TY - JOUR
T1 - Catecholamines, oxytocin and milk removal in dairy cows
AU - Schams, Dieter
AU - Bruckmaier, Rupert
N1 - Funding Information:
This study was in part supported by the Schweizerische Zentralverband fur Milchwirtschaft and the German Research Foundation. We thank Mr A. Prokopp and Mr J. D. Steib for their great help in animal experiments. The technical performance of hormone assays by Mrs R. Admaty, Mrs C. Braun and Mr W. Moses is greatly appreciated. We thank Dr H. Worstorff and Mr A. Prediger for their help in establishing the milking equipment and Mr E. Lehmann and Mr H. Ronge for their contribution in the statistical analysis of the data.
PY - 1989/5
Y1 - 1989/5
N2 - Experiments were designed to study the effects of catecholamines on oxytocin responses and milk removal in dairy cows. Adrenalin, noradrenalin, dopamine, isoproterenol (a β-adrenoceptor agonist), phentolamine (an α-adrenergic blocker) and propranolol (a β-adrenergic blocker) were infused intravenously. In addition, adrenalin was infused together with phentolamine and/or propranolol. Infusions started 8 min before milking and lasted until the end of milking. In some cases electroshocks (for 5 s) were applied immediately before milking in the absence and presence of phentolamine and propranolol. Adrenalin, noradrenalin and dopamine reduced milk removal, but only if administered in supraphysiological amounts. The effect of adrenalin and electroshocks on milk removal could be inhibited by α-, but not by β-adrenergic blockade. The effect of dopamine could be inhibited only partly by phentolamine. Inhibition of milk removal was not mediated by reduced oxytocin responses. Enhanced local release of catecholamines from sympathetic nerves was presumably responsible for lowered milk removal in response to electroshocks. Milk removal was facilitated during α-adrenergic blockade and during β-adrenoceptor stimulation.
AB - Experiments were designed to study the effects of catecholamines on oxytocin responses and milk removal in dairy cows. Adrenalin, noradrenalin, dopamine, isoproterenol (a β-adrenoceptor agonist), phentolamine (an α-adrenergic blocker) and propranolol (a β-adrenergic blocker) were infused intravenously. In addition, adrenalin was infused together with phentolamine and/or propranolol. Infusions started 8 min before milking and lasted until the end of milking. In some cases electroshocks (for 5 s) were applied immediately before milking in the absence and presence of phentolamine and propranolol. Adrenalin, noradrenalin and dopamine reduced milk removal, but only if administered in supraphysiological amounts. The effect of adrenalin and electroshocks on milk removal could be inhibited by α-, but not by β-adrenergic blockade. The effect of dopamine could be inhibited only partly by phentolamine. Inhibition of milk removal was not mediated by reduced oxytocin responses. Enhanced local release of catecholamines from sympathetic nerves was presumably responsible for lowered milk removal in response to electroshocks. Milk removal was facilitated during α-adrenergic blockade and during β-adrenoceptor stimulation.
UR - http://www.scopus.com/inward/record.url?scp=0024660548&partnerID=8YFLogxK
U2 - 10.1017/S0022029900026388
DO - 10.1017/S0022029900026388
M3 - Article
C2 - 2760295
AN - SCOPUS:0024660548
SN - 0022-0299
VL - 56
SP - 167
EP - 177
JO - Journal of Dairy Research
JF - Journal of Dairy Research
IS - 2
ER -