Opioid Peptides in the Regulation of Anterior Pituitary Hormones

Cella, Silvano G.; Locatelli, Vittorio; Müller, Eugenio E.

doi:10.1007/978-3-642-77540-6_19

Cited by 5 publications

(3 citation statements)

References 138 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, centrally acting ß-endo has been implicated in the modulation of pituitary hormones including pro¬ lactin release (Cella et al 1993). Therefore, age-related changes in ß-endo processing have potentially widespread physiological consequences, and ß-endo is therefore strongly implicated as a major regulator of ageing changes in the CNS.…”

Section: Discussionmentioning

confidence: 99%

Hypothalamic processing of β-endrophin in female C57BL/6J mice is altered at middle age

Joshi

Bennett²,

James³

et al. 1995

Journal of Endocrinology

View full text Add to dashboard Cite

beta-Endorphin (beta-endo) (1-31) is the active opioid peptide product of pro-opiomelanocortin processing. Further post-translational modifications of beta-endo(1-31) yield beta-endo(1-27), (1-26) and their acetylated forms which are considered to be opiate receptor antagonists. Mechanistically, alteration in opiatergic properties is likely to result in the loss of a number of physiological functions including reproductive capacity. The purpose of this study was to determine whether there are changes in the way beta-endo neurones process the peptide with age in female C57BL/6J mice. Pooled extracts of arcuate nucleus (ARC) and preoptic area (POA) of 3- to 4-month-old normally cycling (4-5 days at dioestrus), 12- to 13-month-old irregularly cycling (5-7 days at dioestrus), 23- to 24-month-old acyclic (in persistent dioestrus) animals were subjected to reversed-phase HPLC (n = 4 experiments). Column fractions were assayed for beta-endo-like-immunoreactivity by sequence-specific RIAs. The opiate receptor active as well as opiate receptor antagonist forms of beta-endo were present in both ARC and POA at all three age groups although their ratios varied. beta-Endo(1-31), the active opiate, was the predominant form in young animals. At middle age there was a threefold (P < 0.05, ANOVA) increase in the antagonist forms of beta-endo and this was associated with a significant (P < 0.05, ANOVA) increase in the ratio of antagonist to active forms. This was accompanied by a trend toward an increase in acetylated forms of beta-endo in middle-aged mice. HPLC profiles from hypothalami of old animals more closely resembled those of young females. The increase in the antagonist forms of beta-endo at middle age may contribute to a decline of opiatergic influences in the female C57BL/6J mouse and suggest a mechanism whereby alterations in opiate influence over gonadotrophin control may occur.

show abstract

Section: Discussionmentioning

confidence: 99%

Hypothalamic processing of β-endrophin in female C57BL/6J mice is altered at middle age

Joshi

Bennett²,

James³

et al. 1995

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…Many cows in experiment 1, however, did not exhibit a Prl response to naloxone, and this observation agrees with that of Whisnant et al (1986). The general stimulatory role that opiods have on Prl release is believed to be mediated by the hypothalamic-dopaminergic tuberoinfundibular system (see review by Cella, Locatelli and Miiller, 1993). The hypothalamic release of dopamine can be inhibited during a period of stress as a consequence of enhanced release of endogenous opioid peptides (see review by Przewlocki, 1993).…”

Section: Discussionmentioning

confidence: 99%

Naloxone evokes a nutritionally dependent LH response in post partum beef cows but not in mid-luteal phase maiden heifers

Sinclair¹,

Broadbent²,

Hutchinson

1995

Anim. Sci.

