Prolactin measurement

In combination with clinical symptoms, at least three repeated measures of serum prolactin levels greater than 20 ng/mL (20 mcg/L) are needed to confirm the diagnosis because prolactin,... 

Figure 7.9 Effects of MDMA pretreatment on secretion of corticosterone (left panel) and prolactin (right panel) evoked by acute MDMA challenge. Male rats received three i.p. injections of 1.5 or 7.5 mg/kg MDMA, one dose every 2 h. Saline was administered on the same schedule. Then 2 weeks later rats received i.v. injections of 1 and 3 mg/kg MDMA. Blood samples were drawn via indwelling catheters plasma corticosterone and prolactin were measured by RIA.126 Data are mean SEM, expressed as ng/ml of plasma for N = 8 rats/group. Baseline corticosterone and prolactin levels were 73 18 and 2.4 0.6 ng/ml of plasma, respectively. Significant compared to saline-pretreated control group (P < 0.05 Duncan s).

Time-resolved approaches for multi-analyte immunoassays have been described recently. Simultaneous determination of LH, follicle stimulating hormone (FSH), hCG, and prolactin (PRL) in a multisite manual strip format has been reported. 88 Four microtiter wells are attached to a plastic strip, two-by-two and back-to-back, such that the wells can be read on a microtiter plate reader. In a quadruple-label format, the simultaneous quantitative determination of four analytes in dried blood spots can be done using europium, samarium, dysprosium, and terbium. 89 In this approach, thyroid-stimulating hormone, 17-a-hydroxyprogesterone, immunoreactive trypsin, and creatine kinase MM (CK-MM) isoenzyme are determined from dried blood samples spotted on filter paper in a microtiter well coated with a mixture of antibodies. Dissociative fluorescence enhancement of the four ions using cofluorescence-based enhancement solutions enables the time-resolved fluorescence of each ion to be measured through four narrow-band interference filters. 

Fig. 3A, B Neuropeptide effects on anxiety-related behavioiu. A The oxytocin receptor antagonist (black bars) administered intracerebroventricularly (i.c.v.) increased indices of anxiety-related behaviour in pregnant rats as measured on the elevated plus maze. Entries into the closed arms indicate unchanged locomotor activity. B Prolactin is an anxiolytic neuropeptide in female rats as revealed by i.c.v. administration of synthetic prolactin (grey and black bars represent two different doses) and by antisense targeting of the prolactin receptor (R). Vehicle (white bars) vs mixed bases (grey bars) and antisense oligodeoxynu-cleotide (black bars). p<0.05 vs vehicle (white bars). (Adapted from Nemnann et al. 2000) and Torner et al. 2001)...

The relation between prolactin concentrations and osteoporosis has been studied by measuring prolactin concentrations and lumbar spine and hip bone mineral densities in women with schizophrenia taking so-called... 

Two parallel groups of healthy volunteers received 20 mg of citalopram (n = 12) or placebo (n = 6) once daily for 10 d in a randomized, double-blind fashion, followed by concomitant selegiline, 10 mg once daily for 4 d. The safety of this drug combination was assessed by measurements of blood pressure, heart rate, body temperature, and inquiries for adverse events. Blood samples were taken for the analysis of serum concentrations of selegiline, citalopram, and their metabolites. In addition, plasma was obtained to measure prolactin, epinephrine, norepinephrine, and 3,4-dihydroxyphanolglycol (DHPG), the urinary excretion of norepinephrine and 5-hydroindoleacetic acid (5-HIAA), the urinary metabolite of serotonin. 

Fig. 13 YOUDEN diagram obtained after a ring trial for prolactin left evaluation limits for the luminometric measurement using the test kit from manufacturer 44 middle evaluation limits for the luminometric measurement using the test kit from manufacturer 04 right evaluation limits for the fluorimetric measurement using the test kit from manufacturer 04 the respective participants results are emphasised by dark dots...

Serum hormone concentrations reflect both the rate of secretion and clearance by peripheral tissues. In parallel with our studies on prolactin secretion we have evaluated the effects of dietary fat on the metabolic clearance rate of prolactin. Rats were initially treated with ergocryptine to suppress endogenous prolactin secretion. We then measured the disappearance of immuno-reactive prolactin from the sera after a single intravenous injection of prolactin. No significant effect of dietary fat on the clearance of prolactin was observed (Figure 4). 

