Biochemical and physiological effects of catecholamine administration in the horse.

The research investigates the effects of adrenaline administration on various physiological functions and biochemical responses in horses at rest. These include increase in heart rate, sweating, and blood levels of certain biological compounds, as well as the role of different adrenaline receptors.

Introduction

The research study focuses on the evaluation of physiological and biochemical impacts of catecholamine administration in horses. Catecholamines, including adrenaline, are hormones that have significant implications in the body’s acute stress response. In this study, adrenaline is administered intramuscularly in horses at rest to study its effects. Further, the study compares these effects with those arising from isoprenaline, noradrenaline, and treated adrenaline.

Administration and Effects of Adrenaline

• Adrenaline, when given intramuscularly to resting horses, induced various physiological changes. This included an increased heart rate and sweating.
• Along with these physical effects, a range of biochemical reactions was also observed in the blood. The blood levels of lactic dehydrogenase, aldolase, creatine kinase, glucose, lactate, free fatty acids, and glycerol all showed quantifiable increases.

Role of Adrenaline Receptors

• The researchers further analyzed the interactions of different types of adrenaline receptors—alpha and beta receptors. These receptors are found in various parts of the body and regulate the body’s response to adrenaline.
• The beta receptors are suggested to trigger tachycardia (increased heart rate), induce sweating, initiate lipolysis (the breakdown of lipids), and stimulate muscle glycogenolysis (the breakdown of glycogen in the muscles).
• Meanwhile, alpha receptors seem to stimulate liver glycogenolysis (the breakdown of glycogen in the liver) and the leakage of intracellular enzymes.

Comparison to Exercise-Induced Responses

• The study also notices discrepancies between effects of adrenaline injection and the physiological or biochemical responses that occur in horses as a result of exercise.
• The time course and the relative magnitude of effects on different enzymes were not parallel to those produced by physical activity. This indicates that the stress response, though similar, varies in certain aspects when triggered by adrenaline injection versus exercise.