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.

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.

MESENCEPHALIC AREAS CONTROLLING PULSATILE OXYTOCIN RELEASE IN THE SUCKLED RAT

1981 ◽  
Vol 91 (2) ◽  
pp. 233-244 ◽  
Author(s):  
T. S. JUSS ◽  
J. B. WAKERLEY
Keyword(s):  
Medial Geniculate Body ◽  
Milk Ejection ◽  
Ventral Tegmentum ◽  
Irregular Pattern ◽  
Oxytocin Release ◽  
Medial Geniculate ◽  
Radiofrequency Lesions ◽  
Milk Ejection Reflex ◽  
Bilateral Lesions ◽  
And Control

Experiments were performed on anaesthetized lactating rats to investigate the effects of radiofrequency lesions of the mesencephalon on the milk-ejection reflex. In lesioned and control rats, intramammary pressure recordings were used to estimate oxytocin release (number and relative amplitude of the intermittent milk-ejection responses) during a 3-h suckling test with ten pups. Bilateral lesions (diameter 0·5–1·5 mm) of the lateral tegmentum (near the brachium of the inferior colliculus and medial geniculate body) seriously disrupted the milk-ejection reflex, reducing the number of rats ejecting milk (two out of ten v. all 12 controls, P<0·001) and the amount of oxytocin they released (1·35±0·35 (s.e.m.) v. 15·52±2·19 mu. for controls, P<0·05). Unilateral lesions of the lateral tegmentum also impaired milk ejection and, if the suckling stimulus was restricted only to the contralateral nipples, oxytocin release was virtually abolished. Bilateral lesions placed more medially in the intermediate tegmentum were far less disruptive (eight out of nine rats ejected milk), though the amount of oxytocin released in this group (8·64±1·88 mu.) was still significantly (P<0·05) lower than controls. All rats with lesions of the central grey (nine) or ventral tegmentum (eight) displayed reflex milk ejection, as did those with multiple lesions of the tectum, central grey and ventral tegmentum (seven); in these three groups the amounts of oxytocin released (13·88±2·68, 13·10±1·90 and 11·04±1·95 mu. respectively) did not differ significantly from controls. Damage to the ventral tegmentum produced an irregular pattern of milk ejection characterized by occasional abnormally short (<2 min) milk-ejection intervals, though the overall number of responses in 3 h was less than that of controls (20·83±1·82 v. 14·50±1·30 mu., P<0·05). In conclusion, these results delineate two mesencephalic areas of particular importance in the milk-ejection reflex: (a) the lateral tegmentum, which appears to be concerned with transmission of the suckling stimulus from the contralateral nipples and is indispensable for oxytocin release, and (b) the ventral tegmentum which, although not an essential component of the reflex, may contribute to the timing of the intermittent milk-ejection responses.

Effect of stimulation intensity on oxytocin release before, during and after machine milking

2003 ◽  
Vol 70 (3) ◽  
pp. 349-354 ◽  
Author(s):  
Daniel Weiss ◽  
Alen Dzidic ◽  
Rupert M Bruckmaier
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Threshold Level ◽  
Flow Profile ◽  
Milk Ejection ◽  
Machine Milking ◽  
Milk Flow ◽  
Oxytocin Release ◽  
Stimulation Period ◽  
Stimulation Of

Release of oxytocin (OT) is essential for milk ejection in dairy cows (Lefcourt & Akers, 1983; Bruckmaier & Blum, 1998). During milk ejection, alveolar milk is shifted into the cistern, which causes an increase of intracisternal pressure (Bruckmaier et al. 1994). To initiate maximum milk ejection at the start of milking, increasing OT concentration beyond a threshold level is sufficient (Schams et al. 1983). Increasing OT concentration beyond this threshold has no additional effect on intracisternal pressure, i.e., milk ejection (Bruckmaier et al. 1994). Stimulatory effects of milking by hand or by machine or by suckling are well documented (Gorewit et al. 1992; Bar-Peled et al. 1995; Tancin et al. 1995; Bruckmaier & Blum, 1996). At the start of milking, stimulatory effects of machine milking without pre-stimulation or with a manual pre-stimulation and subsequent machine milking cause the release of comparable amounts of OT (Gorewit & Gassman, 1985; Mayer et al. 1985; Bruckmaier & Blum, 1996), whereas the timing of the applied pre-stimulation is important for the shape of the milk flow curve. Should the pre-stimulation period be too short, or absent altogether, the start of the main milk flow is delayed resulting in a bimodal milk flow profile (Bruckmaier & Blum, 1996). Furthermore, the stimulation of only one teat causes an OT release similar to that caused by stimulation of all four teats (Bruckmaier et al. 2001). However, milk production is greater for hand milking or suckling than for machine milking, possibly owing to higher OT concentrations (Gorewit et al. 1992; Bar-Peled et al. 1995).

