Oral glucose tolerance and insulin response after one week's clonidine treatment in hypertensive patients

Acute clonidine administration is known to induce a significant rise in plasma glucose in man. In order to evaluate the possible effect of prolonged drug treatment on glucose metabolism, paired OGTTs were performed in 12 hypertensive patients (6 with normal and 6 with abnormal glucose tolerance) in basal conditions and following 1-week's administration of clonidine (0.15 mg every 8 h) Basal plasma glucose and serum insulin concentration as well as glucose tolerance and insulin response to oral glucose did not change in either group after treatment. Although the mechanism(s) mediating the transient hyperglycemic action of clonidine are not fully understood, the present findings indicate that this drug does not exert diabetogenic effects during chronic treatment, and suggest that homeostatic mechanisms may counteract the acute effect of clonidine on glucose metabolism.

Effect of loperamide, a peripheral opiate agonist, on circulating glucose, free fatty acids, insulin, C-peptide and pituitary hormones in healthy man

The effect of acute oral administration of loperamide (4, 8 and 16 mg), a peripheral opiate agonist used in the treatment of diarrhoea, on several metabolic and endocrine variables has been evaluated in healthy volunteers in comparison with placebo. Plasma glucose was significantly raised by all three doses, whereas serum IRI and C-peptide were decreased and serum FFA was significantly increased only after loperamide 8 and 16 mg; serum PRL, GH, LH and FSH did not change. The data suggest that opiates may be involved in the regulation of glycaemia, probably by modifying islet hormone secretion by acting at a peripheral site, since loperamide does not cross the blood-brain barrier. Although the precise mechanism of these actions is unknown, it is suggested that the effects of loperamide are mediated either by stimulation of opiate receptors per se, or by suppression of acetylcholine release from cholinergic nerve endings. The lack of change in pituitary hormone secretion by loperamide is in agreement with previous observations indicating that opiate effects on PRL, GH and gonadotropins occur at the level of the central nervous system.

[Ileo-ceco-colic invagination. Apropos of a case caused by lymphoma of the last ileal loop]

An unusual case of intestinal invagination due to lymphoma of the last ileal segment serves as a basis for a review of the pathogenetic mechanisms underlying the invagination process and its different onset modalities. Special attention is paid to how chronic invaginations, as a result of their varied, unremarkable symptomatology, often involve mistaken or late diagnosis. The present case is noteworthy because of the summing of factors proper to primary invagination with those of secondary invagination. The hyperperistaltism resulting from the presence of a non-pedunculated mass acted on an intestinal segment in which the anatomico-functional conditions for the establishment of primary invagination were often present., All this was responsible for a chronic basic ileo-caecal invagination process, the cause of progressive limming with acute episodes of further advance of the invaginated part to the transverse colon. It was these acute episodes that gave clinical dignity to the insidious symptomatology reported by the patient thus allowing speedy, correct diagnosis of the ongoing neoplastic process and hence radical surgery with favourable prognosis.

Clonidine-induced hyperglycemia: evidence against a growth hormone-mediated effect

The effects of acute clonidine infusion (0.15 mg over 10 min) on several endocrine and metabolic variables have been evaluated in 12 hypertensive patients and 12 normotensive controls. Plasma glucose increased significantly in comparison with a placebo study in both groups; serum growth hormone showed a significant increase in healthy subjects but did not rise in hypertensive patients; there was no correlation between the increments in plasma glucose and in serum growth hormone in the whole group of subjects; serum-free fatty acids, insulin, prolactin and plasma cortisol did not change in any group. These data, although not excluding a central site of the clonidine hyperglycemic action, contrast the view that it may depend on stimulation of growth hormone release.

Metabolic effects of chronic prazosin treatment

The effects of chronic (3 mg/day for 1 week) administration of the vasodilator drug prazosin on several metabolic and endocrine variables were evaluated in 12 hypertensive patients, 6 with normal and 6 with abnormal oral glucose tolerance test (OGTT). After 1 week prazosin treatment there were no significant modifications in fasting plasma glucose, serum free fatty acids (FFA), cholesterol, triglycerides, insulin (IRI), growth hormone (GH), prolactin (PRL) and gastrin levels; oral glucose tolerance and IRI response to glucose were unchanged in normal subjects, while in chemical diabetics there was a significant improvement in glucose tolerance and a slight increse in IRI secretion. Therefore, the untoward metabolic effects of acute prazosin administration, i.e. increased plasma glucose and serum FFA, are not sustained during chronic treatment, which may even improve glucose metabolism in diabetic patients.

Metabolic effects of prazosin

The effects of oral administration of 2 mg prazosin on several metabolic and endocrine variables were evaluated in 12 patients with hypertension (6 with normal and 6 with abnormal glucose tolerance). Prazosin was followed by a rise in plasma glucose and serum free fatty acids (FFA) in both normal and diabetic subjects; there was a trend upward in serum albumin (IRI), but growth hormone (GH), prolactin (PRL), and gastrin did not change. Although these results are in general agreement with metabolic effects of other alpha adrenergic blockers already reported, the rise in plasma glucose is at variance with studies performed with phentolamine.

