Genistein Alters the Release of Oxytocin, Prostaglandins, Cortisol and LH during Insemination in Gilts

Abstract

Soya products containing phytooestrogens are widely used as feed for pigs. However, limited data are available on the effects of phytooestrogen on the endocrine status of pigs. The aim of this work was to study the impact of the phytooestrogen genistein added to a soya-free diet on the hormonal pattern in gilts during oestrus and artificial insemination (AI). Ten gilts were fed a soya-free diet and fitted with jugular vein catheter through vena auricularis. The gilts were randomly divided into two groups (G- and C-group) where the G-group was given pure genistein, 1 mg/kg body weight (BW) twice daily, per os. Blood samples were collected before, during and after AI. Oxytocin, prostaglandin E₂, prostaglandin F₂(α), 13,14-dihydro-15-keto-prostaglandin F₂(α) (PGFM), cortisol and LH concentrations in blood plasma were analysed. Oxytocin concentrations were almost twice as high in the G-group as in C-group after the AI. Prostaglandin E₂ concentrations were higher in G-group than in C-group during the entire sampling period. After AI, the concentrations of prostaglandin E₂ increased in G-group but not in C-group. Prostaglandin F₂(α) concentration had a pulsatile pattern, with increasing pulses after AI in G-group. Plasma PGFM concentrations increased after AI with a small variation between the groups. Plasma cortisol concentration increased after AI in C-group. LH decreased after AI in G-group. Genistein stimulated elevations of plasma oxytocin and prostaglandin E₂ concentrations and a pulsative pattern in prostaglandin F₂(α) concentration. The possible involvement of genistein in plasma cortisol and basal LH concentrations in gilts given genistein may also be suggested.

Effects of dose and route of administration of genistein on isoflavone concentrations in post-weaned and gestating sows

“…This corroborates current findings in circulating concentrations of IGF-I using a similar dose and route of administration. Interestingly, genistein seems to affect other reproductive hormones as it stimulated the release of oxytocin and prostaglandins in cyclic gilts (Norrby et al, 2011).…”

Effects of Short Term Administration of Genistein on Hypothalamic and Anterior Pituitary Hormones in Ovariectomized Gilts

“…However, in the present study, blood samples were not taken at frequent enough intervals to adequately characterize serum concentrations of LH. When Norrby et al [37] treated gilts with approximately 300 mg of genistein daily for three days, serum concentrations of LH were reduced in genistein treated gilts versus controls. The ability of genistein to increase anterior pituitary LH was presumably due to areduction in LH release.…”

GnRH‐agonist deslorelin implant alters the progesterone release pattern during early pregnancy in gilts

“…GnRHa gilts were intramuscularly implanted with a 4.7‐mg deslorelin implant (Suprelorin ® , Inc. Virbac, France) in the neck, approximately 5 cm caudal from the base of the ear. The implant contained (d‐Trp6, Pro9Net) GnRH that was released slowly at a rate of approximately 20 μg/day in a mouse study (Navarro, ). Peak level was achieved approximately 14 days after insertion of the implant and deslorelin remained measurable until Day 80 after commencing treatment in the dog (Navarro, ; Trigg et al, ).…”

“…The implant contained (d‐Trp6, Pro9Net) GnRH that was released slowly at a rate of approximately 20 μg/day in a mouse study (Navarro, ). Peak level was achieved approximately 14 days after insertion of the implant and deslorelin remained measurable until Day 80 after commencing treatment in the dog (Navarro, ; Trigg et al, ). The deslorelin implant suppresses the pituitary‐gonadal axis (Trigg et al, ) in a dual‐phase mechanism; the implant initially stimulates the pituitary axis for a few hours to release both follicle‐stimulating hormone (FSH) and LH and subsequently activates a complex network of transduction pathways resulting in down‐regulation of the GnRH receptors through the inhibition of mRNA coding for the β subunits of the gonadotropins LH and FSH (Navarro, ; Trigg et al, ).…”

“…Peak level was achieved approximately 14 days after insertion of the implant and deslorelin remained measurable until Day 80 after commencing treatment in the dog (Navarro, ; Trigg et al, ). The deslorelin implant suppresses the pituitary‐gonadal axis (Trigg et al, ) in a dual‐phase mechanism; the implant initially stimulates the pituitary axis for a few hours to release both follicle‐stimulating hormone (FSH) and LH and subsequently activates a complex network of transduction pathways resulting in down‐regulation of the GnRH receptors through the inhibition of mRNA coding for the β subunits of the gonadotropins LH and FSH (Navarro, ; Trigg et al, ). This down‐regulating effect of the deslorelin implant on LH release (and thereby steroids) has been reported to last for months or years, depending on the species, breed, and gender (Lucas, ).…”