title: Role of the serotonergic axis in the reproductive failure associated with aging broiler breeder roosters.
abstract: Reproductive failure associated with aging is a well-known phenomenon. However, the mechanism by which this failure occurs in broiler breeder roosters is still unclear. A previous study conducted in our laboratory, comparing young and aging broiler breeder roosters, demonstrated an elevation in hypothalamic vasoactive intestinal peptide (VIP) and pituitary prolactin (PRL) gene expression accompanied by a deterioration of gonadal axis function. This resulted in a decrease in semen-quality variables as roosters aged. The objective of this study was to examine the involvement of the serotonergic axis in the age-associated reproductive failure in broiler breeder roosters. Cobb roosters aged 64 wk were divided into 3 groups (n = 20 each): parachlorophenylalanine (PCPA) administration, active immunization against chicken VIP, and controls. At 69 wk of age, each group was divided into 2 equal subgroups: 1 received ovine PRL and the other served as controls. Weekly semen volume, concentration and motility, and plasma testosterone, estradiol, and PRL concentrations were examined. At the end of the experiment, roosters were euthanized, testes were weighed, and hypothalamus and pituitary were removed to assay the expression of genes encoding hypothalamic GnRH-I, pituitary FSH, pituitary LH, hypothalamic VIP, and pituitary PRL. Both PCPA administration and active immunization against chicken VIP significantly increased testis weight, semen volume, sperm concentration, ejaculation grade, plasma testosterone level, and GnRH-I, FSH and LH gene expression compared with controls (P ≤ 0.05). In addition, a decrease in plasma estradiol and PRL concentrations and VIP and PRL gene expression was observed in PCPA- and VIP-immunized birds compared with controls (P ≤ 0.05). Administration of PRL in all groups decreased gonadal axis function and semen-quality variables (P ≤ 0.05). Collectively, these results suggest that the increasing expression levels of the serotonergic axis in aging broiler breeder roosters inhibit proper gonadal function and reproductive performance. This article establishes for the first time the inhibitory role of serotonin on reproduction in aging roosters.
authors.affiliation: Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel. Electronic address: Natalie.Avital@mail.huji.ac.il.
authors.forename: N
authors.initials: N
authors.lastname: Avital-Cohen
authors.affiliation: Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Heiblum
authors.affiliation: Department of Life Sciences, Achva Academic College, MP Shikmim 79800, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Rosenstrauch
authors.affiliation: School of Biology, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
authors.forename: Y
authors.initials: Y
authors.lastname: Chaiseha
authors.affiliation: Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: N
authors.initials: N
authors.lastname: Mobarkey
authors.affiliation: Department of Swine and Small Livestock Breeding, Institute of Animal Breeding, Agricultural University of Krakow, Krakow, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Gumułka
authors.affiliation: Department of Animal Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: I
authors.initials: I
authors.lastname: Rozenboim
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D002645:Chickens / Q000502:physiology*; D007248:Infertility, Male / Q000662:veterinary*; D008297:Male; D009929:Organ Size; D011388:Prolactin / Q000378:metabolism; D012661:Semen / Q000502:physiology; D055101:Semen Analysis; D059326:Serotonergic Neurons / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism; D013737:Testis / Q000033:anatomy & histology; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
chemical_list: D012701:Serotonin; D014660:Vasoactive Intestinal Peptide; D011388:Prolactin
keywords: Aging; Prolactin; Reproduction; Semen quality; Vasoactive intestinal peptide