Beta-endorphin, but not oxytocin, substance P or vasoactive-intestinal polypeptide, contributes to progesterone-induced prolactin secretion in monkeys

Melanie Pecins-Thompson, Andrea A. Widmann, Cynthia Bethea

    Research output: Contribution to journalArticle

    8 Citations (Scopus)

    Abstract

    Progesterone (P) stimulates prolactin secretion through a neural mechanism in estrogen (E)primed female monkeys. Several peptides, including β-endorphin (BE), oxytocin (OT), substance P (SP) and vasoactive intestinal polypeptide (VIP) are potential prolactin stimulatory factors and could mediate the effect of P. We hypothesized that the antagonism of a pivotal peptidergic neural system would block P-induced prolactin secretion and that the function of a pivotal peptidergic system would be altered by changes in gonadal steroid concentrations. Therefore it was of interest (1) to examine the effect of infusion of antagonists to these peptides on P-induced prolactin secretion, and (2) to determine BE, OT, SP and VIP levels in the hypothalamus of monkeys of various reproductive states. For the antagonist studies, female monkeys (n = 8) were spayed, adapted to a vest and tether remote sampling system and catheterized prior to antagonist challenges. E-primed monkeys received P injections 48 h prior to antagonist administration. Prolactin increased within 36-48 h of P injection. All antagonist challenges were administered in varying doses during the P-induced prolactin elevation and blood samples were collected every 10 min for prolactin determinations. The opiate antagonist, naloxone (n = 5), reduced serum prolactin in a dose-related manner with a mean IC50 of 1.5 ± 0.6 μg/kg/min. The OT (n = 4), SP (n = 4) or VIP (n = 4) antagonists did not reduce serum prolactin in a dose-related manner. We previously reported that the hypothalamic content of OT is increased by ovarian hormones. To determine whether the hypothalamic content of BE, SP or VIP was related to gonadal status, the peptide levels in 4 hypothalamic regions of monkeys in various physiological states were measured. BE (ng/mg protein) in the medial basal hypothalamus (MBH) was significantly greater in adult females (17.7 ± 6.9; n = 6) as compared to spayed females (0.6 ± 0.2; n = 3) and juvenile females (1.8 ± 1.1; n = 3). Hypothalamic content of SP in the preoptic area and mammillary bodies, but not the MBH, was significantly greater in gonadal intact females than spayed females. VIP content (pg/mg protein) was not significantly different between adult, spayed and juvenile females nor between adult and juvenile males in any hypothalamic area. Taken together these results support a pivotal role for BE in the neural regulation of P-induced prolactin secretion. The involvement of OT, SP, and VIP in a specific manner at the pituitary level is not indicated.

    Original languageEnglish (US)
    Pages (from-to)569-578
    Number of pages10
    JournalNeuroendocrinology
    Volume63
    Issue number6
    StatePublished - Jun 1996

    Fingerprint

    beta-Endorphin
    Vasoactive Intestinal Peptide
    Oxytocin
    Substance P
    Prolactin
    Haplorhini
    Progesterone
    Middle Hypothalamus
    Opiate Alkaloids
    Mammillary Bodies
    Endorphins
    Peptides
    Gastrointestinal Contents
    Injections
    Preoptic Area
    Naloxone
    Serum
    Hypothalamus
    Inhibitory Concentration 50
    Estrogens

    Keywords

    • Beta-endorphin
    • Gonadal steroids
    • Monkey
    • Naloxone
    • Oxytocin
    • Progesterone
    • Prolactin
    • Substance P
    • Vasoactive intestinal peptide

    ASJC Scopus subject areas

    • Endocrinology
    • Neuroscience(all)

    Cite this

    Beta-endorphin, but not oxytocin, substance P or vasoactive-intestinal polypeptide, contributes to progesterone-induced prolactin secretion in monkeys. / Pecins-Thompson, Melanie; Widmann, Andrea A.; Bethea, Cynthia.

    In: Neuroendocrinology, Vol. 63, No. 6, 06.1996, p. 569-578.

