Effect of naloxone on plasma concentrations of prolactin and LH in lactating sows

Mattioli, Michela; Conte, Felix A.; Galeati, Giovanna; Seren, E.

doi:10.1530/jrf.0.0760167

Cited by 60 publications

(35 citation statements)

References 24 publications

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“…The well-known negative feedback of oestradiol observed after injection of oestradiol in non-lactating sows (Elsaesser and Parvizi, 1979;Stevenson et al, 1981) was not apparent in this study or in other studies (Cox et al, 1988 (Ellendorff et al, 1988) (Barb et al, 1986, Mattioli et al, 1986) and since morphine, an endogenous opioid agonist, is able to shorten the duration of oestrus (Esbenshade and Huff, 1989). In the Mei-shan, the duration of OB-induced oestrus was similar to that described by Ellendorff et al (1988) …”

contrasting

confidence: 53%

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Elsaesser

Martinat-Botté²,

Parvizi³

et al. 1992

Reprod. Nutr. Dev.

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Summary ― To investigate endocrine mechanisms associated with the occasional occurrence of fertile oestrus during lactation in the high prolific Chinese Meishan (MS) breed, the incidence of oestrus and changes in plasma luteinizing hormone (LH) levels before and after oestradiol benzoate (OB, 15 5 og/kg body weight) administration on day 22 was compared in 4 MS and 6 Large White (LW) sows. All sows exhibited oestrus in response to OB. Only 1 sow (MS) ovulated in response to OB, became pregnant and farrowed. Mean plasma LH levels before OB were low (MS: 0.38 ± 0.06 ng LH/ml, LW: 0.29 ± 0.04 ng LH/ml, ns). LH levels above 2 ng/ml (surge) occurred in 2/4 MS and 2/6 LW sows at 60 ± 5 h after OB. The MS sow that ovulated had an LH surge level of 4.5 ng/ml plasma at 40 h after OB. These results indicate minor breed differences in the control of LH secretion during lactational anoestrus.

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contrasting

confidence: 53%

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Elsaesser

Martinat-Botté²,

Parvizi³

et al. 1992

Reprod. Nutr. Dev.

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“…This discrepancy is likely to be related to the fact that primiparous sows were used in this study, whereas multiparous sows were used in previous studies (2,4,5). Intervals from weaning to estrus are typically longer and concentrations of LH lower in primiparous than in multiparous sows (1).…”

Section: Discussionmentioning

confidence: 88%

“…Infusion or single injection of the opioid antagonist naloxone increased LH (2,4,5) and decreased PRL (2,5). Administration of morphine prevented the rise in LH induced by transient removal of the litter (cessation of suckling, 3).…”

Section: Introductionmentioning

confidence: 99%

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Opioid control of growth hormone in the suckled sow is primarily mediated through growth hormone releasing factor

Armstrong

Esbenshade

Coffey

et al. 1990

Domestic Animal Endocrinology

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Endogenous opioid peptides mediate the effect of suckling on LH and PRL in the domestic pig. However, the role of opioids in modulating GH during lactation in swine is not known. Primiparous sows that had been immunized against GRF(1-29) conjugated to human serum albumin (GRF-HSA, n=5) or HSA (n=4) were used to determine changes in GH after naloxone. Treatments were imposed in all sows on day 21 of lactation when antibody titers were 9100 ± 1629. All sows received (LV.) naloxone (0.25 mgfkg) or saline (0.0125 mlfkg) at 15 min intervals for 165 min. Active immunization against GRF-HSAduring lactation decreased (P < 0.05) mean concentration (4.8 ± 0.2 vs 2.6 ± 0.1 ng/ml) and frequency (1.5 ± 0.3 vs 0.4 ± 0.2 peaks/4 hr).Concentrations of LH and PRL were similar in GRF-HSA and HSA immunized sows. Naloxone suppressed (P < 0.05) GH in all sows. In USA sows, naloxone abolished episodic release of GU and decreased average, but not basal, concentrations of GU. In sows immunized against GRF-HSA, naloxone decreased (P <0.05) average and basal GH but failed to decrease frequency of GH release. Naloxone failed to alter frequency of LH release. Concentrations of PRL decreased (P < 0.05) after naloxone in all sows. In conclusion, immunization against GRF-USA blocked most of the effect of lactation on GH. Blocking opioid receptors with naloxone decreased GH and PRL in all sows. In contrast to previous findings naloxone had no effect on LH. Opioids alter concentrations of GH through a GRF dependent and GRF independent pathway.

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“…This effect of suckling is mediated, at least in part, through an opioid-dependent mechanism (Mattioli et al, 1986;Barb ef al, 1987;Armstrong etal, 1988a (Armstrong et al, 1990;Rushen et al, 1993). Moreover, GH secretion may be increased by negative energetic balance, through a decrease in insulin and insulin-like growth factor-I (IGF-1) levels, as shown in other species (see review by Phillips, 1986).…”

Section: Energetic Balance and Circulating Metabolitesmentioning

confidence: 98%

Endocrine bases of lactational anoestrus in the sow

Quesnel¹,

Prunier²

1995

Reprod. Nutr. Dev.

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Summary ― Parturition in the sow is followed by a period of anovulation which is prolonged by lactation. Follicular development and luteinizing hormone (LH) secretion are depressed during the last month of pregnancy. After parturition, LH secretion increases but is again inhibited by the establishment of lactation. Lactating sows are submitted to stimuli originating from the young, whose intensity culminates 3-14 d post-partum (pp), and to high nutrient requirements for milk production. The

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Effect of naloxone on plasma concentrations of prolactin and LH in lactating sows

Abstract: Summary. Six

Cited by 60 publications

References 24 publications

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Oestrus and LH reponses to oestradiol during lactational anoestrus in Chinese Meishan and Large White sows

Opioid control of growth hormone in the suckled sow is primarily mediated through growth hormone releasing factor

Endocrine bases of lactational anoestrus in the sow

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