EVALUATION OF VARIATION OF PRE-PRO-HORMONE MELANIN- CONCENTRATING AND NEUROGENESIS mRNA IN MEDIAL PRE-OPTIC AND LATERAL HYPOTHALAMIC AREAS OF LACTATING RATS IN RELATION TO CORTICOSTERONE LEVELS

• Grant number: 22/14595-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2023
• End date: December 31, 2023
• Field of knowledge: Biological Sciences - Morphology - Cytology and Cell Biology
• Principal Investigator: Jackson Cioni Bittencourt
• Grantee: Camila de Carvalho
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 16/02224-1 - The existence of neurogenesis during the lactation period, AP.TEM

Abstract

Introduction: The melanin-concentrating hormone (MCH) is responsible for various motivated behaviors, including maternal behavior. In rats, there is a gradual increase in the number of MCH-immunoreactive neurons (MCH-ir) in the medial preoptic area (MPOA) during lactation. Although the role of MCH in relation to maternal behavior is not fully understood, the emergence of MCH-ir neurons only during this phase in females suggests that it is involved in neurogenesis/neuroplasticity phenomena. Nevertheless, during the postpartum period, the suppressive effects of corticosterone are widely discussed in the literature.Objectives: We aim to study the effects of changes in glucocorticoid levels on MPOA and lateral hypothalamic area (LHA) of cells that express ppMCH mRNA.Materials and Methods: We will use 48 Long-Evans rats (n = 48), 30 females and 18 males. The rats will be mated by the harem method. Primiparous lactating rats will be used to form the following experimental groups: negative control (C-), without manipulation; positive control group (C+), treated with saline injection (0.9% saline solution); Metyrapone (MET) group, treated with metyrapone; Dexamethasone group (DEX), treated with dexamethasone; group formed with nulliparous rats (no manipulation) and a group formed with male (no manipulation) (n = 6 per group). Brain and micropunch collection following stereotaxic coordinates will be performed on postpartum day (PPD) 19. The material collected is immediately immersed in RNA later, forming pools of 2 animals per sample. Then, the material will be submitted to RT-qPCR to quantify gene expression (messenger RNA referring to the genes of interest - ppMCH, CRH, CRHR1, DCX...). The brain sections from which the micropunch will be extracted and fixed then submitted to immunohistochemistry for MCH and Nissl staining to certify the micropunch collection region.Contributions: Our study aims to grasp the neuroplastic/neurogenic phenomena in the hypothalamus during lactation and their relationship with the MCH in the proposed experimental model of alteration of the hypothalamic-pituitary-adrenal axis.