    Research output: Contribution to journalArticle

    @article{0d8abfab68b84951819e011880dcfd03,
    title = "Beta-endorphin, but not oxytocin, substance P or vasoactive-intestinal polypeptide, contributes to progesterone-induced prolactin secretion in monkeys",
    abstract = "Progesterone (P) stimulates prolactin secretion through a neural mechanism in estrogen (E)primed female monkeys. Several peptides, including β-endorphin (BE), oxytocin (OT), substance P (SP) and vasoactive intestinal polypeptide (VIP) are potential prolactin stimulatory factors and could mediate the effect of P. We hypothesized that the antagonism of a pivotal peptidergic neural system would block P-induced prolactin secretion and that the function of a pivotal peptidergic system would be altered by changes in gonadal steroid concentrations. Therefore it was of interest (1) to examine the effect of infusion of antagonists to these peptides on P-induced prolactin secretion, and (2) to determine BE, OT, SP and VIP levels in the hypothalamus of monkeys of various reproductive states. For the antagonist studies, female monkeys (n = 8) were spayed, adapted to a vest and tether remote sampling system and catheterized prior to antagonist challenges. E-primed monkeys received P injections 48 h prior to antagonist administration. Prolactin increased within 36-48 h of P injection. All antagonist challenges were administered in varying doses during the P-induced prolactin elevation and blood samples were collected every 10 min for prolactin determinations. The opiate antagonist, naloxone (n = 5), reduced serum prolactin in a dose-related manner with a mean IC50 of 1.5 ± 0.6 μg/kg/min. The OT (n = 4), SP (n = 4) or VIP (n = 4) antagonists did not reduce serum prolactin in a dose-related manner. We previously reported that the hypothalamic content of OT is increased by ovarian hormones. To determine whether the hypothalamic content of BE, SP or VIP was related to gonadal status, the peptide levels in 4 hypothalamic regions of monkeys in various physiological states were measured. BE (ng/mg protein) in the medial basal hypothalamus (MBH) was significantly greater in adult females (17.7 ± 6.9; n = 6) as compared to spayed females (0.6 ± 0.2; n = 3) and juvenile females (1.8 ± 1.1; n = 3). Hypothalamic content of SP in the preoptic area and mammillary bodies, but not the MBH, was significantly greater in gonadal intact females than spayed females. VIP content (pg/mg protein) was not significantly different between adult, spayed and juvenile females nor between adult and juvenile males in any hypothalamic area. Taken together these results support a pivotal role for BE in the neural regulation of P-induced prolactin secretion. The involvement of OT, SP, and VIP in a specific manner at the pituitary level is not indicated.",
    keywords = "Beta-endorphin, Gonadal steroids, Monkey, Naloxone, Oxytocin, Progesterone, Prolactin, Substance P, Vasoactive intestinal peptide",
    author = "Melanie Pecins-Thompson and Widmann, {Andrea A.} and Cynthia Bethea",
    year = "1996",
    month = "6",
    language = "English (US)",
    volume = "63",
    pages = "569--578",
    journal = "Neuroendocrinology",
    issn = "0028-3835",
    publisher = "S. Karger AG",
    number = "6",

    }

    TY - JOUR

    T1 - Beta-endorphin, but not oxytocin, substance P or vasoactive-intestinal polypeptide, contributes to progesterone-induced prolactin secretion in monkeys

    AU - Pecins-Thompson, Melanie

    AU - Widmann, Andrea A.

