Many metabolic hormones, growth hormone (GH), insulin-like growth factor-I (IGF-I) and insulin affect ovarian functions. However, whether ovarian steroid hormones affect metabolic hormones in cattle remains unknown. This study aimed to determine the effect of sex steroids on the plasma profiles of GH, IGF-I and insulin and their receptors in the liver and adipose tissues of dairy cows. Ovariectomized cows (n = 14) were randomly divided into four groups: control group (n = 3) was treated with saline on Day 0; oestradiol (E2) group (n = 3), with saline and 1 mg oestradiol benzoate (EB) on Day 0 and 5, respectively; progesterone (P4) group (n = 4) with two CIDRs (Pfizer Inc., Tokyo, Japan) from Day 0; and E2 + P4 group (n = 4) with two CIDRs on Day 0 that were removed on Day 6 and were immediately injected with 1 mg EB. The animals were euthanized after the experiment, and liver and adipose tissues samples were quantitatively analysed using real-time PCR for the expression of mRNA for the GH (GHR), IGF-I (IGFR-I) and insulin (IR) receptor mRNAs. Oestradiol benzoate significantly increased the number of peaks (p < 0.05), pulse amplitude (p < 0.05) and area under the curve (AUC; p < 0.01) for plasma GH; moreover, it increased plasma IGF-I concentration (p < 0.05), but it had no effect on the plasma insulin profile. P4 significantly decreased the AUC (p < 0.01), compared with the control group, whereas it did not affect the number of peaks and the amplitude of GH pulses. P4 + E2 did not affect the GH pulse profile. E2 increased the mRNA expression of GHR, IGFR-I and IR in the liver (p < 0.05), whereas both P4 and E2 + P4 did not change their expressions. Our results provide evidence that the metabolic and reproductive endocrine axes may regulate each other to ensure optimal reproductive and metabolic function.
The melatonin receptor 1A (MTNR1A) and inhibin alpha subunit (INHA) genes play a significant role in the reproductive characteristics of animals. Blood samples were collected from 371 goats (Honamli and Hair) reared in Antalya and Burdur. The polymerase chain reaction (PCR) products were digested by RsaI for the MTNR1A gene and HaeII for the INHA gene. Two alleles (A and G) and three genotypes (AA, AG, and GG) were observed for the INHA gene, while two alleles (R and r) and two genotypes (RR and Rr) were observed for the MTNR1A gene. The highest allelic frequency value for G (91.8%) was found in Honamli goat breeds for the INHA gene while the highest value for R (98.1%) was found in Hair goat breeds for the MTNR1A gene. The GG genotype for the INHA gene and the RR genotype for the MTNR1A gene were identified as the most common genotypes of the Honamli and Hair goat breeds. The rr genotype for the MTNR1A gene could not be determined in the breeds. Both Honamli and Hair goat breeds were in Hardy-Weinberg equilibrium for the genes that were studied. In conclusion, this study confirms the existence of genetic polymorphism in the MTNR1A and INHA genes as detected by PCR-RFLP analysis in Honamli and Hair goat breeds.
The aim of this study was to evaluate the effect of buserelin injection on day 12 postinsemination on fertility in lactating dairy cattle. A total of 57 cows were assigned to two groups and four subgroups. In the treatment group, the cows were synchronized with PGF 2α -PGF 2α (group A) or GnRH-PGF 2α (group B) protocol, and buserelin was injected on day 12 postinsemination. Cows in the control group were synchronized with PGF 2α -PGF 2α (group C) or GnRH-PGF 2α (group D) protocol, saline solution was injected on day 12, and served as controls. Pregnancy rates on day 21 and 45 and embryonic death rates were 85.7%, 71.4% and 16.7%, 85.7%, 85.7% and 0.0%, 73.3%, 62.1% and 27.3% and 85.7%, 71.4% and 16.7% in groups A, B, C and D, respectively. There was no significant difference between synchronization protocols for pregnancy rates, and among groups A, B, C and D for pregnancy rates and embryonic death rates. Mean progesterone concentrations in pregnant cows in groups A and B were higher than that in groups C and D, respectively, on day 18 and 21 (p < 0.05). In conclusion, GnRH injection on day 12 postinsemination increased the plasma progesterone concentrations on day 18 and 21 postinsemination. However, it did not alter the pregnancy rates and prevent embryonic deaths.
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