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Biomedical subjects

C L Kragt

Publications and source records attributed to C L Kragt.

At least 19 recordsLinked to original sources
PubMed1977

Luteinizing hormone-releasing hormone, ovariectomy, and silastic vaginal rings in the Rhesus monkey.

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.

Animals↗
PubMed1975

Interactions of prostaglandin E1 (PGE1) and LRH on anterior pituitary function.

Numerous biochemical pathways influence the synthesis and release of anterior pituitary hormones. Releasing factors extracted from the hypothalamus and prostaglandins (PGs) appear to alter a common biochemical activity, adenyl cyclase, in pituitary cells. Luteinizing hormone releasing hormone (LRH), prostaglandin (PGE1), 7 oxa-13-prostynoic acid and cycloheximide were tested for individual and interacting effects on the in vitro release of FSH, LH and prolactin from hemipituitaries of 15 day old female rats. LRH (10 ng/ml) consistently released both LH and FSH in all in vitro experiments and inhibited prolactin release in 1 of 2 experiments. Lower concentrations (5 and 1 ng/ml) also stimulated LH and FSH release but did not influence prolactin release. Concurrent depletion of stored LH and FSH in the gland was observed. PGE1 in a 6.5 hour incubation increased the storage of LH within the gland in the absence of LRH. In a 1.5 hour incubation in the presence of LRH, storage of LH was also increased. PGE1 had no effect on LH and FSH release; however, in 1 of 2 experiments it stimulted prolactin release in the absence of LRH. Prostynoic acid stimulted LH and FSH release but did not synergize with LRH action in the same tissue. Cycloheximide did not affect LH release during the first 30 minutes of incubation; however, the release during the subsequent 1 hour was significantly inhibited. Similar tissue also exposed to cycloheximide was still responsive to LRH during the latter 1 hour incubation period. Cycloheximide had no effect on prolactin storage and release from the same tissue.

Animals↗