Disruption of dopamine D1/D2 receptor complex is involved in the function of haloperidol in cardiac H9c2 cells.

AIMS: Haloperidol is an antipsychotic agent and acts as dopamine D2 receptor (D2R) antagonist, as a prototypical ligand of sigma1 receptors (Sig1R) and it increases expression of type 1 IP3 receptors (IP3R1). However, precise mechanism of haloperidol action on cardiomyocytes through dopaminergic signaling was not described yet. This study investigated a role of dopamine receptors in haloperidol-induced increase in IP3R1 and Sig1R, and compared physiological effect of melperone and haloperidol on basic heart parameters in rats. MATERIALS AND METHODS: We used differentiated NG-108 cells and H9c2 cells. Gene expression, Western blot and immunofluorescence were used to evaluate haloperidol-induced differences; proximity ligation assay (PLA) and immunoprecipitation to determine interactions of D1/D2 receptors. To evaluate cardiac parameters, Wistar albino male rats were used. KEY FINDINGS: We have shown that antagonism of D2R with either haloperidol or melperone results in upregulation of both, IP3R1 and Sig1R, which is associated with increased D2R, but reduced D1R expression. Immunofluorescence, immunoprecipitation and PLA support formation of heteromeric D1/D2 complexes in H9c2 cells. Treatment with haloperidol (but not melperone) caused decrease in systolic and diastolic blood pressure and significant increase in heart rate. SIGNIFICANCE: Because D1R/D2R complexes can engage Gq-like signaling in other experimental systems, these results are consistent with the possibility that disruption of D1R/D2R complex in H9c2 cells might cause a decrease in IP3R1 activity, which in turn may account for the increase expression of IP3R and Sig1R. D2R is probably not responsible for changes in cardiac parameters, since melperone did not have any effect.

Slow sulfide donor GYY4137 differentiates NG108-15 neuronal cells through different intracellular transporters than dbcAMP.

Cellular differentiation is the process, by which a cell changes from one cell type to another, preferentially to the more specialized one. Calcium fluxes play an important role in this action. Differentiated NG108-15 or PC12 cells serve as models for studying neuronal pathways. NG108-15 cell line is a reliable model of cholinergic neuronal cells. These cells differentiate to a neuronal phenotype due to the dibutyryl cAMP (dbcAMP) treatment. We have shown that a slow sulfide donor - GYY4137 - can also act as a differentiating factor in NG108-15 cell line. Calcium is an unavoidable ion required in NG108-15 cell differentiation by both, dbcAMP and GYY4137, since cultivation in EGTA completely prevented differentiation of these cells. In this work we focused primarily on the role of reticular calcium in the process of NG108-15 cell differentiation. We have found that dbcAMP and also GYY4137 decreased reticular calcium concentration by different mechanisms. GYY4137 caused a rapid decrease in type 2 sarco/endoplasmic calcium ATPase (SERCA2) mRNA and protein, which results in lower calcium levels in the endoplasmic reticulum compared to the control, untreated group. The dbcAMP revealed rapid increase in expression of the type 3 IP3 receptor, which participates in a calcium clearance from the endoplasmic reticulum. These results point to the important role of reticular calcium in a NG108-15 cell differentiation.

[DHEA: another hormonal modulator of bone blood flow in rats]. / DHEA: dalsí hormonální modulátor krevního obehu v kostech potkanu.

Dehydroepiandrosterone (DHEA) is a steroid with important effects on the bone tissue. We tried to check up if it influenced also the bone blood flow (similarly as estradiol and testosterone). We administered DHEA (Sigma) dissolved in dimethylsulphoxide s.c. three times weekly for four weeks in the doses of 15-20 mg per rat on 125 mg/kg body weight to female rats--sham-operated or oophorectomized (OOX). In two experiments (A and B) we ascertained the uptake of 85Sr-microspheres, local blood flow, cardiac output, density and ash weight of the burned tibia, in the third experiment (C) 24 hour incorporation of 45Ca and 3H-proline into the bone. The 85Sr-microsphere uptake in the tibia was elevated after OOX in both experiments A and B; this increase was inhibited completely (and statistically significantly versus the OOX group) by the administration of DHEA. Similar and also significant reactions were found in the microsphere uptake values in the distal end of femur. No significant changes could be demonstrated in the diaphysis of femur and calvaria as well as in the cardiac output, output, blood pressure and heart rate. The incorporation of 45Ca and 3H-proline into the tibia (experiment C) was significantly increased after OOX. The administration of DHEA inhibited this increase significantly in the values of 3H-proline. The density of tibia in both experiments A and B and ash weight of tibia in experiment A, suppressed after OOX, were significantly increased after the administration of DHEA to OOX females. The results show that also DHEA--in the experimental conditions used--has similar effect on the bone blood flow as estradiol and testosterone.

