Opioid modulation of FSH, growth hormone and prolactin secretion in the prepuberal gilt

1992 ◽  
Vol 133 (1) ◽  
pp. 13-19 ◽  
Author(s):  
C. R. Barb ◽  
R. R. Kraeling ◽  
G. B. Rampacek
Keyword(s):  
Body Weight ◽  
Prolactin Secretion ◽  
Morphine Treatment ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid ◽  
Gh Secretion ◽  
Age Related ◽  
Artificial Cerebrospinal Fluid ◽  
Serum Gh

ABSTRACT The role of endogenous opioid peptides (EOP) in modulating GH, prolactin (PRL) and FSH secretion was evaluated in prepuberal (P) gilts. In experiment I, P gilts received 1 (n = 2), 3 (n = 3) or 6 (n = 3) mg naloxone (NAL)/kg body weight i.v. Blood was collected every 15 min for 2 h prior to and 2 h after NAL and an additional 1 h after 100 μg gonadotrophinreleasing hormone (GnRH) i.v. In experiment II, P and mature (M) gilts were ovariectomized. Three weeks after ovariectomy, P and M gilts were injected twice a day for 10 days with either 0·85 mg progesterone (P4)/kg body weight or oil vehicle (V), resulting in the following groups: PP4 (n=11), PV (n = 10), MP4 (n=11) and MV (n=10). All gilts received 1 mg NAL/kg body weight on the last day of treatment. Blood samples were collected every 15 min for 4 h before and 2 h after NAL and an additional 1 h after 100μg GnRH i.v. In experiment III, six P and five M gilts were ovariectomized and surgically implanted with intracerebroventricular (i.c.v.) cannulae. Blood was collected every 15 min for 3 h before and 3 h after i.c.v. injection of 500 μg morphine in artificial cerebrospinal fluid (CSF) or 250 μl CSF. In experiment I, all doses of NAL failed to alter PRL secretion, while NAL increased (P<0·05) GH secretion in three out of eight gilts. However, NAL suppressed (P <0·05) FSH concentrations. In experiment II, NAL treatment increased (P<0·01) serum PRL concentrations and suppressed (P <0·05) FSH secretion in MP4 gilts. Serum PRL and FSH concentrations were unaltered by NAL in PV, PP4 and MV gilts. In experiment III, mean serum GH, PRL and FSH concentrations were unaffected by CSF injections. Morphine treatment evoked a rapid increase in serum GH and PRL concentrations in both P and M gilts. In contrast, morphine failed to influence FSH secretion in P gilts but did suppress FSH concentrations in M gilts. These data suggest that EOP receptors are functionally coupled to the GH and PRL secretory systems. There is an age-related change in EOP modulation of PRL secretion, while EOP modulation of FSH secretion is an age- and ovarian-dependent process. Journal of Endocrinology (1992) 133, 13–19

scholarly journals Regulation by endogenous opioids of suckling-induced prolactin secretion in pregnant and lactating rats: role of ovarian steroids

2002 ◽  
Vol 172 (2) ◽  
pp. 255-261 ◽  
Author(s):  
M Soaje ◽  
EG de Di Nasso ◽  
RP Deis
Keyword(s):  
Inhibitory Effect ◽  
Prolactin Secretion ◽  
Endogenous Opioids ◽  
Opioid System ◽  
Serum Prolactin ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid ◽  
Subsequent Increase ◽  
Stimulatory Action

