Characterisation and origins of melanin-concentrating hormone immunoreactive fibres of the posterior lobe of the pituitary and median eminence during lactation in the Long-Evans rat

Author(s)

Costa, Helder C. ^[1] ; Da-Silva, Joelcimar M. ^[1] ; Diniz, Giovanne B. ^[1] ; Motta-Teixeira, Livia C. ^{[2, 1]} ; Da-Silva, Renata J. ^[1] ; Battagello, Daniella S. ^{[3, 1]} ; Sita, V, Luciane ; Machado, Carla de-Moraes ^[4] ; Horta-Junior, Jose A. C. ^{[4, 5]} ; Bittencourt, Jackson C. ^{[3, 6]}

Affiliation

^[1] Univ Sao Paulo, Inst Biomed Sci, Dept Anat, Lab Chem Neuroanat, BR-05508000 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, Sao Paulo - Brazil

^[3] Univ Sao Paulo, Ctr Neurosci & Behav, Inst Psychol, Sao Paulo - Brazil

^[4] Sao Paulo State Univ UNESP, Inst Biosci, Dept Anat, Botucatu, SP - Brazil

^[5] Sao Paulo State Univ UNESP, Electron Microscopy Ctr, Inst Biosci, Botucatu, SP - Brazil

^[6] Sita, Luciane, V, Univ Sao Paulo, Inst Biomed Sci, Dept Anat, Lab Chem Neuroanat, BR-05508000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: Journal of Neuroendocrinology; v. 31, n. 9, SI SEP 2019.
• Web of Science Citations: 3

Abstract

Although the melanin-concentrating hormone (MCH) and its coding mRNA are predominantly found in the tuberal hypothalamus, there is detectable synthesis of MCH in the preoptic hypothalamus exclusively in lactating dams, suggesting a participation of MCH in the alterations that take place after parturition. Also implicated in the dam physiology is oxytocin, a neurohormone released from the posterior pituitary that is necessary for milk ejection. Because the projection fields from oxytocin-immunoreactive (-IR) neurones and the mediobasal preoptic hypothalamus overlap and MCH-IR neurones are found in proximity to oxytocin neurones, we investigated the spatial relationship between MCH and oxytocin fibres. Accordingly, we employed multiple immunohistochemistry labelling for MCH and oxytocin for light and electron microscopy techniques, in addition to i.v. tracer injection combined with in situ hybridisation to identify MCH neurones that project to neurosecretory areas. As described for other strains, lactating Long-Evans dams also display immunoreactivity for MCH in the preoptic hypothalamus on days 12 and 19 of lactation. The appearance of these neurones is contemporaneous with an increase in MCH-IR fibres in both the internal layer of the median eminence and the posterior pituitary. In both regions, MCH- and oxytocin-IR fibres were found in great proximity, although there was no evidence for synaptic interaction between these two populations at the ultrastructural level. The tracer injection revealed that only mediobasal preoptic MCH neurones project to the posterior pituitary, suggesting a neuroendocrine-modulatory role for this population. When taken together, the results obtained in the present study indicate that neuroplasticity events at the mediobasal preoptic hypothalamus that occur during late lactation may be part of a neuroendocrinology control loop involving both MCH and oxytocin. (AU)

• FAPESP's process: 16/02224-1 - The existence of neurogenesis during the lactation period
• Grantee: Jackson Cioni Bittencourt
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/02748-0 - Study of the anatomical basis for a volume transmission mechanism on the Melanin Concentrating Hormone [MCH] peptidergic system
• Grantee: Giovanne Baroni Diniz
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 13/08618-3 - Melanin-Concentrating Hormone (MCH ) Expression in the Lateral Hypothalamic Area of the Rat During the Postnatal Development and Aging
• Grantee: Carla de Moraes Machado
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 14/22313-3 - Influence of the absence of maternal melatonin during pregnancy and lactation on neurogenesis and on somatic and sensorimotor development of the offspring.
• Grantee: Lívia Clemente Motta Teixeira
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 08/02771-6 - Connectivity, neurochemistry and behavioural evaluation of afferents to the first nucleus of the acoustic startle reflex neural circuit: the cochlear root nucleus
• Grantee: José de Anchieta de Castro e Horta Júnior
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 16/18941-4 - Effects of maternal melatonin deprivation during pregnancy and lactation on the offspring neuroimmune system
• Grantee: Lívia Clemente Motta Teixeira
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 09/06769-9 - Distribution of urocortin 3 (UCN 3) in the central nervous system of primate (Cebus apella)
• Grantee: Daniella Sabino Battagello
• Support Opportunities: Scholarships in Brazil - Master