Possible participation of EDRF-NO in the hormonal regulation of bone blood flow in rats.

An increase in bone blood flow (BBF) was observed in rats after castration whereas a decrease in BBF occurred after oestradiol or testosterone. The possible participation of prostaglandins in these changes was demonstrated. The present results show that the endothelium-derived relaxing factor, i. e. nitric oxide (EDRF-NO), might play a role in these hormonal actions on BBF. Until now, almost nothing is known about the possible action of NO on bone circulation. Methylene blue (MB) as a substance blocking EDRF-NO was administered to sham-operated or oophorectomized (OOX) female rats. We determined local blood flow (85Sr-microsphere uptake), cardiac output, blood pressure, heart rate, density of the tibia and ash weight, as well as 24-h incorporation of 45Ca and 3H-proline into the tibia. The administration of MB (0.5% in the food for 4 weeks) significantly lowered both 85Sr-microsphere uptake and blood flow values in the tibia and distal femur of sham-operated and OOX rats. MB lowered cardiac output and blood pressure to the same extent, indicating no change in the vascular resistance. After the administration of MB (0.1% in the food), 85Sr-microsphere uptake decreased significantly in the tibia of OOX females while no significant change was found in soft tissues. Bone density and ash weight were significantly lower in OOX rats and in sham-operated rats after MB treatment. Finally, the 24-h incorporation of both 45Ca and 3H-proline decreased significantly in OOX females after MB administration (0.04% in the food). It can be concluded that 1) MB lowers BBF, suggesting the participation of EDRF-NO in BBF regulation, 2) MB does not influence or may even suppress cardiac output and blood pressure in high dosage, 3) MB lowers 24-hour incorporation of 45Ca and 3H-proline into the tibia of OOX rats, which is in agreement with the circulatory effect, 4) MB lowers bone density and ash weight of the tibia in non-castrated female rats. The effects of MB observed in our experiments partially differ from those of arginine-derived blocking agents. This requires further elucidation.

[Further evidence of the role of prostaglandin on the effects of hormones on blood circulation in bones]. / Dalsí doklady o zprostredkování hormonálních úcinku na kostní krevní obeh prostaglandinem.

In a short communication we demonstrated the inhibitory affect of acetylosalicylic acid (ASA) on the increased bone blood flow and 45Ca and 3H-proline incorporation in oophorectomized (OOX) female rats. This finding suggested probable participation of prostaglandin. The aim of the present work was to confirm and extend the initial observation and to find out, whether the administration of ASA did not affect also the decrease in the bone blood flow after the administration of estradiol benzoate (EB). Local blood flow was determined by means of the uptake of 85Sr-microspheres. In experiment A (females) the local circulatory values were increased after OOX significantly in tibia and distal femur, insignificantly in diaphysis of the femur and calvaria; this increase after OOX was suppressed by simultaneous administration of ASA completely in tibia, partially (and statistically insignificantly) in distal femur and diaphysis of the femur; no effect of ASA could be demonstrated in the calvaria. The blood flow through the kidneys of OOX female rats was decreased after ASA, while no change occurred in muscle and skin. The bone mineral content was significantly lower in both groups of OOX females. In experiment B (males), we observed an increase in local circulatory values after ORX in tibia, distal femur and diaphysis of the femur and suppression of this increase by the administration of ASA. These changes were not demonstrable in the calvaria and soft tissues studied. In experiment C (females), we found that significant decrease in the local circulatory values in the tibia after 4 weeks of administration of EB was not altered by simultaneous administration of ASA. Experiment D (females) proved again that 24 hour incorporation of 45Ca and 3H-proline was markedly suppressed by the administration of ASA not only in OOX females but also in sham operated control rats. Thus, the present results confirm the inhibitory effect of ASA on the increase in bone blood flow after castration, indicating with high probability participation of prostaglandin (PGE2?) (while no effect of ASA could be demonstrated on the decrease in bone blood flow after EB). The described blood flow changes are induced by local vascular reactions and occur in the bones of both female and male rats. Marked suppression by ASA of 45Ca and 3H-proline incorporation supports the circulatory results and indicates an important interconnection between metabolic processes and local circulation in the bone. We conclude that prostaglandin may be one of the factors regulating bone blood flow.