View full text Add to dashboard Cite

Data from two experiments are reported which test the hypothesis that nutrient and/or dry-matter intake and body condition may interact to modify hypothalamic opioidergic activity and thus influence the pulsatile release of LH during the early post-partum period and during the oestrous cycle. Experiment 1 involved 16 multiparous, twinsuckling beef cows, and was a 2 X 2 X 2 factorial design in which the factors were level of post-partum energy intake (80 v. 130 M] metabolizable energy (ME) per day), the digestible undegradable protein (DUP) content of the post-partum diet (14 v. 31 g/kg dry matter), and treatment with either 200 mg or 400 mg naloxone hydrochloride. Blood samples were collected at 15-min intervals for 4h at weeks 4 and 7 post partum. Naloxone was administered intravenously after the eighth sample. Experiment 2 involved 16 cyclic maiden heifers and was also arranged in a factorial manner, with two levels of body condition at the start of the experimental period (2-50 and 3-16 units) and two levels of energy intake thereafter (40 and 80 MJ ME per day). Seven blood samples were collected at 15-min intervals on 4 days consecutively during the mid-luteal phase of the oestrous cycle. On the first 2 of these 4 days naloxone was administered, whilst on the last 2 days a gonadotropin-releasing hormone agonist (buserelin; GnRH) was administered, both after the fourth sample. Plasma from both experiments was assayed for LH and prolactin (Prl).In experiment 1, cows on 130 MJ ME per day returned to oestrus and ovulated earlier than cows on 80 M] ME per day (44-5 v. 55-0 days; s.e.d. = 3-93; P < 0-05). At week 4 post partum the proportional increase in plasma LH following naloxone challenge was greater for cows on 130 M] ME per day than cows on 80 M] ME per day (1 -38 v. 1-12; P < 0-05), but the converse was true at week 7 (1-15 v. 1-68; P < 0-05). Cows on the high DUP diet required a higher dose of naloxone to elicit an LH response. Few heifers in experiment 2 exhibited an LH response to naloxone. In contrast, there were significant dietary treatment effects on the LH response to GnRH (P < 0-01). Relatively thin heifers on 40 M] ME per day exhibited the lowest proportional increases in plasma LH to GnRH challenge, whereas heifers on 80 MJ ME per day and given the higher dose of GnRH produced the greatest plasma LH responses. Mean Prl concentrations before and after feeding in experiment 2 were respectively 13-2 and 10-2 ng/l (P < 0-01). Suckled cows given a high energy diet during the early post-partum period can overcome the opioid mediated block on LH release and resume oestrous cycles earlier than cows given a low energy diet. LH would appear to be inhibited by a non-opioid mechanism in mid-luteal phase heifers. Total pituitary reserves ofLH may be influenced by the animals nutritional status.

show abstract

“…Activation of the hypothalamic-pituitary-adrenal axis (HPA) is known to be an important component of the neuroendocrine response to opiates (Millan and Herz, 1985). Opiates, when given acutely, release CRF from the hypothalamus, ACTH and f3-endorphin from the pituitary, and corticosterone from the adrenal glands (Buckingham, 1982;Buckingham and Cooper, 1986;Cella et al, 1993;Hollt et al, 1978;Kiem et al, 1991). Although tolerance of hormonal effects of opiates has been reported (Ignar and Kuhn, 1990;Milanes et al, 1993), repeated morphine administration in increasing doses leads to down-regulation of glucocorticoid receptors in the hippocampus, impairment of the HPA feedback inhibition mechanism, and hypersecretion of corticosterone (Budziszewska et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

The effect of N-nitro-L-arginine methyl ester on morphine-induced changes in the plasma corticosterone and testosterone levels in mice

Budziszewska

Leśkiewicz²,

Jaworska-Feil³

et al. 2009

Exp Clin Endocrinol Diabetes

View full text Add to dashboard Cite

Effects of the nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg i.p.), on morphine-induced changes in the plasma corticosterone and testosterone levels were studied in male mice. Acute morphine administration (15 and 30 mg/kg i.p.) enhanced the corticosterone level after 1 and 2 hr (at a dose of 30 mg/kg only). A 4-day treatment with increasing doses of morphine, from 15 to 50 mg/kg i.p., increased the plasma corticosterone concentration at 2 hr after the last injection. Single administration of L-NAME (30 mg/kg i.p.) had no effect on the corticosterone level, whereas its repeated injections (30 mg/kg i.p., twice a day for four days) elevated the hormone concentration at 2 hr after the last dose. Pretreatment of mice with L-NAME enhanced the stimulatory effects of both acute and repeated morphine administration on the corticosterone level. D-NAME (30 mg/kg i.p.), an inactive form of the nitric oxide synthase inhibitor, had no effect on the morphine-induced changes in the corticosterone level. Acute morphine administration had no effect on the plasma testosterone level after 1 or 2 hr, whereas repeated drug injections decreased the hormone concentration after 2 hr. Single or repeated L-NAME administration did not influence the testosterone level in either control or morphine-treated animals. The above results indicate that inhibition of nitric oxide synthase enhances the stimulatory effect of morphine on corticosterone secretion, but does not influence the inhibitory effect of repeated morphine on the plasma testosterone concentration in mice.

show abstract

Opioid Peptides in the Regulation of Anterior Pituitary Hormones

Cited by 5 publications

References 138 publications

Hypothalamic processing of β-endrophin in female C57BL/6J mice is altered at middle age

Hypothalamic processing of β-endrophin in female C57BL/6J mice is altered at middle age

Naloxone evokes a nutritionally dependent LH response in post partum beef cows but not in mid-luteal phase maiden heifers

The effect of N-nitro-L-arginine methyl ester on morphine-induced changes in the plasma corticosterone and testosterone levels in mice

Contact Info

Product

Resources

About