[Immunohistochemical study of CART-peptide in striato-nigral projections at dopamine loss].

The increase of CART-peptide optical density was found immunohistochemically in nucleus accumbens neurons and in their terminals in substantia nigra in Wistar rats after 28% reduction of dopaminergic neurons in a substantia nigra (in the model of lactacystin induced proteo some disfunction). At the same time after in vitro incubation of nigro-accumbal brain slice with AMPT (alpha-methyl-paratirosine--dopamine inhibitor) for 4 h the reduction of tyrosine hydroxylase optical density (the enzyme limiting dopamine synthesis) in substantia nigr neurons was found and optical density of CART-peptide in nucleus accumbens and substantia nigra was also revealed. In both experiments data about activation of CARTergic neurons in stria to-nigral projections testifies on participation of CART-peptide in compensatory brain mechanisms at dopamine loss and its role as modulator of dopaminergic brain neurons functional activity.

[Sleep changes during degeneration of neurons in the substantia nigra induced by inhibitor of proteasomes lactacystin in rats].

A decrease in activity of ubiquitin proteasome system results in accumulation of toxic forms of protein and cell degeneration, including dopamine (DA)-ergic neurons in the substantia nigra; these neurons are remarkable for their low proteolytic activity of proteosomes that makes them more vulnerable, especially when subjected to the neurotoxin action or Parkinson's disease (PD). The goal of the present study is to develop a model on the basis of inhibition of proteasome activity of nigral cell degeneration which is not accompanied by disturbances in motor behavior but leads to changes in sleep-wake cycle characteristic of the non-motor behaviour. We determined the optimal dose of natural inhibitor of proteasome lactacystin (0.4 mkg) and developed a preclinical model of PD in Wistar rats. We established that on the 14th day following lactacystin double (with one-week interval) bilateral injection into the substantia nigra the developing effects involved 28 % degeneration of DA-ergic neurons in the compact part of the substantia nigra, absence of disorders in motor behaviour, and increase in the total time of rapid eye movement sleep by 37 % at the second half of inactive day phase. These data and an increase in the level of key enzyme of DA synthesis tyrosine hydroxylase (TH) in survived neurons in the substantia nigra as well as the presence of the inverse correlation dependency (r = -0.8, p < 0.01) between the number of survived neurons and the level of TH inside them suggest a hypothesis that the increase in the duration of rapid eye movement sleep could be a non-motor marker of the preclinical stage of PD reflecting a reservation of compensatory potentials in the nigrostriatal system.