Growth hormone secretion in hypertensive patients: evidence for a derangement in central adrenergic function

1. In an attempt to test the hypothesis of a derangement in central catecholaminergic function in hypertensive patients, the serum growth hormone and prolactin responses to the alpha-adrenergic agonist clonidine (0.15 mg infused intravenously) and to L-dopa administration (500 mg orally) were evaluated in 15 hypertensive and 15 normotensive subjects matched for sex, age and body weight. 2. Whereas L-dopa elicited a growth hormone response of similar magnitude in both groups, clonidine infusion induced a significant increase in serum growth hormone in normotensive, but not in hypertensive, subjects. 3. Prolactin levels were equally suppressed by L-dopa and did not change after clonidine in either group. 4. The present study adds neuroendocrine evidence to the concept of a derangement in central alpha-adrenergic function in human hypertension.

Effect of two antiserotoninergic drugs, methysergide and metergoline, on gastric acid secretion and gastrin release in healthy man

The effects of acute oral administration of the antiserotoninergic drugs methysergide (3 mg) and metergoline (4 mg) on basal, submaximal (0.6 micrograms/kg i. m.) and maximal (6 micrograms/kg) pentagastrin-stimulated gastric acid secretion, as well as on basal and food-induced gastrin release, have been evaluated in healthy volunteers. Methysergide significantly increased basal and submaximal pentagastrin-stimulated gastric acid secretion, and metergoline significantly inhibited gastric acidity in all experiments. Basal and stimulated serum gastrin concentrations were not modified by either drug. The effect of methysergide on gastric acid secretion was opposed to that of serotonin and was probably dependent on its antiserotoninergic action, but the decrease in gastric acidity caused by metergoline is not easily explained. Although the effect is similar to that of a dopamine infusion, it does not depend on dopamine infusion, it does not depend on dopamine receptor stimulation, since it was not influenced by pretreatment with metoclopramide. It is suggested that it might be due to the weak anticholinergic and/or antihistaminic properties of metergoline.

Effect of four dopamine receptor antagonists on gastrin secretion in healthy subjects

The effect of 1 week of oral treatment with four antidopaminergic drugs--metoclopramide, sulpiride, haloperidol, and pimozide--on fasting and meal-stimulated serum gastrin levels has been evaluated in healthy subjects. All of the four drugs significantly reduced the gastrin response to a meal, whereas basal concentration was unaffected. It is suggested that this action is mediated by central nervous system dopamine receptor blockade, which might act either via nervous or humoral mechanisms to inhibit gastrin release.

Prolactin release by intravenous cimetidine in man: evidence for a suprapituitary locus on action

In an attempt to identify the sites at which cimetidine stimulates prolactin release, the drug was administered intravenously (6 mg/kg body weight) to healthy subjects under basal conditions, during dopamine infusion (1 microgram/Kg-min for 120 min) and after pretreatment with L-dopa plus carbidopa (250 plus 25 mg every 6 for 1 day). The serum prolactin response to cimetidine was abolished by dopamine infusion and almost completely suppressed by L-dopa plus carbidopa administration. These findings suggest that the drug acts on the central nervous system to stimulate prolactin release. Although the mechanism of this action is unclear, it does not seem to depend on an antidopaminergic effect and may be related to blackade of brain H2 histamine receptors.

Improved oral glucose tolerance following antiserotonin treatment in patients with chemical diabetes

The effects of short-term treatment with either placebo or two serotonin antagonists, cyproheptadine and metergoline, on oral glucose tolerance and insulin secretion have been evaluated in normal subjects and in patients with chemical diabetes. Placebo treatment was not associated with any significant change in the parameters examined. Glucose tolerance in chemical diabetics was significantly improved both after cyproheptadine and metergoline; fasting plasma glucose was also reduced by metergoline. Treatment with the latter drug was also associated with a significant decrease in incremental glucose area in healthy subjects, which was not affected by cyproheptadine. Basal and glucose-stimulated insulin secretion were not affected by either drug in any subjects. Cyproheptadine and metergoline improve glucose metabolism in chemical diabetes probably by reducing insulin resistance. This may depend either on decreased secretion of counter-regulatory hormones or on a direct pharmacological action of the drugs on glucose utilization, possibly mediated by their common antiserotoninergic properties.

Stimulation of prolactin release by intravenous cimetidine: a dose-response study

The PRL response to iv cimetidine was tested in 8 healthy males and 8 females at 4 different dose levels (0.75, 1.5, 3.0 and 6.0 mg/kg bw). Serum PRL levels were significantly increased in comparison with a placebo study by the second cimetidine dose in both sexes. The PRL response was significantly higher in females than in males at all but the lowest dose tested. A significant correlation between the cimetidine dose and the PRL response was observed. There was no significant modifications in serum GH, LH, FSH, IRI and glucose. Present findings demonstrate that the stimulation of PRL release by iv cimetidine is quite specific and dose-dependent.