Ontogeny of erythropoietin receptor mRNA expression in various tissues of the foetal and the neonatal pig.

Erythropoietin receptor (EPOR) mRNA expression in liver, spleen, bone marrow and testes of foetal and neonatal pigs was analysed using a real-time RT-PCR assay. The results showed that early in the foetal life, EPOR expression is greatest in the liver. Later in foetal life, the spleen has the greatest expression of EPOR, whereas at 2 weeks after birth, the main expression of EPOR is found in the bone marrow. These findings contradict our earlier hypothesis that erythropoietin (EPO) acting in a paracrine fashion can account for an extensive erythropoiesis at birth, a point of time when plasma EPO concentrations are low. Results presented in the present paper suggest that the spleen or, alternatively, the bone marrow is able to respond to very low concentrations of circulating EPO around the time of birth. The testes were found to express significant amounts of EPOR. Since EPO mRNA has previously been found in the testes, a paracrine function of EPO may exist in this organ.

Hypotensive effects in cats caused by horseradish peroxidase mediated by metabolites of arachidonic acid.

Horseradish peroxidase (HRP) given intravenously was shown to possess a marked hypotensive effect in cats. The effect was not noticeably influenced by antihistamines. Indomethacin and acetylsalicylic acid completely blocked the hypotensive effect of HRP. It is concluded that the effect of HRP on blood pressure is due to stimulation of the synthesis of metabolites of arachidonic acid.

Plasma concentrations of oxytocin and intramammary pressure in goats during manual stimulation of the udder and hand-milking.

The concentration of oxytocin in the jugular venous plasma of goats was studied by radioimmunoassay and the intramammary pressure measured upon manual stimulation of the udder and hand-milking. Before stimulation the concentrations of oxytocin were close to the limit of detection, about 3 pg/ml. Manual stimulation of the udder resulted in a short-lasting increase in plasma oxytocin in 11 out of 18 experiments carried out on nine goats. There were large variations between and within individuals in the magnitude of the oxytocin increase. Hand-milking was in general as efficient stimulus for oxytocin release. In experiments in which manual stimulation had led to a large increase in plasma oxytocin, the ensuing hand-milking did not lead to a further increase. In three experiments neither manual stimulation of the udder not hand-milking resulted in any significant increase in plasma oxytocin. The intramammary pressure increased upon manual stimulation of the udder and/or hand-milking in four out of six experiments. There was, in general, a close time-relationship between changes in intramammary pressure and plasma oxytocin.

Adenine nucleotides, serotonin, and aggregation properties of platelets of blue foxes (Alopex lagopus) with the Chediak-Higashi syndrome.

Bleeding times, concentrations of serotonin in whole blood, and concentrations of adenine nucleotides as well as aggregation properties of platelets were examined in 18 blue foxes with Chediak-Higashi-like syndrome (CHS) and 16 controls. A claw of each ketamine-sedated fox was cut until bleeding started and the bleeding time was recorded as the time from the first to the last drop. The bleeding time was greatly increased in CHS foxes. Platelet counts of CHS foxes were normal, but aggregation induced by adenosine diphosphate (ADP), serotonin, collagen, and arachidonate was impaired. Adrenaline and serotonin was impaired. Adrenaline and serotonin potentiated the aggregatory effect of ADP on control as well as on CHS platelets. The mean concentration of ADP in CHS platelets was about one-third that in controls, whereas adenosine triphosphate (ATP) was approximately one-half that in controls. Serotonin could not, in most cases, be detected in blood of CHS foxes. These findings suggest that the prolonged bleeding time in the CHS foxes is, at least partly, due to a storage pool deficiency. The drastically reduced, and in some cases absent, aggregation of CHS platelets in response to arachidonate suggests that defective arachidonate metabolism contributes to the impaired hemostasis.

Lack of behavioural effects following intraventricular infusion of somatostatin in the conscious goat.

The effect of IV or intracerebroventricular (ICV) administration of somatostatin was studied on the behaviour of conscious goats. The doses of somatostatin infused IV were 100 and 300 microgram for 30 min and 600 microgram for 6 min. The doses infused ICV were 10 and 100 microgram for 30 min and 600 microgram for 6 min. In contrast to earlier reports on experiments with rats ,no behavioral effects whatsoever were seen in goat. IV infusion of 100 to 600 microgram and ICV infusion of 600 microgram of somatostatin caused a difinite reduction in the secretion of insulin and growth hormone, but had no effect on the concentration of blood glucose. The reason why neither IV nor ICV administration of somatostatin had any behavioural effects in the conscious goat, in contrast to the effects in rat, cannot be explained with certainty. This may be due to species specificity, to the amount of somatostatin reaching the central nervous system, or to some metabolic changes in rat but not in goat.

Ontogeny of erythropoietin mRNA expression in liver, kidneys and testes of the foetal and the neonatal pig.

