system and gonadal function. Quantifiable morphokinesis of the medial amygdaloid nucleus with reference to the estrous cycle].

Karyovolumetric investigation showed that in rat the neurons of the limbic system which are associated with the Pars caudalis of the nucleus amygdaloideus medialis followed a morphokineses which was quantifiable in relation to the oestral cycle. The cell nuclei differed significantly in volume between cycle phases, which was interpreted as morphological correlation between variations in neuronal activity of metabolism. It was thought to be another point in support of the relationship between the amygdala and central-nervous structures of the cerebro-pituitary-gonadal axis.

Amygdala↗
PubMed1975

Studies on extrahypophyseal sites of estrogen action in the induction of ovulation in rats.

To discover possible extrahypophyseal sites of estrogen action in the induction of ovulation, the influence of a s.c. injection of estradiol benzoate (EB) on cell nuclear sizes in the limbic-medial preoptic continuum of progesterone-pretreated cyclic rats was evaluated. The ovulatory dose of 5 mug EB caused a significant increase of nuclear volumes in the medial preoptic nucleus and the anterior and posterior parts of the medial amygdaloid nucleus. Precocious ovulation was induced in prepuberal female rats by unilateral implantation of a molten EB: cholesterol mixture into the posterior part of the mediocortical amygdala (PMCA), but not by implantation into the anterior part of this region (AMCA) or the medial preoptic area (MPA). In adult females injected s.c. with 2.0 mg progesterone on the day post estrus, bilateral implantation of 0.1 or 0.2 mug crystalline EB on the following day did not abolish the delaying effect of progesterone on the preovulatory LH increase and ovulation, when the implants were located in the MPA, lateral septum (LS), bed nucleus of the stria terminalis (BST), AMCA, PMCA or dorsal hippocampus (DHPC), whereas intrapituitary implants were highly effective. However, the bilateral introduction of large tallow pellets containing 0.1 mug EB each, into the LS, BST, AMCA or PMCA advanced ovulation in rats with progesterone-induced 5-day cycles. Equal pellets did neither induced ovulation nor an LH increase after implantation into the MPA or the DHPC. The results suggest that the anterior pituitary, mediocortical amygdala, BST and LS, but not the MPA or DHPC, are sites of the stimulatory feedback of estrogen on gonadotropin secretion in female rats, and that the amygdaloid response to estrogen differs between prepuberal and cyclic females.

Age Factors↗
PubMed1975

Anovulation in adult female rats after neonatal intracerebral implantation of oestrogen.

Four-day-old female rats were bilaterally implanted with paraffin micropellets containing 0.5% oestradiol benzoate (OB) into the mediobasal hypothalamus or the corticomedial amygdala. Controls received intracerebral paraffin pellets or two s.c. OB-paraffin implants. None of the treatments influenced the date of vaginal opening and vaginal cyclicity at 50 days of age. Permanent vaginal oestrus between 100 and 116 days of age and anovulatory ovaries at autopsy on day 116 were found in rats that had been implanted with OB into the mediobasal hypothalamus, but not in the remaining animals. The findings demonstrate that the delayed anovulatory syndrome can be induced in female rats by the neonatal intrahypothalamic implantation of a very low dose of OB, and that the corticomedial amygdala seems not to be a site of oestrogen action in this sterilizing effect.

Animals↗
PubMed1975

Studies on the mechanism of the ovulation-inhibiting effect of 19-norsteroids in cyclic rats.

Experiments performed in cyclic female rats demonstrated an equal ovulation-inhibiting activity of the 19-norgestagens norethynodrel, lynestrenol and norethisterone acetate after injection in oestrus and metoestrus, and after daily administration from oestrus to pro-oestrus. The results furthermore show that, after application of the minimal ovulation-inhibiting doses during oestrus and metoestrus, these substances 1. induce an increase in prolactin secretion, 2., with the exception of norethisterone acetate, possess a hypophysial site of action, 3. are able to induce deciduoma formation following traumatization of the uterus, and 4. maintain the reactivity of the cyclic corpora lutea to the injection of prolactin. The findings suggest that the prolactin-releasing and luteotrophic action of the progestagens studied may form an essential part of the mechanisms that are responsible for the inhibition of ovulation observed in rats after administration over one cycle.

Animals↗