Estrogen-alpha and progesterone receptor expression in cystic endometrial hyperplasia and pyometra in the bitch.

Estrogen-alpha receptor (ER) and progesterone receptor (PR) were examined immunohistochemically in uteri of normal bitches, in uteri of bitches with cystic endometrial hyperplasia-mucometra (CEH-M) and in uteri of bitches with endometritis-pyometra (E-P), under exogenous progesterone treatment. In the CEH-M group, the ER- and PR-scores of all uterine cell types were higher than the ER- and PR-scores of normal uteri, although these differences were not always statistically significant. The ER-scores of E-P group were significantly lower than the ER-scores of the normal uteri and CEH-M group. The PR-scores of the E-P group tended to be higher than the PR-scores of the normal uteri, except for the surface epithelium, although these differences were not statistically significant. Exogenous progesterone treated bitches with CEH-M or E-P showed reduced ER- and PR-scores in the different uterine cell types, compared with the corresponding nontreated CEH-M or E-P group. The differences in ER and PR expression between CEH-M and E-P suggest different factors in the pathogenesis of both entities. Although, these changes in ER and PR expression do not seem to be directly involved in the pathogenesis of CEH-M and E-P. It is suggested that for CEH-M and progestin induced CEH-M a hormone dependent pathway is responsible. For P, the trigger may be bacterial infection.

Immunolocalization of androgen receptors in the canine ovary and their relation to sex steroid hormone concentrations.

Androgens play an essential role as autocrine or paracrine agents in ovarian follicular growth, maturation and luteinization. The aim of this study was to describe the normal cellular distribution of androgen receptors in the canine ovary at different stages of the oestrous cycle. Samples of both ovaries were obtained from 34 dogs, including six pregnant animals and three that had just produced litters. Presence of androgen receptors was visualized by immunohistochemistry on paraffin wax sections using a polyclonal antibody. Nuclear staining for androgen receptors was observed in the surface epithelium, cortical tubules, rete ovarii, follicle cells, thecal cells, luteal cells, granulosa cell cords and ovarian stroma, indicating that androgens have important roles in ovarian function in bitches. In theca interna cells of tertiary follicles, androgen production seems to be more important than androgen receptivity, as immunostaining for androgen receptors in these cells was weak compared with that in other ovarian stromal cells. In primordial and primary follicles, the immunostaining for androgen receptors was rather weak, indicating that androgens are of minor importance in early preantral follicles. In follicle cells of larger preantral and antral follicles, the immunostaining for androgen receptors increased with the stage of the follicle. Corpora lutea expressed less immunostaining, which was not correlated with serum progesterone concentrations, although local actions of progesterone on androgen receptors in corpora lutea cannot be excluded. In general, few correlations were found between immunostaining for androgen receptors and serum sex steroid concentrations, indicating that other factors regulate androgen receptors in the canine ovary.

In vivo evaluation of 4-[123I]iodo-N-[2[4-(6-trifluoromethyl-2-pyridinyl)-1-piperazinyl]ethyl]benzamide, a potential SPECT radioligand for the 5-HT1A receptor.

4-[123I]Iodo-N-[2-[4-(6-trifluoromethyl-2-pyridinyl)-1-piperazinyl]ethyl]benzamide (1.123I), a potential SPECT 5-HT(1A) radioligand, was evaluated in vivo in rats. Biodistribution studies were performed leading to a % ID in the brain of 0.22 at 5 min p.i. No significant differences in % ID/g tissue of the different isolated brain regions (hippocampus, hypothalamus, striatum, cortex and cerebellum) could be demonstrated. Blocking experiments with 8-OH-DPAT, WAY100635 and ketanserin could not show any significant change in tracer uptake in the isolated brain regions. These data suggest that uptake in the brain does not represent binding of 1.123I to the 5-HT(1A) receptor.

Immunolocalization of progesterone receptors in the canine ovary and their relation to sex steroid hormone concentrations.