[The role of EDRF-NO in the regulation of bone blood flow in rats: inhibition with L-NAME]. / Ucast EDRF-NO v regulacích kostního prutoku krve u potkanu: inhibice s L-NAME.

EDRF-NO probably participates-besides the prostaglandins [3, 4]-in local circulatory changes in the bones of female rats with modified level of sex hormones; we could demonstrate it indirectly using methylene blue as a blocking agent [5]. In this paper, we present corresponding results of two experiments with NG-nitro-arginine methyl ester (L-NAME) as a substance blocking the production of endothelium derived relaxing factor, i.e. nitric oxide (EDRF-NO). Circulatory values were estimated by means of 85Sr-microspheres. In experiment A we ascertained whether the duration of L-NAME administration (0.025% in the food) influenced the effect. It could be demonstrated that the effect of one week's, two weeks', or four weeks' administration of L-NAME was the same: 85Sr-microsphere uptake and blood flow throught the tibia of female rats, increased after oophorectomy (OOX, performed four weeks prior to the experiment), was significantly suppressed to the level in sham-operated animals. In the experiment B, L-NAME was administered in the food in concentration of 0.05% for two weeks prior to the experiment. 85Sr-microsphere uptake was decreased significantly after L-NAME in the tibia of sham-operated females, in the tibia and distal femur of OOX animals; no significant changes were found in the diaphysis of femur and in calvaria. Blood flow values were significantly decreased in all bone samples of OOX females and in tibia of sham-operated rats (besides the local reaction also due to the decrease in the cardiac output). In both experiments the cardiac output was decreased and blood pressure elevated after L-NAME. It can be concluded, from the results of both experiments, that the blockade of EDRF-NO production by L-NAME decreases local circulatory values in the bones of female rats-particularly OOX-in a similar way as methylene blue; however, in contrast to methylene blue, L-NAME induces marked increase in the blood pressure and partially decrease in the cardiac output. Thus, as in the case of methylene blue, the effect of L-NAME on the circulation of blood in the rat bones supports the hypothesis of the participation of EDRF-NO in bone blood flow regulations.

[A decrease in blood flow and incorporation of 45Ca and 3H-proline in the bones in pregnant female rats]. / Snízení prutoku krve a inkorporace 45Ca a 3H-prolinu v kostech brezích potkaních samic.

In the experiments on rats, the bone blood flow may be influenced by the deficiency as well by the administration of sex hormones. The aim of this work was to investigate the bone circulation (determined by means of 85Sr-microspheres, experiment A and B) and the incorporation of 45Ca and 3H-proline into the tibia (experiment C) in the last stage of pregnancy (from 18 to 21 days), i.e. in the physiological condition with elevated level of estrogens. In the experiment A and B, the uptake of 85Sr-microspheres and blood flow in pregnant rats was lower in the tibia and distal femur, the blood flow only was significantly lower also in the humerus and the calvaria. In kidneys, liver, muscle and skin, there was no difference in microsphere uptake; the blood flow was in pregnant females lower only in the kidneys. In perirenal fat, the microsphere uptake and blood flow was several times higher in pregnant rats than in controls. 24 hour incorporation of 45Ca and 3H-proline was in pregnant females significantly lower. The bone density and ash weight was higher in pregnant rats in experiment A. Estradiol concentration in plasma was in experiment B in pregnant rats significantly higher (by 24.8%). Thus, in pregnant female rats, we found lower bone blood flow and lower incorporation of 45Ca and 3H-proline along with normal or higher bone mineral content in the condition, where enhanced resorption and formation of the bone had been described. The changes in bone blood flow and possible role of estrogens in this situation remain to be elucidated.

Blood flow and mineral content of the tibia of female and male rats: changes following castration and/or administration of estradiol or testosterone.