    AU - Bethea, Cynthia

    PY - 1996/6

    Y1 - 1996/6

    N2 - Progesterone (P) stimulates prolactin secretion through a neural mechanism in estrogen (E)primed female monkeys. Several peptides, including β-endorphin (BE), oxytocin (OT), substance P (SP) and vasoactive intestinal polypeptide (VIP) are potential prolactin stimulatory factors and could mediate the effect of P. We hypothesized that the antagonism of a pivotal peptidergic neural system would block P-induced prolactin secretion and that the function of a pivotal peptidergic system would be altered by changes in gonadal steroid concentrations. Therefore it was of interest (1) to examine the effect of infusion of antagonists to these peptides on P-induced prolactin secretion, and (2) to determine BE, OT, SP and VIP levels in the hypothalamus of monkeys of various reproductive states. For the antagonist studies, female monkeys (n = 8) were spayed, adapted to a vest and tether remote sampling system and catheterized prior to antagonist challenges. E-primed monkeys received P injections 48 h prior to antagonist administration. Prolactin increased within 36-48 h of P injection. All antagonist challenges were administered in varying doses during the P-induced prolactin elevation and blood samples were collected every 10 min for prolactin determinations. The opiate antagonist, naloxone (n = 5), reduced serum prolactin in a dose-related manner with a mean IC50 of 1.5 ± 0.6 μg/kg/min. The OT (n = 4), SP (n = 4) or VIP (n = 4) antagonists did not reduce serum prolactin in a dose-related manner. We previously reported that the hypothalamic content of OT is increased by ovarian hormones. To determine whether the hypothalamic content of BE, SP or VIP was related to gonadal status, the peptide levels in 4 hypothalamic regions of monkeys in various physiological states were measured. BE (ng/mg protein) in the medial basal hypothalamus (MBH) was significantly greater in adult females (17.7 ± 6.9; n = 6) as compared to spayed females (0.6 ± 0.2; n = 3) and juvenile females (1.8 ± 1.1; n = 3). Hypothalamic content of SP in the preoptic area and mammillary bodies, but not the MBH, was significantly greater in gonadal intact females than spayed females. VIP content (pg/mg protein) was not significantly different between adult, spayed and juvenile females nor between adult and juvenile males in any hypothalamic area. Taken together these results support a pivotal role for BE in the neural regulation of P-induced prolactin secretion. The involvement of OT, SP, and VIP in a specific manner at the pituitary level is not indicated.

    AB - Progesterone (P) stimulates prolactin secretion through a neural mechanism in estrogen (E)primed female monkeys. Several peptides, including β-endorphin (BE), oxytocin (OT), substance P (SP) and vasoactive intestinal polypeptide (VIP) are potential prolactin stimulatory factors and could mediate the effect of P. We hypothesized that the antagonism of a pivotal peptidergic neural system would block P-induced prolactin secretion and that the function of a pivotal peptidergic system would be altered by changes in gonadal steroid concentrations. Therefore it was of interest (1) to examine the effect of infusion of antagonists to these peptides on P-induced prolactin secretion, and (2) to determine BE, OT, SP and VIP levels in the hypothalamus of monkeys of various reproductive states. For the antagonist studies, female monkeys (n = 8) were spayed, adapted to a vest and tether remote sampling system and catheterized prior to antagonist challenges. E-primed monkeys received P injections 48 h prior to antagonist administration. Prolactin increased within 36-48 h of P injection. All antagonist challenges were administered in varying doses during the P-induced prolactin elevation and blood samples were collected every 10 min for prolactin determinations. The opiate antagonist, naloxone (n = 5), reduced serum prolactin in a dose-related manner with a mean IC50 of 1.5 ± 0.6 μg/kg/min. The OT (n = 4), SP (n = 4) or VIP (n = 4) antagonists did not reduce serum prolactin in a dose-related manner. We previously reported that the hypothalamic content of OT is increased by ovarian hormones. To determine whether the hypothalamic content of BE, SP or VIP was related to gonadal status, the peptide levels in 4 hypothalamic regions of monkeys in various physiological states were measured. BE (ng/mg protein) in the medial basal hypothalamus (MBH) was significantly greater in adult females (17.7 ± 6.9; n = 6) as compared to spayed females (0.6 ± 0.2; n = 3) and juvenile females (1.8 ± 1.1; n = 3). Hypothalamic content of SP in the preoptic area and mammillary bodies, but not the MBH, was significantly greater in gonadal intact females than spayed females. VIP content (pg/mg protein) was not significantly different between adult, spayed and juvenile females nor between adult and juvenile males in any hypothalamic area. Taken together these results support a pivotal role for BE in the neural regulation of P-induced prolactin secretion. The involvement of OT, SP, and VIP in a specific manner at the pituitary level is not indicated.

    KW - Beta-endorphin

    KW - Gonadal steroids

    KW - Monkey

    KW - Naloxone

    KW - Oxytocin

    KW - Progesterone

    KW - Prolactin

    KW - Substance P

    KW - Vasoactive intestinal peptide

    UR - http://www.scopus.com/inward/record.url?scp=0029953928&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=0029953928&partnerID=8YFLogxK

    M3 - Article

    C2 - 8793899

    AN - SCOPUS:0029953928

    VL - 63

    SP - 569

    EP - 578

    JO - Neuroendocrinology

    JF - Neuroendocrinology

    SN - 0028-3835

    IS - 6

    ER -