Erythropoietin (EPO) mRNA expression in kidneys, liver and testes of foetal and neonatal pigs was analysed using a competitive RT-PCR assay. The results indicate that in the foetal pig, erythropoietin expression is greatest in the liver, at birth; hepatic and renal expression are nearly identical, and by 5 weeks of age there is mainly renal expression. The dynamics of the renal expression of EPO mRNA in the perinatal period provide a correlate for observations made earlier of plasma EPO concentrations. Early in foetal life (30 days after artificial insemination), the mesonephroi contained large amounts of EPO mRNA. As in the rat, the testes produced EPO mRNA in amounts comparable to the liver on a per gram tissue basis, though much less on a per organ basis.

The porcine erythropoietin gene: cDNA sequence, genomic sequence and expression analyses in piglets.

The porcine erythropoietin (EPO) gene and its cDNA have been cloned and characterized. The cDNA encodes a protein of 194 amino acids. The gene structure and sequence show a high degree of homology to the corresponding human and murine gene. Steroid hormone receptor binding sites are present both in the promoter and in the 3' flanking region of the gene, which also contains an oxygen-sensing sequence. The promoter lacks classical promoter elements such as TATA and CAAT boxes. Expression analyses using a competitive RT-PCR assay showed that the kidneys contain about ten times more erythropoietin mRNA than the liver in five-week-old piglets, thus indicating that the shift from mainly hepatic to mainly renal EPO production has taken place at this age. The testes showed a higher ratio of EPO mRNA to total RNA than the liver. Spleen showed very low levels of expression, while no expression of erythropoietin mRNA was detected in brain tissue, bone marrow, lung, lymph nodes, and ovaries.

Responses of plasma Epo and kidney and liver Epo mRNA to hemorrhage in perinatal pigs.

Despite the fact that pig fetuses in late gestation have extensive erythropoiesis, low blood pO(2) and low hemoglobin concentrations, piglets are born without detectable concentrations of plasma erythropoietin (Epo). In the present study, we have examined the hypothesis that long-term hypoxic stimuli are less efficient than short-term stimuli in stimulating Epo production in perinatal pigs. From fetuses collected by hysterectomy 5 days before term, new-born piglets and piglets 2 and 5 weeks old, blood in amounts corresponding to 2% of body weight was withdrawn from the jugular vein. Twenty-four hours later the animals were killed and their kidney and liver Epo mRNA analysed by a competitive RT-PCR assay. Plasma Epo concentration was estimated by a solid-phase, two-site sequential chemiluminescent enzyme immunometric assay. We found that in nearly fully developed fetuses and in new-born piglets, the concentration of Epo mRNA did not increase upon bleeding. This is in contrast to earlier findings in sheep. In 2- and 5-week-old piglets, bleeding was associated with a 12-15-fold increase in kidney Epo mRNA. In the 2- and 5-week-old piglets, bleeding evoked increased translation of Epo mRNA into the protein hormone. Also in new-born piglets, increased plasma levels of Epo accompanied bleeding, whereas significant changes in gene Epo expression were not observed.

Plasma concentrations of cortisol in cows with hypocalcaemia in relation to their responses to treatment with calcium.

The mean plasma concentration of cortisol at the time of the first treatment for hypocalcaemia at calving was significantly higher in 17 cows which did not recover, than in 53 cows which recovered. Healthy periparturient cows had significantly lower cortisol levels than cows with hypocalcaemia. There was a negative correlation between plasma cortisol and plasma calcium at the time of the first treatment. After adjustment for differences in plasma calcium there was no significant difference between cortisol concentrations in healthy cows and paretic cows which recovered. Plasma cortisol was positively correlated with both packed cell volume (PCV) and serum creatine kinase (CK). At first treatment cows which did not recover had higher levels of PCV and serum CK than cows which recovered, and the difference between the mean plasma cortisol concentrations of these two groups was related to differences in plasma calcium, PCV and serum CK. Plasma cortisol concentrations remained high in cases of protracted paresis.

Effect of iron on erythropoietin production in anaemic piglets.

In the present study the response of plasma erythropoietin to iron injection in anaemic piglets was examined. At the age of 16 days, 4 piglets from the same litter were given 180 mg iron subcutaneously. After iron injection, blood samples for estimation of erythropoietin activity in plasma, haemoglobin concentration, and reticulocyte counts were taken every 6 or 12 h for 3 1/2 days. Plasma erythropoietin activity was estimated by a monoclonal enzyme-immunoassay (ELISA), developed for human erythropoietin. On the day of iron injection, haemoglobin concentration ranged between 41 and 48 g/l, reticulocyte counts from 9 to 17 percent, and plasma erythropoietin between 22 and 144 mU/ml. In 3 of the 4 piglets, iron injection resulted in a 2-6 fold increase in erythropoietin activity. Maximal erythropoietin activities were observed 24-42 h after injection, and after 66 h, the activities were close to the pretreatment values. It is concluded that in our experiment, iron, per se, has stimulated erythropoietin production.

