Masters Theses

Date of Award

12-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Henry G. Kattesh

Committee Members

Tom T. Chen, R. L. Murphree

Abstract

The objectives of this study were (1) to determine the effect of exogenous ACTH upon maternal and conceptus parameters in pregnant gilts and (2) to validate an assay for cytoplasmic progesterone receptors in order to quantitate levels in uterine endometrium of pregnant gilts receiving ACTH injections. Seventy-two gilts of similar age and breeding were mixed and ran-domly placed in groups of 12 in one of six pasture lots and observed through one normal estrous cycle. Upon detection of the second estrus, gilts were double mated at 12 and 24 hours after estrus detection using a different boar at each breeding. Mating was accomplished by artificial insemination using fresh semen. Breeding continued until 48 gilts were obtained. Once bred, gilts were randomly assigned to one of 3 treatments and one of 4 injection periods. Treatments consisted of a single, daily, intramuscular injection of either 0, 40 or 80 USP units of corticotrophin in an aqueous suspension containing zinc hydroxide for repository action, for a period of 5 days. Control gilts received an injection of vehicle containing zinc hydroxide with no corticotrophin activity. The injec-tion periods were 1-5, 6-10, 11-15, or 16-20 days of gestation with day one corresponding to 48 hours postestrus detection. All gilts were slaughtered at approximately 37 days of gestation. Forty—two of the 48 gilts bred conceived; there was no difference (P>.10) in conception rate among the 12 treatment-period combinations. Injections of ACTH, regardless of dosage or period given had no apparent effects on fetal survival or any of the maternal or conceptus parameters measured. Conceptus data were pooled and analyzed for differences according to position within the uterus. The three positions analyzed were the utero—tubal portion, the middle portion and the cervical portion. Average allantoic fluid volume was significantly (P<.05) greater, fetal wet weights were heavier (P<.10) and degenerating fetal numbers were greater (P<.05) in the middle portion while placental lengths were significantly (P<.05) longer in the ovarian portion than the cervical portion of the uterus. Validation of an assay for quantitating uterine cytoplasmic pro-gesterone receptors indicated that a specific protein receptor for pro-gesterone existed having a Kd of 26.3 pM and a binding capacity of 3.4 pmol/mg tissue. It was also determined that 12.5 mg of uterine tissue appears to be saturated at a concentration of 15-20 nM 3H-progesterone for an incubation period of 10 to 14 hours.

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