Prolactin: A diabetogenic hormone

Abstract

Summary. During an oral glucose tolerance test (OGTT) glucose and insulin levels were measured in 26 patients with prolactin-producing pituitary tumours without growth hormone excess. Basal glucose and insulin levels did not differ from the values of an age-matched control group. After glucose load the hyperprolactinaemic patients showed a decrease in glucose tolerance and a hyperinsulinaemia. Bromocriptine (CB 154), which suppressed PRL, improved glucose tolerance and decreased insulin towards normal in a second OGTT. -Human PRL or CB 154 had no significant influence on insulin release due to glucose in the perfused rat pancreas. -These findings suggest a diabetogenic effect of PRL. CB 154 might be a useful drug in improving glucose utilization in hormone-active pituitary tumours.Key words: Prolactin, insulin release, glucose tolerance, pituitary tumours, pancreas perfusions, bromocriptine.Acute administration of ovine prolactin (PRL) has been shown to influence glucose metabolism in animals [1,2], to impair glucose tolerance in hypopituitary dwarfs and in hypophysectomized juvenile-type diabetics [3], and to stimulate lipid metabolism [4]. In order to study the long term effects of endogenous PRL on glucose tolerance and glucose-induced insulin secretion, patients with hyperprolactinaemia were investigated. In vitro experiments with the isolated perfused rat pancreas were undertaken to elucidate the direct effect of hPRL on insulin release. * Presented in part at the 11 th Annual Meeting of the European Association for the Study of Diabetes (EASD), Munich, September 4-6, 1975, and published in abstract form in Diabetologia 11, 357 (1975) Material aud Methods a. In vivo-StudyFifteen female and 11 male patients with hyperprolactinaemia were studied (Tab. 1). Twenty-four patients had a pituitary tumour, one had a craniopharyngioma and one had anormal sella turcica. A galactorrhoeaamenorrhoea syndrome was observed in 9 women.The average body weight was 13 ± 4 % above the ideal body weight and the average age was 34 ± 2 years (mean ± SEM). None of the patients had elevated plasma growth hormone concentrations. Eighteen patients had blunted hGH-secretion after insulin-induced hypoglycaemia. In six subjects TSH levels before and after TRH stimulation were below the lower limit of detection; six patients showed TSH values which were subnormal and two suffered from primary hypothyroidism. Thirteen had secondary hypogonadism, eleven had a latent or manifest secondary adrenal insufficiency and three had diabetes insipidus. The mean basal PRL level (x ± SEM) measured by radioimmunoassay [5] was 2422 ± 800 ng/ml ranging from 47 to 18 860 ng/ml. Our normal range for men is 8.5 to 25 ng/ml and for women up to 37.5 ng/ml. Fourteen patients were on appropriate hormone replacement therapy at the time of the study. Hypothyroidism was treated in all cases except two (Tab. 1) in order to avoid effects of low thyroid hormone levels on glucose tolerance.Fifteen patients (nine females and six males) were treated with bromocripti...

Prolactin response to TRH in diabetic ketoacidosis

“…circulating levels as in patients with pituitary adenomas [1,2]. We found normal basal prolactin concentrations and normal prolactin responses to TRH in patients with severe diabetic ketoacidosis, suggesting no important role for prolactin in this condition.…”

“…There was no correlation between basal prolactin concentrations, or magnitude of prolactin responses to TRH, and any of the metabolic variables measured. These findings do not suggest a role for prolactin in the development of diabetic ketoacidosis.Key words: Prolactin, diabetic ketoacidosis, plasma sodium, plasma osmolality, TRH test.Prolactin is said to have diabetogenic properties [1,2] and, in several animal species, plays a role in sodium and water retention [3]. Elevated prolactin concentrations have been reported in diabetic ketoacidosis and it was suggested that prolactin might participate in sodium retention in this condition [4].…”

“…Prolactin is said to have diabetogenic properties [1,2] and, in several animal species, plays a role in sodium and water retention [3]. Elevated prolactin concentrations have been reported in diabetic ketoacidosis and it was suggested that prolactin might participate in sodium retention in this condition [4].…”

Plasma prolactin response to thyrotropin releasing hormone in children with newly diagnosed insulin dependent diabetes.

“…Since PRL has been considered to be a diabetogenic hormone (Landgraf et al 1977), we thought it of interest to explore PRL secretion in children with newly diagnosed IDD. The previous reports on basal PRL release and the response to provocative stimuli in patients with IDD have been controversial.…”

“…Since it was reported that the administration of prolactin (PRL) elicited hyperglycemia (Rathgeb et al 1971) and that an impaired glucose tolerance and hyperinsulinemia were observed after glucose load in patients with hyperprolactinemia (Landgraf et al 1977), PRL has been considered to exert a diabetogenic action. It, therefore, seems to be of interest to explore PRL release in diabetes mellitus.…”