We studied changes in the local circulation and mineralization of the rat tibia under different experimental conditions. Four experiments were performed on a total of 155 female and male rats: after oophorectomy (OOX) or orchidectomy (ORX), after the administration of estradiol benzoate (EB, Agofollin Depot, 1 mg/rat once a week or 5 mg/kg body weight once every 5 days for 4 weeks), or after the administration of testosterone (T, Agovirin Depot, 25 mg/kg body weight once every 5 days for 4 weeks). We estimated 85Sr-microsphere uptake and blood flow in the tibia, density of the tibia, and ash weight per bone volume unit. The scheme of the experiments was uniform: experiment A--females--controls, OOX, EB, OOX + EB; experiment B--males--controls, ORX, EB, ORX + EB; experiment C--females--controls, OOX, T, OOX + T; experiment D--males--controls, ORX, T, ORX + T. A sham operation was performed on the animals in the uncastrated groups. The results showed that OOX and ORX stimulated the uptake of 85Sr-microspheres and bone blood flow and reduced both bone density and ash weight, whereas T inconstantly and EB constantly reduced 85Sr-microsphere uptake and bone blood flow and increased bone density and ash weight in both sham-operated and castrated animals. The described changes in the bone blood flow and mineral content under the given experimental conditions suggest a relation in the regulations of both processes, a possible association with resorption of bone, and the importance of the circulation of blood in the metabolism of bone tissue.

Inhibitory effect of hydrocortisone on the blood flow and 45Ca and 3H-proline incorporation into bones of female rats.

We studied the effects of hydrocortisone as a possible regulatory factor of bone blood flow and metabolism. Local bone blood flow in the tibia, distal femur, lumbar vertebra and some soft tissues (using 85Sr-microspheres), as well as 45Ca and 3H-proline incorporation into the tibia, bone density and ash weight per ml of the tibia were measured in sham-operated and oophorectomized female rats in which the influence of hydrocortisone administration (0.004% diet for 5 weeks) was followed. Hydrocortisone markedly lowered 85Sr-microsphere uptake and blood flow through the bones of non-castrated female rats as well as elevated circulatory values in oophorectomized rats. The changes were nearly identical in the three bone samples measured; among the soft tissues only the kidneys showed a less pronounced decrease. Circulatory changes in the bones seem to be caused by local vascular reactions. Hydrocortisone also lowered the 24-hour incorporation of 45Ca and 3H-proline into the tibia of both non-castrated and oophorectomized females. In the tibia of oophorectomized rats, hydrocortisone normalized the decreased bone density and ash weight. The adrenocortical hormones are known to block eicosanoid synthesis by the inhibition of arachidonic acid production. It is possible, therefore, that local circulatory changes in the bones of rats, induced by hydrocortisone, are mediated by the changes in prostaglandin production.

Relationships between local circulatory changes in the tibia and kidney of male and female rats after castration and administration of estradiol or testosterone.

The effects of castration and of the four weeks' administration of estradiol or testosterone on the blood circulation in the tibia and the kidney (expressed as the 85Sr-microsphere uptake values, which are not influenced by simultaneous changes in cardiac output) were studied in four experiments on a total of 147 rats (68 females, 79 males), relative weights being noted at the same time. 85Sr-microsphere uptake in the tibia rose markedly after castration in both males and females, fell after estradiol benzoate in intact females and intact and orchidectomized males and also fell after testosterone in intact and oophorectomized females and orchidectomized males. 85Sr-microsphere uptake in the kidney rose after castration only in males in experiments B; it fell after estradiol in orchidectomized males and fell after testosterone in intact females and males and in orchidectomized males. Relative tibial weight fell in castrated females, but in castrated males only in experiment D; after estradiol it rose only in males (intact and orchidectomized) and rose after testosterone in intact and oophorectomized females and orchidectomized males. Relative kidney weight fell after castration in both males and females, rose after estradiol in intact females and intact and orchidectomized males and rose after testosterone in intact and castrated males and females. In all four experiments there was a demonstrable statistically significant correlation between the 85Sr-microsphere uptake values in the tibia and the kidney. The relative weights displayed a similar correlation.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible participation of prostaglandins in the increase in the bone blood flow in oophorectomized female rats.

