Radioimmunoassay of human growth hormone: technique and application to plasma, cerebrospinal fluid, and pituitary extracts

Relationship between prolactin in the serum and cerebrospinal fluid of ovariectomized female rhesus monkeys

The entry of prolactin into the cerebrospinal fluid from the blood, and the relation between levels in the two compartments were studied under a variety of conditions in ovariectomized rhesus monkeys. Prolonged treatment with either domperidone or sulpiride, both dopamine-receptor blockers, elevated prolactin levels in serum and cerebrospinal fluid proportionally equally, so that the cerebrospinal fluid serum ratio was unchanged from controls (circa 12-20%). Gel filtration showed that only 'little' (monomeric) prolactin entered the cerebrospinal fluid in such monkeys. Following acute elevations of blood prolactin after a single injection of either sulpiride or ovine prolactin, cerebrospinal fluid levels increased linearly over a 90 min sampling period, despite falling serum levels. The rate of entry of prolactin into the cerebrospinal fluid was similar after either procedure, and was independent of absolute serum or cerebrospinal fluid levels, suggesting a rate-limiting mechanism. Furthermore, retrograde portal blood flow from the pituitary is not necessary to account for these results. Clearance of prolactin from the third ventricle was studied following intraventricular injection of prolactin. Prolactin was removed from the cerebrospinal fluid by a mechanism whose efficiency compares with that in serum, so that the half-life of prolactin in either compartment is about the same. Measurement of sodium, potassium and calcium in the cerebrospinal fluid during prolonged hyperprolactinaemia showed no change, indicating that the central effects of prolactin are not due to alteration of these electrolytes. These results show that cerebrospinal fluid levels of prolactin, and hence, those surrounding the brain, can be inferred accurately from those in the blood, and suggest that there may be a selective mechanism regulating the entry of prolactin into the cerebral compartment.

Anterior pituitary hormone levels in the cerebrospinal fluid of patients with pituitary and parasellar tumors

Cerebrospinal fluid (CSF) concentrations of growth hormone, prolactin (PRL), adrenocorticotropin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, and the glycoprotein hormone alpha subunit were determined in 30 patients with pituitary and parasellar tumors. Although many of the patients had elevated hormone levels, no differentiation between patients with intrasellar tumors and those with pituitary tumors with suprasellar extension or primary suprasellar tumors could be made based upon the absolute CSF hormone concentration. A highly significant correlation between serum and CSF PRL concentrations was found (r = 0.87; P less than 0.001), suggesting that CSF PRL is derived from the serum. No correlation was found between the serum and CSF concentrations of the other anterior pituitary hormones.

The primary empty sella syndrome: analysis of the clinical characteristics, radiographic features, pituitary function and cerebrospinal fluid adenohypophysial hormone concentrations

Twelve cases of the primary empty sella syndrome were analyzed in regard to clinical findings, roentgenographic features, pituitary function and cerebrospinal fluid adenohypophysial hormone concentration. The findings were compared with those in 247 cases of the primary empty sella syndrome reviewed from the literature in order to determine the major characteristics of this disorder. The majority of patients are obese, multiparous women with normal pituitary reserve, normal visual fields and undetectable adenohypophysiol hormone concentrations in cerebrospinal fluid. In addition occasional patients witll have hypertension, pseudotumor cerebri and cerebrospinal fluid rhinorrhea. Patients who present with the typical features of the primary empty sella syndrome should be evaluated periodically with pituitary function testing, visual field examinations and cerebrospinal fluid adenohypophysial hormone determinations. If these parameters remain normal during careful follow-up studies, the patient is likely to have an empty sella, and pneumoencephalographic and angiographic studies can be avoided.

Distribution of growth hormone and thyroid-stimulating hormone in cerebrospinal fluid and pathological compartments of the central nervous system

Human growth hormone (HGH) radio-immunoassay (RIA) was adapted for an accurate measurement of immunoreactive HGH concentrations in the CSF in different cases of hypothalamic-somatotropin dysfunctions. In control subjects (n = 43) mean HGH levels were 0.35 +/- 0.03 ng/ml in CSF and 1.95 +/- 0.2 ng/ml in plasma with a CSF/plasma ratio of 17%. The thyroid-stimulating hormone (TSH) RIA gave in controls mean basal levels of 2.65 +/- 0.2 muU/ml in CSF and 5.95 +/- 0.3 muU/ml in plasma with a CSF/plasma ratio of 44%. HGH and TSH concentrations in CSF and plasma show a very good correlation; but the regression curves for both hormones are distinctly different and appear specific for each polypeptide hormone. Hypothalamic-somatotropin hyperreactivity was reported in diabetic retinopathy (DR). CSF and plasma HGH concentrations in a group of diabetic patients with progressing retinopathy (n = 27) were not different from those in normal subjects (respectively 0.35 +/- 0.05 in CSF and 2.10 +/- 0.25 ng/ml in plasma with a CSF/plasma ratio of 16%). The HGH regression curve obtained in diabetics is similar to that of controls. These data do not substantiate the hypothesis of an HGH hyperreactivity in diabetic retinopathy. In somatotropin hypersecretion (acromegaly) without adenoma suprasellar extension, higher HGH concentrations recorded in CSF than in plasma cannot be attributed to an anatomical break-down of the CSF blood-brain barrier and suggest an active transport process of pituitary hormones to the CNS. HGH and TSH concentrations were measured in the cystic fluid of CNS tumors. In 1 case of a cystic dysembryoma, the HGH and TSH of CF were considerably increased. In gliomas (n = 8) the HGH and TSH cystic fluid concentrations were more elevated (respectively 0.72 +/- 0.2 ng/ml and 3.6 +/- 0.7 muU/ml) than in the CSF of controls.