The role of cyclic AMP as modulator of prolactin secretion was first suggested by the finding of a stimulatory effect of cyclic AMP derivatives (17-22) and inhibitors of cyclic nucleotide phosphodiesterase activity such as theophylline and IBMX (22-26) on the secretion of this hormone. More convincing evidence supporting a role of cyclic AMP in the action of dopamine on prolactin secretion had to be obtained, however, by measurement of adenohypophysial adenylate cyclase activity or cyclic AMP accumulation under the influence of the catecholamine. As illustrated in Fig. 1, addition of 100 nM dopamine to male rat hemipituitaries led to a rapid inhibition of cyclic AMP accumulation, a maximal effect (30% inhibition) being already obtained 5 min after addition of the catecholamine. Thus, while dopamine is well known to stimulate adenylate cyclase activity in the striatum (27, 28), its effect at the adenohypophysial level in intact cells is inhibitory. Dopamine has also been found to exert parallel inhibitory effects on cyclic AMP levels and prolactin release in ovine adenohypophysial cells in culture (29) and purified rat mammotrophs (30). Using paired hemipituitaries obtained from female rats, Ray and Wallis (22) have found a rapid inhibitory effect of dopamine on cyclic AMP accumulation to approximately 75% of control. 

Concentrations of (10-160) X 10-3IU/liter of TSH in blood can be measured. There is no cross-reactivity with hLH, hFSH, adrenocorticotropic hormone, prolactin, or hCG (Fig. 7). TSH in dried blood samples is stable at room temperature for at least 1 month. The mean coefficients of variation were 12.1% (within assay) and 14.0% (between assays). A good correlation... 

In GH cells SST inhibits prolactin secretion induced by cAMP analogs and K+-induced depolarization in addition to inhibiting adenylyl cyclase activity [192], Similar data were also obtained with ACTH-secreting AtT-20 cells [203]. PTX blocks SST inhibition of ligand-induced and cAMP analog-induced secretions in both GH and AtT-20 cells [106,107]. Thus, it is clear that a G protein is involved in both the cAMP dependent and the cAMP-independent actions of SST. Quin-2 measurements showed that exposure of cells to SST lowers the intracellular Ca2+ levels. This effect is also PTX-sensitive [211-213], The decline in intracellular Ca2+ was concluded to be secondary to SST hyperpolarizing the cells by increasing K+ conductance [214,215]. Acetylcholine, like SST, causes inhibition of adenylyl cyclase, hy-... 

The suprahypothalamic neurotransmitter level can be assessed by a determination of catecholamines in circumscribed brain areas, the technique requires preparation of frozen tissue and isolation of specific nuclei by the micropunch technique. The catecholamines and indolamines can be measured by a radio-enzymatic methods and by a high-pressure liquid chromatography (HPLC) with electrochemical detection. These mechanistic investigations are mostly initiated due to questions arising from the receptor interaction profile of the drug candidate, they may be required to prove that such receptor interactions truly change the functional state of neurotransmitters (functional expression). Mostly, however, the peripheral effects of such neurotransmitter mechanisms (for instance prolactin secretion) are sufficiently distinct. 

For the evolution of histological findings, measurement of pituitary prolactin concentrations should be considered as an additional source of information. 

CRITICAL ASSESSMENT OF THE METHOD The method is of interest because the results can be correlated with measurements of pituitary TSH and prolactin secretion, and tissue content of these hormones. In a number of studies it has been shown, that changes in the secretion of thyroid hormone in the treated animals as well as administration of hormonally active compounds can change the hypothalamic TRH content in characteristic manner (Emerson and Utiger 1975, Schwinn et al. 1976, Simpkins et al. 1976). 

Schwinn G, von zur Muhlen A, Warnecke U (1976) Effects of dexamethasone on thyrotrophin and prolactin plasma levels in rats. Acta Endocrinol (Copenh) 82(3) 486-91 Simpkins JW, Bruni JF, Mioduszewski RJ, Meites J (1976) Serum and pituitary TSH and response to TRH in developing male and female rats. Endocrinology 98(6) 1365-9 Utsumi M, TateiwaM, MakimuraH, Yamada A, Mori H, Kusaka T, Sakoda M,Baba S (1975) Diurnal variation of the human urinary TRH excretion measured by radioimmunoassay. Endocrinol Jpn 22(6) 509-16... 

They are now many modifications of different sensitivity and limit of detection (Utiger 1979, Spencer 2004). In the endocrine safety pharmacology in rats and dogs, the TRH test injection with measurement of the serum TSH response is an established tool for assessment of changes at the level of thyroid hormone secretion, with consecutive modification of the pituitary TSH and prolactin response. 

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