Roland K. Meyer

Myotrophic activity of 19-nortestosterone and other steroids determined by modified levator ani muscle method.

Summary An 8-day rat levator ani muscle assay for myotrophic activity is presented. Preliminary steroid screening results indicate that 19-nortestosterone and other 19-nor analogs of androgens promise to be effective protein-anabolic, and relatively weak androgenic agents. Using the same dose levels of 19-nortestosterone and testosterone, equal myotrophic responses were produced, yet 19-nortestosterone showed only weak androgenic activity and testosterone exhibited strong androgenic activity. Androsterone possesses relatively strong androgenic and only weak myotrophic activity.

Hair Color, Molt, and Testis Size in Male, Short-Tailed Weasels Treated with Melatonin

Melatonin in beeswax was implanted in male weasels (Mustela erminea). Brown weasels and white animals undergoing the spring change to the brown pelage and reproductive activity molted, grew a new white coat, and became reproductively quiescent after treatment. Controls retained or acquired the brown coat and developed or maintained enlarged testes. Treated weasels with pituitary autografts under the kidney capsule grew brown hair after hair growth was initiated by plucking. It is suggested that the pineal gland product, melatonin, initiates changes in the central nervous system and endocrines which result in molting, growth of the white winter pelage, and reproductive quiescence in the weasel.

Delayed Nidation in the Rat Induced by Progesterone.

Summary Nidation of embryos was delayed from 1 to 45 days in rats ovariectomized on the 3rd day after mating, by subcutaneous injection of 4 mg of progesterone per day. Implantation was delayed until such time as 1 μg of estrone per day was given in addition to the progesterone. Recovery of blastocysts from one horn of the uterus during progesterone treatment and subsequent implantation of the embryos in the other horn induced by the progesterone-estrogen indicates that the embryos are maintained in the uterus in a viable, but resting condition during progesterone treatment. If rats were ovariectomized on the 3rd day and untreated for 8 days, nidation of embryos was not observed when progesterone and estrogen was initiated on the 9th day and given for the next 5 to 12 days. Rats ovariectomized on the 4th day after mating were variable in their response to 4 mg of progesterone, some exhibited delay others implanted at the normal time. Delayed nidation up to at least 3 days was obtained in hypophysectomized rats when they were injected only with 4 mg progesterone per day.

Radioimmunoassay estimates of plasma gonadotropin levels in the spawning pink salmon

Abstract A radioimmunoassay technique for measuring salmon gonadotropin is described. The method has been validated by comparing relative potency values of pituitary preparations in both bioassay and radioimmunoassay systems as well as establishing parallelism of dose-response curves obtained for standard salmon gonadotropin, pituitary, and plasma samples. A preliminary study to determine the plasma gonadotropin levels in pink salmon during the period of gonadal growth and development indicated that sexual maturity, including the events of ovulation or spermiation, is associated with an increased secretion of gonadotropin.

Effect of Varying Doses of Progesterone on Implantation in the Ovariectomized Hamster.

Summary No delay in implantation was obtained in hamsters castrated on the second day of pregnancy and given daily doses of progesterone (2-.25 mg). Percentage of implantation obtained decreases as the dose level is lowered to .125 mg daily. At .0625 mg nidation may occur, but, in the majority of cases it either fails or resorption subsequently occurs. Nidation does not take place when .0312 mg is given.

Corticosterone levels in adrenal effluent blood of some gallinaceous birds.

Summary A method is described for obtaining samples of adrenal venous blood from the bird. This allows avian species to be used for routine in vivo studies designed to assess adrenal activity by direct measurement. Levels of corticosterone, expressed as μg %, in adrenal effluent and peripheral plasma were 42.4 and 7.8 in turkeys and 34.8 and 8.6 in pheasants. In domestic fowl the values were 44.3 and 7.3 in Wisco Whites: 48.8 and 12.3 in New Hampshires, and 37.0 and 9.5 in White Rocks. ACTH (8 I.U. intravenously) increased the output of corticosterone from 29.6 to 104.6 μg % in pheasants and from 30.7 to 143.7 μg % in chickens 60 minutes after injection.

