PhD Scientific Days 2022

Neurosciences I. (Poster discussion will take place in the Aula during the Coffee Break)

Examination the role of NUCB2 in the supraoptic nucleus of rats

Text of the abstract

Introduction: NUCB2 is the prohormone of nesfatin-1, an anorexigenic neuropeptide that also inhibits water intake. It is coexpressed with oxytocin (OT) and vasopressin (AVP) in the hypothalamic supraoptic nucleus (SON). Chronic osmotic challenges induce AVP and OT release, as well as morphological changes in the SON.
Aims: To examine the role of nesfatin-1 in the magnocellular cells of the SON.
Methods: For chronic osmotic challenge rats received 2% NaCl instead of tap water ad libitum. In experiment 1, pair-fed rats were also used as controls. Rats were killed after 4 days and NUCB2 mRNA in the SON was measured by RT-PCR. In experiment 2, we silenced the expression of NUCB2 bilaterally in the SON by AAV-delivered shRNA in rats 3 weeks before salt -loading. A scrambled shRNA (scr)-AAV was injected into control rats. The bodyweight as well as the daily water and food intakes of rats were measured. The animals were perfusion-fixed on day 7 of the osmotic challenge. Serial coronal sections containing the SON were immunostained for nesfatin-1, GFAP, IBA, OT and AVP. Alkaline-phosphatase reaction was used to visualize the vessels. The immunostainings were analyzed in microphotographs using the ImageJ software.
Results: Salt loaded animals consumed higher amount of fluid and their food intake was reduced compared to the tap water group. NUCB2 mRNA levels were increased in the salt loaded animals compared to pair-fed and undisturbed controls. Salt loading increased the vascularization in the SON as well as the diameter of the AVP and OT cells, while the AVP and OT immunoreactivity was reduced in the cytoplasm. Microglial cells showed and activated morphology in response to osmostic challenge and the thickness of the ventral glial limitans (VGL) was decreased. Silencing NUCB2 expression triggered similar changes to saltloading and enchanced the effect of saltloading for most of the measured parameters.
Conclusion: Based on our results, we suggest that NUCB2 plays a regulatory role in the development of adaptive responses to salt-loading.
Funding: This work was funded by NKFI K 115422. Project No. TKP2021-EGA-25 and has been implemented with support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021-EGA funding scheme.