Alpha-adrenoceptor involvement in catecholamine-induced hyperglycaemia in conscious fasted rabbits.

In conscious fasted rabbits an intravenous infusion of phenylephrine (20 micrograms kg-1 min-1) induced hyperglycaemia. The increase in blood glucose was accompanied by a modest increase in insulin secretion and a reduction of liver glycogen. Muscle glycogen and blood lactate levels were not altered by treatment with phenylephrine. Prazosin, 1 mg kg-1 s.c., partially attenuated phenylephrine-induced hyperglycaemia. Phenoxybenzamine infusion (16.6 micrograms kg-1 min-1) for 15 min suppressed the increase in blood glucose and the reduction in liver glycogen evoked by phenylephrine. This alpha-adrenoceptor blocker also clearly attenuated the blood glucose elevation observed on infusing adrenaline at 0.3 microgram kg-1 min-1. Blockade by phenoxybenzamine of phenylephrine- and adrenaline-induced hyperglycaemia was not accompanied by a significant increase in immunoreactive insulin plasma levels. Yohimbine infused at a rate of 20 micrograms kg-1 min-1, also completely blocked phenylephrine-induced hyperglycaemia. This suppressor effect was accompanied by a marked rebound in insulin secretion. It is concluded that in normal fasted rabbits stimulation of alpha-adrenoceptors induces hyperglycaemia. The increase in blood glucose depends mainly on liver glycogenolysis and inhibition of insulin secretion. Separate blockade of each component suffices to reduce alpha-adrenoceptor-mediated hyperglycaemia.

Role of alpha 1- and alpha 2-adrenoceptors in catecholamine-induced hyperglycaemia, lipolysis and insulin secretion in conscious fasted rabbits.

1. In conscious fasted rabbits an intravenous infusion of clonidine (2 micrograms kg-1 min-1) induced hyperglycaemia. The increase in blood glucose was accompanied by an inhibition of insulin secretion and basal lipolysis. 2. Yohimbine infused at a rate of 20 micrograms kg-1 min-1 suppressed clonidine-induced hyperglycaemia and blocked the inhibitory effect on insulin secretion mediated by the alpha 2-adrenoceptor agonist. 3. The intravenous infusion of amidephrine (10 micrograms kg-1 min-1) induced an increase in insulin secretion in the absence of patent hyperglycaemia. Prazosin, 0.3 mg kg-1 s.c. selectively antagonized the effect of amidephrine on insulin secretion. 4. Isoprenaline infusion (4.4 micrograms kg-1 min-1) evoked a significant increase in blood glycerol and immunoreactive insulin plasma levels. Both responses were clearly attenuated when alpha 2-adrenoceptors were simultaneously stimulated by selective (clonidine) and less selective (phenylephrine, 20 micrograms kg-1 min-1) agonists. 5. Amidephrine infusion did not induce appreciable changes in blood glycerol nor did it modify, isoprenaline-induced lipolytic response. 6. Simultaneous infusion of isoprenaline and amidephrine induced a remarkable increase in insulin secretion. 7. It is concluded that in normal fasted rabbits stimulation of alpha 2-adrenoceptors depresses basal and beta-adrenoceptor mediated lipolysis and insulin secretion. On the other hand, selective stimulation of alpha 1-adrenoceptors does not affect lipolysis but induces insulin release. Simultaneous stimulation of alpha 1- and beta-adrenoceptors potentiates the insulin secretory response.

In vivo evidence for alpha 2-adrenergic-dependent inhibition of lipid mobilization in the rabbit.

