Calcitonin cells in the intestine of goldfish and a comparison of the number of cells among saline-fed, soup-fed, or high Ca soup-fed fishes.

Calcitonin-immunoreactive cells were found in the intestine of goldfish. These cells were distributed mainly in the anterior part of the intestine, dispersed in the intestinal epithelium. The nucleus was located in the basal portion of the serosal side, and the cytoplasm was elongated to the luminal side. From the anterior part of the intestine, cDNA fragments with the same nucleotide sequence as that of the goldfish calcitonin gene were amplified by RT-PCR method. After administration of one of three kinds of solutions (saline, consommé soup, or high Ca consommé soup) into the digestive tract of the goldfish, the number of those cells was the largest in the consommé group at 6 h after ingestion, although blood Ca levels were the highest in the high Ca consommé group. The function of calcitonin cells in the intestine may be to restrain the acute absorption of nutrients and not to control blood Ca levels.

Development of a time-resolved fluoroimmunoassay (TR-FIA) for testosterone: measurement of serum testosterone concentrations after testosterone treatment in the rainbow trout (Oncorhynchus mykiss).

A sensitive time-resolved fluoroimmunoassay (TR-FIA) for testosterone was developed, and the assay system was used for measuring serum testosterone concentrations in rainbow trout. Testosterone-3-(O-carboxymethyl)oxime-bovine serum albumin (T-3-CMO-BSA) was immobilized by physical adsorption to the wells of microtiter plates. A competitive assay using two antibodies was performed among T-3-CMO-BSA in the solid-phase, unknown amounts of testosterone, testosterone antibodies, and europium labeled secondary antibodies, followed by measurements using a time-resolved fluorometer (DELFIA system). The TR-FIA had a sensitivity of 0.075 pg/50 microliters sample (1.5 pg/ml), and the range of the assay system was between 1.5 pg/ml and 25 ng/ml. The intra- and interassay coefficients of variation for the testosterone TR-FIA were satisfactorily low, and were between 1.62 and 6.38% and 2.96 and 8.29%, respectively. The assay system was applied to measure the serum testosterone concentrations after an injection of testosterone dissolved in saline, propyleneglycol, or coconut oil. Among the three solvents, the coconut oil group showed continuously high serum testosterone level. In contrast, the saline and propyleneglycol groups had maximum concentrations 24 hr after the injection, but their levels were significantly lower than that of the coconut oil group. The testosterone TR-FIA method is sensitive, repeatable, and is as accurate as conventional RIAs. It is very good for measuring serum testosterone concentrations.

Sex-specific effects on the fetal neuroendocrine system during acute stress in late pregnancy of rat and the influence of a simultaneous treatment by tyrosine.

It is well-known that prenatal chronic intermittent stress affects the reproductive system of both sexes. Investigating the effects of an acute maternal stress on the fetal neuroendocrine system, parameters such as hypothalamic catecholamines. CRF, GRF, LH-RH, beta-endorphin, hypophysial beta-endorphin and beta-LPH as well as plasma LH, corticosterone and androstenedione were measured. Pregnant rats of Wistar strain were exposed to restraint stress at day 22 of gestation or to forced immobilization at day 20 of gestation, respectively, and were sacrificed before stress and 10, 30, 60, and 120 min after starting stress. A decrease of fetal hypothalamic catecholamines and an increase of LH-RH content of the hypothalamus as well as of plasma catecholamines were observed under stress on day 22 of gestation. On day 20 of gestation hypothalamic beta-endorphin was depleted in male and unchanged in female fetuses under stress. A depletion of hypothalamic CRF was observed in male fetuses, whereas female fetuses showed an increase of hypothalamic CRF. An increase of GRF was found in fetuses of both sexes. Pituitary opioid content increased in fetuses of both sexes initially, but was depleted secondarily in male fetuses. The LH plasma level was markedly reduced in male, the corticosterone level was elevated in fetuses of both sexes as well as the androstenedione level in female fetuses. A simultaneous treatment of mother animals with tyrosine--a catecholamine precursor--prevented the depletion of hypothalamic and pituitary beta-endorphin as well as in part the reduction of plasma LH levels in male fetuses. Hypothalamic GRF content does not increase under tyrosine treatment in male fetuses, whereas in female fetuses the stress-induced increase of GRF content was rather pronounced under tyrosine than attenuated. These results indicate that fetal hypothalamic neurotransmitters and neurohormones (such as LH-RH, CRF, GRF and opioids) are involved in changing circulating hypophysial and adrenal hormones in fetuses exposed to maternal stress in late pregnancy, whereby sex-specific different pathways might be effective in fetal stress processing. The prenatal administration of tyrosine prevented at least in part--those neurohormonal changes which are affecting the sex-specific brain differentiation.