Plasma erythropoietin in newborn lambs.

In the present study early postnatal changes in erythropoietin (Epo) level and hemoglobin concentration in 8 lambs were examined. Plasma Epo was estimated by a monoclonal enzyme-immunoassay (ELISA), developed for human Epo. In all the lambs, except one, Epo was low, or undetectable, immediately after birth. Within 6-12 h after birth, a marked increase in plasma Epo was found in 4 of the lambs. Within 3-7 days after birth, Epo was back to low levels. In the lamb with high Epo levels at birth, drastic decreases were observed during the next 6 h. There was no obvious correlation between the hemoglobin concentrations and the changes in plasma Epo.

Plasma progesterone in reindeer in relation to ovariectomy and hysterectomy.

Four semi-domesticated reindeer were ovariectomized and 3 both ovariectomized and hysterectomized, 30-70 days before expected parturition. Anaesthesia with etorphine/propyonylphenthiazine was followed by an increase in the plasma concentration of progesterone of peripheral blood. The concentration of progesterone returned to pre-anaesthetic values before ovariectomy. Ovariectomy did not result in any substantial change in the plasma progesterone concentration within an observation period of 35-120 min. Hysterectomy was followed by a marked decrease in peripheral plasma progesterone within 60 min. The progesterone concentration in ovarian venous blood was slightly higher than the jugular venous blood in 1 animal and 150 and 400 times higher in the 2 other animals examined. Thus, despite lack of marked changes of progesterone in jugular venous blood upon ovariectomy, it is concluded that the ovaries are a major production site of progesterone in pregnant reindeer. The progesterone in uterine venous blood was close to that in the jugular vein in 1 animal, and slightly higher in 2 others. This observation, and the maintenance of pregnancy in spite of ovariectomy in 2 out of 4 animals, point to the foeto-placental unit as an additional source of progesterone production.

Corticosteroids in nocturnal blood plasma of cows in the field related to stage of lactation and plasma acetoacetate.

Two materials of nocturnal blood plasma samples, each representing more than 100 cows unselected with respect to health condition, showed acetoacetate variations within a wide range, overlapping with the range for animals with clinical ketosis. Within each of the two materials a statistically significant (P smaller than 0.001) negative correlation (r equal to minus 0.30) was obtained between plasma corticosteroids and log acetoacetate. The lowest corticosteroid and the highest acetoacetate averages were obtained for animals which were within the first month of the lactation cycle. With increasing time post-partum the two components varied inversely, a maximum in corticosteroids coinciding with a minimum in acetoacetate in cows which had calved 2 1/2 to 3 months before the date of sampling. At this stage the mean plasma sugar was about 10 per cent higher than in early lactation. The corticosteroid ranges for different levels of acetoacetate overlapped extensively. Still cows with acetoacetate smaller than or equal to 0.6 mg/100 ml gave significantly higher corticosteroid averages than the rest of the material. But in animals exceeding the 0.6 mg limit no relationship was found between the severity of the ketonaemia and the steroid level. Thus, no difference was obtained between cows with clinical ketosis and animals which were moderately ketonaemic. Some change in adrenal function may be associated with the development of ketonaemic conditions in cows. But no proof has been provided of a direct adrenal involvement in the transformation of a case of subclinical ketosis to the clinical stage.

Plasma insulin and growth hormone concentrations in pregnant sheep I: diurnal variations in mid- and late pregnancy.

Two or three foetal lambs regularly result in a varying degree of carbohydrate shortage in mother ewes in late pregnancy. We have investigated the correlation between plasma insulin, growth hormone and energy substrate concentrations in ewes 8 and 1 weeks before lambing. Plasma growth hormone was fairly constant (2-3 ng/ml) throughout the 24-h cycle 8 weeks before parturition. Seven weeks later higher average levels and increased diurnal fluctuations were observed in 3 out of 4 multiparous ewes. The average post-absorptive insulin levels were reduced by 50 per cent during the same interval. Simultaneously decreased post-absorptive sugar and increased acetoacetate levels were observed. It is concluded that the hormonal adaptations to the increasing carbohydrate deficit in late pregnancy, especially among multiparous ewes, include: a) reduced post-absorptive plasma insulin levels, b) reduced insulin responses to feeding, and c) increased levels of growth hormone in the plasma.

Pyometra in the dog. III.--A pathophysiological investigation. III. Plasma progesterone levels and ovarian morphology.

The peripheral plasma progesterone levels in bitches with spontaneously developed pyometra did not differ significantly from those in normally cycling or pregnant bitches. The macroscopic ovarian morphology gave no indication of an increased corpus luteum activity. Ovarian follicular cysts were found in 4 out of 31 cases. There was no detectable difference of results between 14 bitches that had received hormonal medication 10 years to 1 week previous to the pyometra diagnosis, and the other patients.