Endocrinology, Vol 103, 431-440, Copyright © 1978 by Endocrine Society

ARTICLES

Rabbit ovarian protein kinases. II. Effect of an ovulatory dose of human chorionic gonadotropin or luteinizing hormone on the multiplicity of follicular and luteal protein kinases

M Hunzicker-Dunn and RA Jungmann

DEAE-cellulose chromatography of the 105,000 X g supernatant fraction (cytosol) obtained from popped estrous rabbit follicles revealed the presence of a single form of cAMP-dependent protein kinase, designated protein kinase 3. The iv injection of an ovulatory dose of hCG to estrous rabbits promoted the appearance of a second, transient peak of cytosol cAMP-dependent protein kinase, protein kinase 1. Protein kinase 1 was detected within 10 min of hCG administration but had regressed to undetectable levels by 24 h in corpora lutea (CL) of pseudopregnancy and by 72 h in CL of pregnancy. Ovulation and subsequent CL formation were accompanied by the appearance of a third form of cAMP-dependent protein kinase, designated protein kinase 2. Protein kinase 2 was present within 2 h after hCG administration and persisted as a major form of cytosol cAMP-dependent protein kinase throughout the life span of CL. All three forms of protein kinase were inhibited by the heat- stable protein kinase inhibitor from rabbit skeletal muscle, possessed cAMP-binding activity, and were markedly stimulated by 10(-7) M cAMP. The activity of protein kinase 3 in CL of pregnancy, in corpora albicantia, and in interstitial tissue was markedly greater than that in follicles or in CL of pseudopregnancy, while the activity of protein kinase 2 remained relatively constant throughout the luteal life span. The iv injection of a luteolytic dose of hCG to 4-day pseudopregnant rabbits promoted no alterations of the protein kinase elution profile upon DEAE-cellulose chromatography of the luteal cytosol obtained 10 min to 3 days post-hCG injection. However, with dedifferentiation of corpora albicantia into interstitial tissue, the cAMP dependency of protein kinase 2 was reduced. The results indicate that the enzymatic activity and multiplicity of cAMP-dependent protein kinases in the cytosol of ovarian structures are subject to regulation by LH (hCG) and depend upon the various reproductive stages of the rabbit.