Differential effects of IV and IP muscimol on central dopamine metabolism.

The effect of IV and IP muscimol on the concentrations of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in both the nigrostriatal and mesolimbic dopaminergic pathways has been studied. IV muscimol (2 mg/kg), produced significant decreases in the concentration of DA in both DA systems, while the concentration of DOPAC remained unaltered. However, IP muscimol (5 and 10 mg/kg) caused significant increases in the concentrations of DA or DOPAC in all brain regions examined.

Effect of muscimol on dopamine metabolism of the rat hypothalamus.

Muscimol, a potent GABA receptor agonist, produced increases in DOPAC and dopamine concentrations in the rat hypothalamus. GABAergic receptors, therefore, modulate hypothalamic dopaminergic neurones.

3,4-dihydroxyphenylacetic acid (DOPAC) and the rat mesolimbic dopaminergic pathway: drug effects and evidence for somatodendritic mechanisms.

1 Drug effects on dopamine catabolism of the mesolimbic dopaminergic pathway have been investigated using a sensitive radioenzymatic assay for 3,4-dihydroxyphenylacetic acid (DOPAC). 2 Turnover of DOPAC was less rapid in the ventral tegmentum (containing somata and dendrites) than in the nucleus accumbens (containing nerve terminals): 9 and 115 ng g-1 min-1 for ventral tegmentum and nucleus accumbens respectively. 3 Reserpine (5 mg/kg, 1 h) elevated DOPAC concentration to a greater extent in ventral tegmentum than in nucleus accumbens.

Mesolimbic dopaminergic neurones and somatodendritic mechanisms.

The concept that a neurone may release transmitter from both dendritic and axonal sites was investigated by studying mesolimbic dopaminergic neurones. The rat ventral tegmentum (containing dendrites and somata of mesolimbic dopaminergic neurones) possessed high levels of dopamine and tyrosine hydroxylase. Slices of ventral tegmentum accumulated [3H]dopamine (15 or 60 nM) and stimulus-induced release of [3H]dopamine was observed after elevated potassium (44 mM).

Serum concentrations of individual monocarboxylic short-chain fatty acids C2-C6 in underweight children.

The serum concentrations of individual short-chain fatty acids containing 2-6 carbon atoms were studied in 12 underweight children. Mean n-butyric and iso-valeric acid levels were significantly elevated in underweight children, while those of n-valeric and iso-caproic acids were not significantly higher than in the control group. The level of total free fatty acids was also increased in the underweight group.

Monocarboxylic short-chain fatty acids C2-C6 in serum of obese children.

The serum concentrations of monocarboxylic short-chain fatty acids (acetic to n-caproic) were estimated in 12 children with simple obesity aged 4-16 years and in a control group of 35 normal subjects. In the obese patients, significantly decreased values for acetic and n-caproic acid and an increased total free fatty acid level were found. The presumable causes of the phenomenon are discussed.

The concentration of invidual monocarboxylic short chain fatty acids in serum of normal children.

The normal serum concentrations of short-chain fatty acids C2--C6 (acetic to n-caproic) were estimated by gas chromatography in 35 children aged 4-16 years. Individual fluctuations were wide. The highest mean level concerned acetic acid (6.