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

scholarly journals Milk removal in familiar and unfamiliar surroundings: concentrations of oxytocin, prolactin, cortisol and β–endorphin

1993 ◽  
Vol 60 (4) ◽  
pp. 449-456 ◽  
Author(s):  
Rupert M. Bruckmaier ◽  
Dieter Schams ◽  
Jürg W. Blum
Keyword(s):  
The Other ◽  
Operating Theatre ◽  
Flow Curves ◽  
Blood Samples ◽  
Milk Flow ◽  
Total Milk ◽  
Oxytocin Release ◽  
Central Inhibition ◽  
Vaginal Stimulation

SummaryEight cows were machine milked either in an operating theatre or in their familiar barn. During the experiments, milk flow curves were recorded and blood samples were taken for determination of concentrations of oxytocin, prolactin, cortisol and β–endorphin. The milking cluster was attached without udder preparation. After cessation of milk flow, air was blown into the vagina for 2 min. When milk flow had stopped again, 1 i.u. oxytocin and finally 10 i.u. oxytocin were injected to remove the remaining milk. After the start of milking, oxytocin remained basal in unfamiliar, but increased in familiar surroundings. Therefore, during normal milking only 9% of total milk was removed in unfamiliar, whereas 79% was available in familiar surroundings. In response to subsequent vaginal stimulation in the operating theatre, oxytocin increased transiently in five cows and 15–71% of the milk was removed in these animals. In the other three cows in the operating theatre, oxytocin remained basal during vaginal stimulation, and no more milk was available. After injection of 1 i.u. oxytocin, 56 and 11%, and after injection of 10 i.u. oxytocin, 13 and 8% of milk was removed in unfamiliar and familiar surroundings respectively. Concentrations of prolactin increased during the course of milking in both treatments. Premilking concentrations of cortisol and β–endorphin were elevated in unfamiliar as compared with familiar surroundings. During the course of milking, cortisol increased slightly and β–endorphin decreased in unfamiliar, whereas both hormones increased markedly during milking in familiar surroundings. We conclude that disturbed milk removal in unfamiliar surroundings is due to central inhibition of oxytocin release during normal milking and partly also to a response to vaginal stimulation. This blockade is possibly associated with elevated concentrations of β–endorphin.

Lactational changes in oxytocin release, intramammary pressure and milking characteristics in dairy cows

1991 ◽  
Vol 58 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Harald Mayer ◽  
Rupert Bruckmaier ◽  
Dieter Schams
Keyword(s):  
Dairy Cows ◽  
Milk Yield ◽  
Maximum Flow ◽  
Pressure Increase ◽  
Maximum Pressure ◽  
Early Lactation ◽  
Milk Ejection ◽  
Milk Flow ◽  
Oxytocin Release ◽  
Almost All

SummaryTwo experiments were conducted to investigate possible changes of milking-related oxytocin release (Expt 1) and of intramammary pressure and milking characteristics (Expt 2) throughout entire lactations in German Braunvieh dairy cows. Mean oxytocin concentrations after stimulation at onset of milking increased from 18·3 ± 15·9 to 30·7 ± 24·1 pg/ml in Expt 1 and decreased from 23·9 ± 17·6 to 15·4 ± 9·1 pg/ml in Expt 2, respectively, but remained above the level necessary to elicit complete milk ejection in both trials. Premilking baseline intramammary pressure had its maximum in early lactation until about month 4 and then decreased to ∼50% of its initial level. Ejection pressure followed a similar pattern, but dropped only to ∼75% of its maximum. This was due to the constant elevation of pressure increase, reaching its highest level in late lactation. Time from commencement of stimulation until maximum pressure exceeded 1 min in almost all instances even in early lactation and increased throughout lactation. Despite the normal decrease of milk yield average milk flow fell only slightly while maximum flow rate remained almost constant. Pressure increase, milk yield and milk flow were not different after 1 min and after extended stimulation. Thus there were no indications of a decreasing sensitivity of the milk ejection reflex during lactation, and milking characteristics were positively affected by intense teat stimulation. Suggestions for practical dairying are made.

scholarly journals Reduced claw vacuum and b-phase during low milk flow does not impact oxytocin release and milking performance

2017 ◽  
Vol 85 (1) ◽  
pp. 70-77
Author(s):  
Anna-Lena Neuheuser ◽  
Ann-Catherine Schwinn ◽  
Olga Wellnitz ◽  
Lorenzo E. Hernández-Castellano ◽  
Rupert M. Bruckmaier
Keyword(s):  
Wall Thickness ◽  
Cross Sections ◽  
Peak Flow ◽  
Milk Ejection ◽  
Flow Curves ◽  
Flow Rates ◽  
Milk Flow ◽  
Oxytocin Release

