Effects of hypophysectomy and administration of pituitary hormones on luteal function and uptake of high density lipoproteins by luteinized ovaries and adrenals of the rat
The role of plasma lipoproteins and hypophyseal hormones in the maintenance of progesterone secretion by the rat corpus luteum was investigated. In the first experiment, rats were treated daily from days 1-6 of pregnancy with 5 mg/kg 4-aminopyrozolopyramidine (4APP), a blocker of hepatic lipoprotein secretion, or with 5 mg/kg 4APP and 1 or 2 mg ovine PRL or 0.1 ml 0.5% phosphoric acid (4APP vehicle). The administration of 4APP reduced serum cholesterol and progesterone levels on days 2-6 of pregnancy and ovarian progesterone on day 6. The reduced progesterone secretion had no effect on embryo implantation. PRL, in the doses used, was incapable of abrogating the effects of 4APP on circulating or ovarian progesterone levels. Ovaries and adrenals, but not kidneys, of pseudopregnant rats exhibited specific and saturable uptake of porcine high density lipoprotein (HDL). Time-course studies indicated that the uptake of HDL was rapid in ovaries compared to that in adrenals. Ovaries from rats not only exhibited uptake of porcine HDL, but also were capable of using it for progesterone synthesis. Treatment with 4APP increased the adrenal uptake of HDL, but ovarian uptake was not different from that in the control group. Hypophysectomy reduced both adrenal and ovarian uptake of HDL. In adrenals only ACTH at the dose employed ameliorated reduction of HDL uptake induced by hypophysectomy, while in the ovaries, both PRL and LH reversed the effect of hypophysectomy. The effect of PRL on uptake was specific to (/sup 125/I)HDL and did not alter (/sup 125/I)albumin uptake. It is concluded that: 1) hypophysectomy reduces HDL uptake in the luteinized rat ovary; and 2) PRL and LH replacement therapy maintain ovarian uptake of HDL, suggesting a direct effect of these luteotropins on lipoprotein uptake.
- Research Organization:
- Univ. of Saskatchewan, Saskatoon, Canada
- OSTI ID:
- 5609528
- Journal Information:
- Endocrinology; (United States), Vol. 116:4
- Country of Publication:
- United States
- Language:
- English
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LH
BIOLOGICAL FUNCTIONS
LIPOPROTEINS
UPTAKE
LTH
PROGESTERONE
BIOSYNTHESIS
ADRENAL GLANDS
ALBUMINS
BLOOD CHEMISTRY
CHOLESTEROL
HYPOPHYSECTOMY
IODINE 125
OVARIES
PREGNANCY
PURINES
RATS
TRACER TECHNIQUES
ANIMALS
AROMATICS
AZAARENES
BETA DECAY RADIOISOTOPES
BODY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
FEMALE GENITALS
FUNCTIONS
GLANDS
GONADOTROPINS
GONADS
HETEROCYCLIC COMPOUNDS
HORMONES
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KETONES
LIPIDS
MAMMALS
MEDICINE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
PREGNANES
PROTEINS
RADIOISOTOPES
RODENTS
STEROID HORMONES
STEROIDS
STEROLS
SURGERY
SYNTHESIS
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques
550501 - Metabolism- Tracer Techniques