Disease relevance of SC 21009

• These data indicate that norgestomet implants increased rate of weight gain, reduced estrous activity, and reduced the occurrence of pregnancy in heifers on pasture [1].
• Heifers with Norgestomet implants had higher body weight gains during the last 66 days (P < 0.05), and during the entire 122-day trial (P < 0.07) than heifers with placebo implants [2].
• In MCF-7 breast cancer cell bioassays, norgestomet showed weak estrogenic activity, but only at concentrations greater than 1 micromolar [3].
• Dystocia (P < 0.05), retention of fetal membranes (P < 0.01), and calf mortality (P < 0.01) were higher for the ovariectomized heifers with norgestomet implants than for the control heifers [4].

High impact information on SC 21009

• In experiment 1, 16 cycling cows received a norgestomet ear implant at proestrus (Day 1) for 9 days to mimic the subluteal phase [5].
• On Day 7 (Day 0 = behavioral estrus), implants containing norgestomet were inserted, and they remained in place for 10 days [6].
• Controls were treated with 25 mg PGF2 alpha at the time norgestomet implants were removed from heifers of the other treatment groups [6].
• At 17-25 days postpartum in experiments 1, 2, and 3, suckled beef cows were assigned at random to receive 6 mg norgestomet, via ear-implant, for 9 days (NOR) or to serve as controls (CON) [7].
• At 19 to 23 days postpartum, cows were allotted to receive a norgestomet implant for 9 days (normal luteal phase) or to serve as untreated controls (short luteal phase) [8].

Biological context of SC 21009

• Ten cows received norgestomet implants for 9 days prior to induced ovulation (Normal CL) and 14 served as untreated controls (Subnormal CL) [9].
• Eleven suckled beef cows received ear implants of 6 mg norgestomet for 9 days (expected normal luteal phase) and 11 served as controls (expected short luteal phase) [10].
• Treatment with both norgestomet and rboIFN-alpha I1 delayed (P less than 0.01) luteolysis [11].
• Mechanisms regulating norgestomet inhibition of endometrial gland morphogenesis in the neonatal ovine uterus [12].
• In ewes, the uterine gland knockout (UGKO) phenotype is caused by neonatal exposure to norgestomet to arrest uterine gland development and produce an adult which has a uterus characterized by the lack of endometrial glands [13].

Anatomical context of SC 21009

• Follicles from norgestomet-treated cows were heavier (p less than 0.01) than follicles from control cows, mostly due to greater amounts of follicular fluid (p less than 0.01) [10].
• In control cows (N = 5) induced to ovulate at Day 28 to 36 post partum by injection of 1000 i.u. hCG, corpora lutea had an average lifespan of only 8 days [14].
• Cows in the normal cycle group (n = 5; control) and the normal cycle/endometrium group (n = 10) received norgestomet implants for 9 days beginning 21-23 days post partum and calves were weaned at implant insertion [15].
• Short term treatment with progesterone 7 days before the end of a 17 day period of norgestomet treatment resulted in precise synchrony of ovulation without the ovulation of a persistent dominant ovarian follicle [16].
• Most oocytes were degenerate in Norgestomet-implanted animals [17].

Associations of SC 21009 with other chemical compounds

• The Normal Cycle (n = 5, control) and Normal Cycle/Explant (n = 8; endometrial explants) groups received norgestomet (progestin) implants for 9 days beginning 21-23 days postpartum, and calves were weaned at implant insertion [18].
• On day 8 of the cycle, cows (n = 8) received a luteolytic dose of prostaglandin F2 alpha (PGF2 alpha; 25 mg) and an ear implant of Norgestomet (6 mg) [19].
• Follicular dynamics and temporal relationships among body temperature, oestrus, the surge of luteinizing hormone and ovulation in Holstein heifers treated with norgestomet [20].
• The effect of estrogen administered with norgestomet implants in the expression of behavioral estrous of Zebu cattle was studied in a herd of 18 cycling Brahman cows, in two trials [21].
• Four studies are described involving 3050 single suckled mainly Hereford-Friesian cross beef cows treated with norgestomet and oestradiol valerate to control the ovarian cycle [22].

Gene context of SC 21009

• On Day 5 (Short d 5 and Norgestomet d 5) or Day 16 (Norgestomet d 16) following first postpartum estrus, each animal was injected (i.v.) with 100 IU oxytocin [23].
• As expected, the proportion of anoestrous cows that formed a corpus luteum with a normal lifespan was greater (P < 0.01) in cows treated with norgestomet (Expt 1, 17 of 24; Expt 2, 18 of 22) than in control cows (Expt 1, 2 of 16; Expt 2, 3 of 18) [24].
• Lengths of luteal phases (days; mean +/- SEM) were 8.4 +/- 0.7 (group 1, saline), 14.1 +/- 1.0 (group 2, rboIFN-alpha I1), 18.6 +/- 1.3 (group 3, norgestomet-saline) and 20.8 +/- 1.2 (group 4, norgestomet-rboIFN-alpha I1) [11].
• On day 0, N and NFM cows received a 6 mg implant of norgestomet [25].
• In summary, ergotamine lowered prolactin and elevated PGFM concentrations in follicular phase heifers and cows on norgestomet therapy [26].

Analytical, diagnostic and therapeutic context of SC 21009

• In a 5-year study (1973-1977), 281 cycling beef heifers were treated with a 7-day norgestomet (SC21009) ear implant and an intramuscular injection of prostaglandin F(2alpha) (PGF(2alpha)) at the time of implant removal or 24 hr before implant removal [27].
• The pregnancy rates were 51.9 and 49.6 per cent for the norgestomet-treated and control groups, respectively [28].
• Clinical use of Norgestomet ear implants or intravaginal pessaries for synchronization of estrus in anestrous dairy goats [29].
• Norgestomet implants synchronize estrus and enhance fertility in beef heifers subsequent to a timed artificial insemination [30].
• Half the recipients received an ear implant impregnated with 3 mg norgestomet on the day of embryo transfer [28].

References