1.Responsiveness of prepubertal crossbred bull calves to exogenous GnRH and its impact on reproductive hormones under tropical conditions.
Bharath Kumar BS1, Pandita S1, Prakash BS2, Mallick S1, Mili B1. Springerplus. 2016 Mar 8;5:288. doi: 10.1186/s40064-016-1956-4. eCollection 2016.
This study investigated the age related variations in luteinizing hormone (LH), androstenedione, testosterone, and total estrogens response to exogenous gonadotropin-releasing hormone (GnRH) in Holstein-Friesian (HF) × Tharparkar bull calves. Fifteen bull calves were selected and, based on their age, were divided into Group I (14-16 months, n = 5), Group II (9-12 months, n = 5), and Group III (6-8 months, n = 5). All bull calves were administered with 10 µg of GnRH intramuscularly. Blood samples were collected at an interval of 30 min commencing 1 h prior to GnRH treatment until 4 h post-GnRH treatment and thereafter, at an interval of 1 h for the next 3 h. Endocrine response in terms of pretreatment values, peak values, area under curve, and time taken to attain peak values for LH, androstenedione, testosterone, and total estrogens was evaluated in all the bull calves. Significant differences were observed in pretreatment values, peak concentrations, and area under curve for androstenedione and testosterone between the groups; with response being higher in Group I bull calves.
2.Pregnancy Rate and Preservation of Cyclic Ovarian Function With Gonadotropin-Releasing Hormone Agonist Cotreatment During Chemotherapy.
Blumenfeld Z1. JAMA Oncol. 2016 Apr 1;2(4):545-546. doi: 10.1001/jamaoncol.2015.5740.
3.Does lower dose of long-acting triptorelin maintain pituitary suppression and produce good live birth rate in long down-regulation protocol for in-vitro fertilization?
Chen X1, Feng SX1, Guo PP1, He YX1, Liu YD1, Ye DS1, Chen SL2. J Huazhong Univ Sci Technolog Med Sci. 2016 Apr;36(2):215-20. doi: 10.1007/s11596-016-1569-8. Epub 2016 Apr 13.
The effects of pituitary suppression with one-third depot of long-acting gonadotropin-releasing hormone (GnRH) agonist in GnRH agonist long protocol for in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) were investigated. A retrospective cohort study was performed on 3186 cycles undergoing IVF/ICSI with GnRH agonist long protocol in a university-affiliated infertility center. The pituitary was suppressed with depot triptorelin of 1.25 mg or 1.875 mg. There was no significant difference in live birth rate between 1.25 mg triptorelin group and 1.875 mg triptorelin group (41.2% vs. 43.7%). The mean luteinizing hormone (LH) level on follicle-stimulating hormone (FSH) starting day was significantly higher in 1.25 mg triptorelin group. The mean LH level on the day of human chorionic gonadotrophin (hCG) administration was slightly but statistically higher in 1.25 mg triptorelin group. There was no significant difference in the total FSH dose between the two groups.
4.Reproductive Neuroendocrine Pathways of Social Behavior.
Parhar IS1, Ogawa S1, Ubuka T1. Front Endocrinol (Lausanne). 2016 Mar 31;7:28. doi: 10.3389/fendo.2016.00028. eCollection 2016.
Social behaviors are key components of reproduction, because they are essential for successful fertilization. Social behaviors, such as courtship, mating, and aggression, are strongly associated with sex steroids, such as testosterone, estradiol, and progesterone. Secretion of sex steroids from the gonads is regulated by the hypothalamus-pituitary-gonadal (HPG) axis in vertebrates. Gonadotropin-releasing hormone (GnRH) is a pivotal hypothalamic neuropeptide that stimulates gonadotropin release from the pituitary. In recent years, the role of neuropeptides containing the C-terminal Arg-Phe-NH2 (RFamide peptides) has been emphasized in vertebrate reproduction. In particular, two key RFamide peptides, kisspeptin and gonadotropin-inhibitory hormone (GnIH), emerged as critical accelerator and suppressor of gonadotropin secretion. Kisspeptin stimulates GnRH release by directly acting on GnRH neurons, whereas GnIH inhibits gonadotropin release by inhibiting kisspeptin, GnRH neurons, or pituitary gonadotropes.
