Phylo- and Ontogenetic Establishment of Dopamine Regulation of the Sleep–Waking Cycle in Vertebrates

Abstract

Results obtained from comparative immunohistochemical studies of dopamine-containing neurons and fibers in the telencephalic and diencephalic parts of the brain in cold-blooded animals (frogs) and warmblooded (14- and 30-day-old rat pups and adult) vertebrates are presented. The dynamics of quantitative changes in tyrosine hydroxylase and D1- and D2-immunoreactive structures during the sleep–waking cycle were studied using a sleep deprivation model. Morphofunctional correlations were seen in the nature of the responses of the dopaminergic neurotransmitter system to sleep deprivation during phylo- and ontogenesis. In addition, the effects of dopamine agonists and antagonists on the sleep–waking cycle were studied in frogs and young rats. Dopamine and its agonist apomorphine were found to promote increases in the state of immobility of the cataplexy type (this being a homolog of sleep) in frogs, while in rats it promoted increases in waking and catalepsy. The D1 receptor antagonist SCH 23390 induced increases in the quantity of waking and the state of immobility of the catatonia type in frogs, while the D2 receptor antagonist promoted increases only in the state of immobility of the catalepsy type in the sleep–waking cycle. In one-month-old rats, administration of the dopamine antagonist haloperidol initially induced increases in the proportion of the cataleptic stage, which was followed by onset of deep slow-wave sleep. We address the question of the formation of the regulatory role of the dopaminergic system in the sleep–waking cycle during phylo- and ontogenesis, when dopamine shows a transition from predominantly diencephalic neurosecretory influences to predominantly telencephalic neurotransmitter influences.