No abstract

To determine whether cortisol has an effect on hypothalamic-pituitary-gonadal function, we studied 11 eumenorrheic women in the early follicular phase of consecutive menstrual cycles by performing daytime 10-min blood sampling, one before and one during hydrocortisone administration. Daily blood sampling for gonadotropins and sex steroids was also performed. LH pulsations were determined by modification of a widely used threshold method and compared by paired t-testing. The LH interpulse interval was significantly prolonged (95 +/- 5 to 119 +/- 14 min; p = 0.001), and the mean LH pulse amplitude remained unchanged (1.3 +/- 0.1 and 1.5 +/- 0.2 mIU/ml) with glucocorticoid exposure. Mean estradiol was not altered (46 +/- 5 and 43 +/- 3 pg/ml), but mean LH and FSH from pooled serum aliquots were slightly but significantly reduced (2.6 +/- 0.2 to 2.2 +/- 0.2, 5.5 +/- 0.4 to 4.5 +/- 0.3 mIU/ml; p = 0.004, 0.012, respectively). Mean progesterone levels were also decreased (0.8 +/- 0.3 to 0.5 +/- 0.2 ng/ml; p = 0.011) in the presence of exogenous glucocorticoid. Twenty-four-hour urinary free cortisol levels confirmed a substantial increase in free cortisol excretion (74 +/- 10 to 305 +/- 50 micrograms/day; p = 0.001). These results demonstrate that cortisol can slow LH pulse frequency and, by inference, hypothalamic GnRH secretion, in a manner that appears independent of corticotropin releasing factor. Excess cortisol alone may therefore play a role in the development of stress-associated menstrual disturbances.

We optimized storage conditions and validated a sensitive immunofluorometric assay (IFMA) for urinary gonadotropins. Assay linearity and parallelism for luteinizing hormone (LH) and follicle-stimulating hormone (FSH) was observed to 0.04 IU/L. Urinary LH and FSH were unaffected by changes of osmolarity from 0.5 to 3.0 mOsm/kg, and from pH 4.5 to 10.5. Serum and urine measurements of the hormones correlated well over a wide range of values: for LH, R2 = 0.94, P < 0.01; for FSH, R2 = 0.71, P < 0.01 (n = 304). Preservation of urine with glycerol (70 mL/L) and storage at -20 degrees C yielded > 80% recovery of LH and FSH after 51 weeks; this was comparable with recovery for acetone extracts of urine. Untreated urine showed loss of activity by 4 weeks of storage. Preserving urine specimens with glycerol is a simple method of storage for longitudinal study and compares favorably with acetone extraction. IFMAs can measure urinary gonadotropins reproducibly over a wide range of pH and osmotic conditions.

Methionine-auxotrophic L1210 cells were used to study the effect of methotrexate (MTX) on methionine uptake and metabolism. MTX was shown to inhibit amino acid transport systems and cause a decrease of methionine uptake into L1210 cells. Conversely, a nonmetabolizable amino acid analogue reduced MTX uptake into L1210 cells. MTX also blocked the transfer of the beta carbon from serine into methionine. Therefore, methionine deprivation may be an additional mechanism of action for MTX in methionine-auxotrophic tumor cells.

No abstract