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Neurochemical coding for feeding in sheep and steers
Journal of Comparative and Physiological Psychology
|January 1, 1975
Summary
Alpha-adrenergic agonists stimulate feeding in sheep but reduce it in steers. This suggests distinct alpha-adrenergic pathways regulate feeding behaviors in different species.
Area of Science:
- Neuroscience
- Animal Behavior
- Pharmacology
Background:
- The role of adrenergic systems in regulating feeding behavior is complex and species-dependent.
- Alpha-adrenergic receptors are implicated in central control of appetite.
Purpose of the Study:
- To investigate the differential effects of alpha-adrenergic stimulation and blockade on feeding responses in sheep and steers.
- To elucidate the involvement of alpha-adrenergic pathways in appetite regulation.
Main Methods:
- Intraventricular injections of alpha-adrenergic agonists (1-norepinephrine, 1-phenylephrine) and antagonists (phenoxybenzamine, propranolol) were administered to sheep and steers.
- Feeding intake was measured over 2-hour tests.
Main Results:
- In sheep, 1-norepinephrine significantly increased feed intake, an effect blocked by phenoxybenzamine.
- In steers, 1-norepinephrine induced hypophagia (reduced feeding), which was also blocked by phenoxybenzamine.
- Phenoxybenzamine alone increased feeding in steers but decreased it in sheep.
Conclusions:
- The findings support a hypothesis of an alpha-adrenergic-coded system for feeding in sheep.
- Conversely, the data suggest an alpha-adrenergic-coded system for satiety in steers.
- Adrenergic regulation of feeding behavior exhibits species-specific differences.