The Effect of Parachlorophenylalanine and Active Immunization Against Vasoactive Intestinal Peptide on Reproductive Activities of Broiler Breeder Hens Photostimulated with Green Light1

Abstract

Photostimulation of retinal photoreceptors appears to inhibit reproductive activity in birds. In the present study, the involvement of serotonin and vasoactive intestinal peptide was investigated in relation to reproductive failure associated with retinal photostimulation. Hens at 23 wk of age were divided into six rooms equipped with individual cages. At 24 wk of age, three rooms were photostimulated (14L:10D) with white light (control). Three rooms had two parallel lighting systems, red (660 nm) and green (560 nm), which were both on during 6 h of the 14-h light period. Upon photostimulation, the red light was turned off after 6 h, and the green light was left on for a total of 14 h (Green). Five hens from each room served as controls, five hens were immunized against vasoactive intestinal peptide, and five hens received parachlorophenylalanine, an inhibitor of serotonin biosynthesis. Parachlorophenylalanine treatment increased reproductive performance and mRNA expression of GnRH-I, LH-beta and FSH-beta (P < 0.05) in the Green group to levels which did not differ from those of the White (control) group. Immunization against vasoactive intestinal peptide reduced plasma concentration and pituitary mRNA expression of prolactin but did not affect expression of gonadal axis genes. Collectively, the results suggest that retinal photostimulation inhibits the reproductive axis through serotonin and not through vasoactive intestinal peptide.

Red light is necessary to activate the reproductive axis in chickens independently of the retina of the eye

“…This is supported by evidence that melatonin from both the pineal gland and the retina of the eye contribute to the production of GnIH and is in part responsible for inhibiting LH release in both quails and chickens (Chowdhury et al, 2013). Moreover, stimulation of the retina of the eye with green light in broiler breeders results in decreased reproductive performances (Mobarkey et al, 2010), and supplementation with the serotonin inhibitor parachlorophenylalanine partially restored egg production (Mobarkey et al, 2013). It is possible that stimulation of the retina with green light promotes the synthesis of serotonin, which is further converted into melatonin during the dark phases, inhibiting the reproductive axis via GnIH.…”

“…Although the relative contribution of the retina of the eye and hypothalamic photoreceptors on reproduction is still controversial, experimental evidence showed that hypothalamic photostimulation activates the reproductive axis (Dawson et al, 2001;Saldanha et al, 2001), whereas retinal stimulation may decrease reproductive performance in chickens (Siopes and Wilson, 1980;Mobarkey et al, 2010;Gongruttananun, 2011;Mobarkey et al, 2013). However, it is still unclear whether light wavelength is a deciding factor.…”

Does prolactin mediate parental and life-history decisions in response to environmental conditions in birds? A review

“…An experimental increase in prolactin levels also results in a decreased egg production in turkeys . However, the relationship between stress, prolactin and egg production remains unclear because egg production could be reduced in a context of stress even if prolactin levels are maintained experimentally low (Rozenboim et al, 2004;Mobarkey et al, 2013). Some studies also failed to find any correlation between prolactin levels and LH levels (e.g.…”

“…Small et al, 2007;Schaper et al, 2012;Ryan et al, 2014) suggesting that prolactin and LH levels or egg production may be uncoupled under some circumstances (such as in determinate layers that always lay the same clutch size). Because of this potential disconnection between prolactin levels and egg laying, other specific hormones could be involved and play a major role in clutch size determination (Rozenboim et al, 2004;Mobarkey et al, 2013). Serotonin is known to inhibit the reproductive endocrine axis (El Halawani et al, 1983), and to be closely linked to prolactin levels or its precursors (Hargis and Burke, 1984;El Halawani et al, 1988).…”

Prokaryotic Expression and Active Immunisation against Recombinant-Derived Prolactin Fusion Protein on Broodiness and Egg-Laying in Wanxi-White Goose

“…Active immunisation of broiler breeder chickens (Cobb 500) with VIP decreased broodiness and increased egg production, without affecting fertility nor hatchability (Mobarkey et al, 2013). Active immunisation against VIPdepressed reproductive activity and PRL administration restored reproduction ability of ageing roosters and increased semen quality in young White Leghorn roosters (Avital-Cohen et al, 2011, 2012.…”