Formation of follicular cysts in cattle and therapeutic effects of controlled internal drug release.
Follicular cysts in cattle result from excessive growth of the dominant follicle without ovulation and still constitute a major reproductive disorder in this species. One key hormonal characteristic of cows with follicular cysts is the lack of an LH surge, although they have increased plasma estradiol concentrations. Another is a relatively high level of pulsatile secretion of LH that promotes continued growth of the dominant follicle. These LH characteristics seem to result from a functional abnormality in the feedback regulation of LH secretion by estradiol. Treatment with controlled internal drug release devices that increase circulating progesterone levels is effective in resolving follicular cystic conditions by 1) lowering pulsatile LH secretion and 2) restoring the ability of the hypothalamo-pituitary axis to generate an LH surge in response to an increase in circulating estradiol.
Kimotsuki Livestock Hygiene Service Center, Kanoya, Kagoshima, Japan.
Junichi
J
Todoroki
Hiroyuki
H
Kaneko
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000503:physiopathology*; D004622:Embryo, Mammalian; D004958:Estradiol / Q000276:immunology / Q000502:physiology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D012739:Gonadal Steroid Hormones / Q000097:blood; D007265:Inhibins / Q000097:blood; D007986:Luteinizing Hormone / Q000187:drug effects / Q000378:metabolism*; D010048:Ovarian Cysts / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control / Q000662:veterinary*; D006080:Ovarian Follicle / Q000187:drug effects; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*
D012739:Gonadal Steroid Hormones; C422362:inhibin A; D011374:Progesterone; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone