Location: Forage-animal Production ResearchTitle: Influence of intra-abomasal administration of L-DOPA on circulating catecholamines and feed intake in cattle
|VALENTE, ERITON - Western Paraná State University|
|EGERT-MCLEAN, AMANDA - University Of Tennessee|
|COSTA, GUSTAVO - Western Paraná State University|
|MAY, JOHN - University Of Kentucky|
|HARMON, DAVID - University Of Kentucky|
Submitted to: Frontiers in Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2023
Publication Date: 2/15/2023
Citation: Valente, E.E., Klotz, J.L., Egert-Mclean, A.M., Costa, G.W., May, J.B., Harmon, D.L. 2023. Influence of intra-abomasal administration of L-DOPA on circulating catecholamines and feed intake in cattle. Frontiers in Animal Science. 4. Article 1127575. https://doi.org/10.3389/fanim.2023.1127575.
Interpretive Summary: The ability to improve feed intake in livestock is very desirable and can give producers the ability to improve production efficiency. Dopamine plays important roles in many systems and those are involved with reward sensation and energy balance are of interest. The role of dopamine in control of feed intake is very complex and not completely understood. The dopamine precursor compound L-DOPA can be used to increase dopamine synthesis, but there are few studies that have evaluated L-DOPA in cattle. Thus, the objective of this study was to evaluate the post-ruminal infusion of L-DOPA on circulating metabolites, energy metabolism and feed intake using ruminally cannulated cattle. The results showed that post-rumninal infusion of L-DOPA did indeed result in an increase in circulating dopamine. L-DOPA was rapidly cleared from the blood, whereas dopamine remained elevated. However, there were no effects on other energy metabolites or feed intake. These results will be primarily of interest to other research scientists looking to better understand the mechanisms responsible for feed intake regulation.
Technical Abstract: Dopamine has multiple physiological functions including feed intake control in which it can act as an anorectic or orexigenic agent. This study had the objective to evaluate intra-abomasal administration of L-DOPA from a plant extract on circulating catecholamines, energy metabolism and feed intake in cattle. Eight Holstein steers (340 ± 20 kg) fitted with ruminal cannula were used in a replicated 4 x 4 Latin Square design experiment. Intra-abomasal infusion of L-DOPA at 0, 0.5, 1 and 2 mg/kg BW was carried out for seven days and blood samples were collected at 0, 30, 60, 120, 240 and 480 min from L-DOPA infusion on day 7. The area under the curve (AUC) of plasma L-DOPA and free dopamine increased quadratically with the administration of L-DOPA. However, the AUC of plasma total dopamine had a positive linear response with the increase of L-DOPA. Conversely, the serum 5-HTP, plasma serotonin, serum serotonin, serum tyrosine, plasma glucose and plasma free fatty acids were not affected by the intra-abomasal infusion of L-DOPA. The circulating concentration of the epinephrine, norepinephrine, serotonin, glucose and free fatty acids did not change with L-DOPA infusion. It can be concluded that intra-abomasal L-DOPA administration produced a strong increase in circulating dopamine with no change in energy metabolites and feed intake in cattle.