The aim of this study was to verify the possible role of prostaglandin (PG) in the increase in the bone blood flow of female rats after oophorectomy (OOX). In two experiments we determined blood flow in the tibia and distal femur (85Sr-microspheres) and 24-h incorporation of 45Ca and 3H-proline. Acetylosalicyclic acid (ASA, 0.13% in the food for 4 weeks) was used to suppress the production of PG. There was an increase in the bone blood flow after OOX (performed 4 weeks prior to the experiment), no change after ASA alone and significant reduction by ASA of the OOX-induced increase in the bone blood flow. In both groups of OOX females there was a decrease in tibial bone density and ash weight. The changes in 45Ca incorporation were similar to those in the blood flow while the changes in 3H-proline incorporation were not significant. Thus, the effect of ASA, i.e. suppression of the OOX-induced increase in the bone blood flow, is consistent with the possible role of PG (probably PGE2) in the increase in bone blood flow of OOX female rats.

[The effect of estradiol, norethisterone and testosterone on regional circulation and relative weight of the testes, ovaries and uterus in rats]. / Vliv estradiolu, norethisteronu a testosteronu na místní krevnií obeh a relativiní hmotnost varlat, vajecníku a delohy potkanu.

In nine experiments of 188 rats (85 males and 103 females), relative weight and local blood flow (with 85Sr-microspheres) was estimated in testes, ovaries and uterus after the administration of estradiol benzoate (Agofollin Depot 1 mg per rat or 5 mg per kg s.c. in time intervals of 3 to 7 days), norethisterone (Norethisterone tablets 0.01 or 0.02% in the food) or testosterone (Agovirin Depot 25 mg per kg s.c. every 5 days); all preparations were administered for four weeks. With one exception (norethisterone in males), the results of two experiments performed in the same manner are presented in every experimental situation. After estradiol, the body weight of rats in both sexes is lowered, relative weight of the uterus increased. The local circulatory indicators i.e. 85Sr-microsphere uptake in % dose per g, blood flow in (ml.min-1).g-1 and organ flow fraction % of cardiac output are decreased in the testes and unchanged on the ovaries. As regards the uterus, in the first experiment the 85Sr-microsphere uptake and the blood flow is significantly lower, in the second experiment these values remain unchanged and flow fraction is increased due to enlargement of the uterus. Norethisterone lowers the body weight and relative weight of the testes; in one experiment it increases relative weight of the uterus. Local circulatory indicators are decreased in the testes and inconstantly in the ovaries, whereas in the uterus the decreases are insignificant. Testosterone does not change the body weight. In one experiment, it increases the cardiac output per 100g of body weight; relative weight of the testes is lowered in one experiment and in the ovaries in both experiments, and markedly increased in the uterus. Local circulatory indicators were decreased in the testes, ovaries and uterus but approximately one half of the differences are significant. Thus, with one exception, all statistically significant local circulatory changes after the administration of the hormonal preparations are decreasing; the suppressive action is evident in the local circulation in sexual organs of the animals of the corresponding sex as well as in animals of the other sex. The suppression of the local circulation in testes and ovaries is probably in connection with endocrine regulations; the decrease of microsphere uptake and blood flow per g in the uterus may participate in insufficient adaptation of the blood supply in the enlargement of the uterus after four weeks' administration of estradiol and testosterone.

[Local blood circulation and bone mineral content in the bones of rats: the effect of castration, estradiol and testosterone in male and female rats]. / Místní krevní obeh a obsah minerálu v kostech potkanu: úcinky kastrace, estradiolu a testosteronu u samic a samcu.

Four experiments on 76 female and 79 male rats were performed in which we followed up the effect of four weeks' administration of estradiol benzoate (Agofollin Depot 1 mg per rat once a week or 5 mg per kg once every 5 days s. c.) and testosterone isobutyrate (Agovirin Depot 25 mg per kg once every 5 days s. c.) on the local circulation in the tibia and distal femur (by means of 85 Sr-microsphere uptake) and on bone density and ash weight related to bone volume. Local circulatory values increase in the bones after oophorectomy (OOX) and orchidectomy (ORX) and decrease after estradiol in sham-operated rats of both sexes; testosterone inconstantly reduces the 85Sr-microsphere uptake in the bones of sham-operated male rats. Estradiol decreases local circulatory values in OOX females and ORX males to the level observed in sham-operated animals. Testosterone has a similar inhibitory effect in ORX males as estradiol; less pronounced, but statistically significant lowering occurs also in the tibia of OOX females. Density of the tibia and ash weight related to bone volume unit falls after OOX and ORX and rises constantly after estradiol; after testosterone administration, it does not change in sham-operated rats and OOX females, but rises in ORX males. Probably the most important finding is that also testosterone reduces local circulation in the bones of rats, though less regularly and less markedly than estradiol (in the dosage used).

