Changes in pain threshold during pregnancy and parturition in the sow and the involvement of opioids

1996 ◽  
Vol 1996 ◽  
pp. 32-32
Author(s):  
S. Jarvis ◽  
K. A. McLean ◽  
S. Calvert ◽  
J. Chirnside ◽  
L. Deans ◽  
...  
Keyword(s):  
Birth Interval ◽  
Pain Threshold ◽  
Endogenous Opioids ◽  
Environmental Disturbance ◽  
Opioid Activity ◽  
Oxytocin Release ◽  
Naloxone Treatment

Endogenous opioids are known to inhibit oxytocin release from the neurohypopysis (Bicknell et al, 1982). This mechanism has been suggested to be involved in the timing of parturition and delivery of young (Leng et al, 1985). Environmental disturbance in the rat (Leng et al, 1988) and pig (Lawrence et al, 1992) during parturition resulted in a naloxone reversible increase in birth interval, and an increase in plasma oxytocin concentration after naloxone treatment suggesting stress-induced opioid inhibition of oxytocin. Pain, which is associated with parturition, results in increased opioid activity and may be involved in the inhibition of oxytocin. Pregnancy-induced analgesia has been shown in the human (Whipple et al, 1990) and the rat (Gintzler, 1980), with the latter suggesting involvement of an opioid mechanism. This study aimed to determine whether an increase in pain threshold occurred over pregnancy and parturition in the pig and whether this was opioid-mediated.

Changes in pain threshold during pregnancy and parturition in the sow and the involvement of opioids

1996 ◽  
Vol 1996 ◽  
pp. 32-32
Author(s):  
S. Jarvis ◽  
K. A. McLean ◽  
S. Calvert ◽  
J. Chirnside ◽  
L. Deans ◽  
...  
Keyword(s):  
Birth Interval ◽  
Pain Threshold ◽  
Endogenous Opioids ◽  
Environmental Disturbance ◽  
Opioid Activity ◽  
Oxytocin Release ◽  
Naloxone Treatment

Endogenous opioids are known to inhibit oxytocin release from the neurohypopysis (Bicknell et al, 1982). This mechanism has been suggested to be involved in the timing of parturition and delivery of young (Leng et al, 1985). Environmental disturbance in the rat (Leng et al, 1988) and pig (Lawrence et al, 1992) during parturition resulted in a naloxone reversible increase in birth interval, and an increase in plasma oxytocin concentration after naloxone treatment suggesting stress-induced opioid inhibition of oxytocin. Pain, which is associated with parturition, results in increased opioid activity and may be involved in the inhibition of oxytocin. Pregnancy-induced analgesia has been shown in the human (Whipple et al, 1990) and the rat (Gintzler, 1980), with the latter suggesting involvement of an opioid mechanism. This study aimed to determine whether an increase in pain threshold occurred over pregnancy and parturition in the pig and whether this was opioid-mediated.

Inhibition of oxytocin release and milk let-down in postpartum primiparous cows is not abolished by naloxone

2001 ◽  
Vol 68 (4) ◽  
pp. 559-568 ◽  
Author(s):  
WOLF-DIETER KRAETZL ◽  
VLADIMIR TANCIN ◽  
DIETER SCHAMS
Keyword(s):  
Post Partum ◽  
Endogenous Opioids ◽  
Opioid Antagonist ◽  
Milk Ejection ◽  
Brown Swiss ◽  
Machine Milking ◽  
Oxytocin Release ◽  
Naloxone Treatment ◽  
Vaginal Stimulation

About 10% of primiparous cows have no milk ejection during the first milkings after delivery. Therefore, 17 Brown Swiss dairy cows in their first lactation were used to evaluate the extent of disturbed milk let-down and the corresponding oxytocin (OT) plasma values in the 1st 5 days after delivery. The first milking was 9–22 h after parturition and served for classification of the cows to groups with inhibited (INH), bimodal (BIMO) or normal (NOR) milk let-down. The OT plasma levels before the start of manual teat stimulation and machine milking were comparably high during the first milking especially in NOR and BIMO cows. Ten minutes before the second milking (M2), 300 mg of the opioid antagonist naloxone was injected to test whether the disturbance was affected by the action of endogenous opioids on the neurohypophysis. The milk yield was not influenced by the naloxone treatment, and the INH cows had milk ejection only after a vaginal stimulation. Afterwards, the cows were milked twice every day, until the milk let-down and the OT release were unaffected (equal to control milking). Then, at the next milking, the cows were injected with 300 mg morphine 10 min before milking. The central OT release in response to manual teat stimulation and machine milking was completely blocked in all cows, but a vaginal stimulation was able to abolish this block, at least partially, in 16 cows. Thus, morphine produced a milk let-down characteristic as in the INH cows during the first three milkings. For the following milking, the cows were pre-treated with 300 mg naloxone (−15 min) plus 300 mg morphine (−10 min) before milking. The OT release and the milk yields were unaffected when compared with the control milking. This experiment demonstrates that exogenous opioids can affect the central release of OT in a naloxone-reversible manner even very soon after parturition. However, endogenous opioids are probably not the main mediators of disturbed central OT release and alveolar milk ejection in post-partum primiparous cows.