The aim of the present study was to describe the normal cellular distribution of progesterone receptors in the canine ovary at different stages of the oestrous cycle. Samples of both ovaries were obtained from 75 healthy adult bitches of various breeds and ages, including five pregnant bitches and three bitches that had just delivered. The presence of progesterone receptors was visualized by immunohistochemistry on paraffin wax sections using a monoclonal antibody. Nuclear staining for progesterone receptors was observed in the surface epithelium, cortical tubules, rete ovarii, follicle cells, thecal cells, luteal cells, granulosa cell cords and ovarian stroma. The staining intensity for progesterone receptors in the follicle cells increased with the stage of follicle development, indicating an intrafollicular role of progesterone in the mechanism of ovulation and luteinization. The stronger staining intensities for progesterone receptors in thecal cells compared with follicle cells may be explained by the fact that thecal cells mediate some effects of steroid hormones on the follicle cells in secondary and tertiary follicles. Little correlation was found between the expression of progesterone receptors in follicle cells and oestradiol, progesterone or testosterone concentrations. This finding indicates a different regulating mechanism for progesterone receptors in canine ovarian follicles compared with other tissues of the genital tract. During pregnancy all groups of ovarian cells had lower staining intensity scores than during the oestrous cycle, although the sex steroid hormone concentrations in pregnant bitches were similar to those in non-pregnant bitches during the luteal phase of the oestrous cycle. The lower expression of progesterone receptors during pregnancy may be due to higher tissue concentrations of progesterone that are not reflected in the serum because of haemodilution and increased metabolism and clearance during pregnancy.

Cystic endometrial hyperplasia-pyometra complex in the bitch: should the two entities be disconnected?

The uteri of 26 clinically healthy bitches and 42 bitches with a clinical suspicion of pyometra were examined histologically using a computerized image analysis system. Histologic lesions were characterised mainly by thickening or atrophy of the endometrium and by varying degrees of cystic changes of the glands. These lesions were observed in most of the clinically healthy bitches as well as in all of the clinically ill animals. In most of the ill bitches a variable degree of inflammation also was found. Some bitches with clinical signs indicative for pyometra had no inflammatory reaction in the uterus. These bitches were misdiagnosed as suffering from pyometra, confirming the difficulty of diagnosing pyometra by simple clinical examination. Determination of sex hormone serum levels revealed that all dogs in both groups were either in metestrus or in anestrus. Based on the results of this study the cystic endometrial hyperplasia-pyometra complex can be divided in two entities: a cystic endometrial hyperplasia-mucometra complex and an endometritis-pyometra complex. Both entities bear many similarities with each other, except for the inflammatory reaction in the endometritis-pyometra complex. It is concluded from this study that the latter complex probably does not necessarily follow the former, but that both can arise de novo.

Immunohistochemical detection of the estrogen receptor-alpha and progesterone receptor in the canine pregnant uterus and placental labyrinth.

The presence of hormone receptors is as important as the amount of hormone to predict hormone action. Therefore, the presence of estrogen receptors of the alpha subtype (ER-alpha) and progesterone receptors (PR) was evaluated in six pregnant uteri including the placenta and in three postpartum uteri of dogs. This preliminary study is part of our immunohistochemical research project on steroid hormone receptor distribution in the canine female genital tract. Specific staining for ER-alpha or PR was found only in cell nuclei. Staining for ER-alpha was rare in the various cell types of pregnant and postpartum uteri. Staining for PR was absent or weak in epithelial cells. Moderate staining for PR was observed in endometrial stromal cells and myometrial smooth muscle cells, two cell types playing an important role in the maintenance of pregnancy. Stromal cells stained more frequently positive for ER-alpha and PR than epithelial cells, indicating that both hormones may act on epithelial cells indirectly via stromal cells. In the placental labyrinth, fetal cells showed no evidence of ER-alpha or PR. In contrast, both receptors were present in maternal mesenchymal cells that were located around the basement membrane of the maternal blood vessels. These cells showed signs of decidualization. No difference in PR distribution was seen between pregnant and postpartum uterine tissue, suggesting that during parturition the decrease in serum progesterone levels and the concomitant increase in the estrogen/progesterone ratio are probably more important than the decline in receptor availability.

Immunohistochemical detection of progesterone receptors in the canine uterus and their relation to sex steroid hormone levels.

The aim of this immunohistochemical study is to describe the normal distribution of progesterone receptors in the various cell types of the canine uterine horns, body and cervix. The results can be used for research on uterine and endocrinological pathology, since the impact of progesterone on different uterine cell types is partly determined by the receptor availability. Nuclear staining for progesterone receptors was observed in epithelial cells of the surface epithelium, glandular ducts and basal glands of the endometrium, in endometrial stroma cells and in myometrial smooth muscle cells. This staining was positively correlated with the estradiol-17 beta:progesterone ratio, and reflects the positive effect of estradiol-17 beta and the negative influence of progesterone on the receptors. Staining scores were high during proestrus and decreased through estrus to early metestrus. In late metestrus, staining scores of the stromal and smooth muscle cells increased again. In anestrus, high scores of the surface-epithelial cells contrasted with minimal scores of the basal glands. This finding suggests a different hormonal regulation of the progesterone receptor expression in both epithelial cell groups. The higher staining intensities for progesterone receptors in stromal cells compared with epithelial cells might be explained by the fact that stromal cells mediate some effects of steroid hormones on the epithelial cells in the genital tract. Therefore, the role of stromal cells in regulation of the cyclic endometrial changes and in pathologic changes of uterine tissue should not be underestimated.