[Local blood circulation, uptake of 45Ca, 85Sr and 3H-proline and mineral levels in the tibia of female rats: comparison and changes after administration of estradiol]. / Místní krevní obeh, inkorporace 45Ca, 85Sr a 3H-prolinu a obsah minerálu v kosti holenni potkaních samic: srovnání zmen po podávání estradiolu.

After six weeks' administration of estradiol benzoate (Agofollin Depot, 1 mg s.c. once a week) we determined in the first part of 70 days old female rats the uptake of 85Sr-microspheres and local blood flow in the tibia, in the second part 24 hours' incorporation of 45Ca and 3H-proline and in the third part 2 hours' uptake of 85Sr, bone density and ash weight related to 1 ml of bone volume. We observed the following statistically significant changes: decrease in the uptake of 85Sr-microspheres and local blood flow, decrease in the incorporation of 45Ca, 3H-proline and 85Sr, increase in the density and ash weight of the tibia. The rise of bone mineral content simultaneously with reduced indicators of bone formation and particularly of the mineralization seems to be in the connection with the suppression of bone resorption under the influence of estrogen. Qualitatively identical reactions of circulatory and metabolic indicators to the administration of estradiol may be a reflection of mutual physiological interconnections.

[Hydrocortisone decreases blood flow in bones in sham-operated and oophorectomized female rats]. / Hydrokortizon snizuje prutok krve kostmi u náznakove operovaných i ooforektomovaných potkaních samic.

In an experiment on 38 75-day-old female rats--sham-operated or oophorectomized (OOX)--the authors assessed the effect of hydrocortisone administration (0.01% in the diet for four weeks) on the blood flow in the tibia and distal end of the femur (uptake of 85Sr microparticles). In the tibia they assessed also the density (according to the Archimed principle) and the weight of ashes per volume unit of bone. OOX increases significantly local circulation in both bones. After hydrocortisone these values are significantly lower in sham-operated and OOX rats as compared with controls and also significantly lower in the group OOX+hydrocortisone, as compared with group OOX. The density and weight of ashes from the tibia are not affected by hydrocortisone; the minute volume of the heart per 100 g body weight of rats is not altered in any group. The mechanism of the described hydrocortisone effects on circulation is not known. In the discussion the authors indicate possible associations of blood flow and the osteoblast and prostaglandin function in bony tissue.

Further findings on the inhibitory effect of estradiol benzoate on the circulation and on 45Ca and 3H-proline incorporation in rat bones.

Various aspects of the effect of estradiol benzoate (EB, Agofollin Depot, Czechoslovakia, usually in a s.c. dose of 5 mg/kg body weight once a week), on the local circulation (the uptake of 85Sr-microspheres), the incorporation of 45Ca and 3H-proline, bone density and ash weight related to bone volume were studied in six experiments in the tibia and distal femur of 224 rats. 1. The dose-response. In rats treated four weeks with doses of 0.5, 1.0, 1.5 and 2.0 mg EB per rat once a week, a significant correlation with the uptake of 85Sr-microspheres (r = -0.56), the blood flow (r = -0.56), the incorporations of 45Ca (r = -0.89) and 3H-proline (r = -0.35) and body weight (r = -0.71) was demonstrated. 2. The time course of changes after 1, 2, 4 and 8 weeks administration of EB. Circulatory values were not significantly lowered until after four weeks, 45Ca incorporation and body weight were significantly lower after only one week and 3H-proline incorporation did not fall until after eight weeks. The course of the uptake of 85Sr-microspheres and the incorporation of 45Ca were very similar. 3. Comparison of males and females. EB reduced circulatory values and 45Ca and 3H-proline incorporation and increased bone density and bone ash weight in both males and females. Conclusions. The decrease in the local bone blood flow after EB showed a significant dose-effect correlation; the decrease in circulatory values, on using the given administration method, is significant after four weeks. The inhibitory effect of EB on the bone blood flow is not sex-specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Different effects of oestradiol benzoate and norethisterone on the blood flow and mineral content in rat bones.