Inhibition of oxytocin release during repeated milking in unfamiliar surroundings: the importance of opioids and adrenal cortex sensitivity

2002 ◽  
Vol 69 (1) ◽  
pp. 63-73 ◽  
Author(s):  
JULIANA MAČUHOVÁ ◽  
VLADIMIR TANČIN ◽  
WOLF-DIETER KRAETZL ◽  
HEINRICH H. D. MEYER ◽  
RUPERT M. BRUCKMAIER
Keyword(s):  
Endogenous Opioids ◽  
Opioid Antagonist ◽  
Control Group ◽  
Research Station ◽  
Milk Ejection ◽  
Milk Flow ◽  
Oxytocin Release ◽  
And Control ◽  
Naloxone Treatment ◽  
Vaginal Stimulation

The aim of this study was to test if the opioid antagonist naloxone has a beneficial effect on normalization of oxytocin (OT) release during repeated milking of cows in unfamiliar surroundings. One control milking without naloxone treatment in all cows was performed in the familiar parlour. For four successive evening milkings, cows were transported to, and milked in, the operating theatre of the research station without (control group) or with naloxone administration (1 mg/kg BW) (naloxone group) before milking. After cessation of spontaneous milk flow, but not before 3 min of milking, vaginal stimulation was applied for 2 min. After milk flow ceased again, 10 IU of OT was injected intravenously to remove the remaining milk including residual milk. Milk flow was recorded continuously and blood samples were collected via a jugular vein cannula at 1-min intervals from 1 min before the start of milking until i.v. injection of OT. The inhibition of milk ejection and its normalization during repeated milking in unfamiliar surroundings was not influenced by naloxone treatment. Concentrations of cortisol and β-endorphin during control milking and all relocations were similar in the naloxone and control groups, although their concentrations were higher after relocations than in the control. Therefore, a role of endogenous opioids in the inhibition of milk ejection in unfamiliar surroundings could not be demonstrated. In addition, the effect of exogenous ACTH1–24 (8 IU, i.v.) on the release of cortisol related to the response of cows milked in unfamiliar surroundings was studied. Cows with totally inhibited milk ejection in response to vaginal stimulation during milking after first relocation had numerically, but not significantly lower cortisol levels (8·8±3·4 ng/ml; AUC/min) in response to ACTH than did cows with at least partial milk ejection (38·7±12·9 ng/ml). Thus animals with a higher adrenal response to ACTH seemed to have less severe inhibition of milk ejection.

scholarly journals Zastosowanie elektroterapii TENS w łagodzeniu bólu porodowego / Application of TENS electrotherapy in alleviating labour pain

2016 ◽  
Vol 15 (2) ◽  
pp. 59-62
Author(s):  
Magdalena Sowa ◽  
Katarzyna Ciechanowska ◽  
Iwona Głowacka
Keyword(s):  
Electrical Stimulation ◽  
Pain Threshold ◽  
Labour Pain ◽  
Endogenous Opioids ◽  
Transcutaneous Electrical Stimulation ◽  
Pain Sensation ◽  
Transcutaneous Electric Nerve Stimulation ◽  
Obstetric Practice ◽  
Electric Nerve Stimulation ◽  
The Impact

Abstract Introduction. Easing labour pain is an extremely important issue in obstetric practice. Various physiotherapy methods are increasingly often applied in obstetric practice. Transcutaneous electric nerve stimulation (TENS) aiming at central and peripheral modulation of pain sensation is one of them.Aim. The aim of the study was to analyse the impact of transcutaneous electrical stimulation (TENS) on easing labour pain.Summary. The TENS method is regarded as effective since it increases both the pain threshold and secretion of endogenous opioids. Non-pharmacological methods of pain management during labour, including electrotherapy TENS methods are safe and can be used in most patients.

