Effects of African Trypanosomiasis on Brain Levels of Dopamine, Serotonin, 5‐Hydroxyindoleacetic Acid, and Homovanillic Acid in the Rabbit

Abstract

Serotonin (5-HT) levels fell by 21% in the mid-brain-thalamus-hypothalamus (MTH) region of the rabbit brain after chronic infection with the protozoan Trypanosoma brucei gambiense. 5-HT did not decrease significantly in the caudate/putamen (CP) or the pons/medulla (PM) region. 5-Hydroxyindoleacetic acid (5-HIAA) levels were unchanged in the MTH and caudate/putamen (CP) but increased by 17% in the pons/medulla (PM) after infection. Dopamine (DA) levels rose by 19% and homovanillic acid (HVA) by 33% in the PM during infection. DA and HVA tended to be lower in the CP of infected rabbits, but the apparent decreases were not statistically significant. DA and HVA levels in the MTH were also unchanged by infection. These neurochemical changes may be involved in the behavioral symptoms that frequently accompany this disease in man and cattle.

Trypanosoma brucei infection induces apoptosis and up-regulates neuroleukin expression in the cerebellum

“…Macrophage cannabinoid receptor 2 (CB2-R), dopamine receptor 4 (DRD4) and prostaglandin-E2 receptor (PGD2-R) mRNA were up-regulated in infected mice but not in controls. Cannabinoids bind highly in the Substantia Nigra (SN), Globus Pallidus (GP) and cerebellum, and alter sleep cycles, whereas dopamine affects the brain processes that control movement, emotional response and ability to experience pleasure and pain (Stibbs, 1984;Herkenham et al, 1990). As there is up-regulation of NLK, CB2-R and DRD4 during apoptosis seen in the cerebellum at peak parasitaemia, these neurotransmitter receptors may be involved in the alterations in the sleep/ wake cycle (controlled in the LC region) seen in the sleeping-sickness syndrome (Stibbs, 1984).…”