Immunocytochemical Analysis of Calretinin in the Frontal Cortex of Chinchilla

Abstract

The aim of the study was to define morphology and distribution of calretinin (CR) positive neurons in the frontal cortex of adult chinchilla males and intracellular localisation of the protein in this area. The brains of 5 adult chinchilla males were used in the study. CR immunoreactive neurons were shown with peroxidase-antiperoxidase immunohistochemical reaction using a specific monoclonal antibody. Intensive CR immunoreactivity was demonstrated mainly in few polymorphic neurons of II, III, and V layers. Cytoplasmic and nuclear reaction product in most CR positive neurons was diffuse and in some neurons of layer V in the form of granules localised peripherally. In a few cells more intensive staining was observed in the nuclei than in the cytoplasm. The results indicate the presence of heteromorphic CR positive neurons in specific layers of the frontal cortex. Nuclear localisation of CR in neurons suggests passive transport of this protein, which may affect the nuclear genes. This protein is a neuroprotector maintaining appropriate level of calcium, modulating neuronal activity, and synaptic conduction in the frontal cortex of chinchilla.

Most calbindin‐immunoreactive neurons, but few calretinin‐immunoreactive neurons, express the m1 acetylcholine receptor in the middle temporal visual area of the macaque monkey

“…Calcium‐binding proteins can be expressed in the cell nucleus (Bachs & Carafoli, ; Gilchrist & Pierce, ; Nash, Opas, & Michalak, ). CR expression, specifically, has been reported in the nucleus of neurons in the frontal cortex of the chinchilla (Krawczyk, Szalak, & Jaworska‐Adamu, ). The nuclear immunoreactivity is thought to be due to the low molecular weight variant of CR (29 kDa), which (due to its smaller size) can be passively transported through the nuclear pores where it may alter gene expression (Schwaller, Durussel, Jermann, Herrmann, & Cox, ).…”

Most calbindin-immunoreactive neurons, but few calretinin-immunoreative neurons, express the m1 acetylcholine receptor in the middle temporal visual area of the macaque monkey

“…Calcium-binding proteins can be expressed in the cell nucleus (Bachs and Carafoli, 1987;Gilchrist and Pierce, 1993;Nash et al, 1994). CR expression, specifically, has been reported in the nucleus of neurons in the frontal cortex of the chinchilla (Krawczyk et al, 2012). The nuclear immunoreactivity is thought to be due to the low molecular weight variant of CR (29 kDa), which (due to its smaller size) can be passively transported through the nuclear pores where it may alter gene expression (Schwaller et al, 1997).…”

Cortical interneurons in schizophrenia – cause or effect?

“…Furthermore, CR + neurons are relatively unaltered in most other neuropsychiatric or neurodegenerative disorders, such as Alzheimer’s disease and depression ( 91 ). CR is a calcium-binding protein that protects neurons from calcium cytotoxicity, and this neuroprotective role might provide CR + neurons with a unique resistance to various noxae ( 92 ). Nevertheless, this would still not explain why other neuron populations expressing different types of calcium-binding protein, particularly PV, are significantly affected in schizophrenia and other disorders.…”