Oxytocin release, milking characteristics, and teat condition were investigated with reduced claw vacuum and pulsation settings compared to milking at regular settings with or without pre-stimulation. The reduced vacuum and pulsation settings during low milk flow are expected to protect the teat tissue before the occurrence of milk ejection at the start of milking, and at the end of milking during a potential overmilking period, i.e. at a milk flow <200 g/min. Seven cows were machine-milked either after a 60 s manual pre-stimulation, or without pre-stimulation and reduced vacuum and pulsation settings, or at full vacuum and normal pulsation during the start of milking. Plasma oxytocin (OT) concentration increased similarly in response to manual pre-stimulation and to both milking with reduced, or with full vacuum and pulsation settings, however delayed by 1 min if the cluster was attached without pre-stimulation. In all treatments OT concentrations remained elevated throughout milking. Milk flow curves were mostly non-bimodal at milkings after manual pre-stimulation and bimodal at milkings without pre-stimulation. The main milking time was shorter and average milk flow was higher during milking after pre-stimulation, but did not differ between treatments without pre-stimulation. Milk yields and peak flow rates were not affected by treatments. Either reduced or full vacuum settings were again applied during an intended overmilking from 200 to 100 g/min of milk flow towards the end of milk harvest. Pre-milking teat ultrasound cross sections were recorded one day before the experiment started. Post-milking ultrasound cross sections were performed at 15 min after each experimental milking. Teat wall thickness was increased after milking as compared to pre-milking but did not differ among treatments. In conclusion, OT release and milking performance are similar if milking is performed with pre-stimulation, or without pre-stimulation but reduced claw vacuum and b-phase during low milk flow.

scholarly journals Simultaneous recording of oxytocin release, milk ejection and milk flow during milking of dairy cows with and without prestimulation

1996 ◽  
Vol 63 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Rupert M. Bruckmaier ◽  
Jürg W. Blum
Keyword(s):  
Flow Rate ◽  
Simultaneous Recording ◽  
Milk Ejection ◽  
Flow Curves ◽  
Milk Flow ◽  
Oxytocin Release ◽  
Plateau Time ◽  
Milking Machine ◽  
Left Front

SummaryThe effects of manual teat stimulation compared with stimulation by the liner of a conventional milking machine and the influence of milk ejection on the course of milk flow during the entire milking were investigated. Twelve cows were milked with or without prestimulation on three quarters and milk flow was recorded while intramammary pressure (IMP) was recorded in the left front quarter and blood samples for the determination of oxytocin (OT) were taken at 1 min intervals. OT concentrations increased very similarly in response to manual teat stimulation or liner stimulation and remained elevated during the entire milking procedure. Milk flow curves were generally bimodal without stimulation and not bimodal during milking after prestimulation. Milk yield was not significantly lower in milkings without than with stimulation, whereas machine-on time was prolonged and peak milk flow rate was reduced during milking without stimulation. Time to reach milk flow plateau, time to reach peak flow rate and IMP profiles were similar in both treatments if time was calculated from the start of stimulation. IMP increased similarly in response to manual or liner teat stimulation. In milkings with and without prestimulation IMP did not reach its maximum until the start of milking. In bimodal milk flow curves the second increase of milk flow occurred concomitantly with the start of IMP increase; ejection IMP generally occurred concomitantly with the milk flow plateau. In some cases during milking without prestimulation only small and transient OT release was observed. In response, IMP did not increase to its maximum and increased further in response to a stripping-related OT release. During the course of milking IMP decreased slightly because of the emptying of the three milked quarters. After the end of milking, and with OT concentrations decreasing to the premilking values, IMP again decreased slightly to another plateau, probably owing to myoepithelial relaxation. Thus the course of milk ejection, i.e. the IMP profile, influenced milk removal markedly during early milking.

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.

scholarly journals Factors affecting milk ejection and removal during milking and suckling of dairy cows

2015 ◽  
Vol 46 (No. 4) ◽  
pp. 108-118 ◽  
Author(s):  
V. Tančin ◽  
R.M. Bruckmaier
Keyword(s):  
Dairy Cows ◽  
Blood Circulation ◽  
Endogenous Opioids ◽  
Milk Ejection ◽  
Factors Affecting ◽  
Oxytocin Release ◽  
Central Inhibition ◽  
Calf Removal ◽  
Milk Ejection Reflex ◽  
Central Level

The release of oxytocin and milk ejection occurrence in response to teat stimulation are crucial for fast and complete milk removal during milking or suckling. The milk ejection reflex can be disturbed at central or peripheral level under different experimental and practical conditions. The central disturbance results in the lack or insufficient ejection of the alveolar milk into the cistern due to inhibited oxytocin release from pituitary into the blood circulation. The important role in the pathophysiological regulation of the inhibited release of oxytocin is played by an opioid system. Endogenous opioids have suppressive effects on oxytocin release under the normal conditions of milk removal. However under the conditions of disturbed milk ejection their role in dairy cows was not confirmed. Other possible mechanisms involved in the central inhibition of oxytocin release are discussed. In dairy cows as compared with rats the mechanisms involved in the regulation of oxytocin release at the central level remain unclear. The central inhibition of oxytocin release has often been observed in dairy practice during milking of primiparous cows after parturition, suckling by alien calf, calf removal before milking, milking of cows in the presence of own calf, relocation and milking in an unknown milking place. If sufficient released oxytocin cannot induce the transfer of milk from alveoli to cistern, peripheral mechanisms are involved. Peripheral mechanisms are related to the increased levels of catecholamines and/or activation sympathetic nervous system at the udder level. In conclusion, the release of oxytocin and milk ejection efficiency can be very easily suppressed by many factors. The effect of milking conditions on regulation of milk ejection has to be considered. Thus the physiological requirements of dairy cows have to be respected.

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