Scene Preferences, Aesthetic Appeal, and Curiosity

2021 ◽  
pp. 61-65
Author(s):  
Edward A. Vessel ◽  
Xiaomin Yue ◽  
Irving Biederman
Keyword(s):  
Neural Network ◽  
Network Modeling ◽  
Endogenous Opioids ◽  
Neural Network Modeling ◽  
Opioid Activity ◽  
Hedonic Value ◽  
Aesthetic Responses ◽  
Neural Ensembles ◽  
Parahippocampal Cortex ◽  
Cognitive Experience

A gradient of µ-opioid receptors extends from early sensory areas of the cerebral cortex to associative cortex, with the greatest density of receptors in the most anterior associative regions. In 2006, Biederman and Vessel proposed that the hedonic value of perceptual and cognitive experience is a function of activation of this gradient. A desire for opioid activity provided by this gradient renders us infovores, always seeking novel but richly interpretable experiences. Richly interpretable experiences engage the opioid-dense anterior regions of the gradient, while novel experiences engage neural ensembles that have yet to undergo adaptation. Support for this proposal derives from the greater activity elicited in opioid-rich parahippocampal cortex for preferred over nonpreferred scenes, with neural network modeling of visual aesthetic responses suggesting that representations in later stages are more predictive of aesthetic responses, and psychopharmacological experiments that support the potential involvement of endogenous opioids.

scholarly journals  The role of beta-endorphin in horses: a review

2011 ◽  
Vol 56 (No. 9) ◽  
pp. 423-429 ◽  
Author(s):  
M. Golynski ◽  
W. Krumrych ◽  
K. Lutnicki
Keyword(s):  
Pain Threshold ◽  
Social Activity ◽  
Prognostic Indicator ◽  
Endogenous Opioids ◽  
Oxygen Species ◽  
Endogenous Opioid System ◽  
Endogenous Opioid ◽  
Beta Endorphin ◽  
Opium Alkaloids

  Opium alkaloids counterparts are secreted by human and animal organisms but the role of endogenous opioid peptides in horses has not yet been fully elucidated. Endogenous opioids are involved in regulating food intake, sexual and social activity, pain relief and pain threshold regulation in horses as well as in regulating the functions of the immune system. The aim of this review is to describe the endogenous opioid system in the horse and its function during stress, illness, reproduction, and its influence on immunity and on the formation of reactive oxygen species (ROS) in horses. What is currently known concerning beta-endorphin suggests that they can be a promising diagnostic or prognostic indicator of many pathologic states in horses.

Relaxin acts centrally to inhibit oxytocin release during parturition: an effect that is reversed by naloxone

1986 ◽  
Vol 111 (1) ◽  
pp. 99-102 ◽  
Author(s):  
S. A. Jones ◽  
A. J. S. Summerlee
Keyword(s):  
Jugular Vein ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Opioid System ◽  
Opioid Antagonist ◽  
Unoperated Control ◽  
Osmotic Minipumps ◽  
Oxytocin Release ◽  
Naloxone Treatment

ABSTRACT Experiments were carried out to establish whether infusion of relaxin prolongs gestation and labour in the rat by suppressing release of oxytocin, and whether the effects of relaxin on birth could be reversed by the opioid antagonist naloxone. Female rats were implanted with subcutaneous osmotic minipumps for the infusion of purified porcine relaxin into the jugular vein for 84 h from either day 19 or day 20 of gestation. Infusion of relaxin delayed the onset of labour and in those animals which delivered during relaxin infusion, delivery was longer by approximately 45 min. Plasma oxytocin levels 40 min after delivery of the first fetus were 45·25 ± 3·6 pmol/l (mean ± s.d.) in unoperated controls and significantly (P < 0·01) depressed (23·89 ± 3·9) in rats that delivered during infusion of relaxin. Rats that delivered after the infusion of relaxin had finished, gave birth significantly (P < 0·05) faster than controls and plasma oxytocin levels were significantly (P < 0·01) raised (77·87 ±15·9 pmol/l). Naloxone treatment (1 mg/kg; i.m.) given immediately after the delivery of the first fetus reversed the inhibitory effect of relaxin and the interval between successive deliveries was slightly faster than that of controls. Plasma oxytocin levels in relaxin-infused naloxone-treated rats were significantly (P < 0·01) higher than values in unoperated control rats. The results confirm that relaxin suppresses oxytocin release possibly through an opioid system and this may be important in the control of the timing of birth. J. Endocr. (1986) 111, 99–102

Adrenal secretion of BAM-22P, a potent opioid peptide, is enhanced in rats with acute cholestasis

1994 ◽  
Vol 266 (2) ◽  
pp. G201-G205 ◽  
Author(s):  
M. G. Swain ◽  
L. MacArthur ◽  
J. Vergalla ◽  
E. A. Jones
Keyword(s):  
Mrna Expression ◽  
Adrenal Medulla ◽  
Opioid Peptide ◽  
Endogenous Opioids ◽  
Mrna Levels ◽  
Opioid Agonist ◽  
Opioid Activity ◽  
Proenkephalin Mrna ◽  
Adrenal Secretion ◽  
Acute Cholestasis

