NEURONS IN THE RAT OLFACTORY NEUROGENIC AREA: A MORPHOLOGICAL STUDY

Postnatal neurogenesis in the subventricular zone (SVZ) and the rostral migratory stream (RMS) is regulated by mechanisms that remain insufficiently understood. Accumulating evidence indicates that neurogenesis within the SVZ/RMS could by regulated by neurons residing in these neurogenic niches. In the adult rat RMS, two morphologically and biochemically distinct populations of mature neurons have been identified: nitric oxide (NO) - producing neurons and neurons expressing secretagogin (SCGN). The aim of our work was to obtain new morphological data about these two neuronal populations in the olfactory neurogenic region of adult rats. We focused on the identification of NO- and SCGN-producing neurons in the SVZ and analyzed the distribution and the number of these cell types in individual parts of the RMS (vertical arm, elbow, and horizontal arm). Double immunofluorescence labeling for neuronal nitric oxide synthase (nNOS) and SCGN confirmed the presence of nNOS+ and SCGN+ neurons in the SVZ/RMS, each exhibiting distinct morphological features and distribution patterns. Quantitative analysis revealed a significantly higher number of SCGN+ neurons than NO+ neurons was observed in the SVZ as well as in all three anatomical parts of the RMS. Immunofluorescent labeling of nitrergic and SCGN-producing cells with the neuronal marker NeuN confirmed the neuronal identity of both cell types in the SVZ/RMS. In addition to SCGN⁺/NeuN⁺ and NO⁺/NeuN⁺ cells, NeuN-positive cells lacking SCGN and NO immunoreactivity were observed in the SVZ/RMS, suggesting the presence of additional neuronal population(s) in these regions of the adult rat.

Supported by APVV-23-0274 a VEGA 2/0101/25