The role of RFamide-related peptide 3 (RFRP3) in regulation of the neuroendocrine reproductive and growth axes of the boar

Abstract

a b s t r a c tRFamide-related peptide 3 (RFRP3) has been implicated in regulating reproduction and growth. This regulation appears to be dependent upon sex, species, physiological status, and developmental stage. The objective of the present study was to evaluate the effects of RFRP3 on circulating concentrations of luteinizing hormone (LH) and growth hormone (GH) in mature boars. The hypothesis was RFRP3 would reduce circulating concentrations of LH and increase concentrations of GH. Meishan boars (716.6 ± 2.8 days of age; 125.0 ± 12.4 kg BW) were randomly assigned to treatment: saline (n = 4) or RFRP3 (8.5 mg; n = 5). Plasma was collected at 15-min intervals during 3 periods: pre-treatment, treatment, and posttreatment. During the treatment period, saline or RFRP3 were administered at 15-min intervals. Treatment was administered as a loading dose of 5 mg RFRP3, followed by seven repeated injections of 0.5 mg RFRP3. Pulsatile secretion of LH and GH were not affected by saline treatment. Mean concentrations of LH in RFRP3-treated boars were greater (P < 0.01) in the pre-treatment period than in the treatment and post-treatment periods; however, the individual response to RFRP3 challenge was varied. RFRP3 suppressed (P < 0.05) mean concentrations of GH during the treatment period. It is concluded that RFRP3 can act to suppress LH secretion in some boars, but the minimal and varied response between animals does not strongly support the idea that RFRP3 is a potent hypohysiotropic hormone in the pig. Results indicate that RFRP3 may function in regulating the growth axis of swine.Published by Elsevier B.V.

GnRHand the photoperiodic control of seasonal reproduction: Delegating the task to kisspeptin andRFRP‐3

“…256 However, further studies in rodents, ewes, pigs and horses did not yield any support for a hypophysiotropic effect of RFRP-3. 218,236,245,248,257 Furthermore, although RFRP-3 is detected in the ewe portal blood, its circulating levels show no correlation with LH levels in the peripheral blood. 258 Importantly, ablation of the NpffR2 gene does not compromise mice fertility, although several minor to moderate effects were reported.…”

RFamide peptides, the novel regulators of mammalian HPG axis: A review

“…These findings suggest the role of RFRP-3 to suppress HPG axis before puberty. Johnson and Fraley [ 69 ] reported that there are no alterations in the pubertal onset in RFRP-3 and GPR 147 knocked down models. Lima et al .…”

The neuroendocrine pathways and mechanisms for the control of the reproduction in female pigs

“…When RFRP-3 was largely infused into the peripheral circulation of OVX gilts, LH secretion remained unchanged, unless very high doses were given. It also took large pharmacological doses of RFRP-3 to impact the pulsatile secretion of LH in intact mature boars ( Thorson et al, 2015 ). As noted, the porcine RFRP preproprotein can yield an RFRP-2 peptide that ruminants and rodents do not produce ( Yoshida et al, 2003 ).…”