Induction of estrous cycles in old non-cyclic rats by progesterone, ACTH, ether stress or L-dopa

Cycling was induced in old non-cyclic, constant estrous rats by daily injections of progesterone, ACTH or L-dopa or by subjection to ether stress. Progesterone and ACTH were the most effective agents used for re-establishing estrous cycles in these rats. Most of the progesterone- and ACTH-treated rats showed regular cycles, and their ovaries had many corpora lutea; they also showed proestrous serum LH surges. Ether stress and L-dopa mostly induced irregular cycles and fewer corpora lutea in the ovaries; a smaller number of these rats showed proestrous LH surges. After treatment with each of these agents was discontinued, most of the rats returned to constant estrus or irregular cycling.

Effects of hyper- and hypothyroidism on serum LH and FSH levels in intact and gonadectomized male and female rats

The effects of hypo- and hyper-thyroidism on serum LH and FSH were determined in both intact and castrated male and female rats. Thyro-parathyroidectomy (Tx) for 30 days in rats with intact gonads resulted in a significant reduction in serum LH and FSH, and also in a decrease in serum testosterone in males. Administration of 2.5 mug thyroxine (T4)/100 g BW to Tx rats of both sexes returned serum LH and FSH levels to those of intact rats, and in males also restored normal serum testosterone levels. Tx superimposed upon castration resulted in a significantly greater increase in serum LH and FSH than produced by castration alone. Administration of 2.5 mug T4/100 g body weight to castrate-Tx rats reduced serum LH and FSH values to those of castrate rats, whereas 10 mug T4/100 g BW evoked a further decrease in serum LH but no additional reduction in serum FSH. When both 2.5 mug T4/100 g BW and 2 mug estradiol benzoate were injected into Tx-ovariectomized rats, the decrease in serum LH and FSH was much greater than produced by T4 alone. These observations indicate that hypothyroidism results in decreased release of LH and FSH in rats with intact gonads, and in increased release of LH and FSH in castrate rats of both sexes. Administration of a replacement dose of T4 can restore LH and FSH release to normal in Tx rats with intact gonads, and to castration levels in Tx-castrate rats.

Effects of thyroid and ovaries on prolactin binding activity in rat liver

125I-radiolabeled ovine prolactin (oPRL) binding activity was measured in microsomal membranes of liver tissue from intact, ovariectomized, ovariectomized-thyroidectomized, and ovariectomized-thyroidectomized rats injected with thyroxine (T4) or estradiol benzoate (EB). Thyroidectomy and ovariectomy each reduced PRL binding activity in liver tissue significantly. The combination of ovariectomy and thyroidectomy decreased PRL binding activity more than thyroidectomy or ovariectomy alone. Doses of 2.5 mug or 10 mug T4/100 g BW daily returned PRL binding activity in the thyroidectomized rats to intact control values, and in the ovariectomized-thyroidectomized rats to the ovariectomized values. A dose of 2 mug EB/rat increased PRL binding activity significantly in ovariectomized-thyroidectomized rats, and a combination of 2 mug EB and 2.5 mug T4/100E that of intact controls. Scatchard analysis showed that ovariectomy and thyroidectomy decreased the number of PRL binding sites in the liver as compared to those in intact controls or in ovariectomized-thyroidectomized rats treated with EB and T4. It is concluded that the thyroid and ovaries are important regulators of PRL binding activity in the liver of the rat.

Serum prolactin levels and prolactin binding activity in adrenals and kidneys of male rats after dehydration, salt loading, and unilateral nephrectomy

Serum prolactin (PRL) levels and PRL binding activity in microsomal membranes from kidneys and adrenals were measured in control, water-deprived, unilaterally nephrectomized, and salt-loaded male rats. Unilateral nephrectomy and water deprivation increased serum prolactin levels significantly. Unilateral nephrectomy did not alter PRL binding activity in the kidneys, but significantly increased it in the adrenal glands. Salt loading had no effect on serum prolactin levels or PRL binding in the kidneys; but significantly increased PRL binding in the adrenal glands. Inhibition curves and tests of cross reactivity with LH, FSH, TSH, and GH showed that binding of PRL to its receptors in the kidneys and adrenals was specific. These observations suggest that PRL has a role in salt and water metabolism and that PRL receptors in the kidney and adrenals participate in this regulatory system.

Intermittent catheterization rather than urinary diversion in children with meningomyelocele

Fifteen girls more than 4 years old and with neuromuscular defects of meningomyelocele are maintaining adequate urinary continence through the use of intraurethral catheterization done by themselves or their parents. Urinary diversion has been necessary in only 1 child. The indwelling catheter has allowed heavily trabeculated bladders to become smooth enough for an antirflux operation to be successful, although the period of followup is only 2 years. Upper tract deterioration has not been observed and urine has been maintained sterile without the help of medication 50 per cent of the time when catheterizations have been done on a routine 3-hour schedule. For this method to be sucessful and replace conduit deversion, parents, child, nurse and physician must be a well-knit team. With the hope that a reliable artificial urinary sphincter will eventually provide contience for some children, one is further justified in pursuing urinary continence by use of the catheter, instead of resorting early to permanent conduit conversion.

Prolactin binding activity on the crop sacs of juvenile, mature, parent and prolactin-injected pigeons

Specific prolactin (PRL) binding activity of lactoperoxidase catalyzed 125I-labeled ovine-PRL was determined in a membrane-rich particulate fraction of pigeon crop sacs. Levels of TSH, LH or FSH as high as 1000 ng each were unable to displace the 125I-o-PRL bound to 600 mug of crop sac microsomal protein, whereas competitive displacement was achieved with as little as 0.5 ng unlabeled PRL. Ovine GH exhibited some cross reactivity when incubated in amounts greater than 500 ng, but this could be accounted for by its stated PRL contamination. Specific PRL binding activities were determined in juvenile and mature pigeons with unstimulated crop sacs, and parent pigeons with 'crop milk' and mature birds injected with PRL for 4 days. Crop sacs from juvenile birds contained approximately twice as much binding activity as crop sacs from mature pigeons. Parent and PRL injected pigeons, each with proliferated crop sac epithelium, exhibited 4-5 times as much specific PRL binding as the non-proliferated crops from juvenile or mature birds. These results show that the pigeon crop sac contains specific binding sites for PRL, and that the crop sac response to PRL is associated with an increase in PRL binding activity.

New rifampin-resistant mutant of Escherichia coli

A rifampin-resistant ribonucleic acid (RNA) polymerase mutant, rif(r)51, derived from a presumptive RNA synthesis mutant of Escherichia coli K-12, complements rif(r) RNA polymerase mutants isolated from other strains of E. coli K-12.