Study of Enteral versus Parenteral Application of the Gonadotropin Releasing Hormone Agonist Gonadorelin[6-D-Phe] (D-Phe6-LHRH) on LH Secretion in Goettinger Miniature Pigs

Abstract

Abstract. With respect to the assessment of residue situation and as a part of preclinical trials to determine the biological activities of potential gonadotropin releasing hormone (GnRH) residues in porcine organisms the GnRH agonist Gonadorelin[6-D-Phe] (D-Phe 6 -LHRH) was administered either enterally or intramuscularly (i.m.) to female Goettinger miniature pigs in order to evaluate the GnRHinduced luteinizing hormone (LH) surge. Gilts received an (i) enteral application of 10 mg D-Phe 6 -LHRH via a probang (enteral group, n=7), (ii) i.m. injection of 0.1 mg D-Phe 6 -LHRH (parenteral group, n= 5), or (iii) saline injection (control group, n=4). The GnRH and saline applications were repeated every second day with up to seven repetitions. Blood samples were collected via previously fitted jugular catheters immediately before injections, over an 8 h period in 1 h intervals beginning 2 h after injections, and at 24, 26, 28 and 30 h after applications. Enteral application of D-Phe 6 -LHRH induced an LH surge in 23 of 30 treatments. All gilts in the parenteral group exhibited LH release after each DPhe 6 -LHRH application (P<0.05), whereas no LH surges were observed after saline injection in the control group. A significant (P<0.05) LH rise to mean maximum LH concentrations of 3.25 ± 0.43 and 3.05 ± 0.26 ng/ml occurred in both the enteral and parenteral groups, but there was no difference in the time interval after GnRH (2.6 ± 0.3 vs. 2.3 ± 0.3 h) and the mean duration of LH peak (6.5 ± 0.4 and 6.8 ± 0.3 h) between the treatment groups. In conclusion, (i) enteral application of 10 mg D-Phe 6 -LHRH induced LH release in a physiological range from the pituitary of female minipigs, and (ii) neither an accumulative effect nor a cumulative LH response were found after repeated GnRH application. Furthermore, (iii) in regard to consumer protection and gonadotropin secretion, D-Phe 6 -LHRH residues can be excluded from having long-term effects.

Ovulation induction in rabbit does: Current knowledge and perspectives

“…• reduce the insemination dose and sperm concentration to lower vaginal reabsorption; • study other routes of administration as suggested by Gudmundsson et al (1984), Roberts et al (1999), Bassol et al (1997) and Brüssow et al (2007); • evaluate the effects of the physiological status of does and semen treatment (i.e., estrus, secretions, inflammatory status, and seminal plasma); • improve the knowledge base regarding intraovarian factors that affect ovulation in rabbits (Lindner et al, 1977).…”

Concentration of platelets and growth factors in platelet-rich plasma from Goettingen minipigs

“…Despite the increased interest in the mini-pig in experimental medicine [ 18 ], [ 19 ], [ 20 ] and especially in orthopedics [ 21 ], [ 22 ] little is known about the presence and concentration of growth factors for this species. The aim of the present investigation was to study the concentration of platelets and of selected growth factors in PRP preparations of minipigs in order to characterize it as a possible autologous source of growth factors.…”