Selective specificity of calcium-binding proteins calbindin and calretinin expression in the magnocellular neurosecretory hypothalamic nuclei of tortoises and turtles.

We have studied the distribution of calcium-binding proteins in the magnocellular neurosecretory nuclei of nonapeptidergic neurosecretory nuclei of the preoptic-hypothalamic complex in a tortoise (Testudo horsfieldi) and a pond turtle (Emys orbicularis) using immunohistochemistry. We have found that different types of cells in the paraventricular and supraoptic nuclei predominantly express calbindin and, to a lesser extent, calretinin, but not parvalbumin. The selective calbindin/calretinin control of the neurohormone secretion in these hypothalamic nuclei is an evolutionary conservative feature typical of reptiles and mammals.

Distribution of calcium-binding proteins, parvalbumin and calbindin, in the midbrain auditory center (MLd) of a pigeon.

Immunohistochemical distribution of calcium-binding proteins, parvalbumin (PV) and calbindin (CB), has been studied in the mesencephalic auditory center (MLd) of pigeon (Columba livia). In the central region of the MLd (core, ICC), an overlap in distribution of the PVand CB-immunopositive (ip) neurons and neuropil has been observed, with different patterns in the central and peripheral parts. In the peripheral region of the MLd (belt, ICS, and ICX), both neurons and neuropil contained only CB.

[NEURONS IN VISUAL THALAMIC CENTERS OF TURTLES, PROJECTING UPON THE TELENCEPHALON, EXPRESS DIFFERENT TYPES OF CALCIUM-BINDING PROTEINS: COMBINED IMMUNOHISTOCHEMICAL AND TRACER STUDY].

In turtles (Testudo horsfieldi, Emys orbicularis) the immunoreactivity for calbindin (CB), parvalbumin (PV), calretinin (CR), and colocalization of PV and CB in neurons of visual thalamic nuclei (Rot, GLD) projecting to the telencephalon were studied using combined immunohistochemical and tracer method. The predominance of CB-ir neurons in Rot, CB-ir and CR-ir neurons in GLD and a lower amount of PV-ir neurons in both nuclei were shown. With double labeling fluoroimmunohistochemistry technique the colocalization of PV with CB was revealed in the majority of PV-ir neurons and in a fewer number of CB-ir neurons within both nuclei.

Distribution of calcium-binding proteins in the pigeon visual thalamic centers and related pretectal and mesencephalic nuclei. Phylogenetic and functional determinants.

Multichannel processing of environmental information constitutes a fundamental basis of functioning of sensory systems in the vertebrate brain. Two distinct parallel visual systems - the tectofugal and thalamofugal exist in all amniotes. The vertebrate central nervous system contains high concentrations of intracellular calcium-binding proteins (CaBPrs) and each of them has a restricted expression pattern in different brain regions and specific neuronal subpopulations.

[Turtle isthmic complex of visual nuclei: immunohistochemical study of gamma-aminobutyric acid, choline acetyltransferase, calcium-binding proteins and cytochrome oxidase activity].

The distribution of the immunoreactivity for gamma-aminobutyric acid (GABA), choline acetyltransferase (ChAT), calcium-binding proteins (CaBPr) and histochemistry of cytochrome oxidase activity (CO) was studied in turtles (Testudo horsfieldi, Emys orbicularis) isthmal complex of visual nuclei. Magnocellular nucleus (IMc) was shown to reveal mainly the strongly stained GABA-, parvalbumin (PV)-ir neurons and CO-positive cells, as well as variable both in number and degree of intensity of ChAT-, cal- bindin (CB)-, and calretinin (CR)-ir cells. After the local tracer injection into the optic tectum GABA-ir neurons containing also retrograde label were found in IMc.