Evidence suggests that endogenous opioid peptides are implicated in the suckling-induced prolactin rise. We explored the role of the opioid system and the participation of ovarian hormones in the regulation of prolactin induced by the suckling stimulus at the end of pregnancy in rats with developed maternal behavior, and during lactation. Suckling for 24 h induced a significant increase in serum prolactin on day 19 of pregnancy, which was increased more than three times when naloxone (2 mg/kg s.c.) or mifepristone (2 mg/kg) was administered. The combination of naloxone and mifepristone did not increase serum prolactin more than either compound alone. Administration of tamoxifen (500 microg/kg orally) on days 14 and 15 of pregnancy completely abolished the effect of naloxone, indicating a role for estrogens in establishing this inhibitory role of opioids. To examine the participation of the opioid system during lactation, we used groups of rats on days 1, 3, 5, 12 and 19 postpartum either (i) isolated from the pups for 4 h, or (ii) isolated from the pups for 3.5 h and reunited with them and suckled for 30 min. Naloxone, given just before replacing the pups, prevented the increase in serum prolactin levels observed in the suckled group of rats but had no effect on the basal levels of the isolated rats. To examine whether the participation of the opioid system in the release of prolactin is dependent on the variation of progesterone levels, rats on day 20 of pregnancy were implanted with two cannulae containing progesterone (that blocked postpartum ovulation) or cholesterol, and cesarean surgery was performed on day 21. To maintain lactation, pups (1-3 days old) were replaced every 24 h, and 4 days after the cesarean eight pups were placed in the cage at 1800 h to maintain a strong suckling stimulus during the following 24 h. Naloxone administration significantly reduced serum prolactin levels in control (cholesterol) rats but progesterone implants prevented the inhibitory effect of naloxone and this effect was not modified by treatment with estrogen. These results indicate that the opioid system modulates suckling-induced prolactin secretion, passing from an inhibitory action before delivery to a stimulatory action during lactation. This regulatory shift seems to be dependent on the fall in progesterone concentration at the end of pregnancy and the subsequent increase after the postpartum ovulation and luteal phase.

Pineal denervation by cervical sympathetic ganglionectomy suppresses the role of photoperiod on pregnancy or pseudopregnancy, body weight and moulting periods in the mink (Mustela vison)

1985 ◽  
Vol 107 (1) ◽  
pp. 31-39 ◽  
Author(s):  
L. Martinet ◽  
D. Allain ◽  
Y. Chabi
Keyword(s):  
Body Weight ◽  
Environmental Factors ◽  
Prolactin Secretion ◽  
Corpora Lutea ◽  
Progesterone Secretion ◽  
Cervical Ganglion ◽  
Cervical Sympathetic ◽  
Implantation Period ◽  
Short Days

ABSTRACT In mink, termination of the delayed implantation period, following reactivation of the corpora lutea, and onset of the spring moult are associated with a rise in prolactin secretion triggered by increasing daylength, while decreasing daylength induces the autumn moult. To establish whether suppression of the function of the pineal rendered the mink unresponsive to daylength changes, the superior cervical ganglion was removed bilaterally 2–4 weeks before mating. Intact and operated females were then left outdoors or were put under a lighting regime of either 15 h light: 9 h darkness (15L: 9D) or 8L: 16D. In July, at the end of the spring moult, the 15L: 9D lighting regime was changed to one of 8L: 16D. Under artificial photoperiods ganglionectomy suppressed the stimulatory role of long days and the inhibitory role of short days on prolactin secretion, and consequently on progesterone secretion and spring moult. Neither was the autumn moult, induced early in intact females by the change to a short photoperiod, advanced in ganglionectomized females, showing that the latter were unresponsive to the artificial modification of the photoperiod. However, in animals kept outdoors, prolactin and progesterone secretion and spring moult were not changed by ganglionectomy. Increase in body weight and autumn moult were only slightly delayed by the operation suggesting that other environmental factors had replaced the synchronizing effect of the daylength changes. Alternatively the desynchronization between intact females responsive to photoperiodism and those rendered unresponsive may be too slow to be observed soon after ganglionectomy. J. Endocr. (1985) 107, 31–39

The role of opiates and endogenous opioid peptides in the regulation of rat TSH secretion

1981 ◽  
Vol 219 (2) ◽  
pp. 335-344 ◽  
Author(s):  
Burt Sharp ◽  
John E. Morley ◽  
Harold E. Carlson ◽  
Jody Gordon ◽  
Jacqueline Briggs ◽  
...  
Keyword(s):  
Opioid Peptides ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid ◽  
Tsh Secretion

