Perusing structural variations in neurons of Substantia Nigra of normal vs addicted subjects: A morpho-histological comparison

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Introduction. Substantia Nigra, or the “Black Substance”, is a part of the basal ganglia (also called basal nuclei) that is located in the midbrain. Substantia Nigra is divided into 2 parts namely, medially located Pars Compacta and laterally present Pars Reticulata. Pars Compacta is seen as dark coloured region with high neuronal density having pigment melanin. Melanin has been known to increase in concentration in the dopaminergic neurons with age indicating it`s protective function by chelating metals. Pars Reticulata is less densely packed with neurons and have higher concentration of lipofuscin inclusions. Lipofuscin is yellow-brown inclusion, seen in the form of granules and is composed of lipid residues from lysosomal digestion. Studies suggest that lipofuscin inclusion are cellular marker for ageing. Nissl bodies are also seen in neurons which represents rough endoplasmic reticulum (RER). Nissl bodies synthesize proteins for intracellular use and cellular signalling.

Aim. To visualize Substantia Nigra in normal and addicted subjects using light microscope and scanning electron microscope (SEM) to account for histological and morphological variations along with assessing its clinical implications in both groups.

Materials and Methods. 20 brain tissue samples with a history of alcohol use and drug abuse were studied and compared with 13 control cases in this study. 10 visual fields were assessed in each histological slide using light microscope (40×). Both Pars Compacta and Pars Reticulata were visualized for Nissl substance, melanin/lipofuscin inclusions and overall count of neurons in both groups. The results were tabulated and analysed using Ms Excel and SPSS program v.23.0 .

Results. In Pars Compacta, 1813 neurons were analyzed in the control group and 81.5% of them demonstrated melanin inclusions. Nissl granules were seen in over 1590 (88%) neurons in both compact (48%) and diffuse (52%) arrangement. Among Nissl bodies, diffused arrangement remained dominant form but closely followed by the compact form. When compared with the addicted group, 1331 neurons were analysed with only about 79% of them having melanin inclusions and only 75% showing Nissl bodies. The diffuse (46%) arrangement was less prominent than the compact one (54%) in this group. Identical results were obtained for Pars Reticulata when compared between both groups.

Conclusions. Lower number of neurons in Pars Compacta and Pars Reticulata of Substantia Nigra of addicted population shows the possible effects of drug abuse and alcoholism on the cellular level. Lower density of Nissl bodies and lipofuscin/melanin granules also indicate progressive loss of function and normal working of these neurons. This may have direct implications on individual behavior due to neuronal imbalance.
Original languageEnglish
Number of pages2
Publication statusPublished - 9 May 2019
EventXXIV Student International Conference of Morphology Sciences - Institute of Anatomy and Anthropology, Riga Stradins University, Riga, Latvia
Duration: 9 May 20199 May 2019
Conference number: 24


ConferenceXXIV Student International Conference of Morphology Sciences
Internet address

Field of Science*

  • 3.1 Basic medicine

Publication Type*

  • 3.4. Other publications in conference proceedings (including local)


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