[Brain tyrosine hydroxylase activity in behavior-selected silver foxes]

Area of Science:

• Neuroscience
• Animal Behavior
• Biochemistry

Background:

• The biosynthesis of catecholamines, crucial neurotransmitters, is regulated by enzymes like tyrosine hydroxylase.
• Behavioral traits, such as domestication and aggression, can be influenced by neurochemical differences.
• Understanding these links is key to deciphering the biological underpinnings of behavior.

Purpose of the Study:

• To investigate the activity of tyrosine hydroxylase, a key enzyme in catecholamine biosynthesis, in the brains of silver foxes selected for either domestic or aggressive behavior.
• To compare enzyme kinetics, specifically the Michaelis constant (KM), between these two behavioral groups.

Main Methods:

• Comparative analysis of tyrosine hydroxylase activity in brain regions (locus coeruleus, hypothalamus, cortex, corpus striatum) of domesticated and aggressive silver foxes.
• Enzyme kinetic studies measuring the Michaelis constant (KM) for tyrosine in brain homogenates from both groups.

Main Results:

• Domesticated foxes exhibited significantly higher tyrosine hydroxylase activity in the locus coeruleus, hypothalamus, and cortex compared to aggressive foxes.
• No significant difference in tyrosine hydroxylase activity was observed in the corpus striatum between the groups.
• The Michaelis constant (KM) for tyrosine was similar in the locus coeruleus and aggressive corpus striatum, but higher in the hypothalamus and domesticated corpus striatum.

Conclusions:

• Selection for domestic behavior in silver foxes appears to increase catecholamine biosynthesis, likely by increasing the number of tyrosine hydroxylase enzyme molecules.
• Elevated tyrosine hydroxylase activity in the noradrenaline system correlates with altered behavioral patterns resulting from domestication selection.