Endogenous opioids and ventilatory responses to hypercapnia in normal humans

1985 ◽  
Vol 58 (5) ◽  
pp. 1415-1420 ◽  
Author(s):  
S. E. Weinberger ◽  
R. A. Steinbrook ◽  
D. B. Carr ◽  
E. R. von Gal ◽  
J. E. Fisher ◽  
...  
Keyword(s):  
Opioid Peptides ◽  
Endogenous Opioids ◽  
Opiate Antagonist ◽  
Endogenous Opioid Peptides ◽  
Short Term ◽  
Endogenous Opioid ◽  
Beta Endorphin ◽  
Ventilatory Responses ◽  
Normal Humans

Though administration of opioid peptides depresses ventilation and ventilatory responsiveness, the role of endogenous opioid peptides in modulating ventilatory responsiveness is not clear. We studied the interaction of endogenous opioids and ventilatory responses in 12 adult male volunteers by relating hypercapnic responsiveness to plasma levels of immunoactive beta-endorphin and by administering the opiate antagonist naloxone. Ventilatory responsiveness to hypercapnia was not altered by pretreatment with naloxone, and this by itself suggests that endogenous opioids have no role in modulating this response. However, there was an inverse relationship between basal levels of immunoactive beta-endorphin in plasma and ventilatory responsiveness to CO2. Furthermore, plasma beta-endorphin levels rose after short-term hypercapnia but only when subjects had been pretreated with naloxone. We conclude that measurement of plasma endorphin levels suggests relationships between endogenous opioid peptides and ventilatory responses to CO2 that are not apparent in studies limited to assessing the effect of naloxone.

scholarly journals A hypothesis for endogenous opioid peptides in uraemic pruritus: role of enkephalin

2001 ◽  
Vol 16 (9) ◽  
pp. 1953-1954 ◽  
Author(s):  
P. Odou ◽  
R. Azar ◽  
M. Luyckx ◽  
C. Brunet ◽  
T. Dine
Keyword(s):  
Opioid Peptides ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid

Effect of actively immunizing sheep against growth hormone-releasing hormone or somatostatin on spontaneous pulsatile and neostigmine-induced growth hormone secretion

1995 ◽  
Vol 144 (1) ◽  
pp. 83-90 ◽  
Author(s):  
E Magnan ◽  
L Mazzocchi ◽  
M Cataldi ◽  
V Guillaume ◽  
A Dutour ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Physiological Role ◽  
Gh Secretion ◽  
Igf I ◽  
Plasma Gh ◽  
Hypophysial Portal

Abstract The physiological role of endogenous circulating GHreleasing hormone (GHRH) and somatostatin (SRIH) on spontaneous pulsatile and neostigmine-induced secretion of GH was investigated in adult rams actively immunized against each neuropeptide. All animals developed antibodies at concentrations sufficient for immunoneutralization of GHRH and SRIH levels in hypophysial portal blood. In the anti GHRH group, plasma GH levels were very low; the amplitude of GH pulses was strikingly reduced, although their number was unchanged. No stimulation of GH release was observed after neostigmine administration. The reduction of GH secretion was associated with a decreased body weight and a significant reduction in plasma IGF-I concentration. In the antiSRIH group, no changes in basal and pulsatile GH secretion or the GH response to neostigmine were observed as compared to controls. Body weight was not significantly altered and plasma IGF-I levels were reduced in these animals. These results suggest that in sheep, circulating SRIH (in the systemic and hypophysial portal vasculature) does not play a significant role in pulsatile and neostigmine-induced secretion of GH. The mechanisms of its influence on body weight and production of IGF-I remain to be determined. Journal of Endocrinology (1995) 144, 83–90

Inflammation Mobilizes Local Resources to Control Hyperalgesia: The Role of Endogenous Opioid Peptides

Pharmacology ◽  
2012 ◽  
Vol 89 (1-2) ◽  
pp. 22-28 ◽  
Author(s):  
Daniela P. Alves ◽  
Patrícia G. da Motta ◽  
Patrícia P. Lima ◽  
Celso M. Queiroz-Junior ◽  
Marcelo V. Caliari ◽  
...  
Keyword(s):  
Opioid Peptides ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid ◽  
Local Resources
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