Pharmacological evaluation of [11C]donepezil as a tracer for visualization of acetylcholinesterase by PET.

Donepezil is a highly potent and selective reversible achetylcholinesterase inhibitor. [(11)C]Donepezil is prepared by methylation with [(11)C]CH(3)I of the corresponding 6'-O-desmethylprecursor. Tissue distribution in mice revealed a high uptake in brain and rapid clearance from the blood. Metabolization studies in mice indicated the formation of one (11)C-labeled polar metabolite that didn't penetrate the blood-brain barrier. Regional brain distribution in rabbits didn't reflect the measured achetylcholinesterase distribution in rabbit brain.

Immunohistochemical detection of estrogen receptors in the canine uterus and their relation to sex steroid hormone levels.

Cyclic changes in estrogen receptor expression in the uterine tissue of 60 female dogs were evaluated, using an immunohistochemical technique on formalin-fixed paraffin-embedded sections. The expression of estrogen receptors in the uterine horns, body and cervix was quantified by means of an immunohistochemical score. A negative correlation was found between staining scores in the uterine horns and serum progesterone levels. Generally, staining scores in the uterine horns were highest during proestrus, declined during estrus and were lowest during early metestrus. During anestrus high staining scores for estrogen receptors were observed, indicating sensitivity for estrogens in a sexual quiescence stage. Compared with the uterine horns, high staining scores were found in the uterine body and cervix during estrus and metestrus. No positive staining for estrogen receptors was detected in 1 pregnant uterus. Fluctuations in estrogen receptors were more pronounced in endometrial stroma cells than in epithelial cells of the uterine horns. The importance of stromal cells in the sexual cyclicity of the canine uterus should not be underestimated when studying uterine endocrinology and pathology.

Variation in the estrogen receptor content of canine uterine tissue throughout the estrous cycle.

The estrogen receptor (ER) was visualized immunohistochemically in paraffin sections of the canine uterus using a monoclonal antibody. The ER-expression was quantified by means of an immunohistochemical score. In the uterine horns highest scores were found during proestrus and lowest scores during early metestrus. Staining scores in the uterine body and cervix were high during estrus and metestrus compared with the uterine horns. A negative correlation was found between serum progesterone levels and immunohistochemical staining for ER in the uterine horns. The fluctuations in immunohistochemical scores were more pronounced in the endometrial stroma cells than in the epithelial cells of the uterine horns and therefore stromal cells may be of higher importance than epithelial cells concerning cyclic endometrial changes and uterine pathology.

Immunohistochemical analysis of estrogen receptors in cystic-endometritis-pyometra complex in the bitch.

Monoclonal antibodies to human estrogen receptor were used with an indirect immunohistochemical technique to localize in formalin-fixed, paraffin-embedded sections of the genital tract of the bitch. The presence of estrogen receptors in the uterus of dogs with cystic hyperplasia endometritis complex (CHE) was compared with normal uteri from dogs at the same stage of estrous cycle. Lower estrogen receptor expression was found in the squamous metaplastic epithelium covering the luminal surface of the endometrium from dogs with CHE than in the columnar epithelium from normal dogs. In contrast, the basal glands from uteri of CHE group dogs contained more estrogen receptor than glands from normal dogs at the same stage of estrous cycle. This was most pronounced and statistically significant in the late secretary stage of the estrous cycle. When the glands presented cystic degeneration, the estrogen receptor labeling was less pronounced. The highest estrogen receptor score was present in normal glands from dogs treated with progestins. In this group even cystic degenerated glands contained high estrogen receptor concentrations compared with those of the other groups. From this study it was concluded that the down regulation of estrogen receptor expression in the endometrial glands under the influence of rising progesterone concentrations is defective in dogs with CHE. Therefore it is suggested that the regulation of estrogen receptor expression in endometrial glands may play an important role in the pathogenesis of CHE in the bitch.