Both alpha- and beta-agonists were infused i.v. in unanesthetized rabbits. The alpha-adrenergic effect on lipid mobilization was investigated by comparing the modifications of blood glycerol levels induced by clonidine (alpha 2-agonist) and amidephrine (alpha 1-agonist) alone or in combination with isoprenaline (beta-agonist). Clonidine (2 micrograms X kg-1 X min-1) was found to significantly reduce the basal or isoprenaline-stimulated glycerol levels whereas amidephrine (10 micrograms X kg-1 X min-1) was without any effect. Plasma IRI levels were also reduced by clonidine. The results suggest that the reduction of lipid mobilization produced by clonidine could have been the consequence of the stimulation of the alpha 2-adrenergic antilipolytic receptors previously shown to be present in isolated fat cell membranes.

Changes in serum insulin levels during orthotopic liver transplantation in the pig.

Insulin and glucose levels were measured in 13 orthotopic liver transplantations in pigs. After portal revascularization a significant increase in the glucose levels takes place (p less than 0.01). When the infrahepatic vena cava clamp is removed, a significant increase in glucose and insulin concentrations (p less than 0.05) takes place. After the end of the operation the insulin levels decrease significantly with respect to initial values (p less than 0.05).

Study of the secretion of substance P, neurotensin and somatostatin in patients with cholelithiasis.

A comparative, case-control study on the pre- and postprandial release of three gastrointestinal peptides implicated in gallbladder motility has been carried out in humans in the attempt to determine their possible role in the pathogenesis of cholelithiasis. Fifty-seven adult patients (40 females and 17 males) with an ultrasound diagnosis of gallstones and 20 healthy subjects (9 females and 11 males) without cholelithiasis or other digestive pathology were studied. Plasma substance P, neurotensin and somatostatin were measured by means of RIA-I125 in basal fasting conditions and 30, 60 and 90 minutes after the oral intake of a semiliquid mixed meal. The levels of secretion of each hormone were compared in patients and healthy controls on an overall basis and in terms of sex, age and body weight. We found a basal and postprandial hypersecretion of substance P in patients with gallstones when compared with controls. Individuals with cholelithiasis showed a moderate decrease in neurotensin secretion after the oral meal. Somatostatin release was unchanged. In conclusion, patients with gallstones may present a functional disorder in the secretion of gastrointestinal hormones involved in gallbladder motility.

[The role of hyperprolactinaemia in sterility where the cycle is anovulatory and where there is deficit of progestogen. (Investigations of the pituitary reserves of FSH, LH and prolactin) (author's transl)]. / Du rôle de l'hyperprolactinémie dans la stérilité par cycle anovulatoire et par insuffisance progestative. (Investigations sur la réserve hypophysaire de FSH, LH et prolactine.

We have measured by radio-immunological assays the levels of prolactin (PRL), of FSH and of LH in the plasma in 7 cases where sterility was due to persistent anovulatory cycles and in 6 cases where there was a progesterone deficiency as the sole aetiological factor. Then we stimulated the release of these three hormones by giving 300 micrograms of TRF, PRL, and 100 micrograms of LH-RH, of FSH and of LH. The results were compared with those obtained in 7 cases of normal young women with clear-cut biphasic cycles used as controls. These results show that a rise in the reserves of prolactin in the pituitary is very common in anovulatory cycles and in progesterone deficiency. In every case where the prolactin is raised LH is significantly lowered, where as the levels of FSH do not show much variation between those found in normal women. Thus an inverse relationship between PRL and LH has been demonstrated and its significance has been commented on.

[Blood copper levels in pregnant women in the first trimester as a prognostic feature of fetal wellbeing]. / Taux de cuivre sérique chez les femmes enceintes pendant le premier trimestre comme pronostic de bien-être foetal.

The authors have performed 173 assays of the serum copper in 64 pregnant women and in 109 foetal blood samples taken at the time of delivery in an attempt to define an early indicator of a pathological process affecting the foetus, the pregnancy and the delivery. They observed a significant increase in the serum copper level during the first trimester of at risk pregnancies and the increased serum copper level is maintained from the start and throughout the pregnancy, in high risk pregnancies. The serum copper level therefore appears to be a good indicator of certain foetal, placental or maternal abnormalities, especially in high risk pregnancies.