In three experiments (2 on females, 1 on males), we determined the blood flow in the tibia and the distal part of the femur, together with cardiac output (by means of 85Sr-microspheres), tibial bone density and tibial ash weight related to bone volume. We found that 1) the bone blood flow always fell significantly after oestradiol benzoate, 2) no change occurred after norethisterone in doses corresponding to those of oestradiol benzoate, but the blood flow showed a tendency to fall after doses one order higher (it decreased significantly in one case only), 3) the density of the tibia and tibial ash weight related to bone volume rose nonsignificantly after oestradiol benzoate, but fell (mostly statistically significantly) after norethisterone. The lowering of the bone mineral indexes in rat bones after norethisterone is a surprising and potentially significant finding requiring further verification.

[Increased blood flow and incorporation of 3H-proline and 45Ca into the bones of female rats after oophorectomy]. / Vzestup prutoku krve a inkorporace 3H-prolinu a 45Ca v kostech potkaních samic po ooforektomii.

In the submitted experiment the authors investigated changes of the local circulation (by assessing retention of 85Sr microparticles) and incorporation of 3H-proline and 45Ca in bone of female rats following oophorectomy (OOX). Four weeks after OOX retention of 85Sr microparticles in % from 1 g tissue rises significantly in the tibia, distal epiphysis of the femur and in vertebrae (insignificantly in the metaphysis and calva); the blood flow in (1 min-1).kg-1 is significantly increased in the tibia and diaphysis of the femur (the differences are less significant as the scatter of values is greater). No differentiation was found in the circulatory response with regard to the content of compact and trabecular tissue in the tested bone or part of a bone. In the examined soft tissues after OOX no detectable changes of the local circulation were found. It appears thus that the local circulatory reaction after OOX is specific only for bony tissue. Twenty-four hour incorporation of 3H-proline and 45Ca into the tibia of female rats is significantly raised after OOX - along with a rise of circulatory values these changes are obviously part of the enhanced metabolic activity of bony tissue after OOX. The specific reaction of the local circulation in bones to oestrogen deficiency is a potentially significant aspect of their action.

[Reduced blood flow in bones in female rats after administration of estrogen]. / Pokles prutoku krve kostmi potkaních samic po estrogenu.

The authors submit the results of investigations of the action of oestrogens on the blood flow in bones and other tissues of female rats (by means of 85Sr microparticles) on the incorporation of 3H-proline and 45Ca into bone marrow and on bone density and weight of the ashes. Daily s.c. injections of oestradiol dipropionate (Agofollin Spofa, CSFR, 0.1 mg per 100 g) reduce the blood flow in the tibia already on the first days and significantly on the 9th day of administration. After four injections of oestradiol benzoate with protracted action (Agofollin Depot Spofa, 1 mg.s.c. once a week) the retention of 85Sr microparticles is significantly reduced in the distal epiphysis of the femur, in both terminal portions of the tibia and in vertebrae; the blood flow is significantly reduced in the distal epiphysis of the femur and in the proximal end of the tibia. Among various soft tissues where measurements were made only in the kidneys a significant drop of the local circulation was recorded. Twenty-four hour incorporation of 3H-proline and 45Ca into the tibia is significantly reduced after depot oestradiol benzoate. Under the same conditions an inconstant significant rise of bone density or weight of the ash per volume of bone was found. Oestrogen administration to female rats thus causes a drop of the local circulation in bones, in particular in trabecular tissue (among soft parts only in the kidneys) and at the same time a reduced formation of bone matrix and the process of mineralization. So far we are unable to explain the mechanism and impact of the observed reactions.

Estradiol benzoate decreases the blood flow through the tibia of female rats.

Effect of estradiol benzoate (EB, Agofollin Depot Spofa, CSSR, 1 mg s.c. once a week for 4 weeks) on local blood flow through the tibia of intact and oophorectomized (OOX) female rats was studied using the 85Sr-microsphere method. In experiment A, the 85Sr-microsphere uptake and blood flow was increased 4 weeks after OOX and significantly decreased after EB in both the intact and OOX animals. In experiment B (intact female rats), the decrease after EB was confirmed both in microsphere uptake and tibial blood flow (48.8% and 57.1% respectively). No changes in the cardiac output and the marked fall of the uptake of labelled microspheres suggest a local circulatory reaction.