Biomedical subjects
Publications and source records attributed to R R Gala.
The addition of dopamine to anterior pituitary incubations resulted in a marked decrease (88% for 3H prolactin and 69% for RIA prolactin) in prolactin release. Incubation with the cholinergic agonists carbacol, arecoline and nicotine resulted in no significant change in prolactin secretion.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The infusion of dopamine into the renal artery resulted in decreased prolactin release from 3 anterior pituitary glands transplanted under the kidney capsule. Prolactin levels continually decreased over a 5 min period after DA infusion was terminated and thereafter approached preinfusion levels by the end of 10 min.
Explore the source record for details and available documents.
The interaction of estradiol and luteinizing hormone-releasing hormone (LRH) may be a critical physiologic mechanism regulating the occurrence of ovulation in many species. These studies were conducted to assess (1) the effects of intramuscular injections of LRH in the intact female rhesus monkey and (2) the effects of estradiol in a Silastic delivery system in ovariectomized female rhesus monkeys. No changes in blood levels of luteinizing hormone (LH) were detected in response to 200 micrograms of LRH. Ovulation did not occur 48 hours after treatment. Ovariectomy decreased estradiol, increased LH, and had no effect on prolactin concentrations in sera. Insertion of a vaginal ring containing 10% estradiol increased blood estradiol levels 100-fold. Serum prolactin levels were unaffected; however, LH concentrations were altered in a multiphasic fashion. After the ring had been in place for 15 days, vaginal blood similar to menstrual flow was observed following removal.
The proportion of serum prolactin heterogeneity were investigated in a patient with a pituitary adenoma producing both prolactin and growth hormone. Glucose tolerance (GTT) and insulin tolerance (ITT) tests were performed alone and in combination with chlorpromazine both before and after hypophysectomy. Serum prolactin multiple forms were separated by Sephadex G-100 column chromatography at 3 degrees C. None of the provocative tests altered the already elevated serum prolactin either before (300 ng/ml) or after (100 ng/ml)hypophysectomy. Chlorpromazine or ITT did not alter the proportion of prolactin heterogeneity; GTT, whether in conjunction with chlorpromazine or alone and both before and after hypophysectomy, increased the proportions of the larger molecular species. In five tests in which the GTT was not performed the prolactin heterogeneity was as follows: 'void volume', 4.9%; 'big', 13.1%; 'little', 82.1%; in those experiments in which the GTT was performed the proportions of prolactin heterogeneity were: 'void volume', 13.5%, 'big', 19.2%; 'little', 67.3%.
Serum samples were obtained from 7 subjects (6 men and 1 woman) in the morning (09.00 h) and in the afternoon (15.00 h) of each week for a period of 13 months and assayed for prolactin by RIA. In addition, 4 female monkeys were sampled once weekly in the afternoon for approximately two years. The data were analyzed for cyclicity by power spectrum analysis. In both species a serum prolactin circannual cycle was not obvious. In most subjects statistically significant (P less than 0.05) cycles were observed; however, there was considerable variability among individuals in the duration of the cycle, which ranged between 4 and 50 weeks. A similar result was also observed for the monkey data; here the cycles ranged between 7 and 51 weeks. The physiologic significance of these cycles is unknown at present. It is suggested that although there appears to be no diurnal serum prolactin circannual cycle, this does not rule out the possibility that there may be a nocturnal circannual cycle.
The effect of restraint on plasma prolactin and corticosterone concentrations was investigated in chronically catheterized, ovariectomized (OVX) or ovariectomized, oestrogen-treated (OVX-PEP) rats. Restraint was induced by tying the hind legs together. In OVX rats, prolactin levels were unchanged following restraint, either during the morning (10.00 h) or afternoon (14.00 h). Prolactin levels increased in OVX-PEP animals when restraint was initiated in the morning; when restraint was initiated in the afternoon the prolactin response depended upon the level of prolactin before restraint. If levels were low (pre-surge) the response to restraint was similar to that observed in the morning; if prolactin levels were high (surge) the response to restraint was reversed and the prolactin level declined. The morning prolactin response to restraint was significantly inhibited and the afternoon surge was retarded in adrenalectomized OVX-PEP (OVX-PEP-ADX) rats; however, in OVX-PEP animals maintained on 0-9% NaCl drinking solution, the morning prolactin response to restraint was also blunted, although the afternoon surge was normal. In OVX-PEP-ADX animals injected with either vehicle alone, or 2 or 4 mg corticosterone for 4 days, and sampled on the morning of day 5, the prolactin response to restraint was absent. Furthermore, when OVX-PEP animals were injected daily with either vehicle or 4 mg corticosterone/day, they showed no increase in prolactin in response to restraint when values were compared with those of uninjected animals. Corticosterone levels after restraint were higher than initial values in all of the above experimental conditions.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The infusion of linear somatostatin did not block prolactin release induced by either perphenazine, TRH or serotonin. Somatostatin infusion, however, potentiated prolactin release induced by perphenazine and TRH but not that induced by serotonin.