The adrenal gland is known to produce and release endogenous opioids into the circulation. Bovine adrenal medulla docosapeptide (BAM-22P) is a potent opioid agonist, derived from the proenkephalin A gene, which is present in the adrenal medulla. This study was undertaken to determine whether BAM-22P is released into plasma during acute cholestatic liver injury, which increases plasma total opioid activity. Acute cholestasis was induced by bile duct ligation or administration of the hepatotoxin alpha-naphthylisothiocyanate. Plasma levels of BAM-22P were determined by a sensitive radioimmunoassay, and the specificity of the assay was confirmed using high-performance liquid chromatography. Plasma BAM-22P levels was cholestatic rats were significantly higher than those in control rats. This increase in plasma BAM-22P levels was completely prevented by adrenalectomy. Adrenal steady-state levels of proenkephalin mRNA, as determined by Northern blot hybridization analyses, were also increased significantly in cholestatic rats. These increases in proenkephalin mRNA levels were not paralleled by changes in adrenal BAM-22P peptide levels, which were similar in cholestatic rats and their respective controls. Similar levels of proenkephalin mRNA expression were observed in innervated and denervated adrenal glands from cholestatic rats, suggesting that the increase in adrenal proenkephalin mRNA levels in acute cholestasis is not due to splanchnic nerve activation. Thus acute cholestasis in the rat is associated with adrenal secretion and accumulation in plasma of the highly potent opioid peptide BAM-22P and an augmentation of adrenal proenkephalin mRNA expression. The increase in plasma BAM-22P levels may contribute substantially to the increase in total circulating opioid activity documented in cholestatic rats.

A sex difference in endogenous opioid regulation of the posterior pituitary response to stress in the rat

1986 ◽  
Vol 111 (2) ◽  
pp. 239-244 ◽  
Author(s):  
D. A. Carter ◽  
T. D. M. Williams ◽  
S. L. Lightman
Keyword(s):  
Sex Difference ◽  
Gonadal Hormones ◽  
Endogenous Opioids ◽  
Female Rats ◽  
Male Rats ◽  
Posterior Pituitary ◽  
Endogenous Opioid ◽  
Chronic Morphine ◽  
Response To Stress ◽  
Naloxone Treatment

ABSTRACT The influence of endogenous opioids on the posterior pituitary response to stress was investigated by measuring plasma hormone levels in immobilized male and female rats following either acute naloxone treatment or prolonged morphine administration. Naloxone significantly potentiated the oxytocin and arginine vasopressin (AVP) response to immobilization, but in female rats only. The responses of morphine-treated male rats showed differences compared with vehicle-treated controls, although chronic morphine treatment did not reliably alter the oxytocin or AVP responses to immobilization in males or females. In a further experiment to investigate the role of gonadal hormones in determining the sex difference in responsiveness to naloxone, it was found that acute naloxone treatment significantly potentiated the posterior pituitary response to stress in castrated male rats. These results extend previous studies showing a sex difference in stress-induced secretion of posterior pituitary hormones, providing evidence of a sexual dimorphism in the endogenous opioid regulation of this response which is partly determined by circulating gonadal hormones. J. Endocr. (1986) 111, 239–244

Changes of sensory and pain threshold after transcutaneous electrical nerve stimulation – TENS

Ból ◽  
2019 ◽  
Vol 20 (4) ◽  
pp. 1-13
Author(s):  
Joanna Witkoś ◽  
Jan Budziosz
Keyword(s):  
Physical Therapy ◽  
Nerve Stimulation ◽  
Transcutaneous Electrical Nerve Stimulation ◽  
Pain Threshold ◽  
Musculoskeletal Diseases ◽  
Endogenous Opioids ◽  
Sensory Threshold ◽  
Activity Increase ◽  
Electrical Nerve Stimulation ◽  
Positive Effects

Non-invasive electrotherapy it is a safe way to use electric current in physical therapy to treat pain related to musculoskeletal diseases. Electrotherapy mediated analgesia results from stimulation of pain inhibiting receptors activity increase as well endogenous opioids secretion rise. Physical therapy applies different modalities to ease the pain whereas transcutaneous electrical nerve stimulation (TENS) is one of them. The aim of this study was assessment of impact of transcutaneous electrical nerve stimulation on sensory threshold and threshold of pain. Study included 33 females and 30 males, healthy volonteers aged 21–25 years. In participants single convectional transcutaneous electrical nerve stimulation was performed. Sensory and pain threshold were assessed before stimulation, immediately after stimulation and in 15th and 30th minute after stimulation. Measurements were performed with PainMatcher device. The results have proved that single convectional TENS leads to sensory threshold decrease and increase of pain threshold. The research confirms positive effects of TENS in antinociceptic processes.

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