The role of the pituitary in regulating steroid secretion by the avian adrenal

Abstract Two weeks after hypophysectomy the “resting” level of corticosterone in the effluent blood from the adrenals of hypophysectomized chickens was 40% lower than in intact fowl. The output of corticosterone by hypophysectomized chickens, intact chickens, or intact pheasants increased during the time a series of hourly blood samples were collected from the adrenal vein. However, the magnitude of response in the hypophysectomized chickens was considerably less than that of intact birds. Intravenous administration of ACTH to hypophysectomized chickens or to intact pheasants elevated the amount of corticosterone in adrenal venous blood. It was concluded that the avian pituitary plays a major role in controlling the output of corticosterone by the adrenal, although the adrenals of these galliform birds are capable of functioning independently of pituitary regulation to a limited extent.

Effect of limited food intake on cyclic annual changes in ring-necked pheasant hens.

Annual changes in body weight, food intake, lipid indices, egg laying, and organ weights are reported for ring-necked pheasant (Phasianus colchicus) hens maintained on wire, on ad libitum and limited amounts of a high protein diet. Birds were autopsied at 3-month intervals for organ weight data. In control birds, body weights rose gradually throughout fall and early winter, rapidly increased in February and March, and reached a maximum in April. Food intake in the control pheasants closely paralleled the changes in body weights, but greatest intake occurred a month later coincident with the period of maximum egg production. Birds on limited intake maintained their body weight until the early reproductive season when a decline in weight occurred. Egg laying was markedly depressed and delayed in limited intake birds, although egg size and composition were normal. Laying in limited intake pheasants was 9 percent of that of control birds. Depot fat was found to parallel closely the changes in body weight and food intake. Liver lipids were lower in limited intake birds during all but the reproductive season. Plasma lipid values were statistically higher in limited intake birds during the nonreproductive season. The liver and intestine weights were greater in the limited intake birds. It is suggested that these data represent changes which help increase alimentary efficiency.

Nidation in Progesterone-Treated, Estrogen-Deficient Hamsters, Mesocricetus auratus (Waterhouse).

Summary 1. In the hamster, when ovarian hormones are lacking, due to ovariectomy, or hypophysectomy, implantation does not occur and blastocysts are not recovered. 2. Implantation does not occur in hypophysectomized hamsters with pituitary autografts. 3. Doses of progesterone, 2-4 mg daily, do not affect time of implantation in the intact hamster. 4. Implantation occurs with no apparent delay in hamsters made estrogen-deficient by ovariectomy, ovariectomy and adrenalectomy, or hypophysectomy and given daily injections of 2-4 mg progesterone. In experiments designed to eliminate estrogen in injection media and diet, implantation also occurred when progesterone was given to ovariectomized hamsters. This suggests that progesterone alone is required for maintenance of blastocyst and nidation in the hamster.

A Biological Method for Determining Small Quantities of Sodium Retaining Substances.

Summary 1. A practical micro-bioassay technic for desoxycorticosterone acetate activity is proposed, using albino, urethra-ligated, bilaterally adrenalectomized, male rats of 150-155 g weight. 2. A calibration curve is demonstrated using desoxycorticosterone acetate as the standard hormone and the percentage sodium retained as the measure of its activity. Two μg DC A injected subcutaneously in 2 stages produce a highly significant retention of administered sodium. 3. The proposed bioassay requires 30 lapsed hours and a minimum of special technical skills and apparatus, but a high degree of sensitivity and a satisfactory degree of precision are indicated. 4. No consistent correlation was found between urine volume changes and DCA dosage levels. A significant change in urine volume was observed with 4 μg DCA relative to the control group of animals, but not with the higher or lower doses of DCA studied.