Oral Presentation ESA-SRB-APEG-NZSE 2022

Colocalisation of prolactin receptors on warm-sensitive neurons in the preoptic area. (#192)

Matt Gillett 1 2 , Zin Khant Aung 1 2 , Dave Grattan 1 2 3 , Sharon Ladyman 1 2 3
  1. Centre for Neuroendocrinology, University of Otago, Dunedin, Otago, New Zealand
  2. Department of Anatomy, University of Otago, Dunedin, OTAGO, New Zealand
  3. Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand

PACAP expressing neurons are found in discrete areas within the hypothalamus of the brain and have been implicated in a wide range of physiological functions such as food intake, fertility, anxiety, and thermoregulation. During pregnancy and lactation, the maternal brain undergoes many adaptations to support optimal outcomes, such as increases in food intake, infertility, suppression of anxiety and changes in body temperature.  Many of these maternal physiological changes are hypothesized to be induced by the hormonal milieu of pregnancy, particularly the increasing level of prolactin and its homologue placental lactogen. Here, we examine the colocalization of prolactin receptor (Prlr) with PACAP in the mouse hypothalamus with the aim of determining if PACAP neurons could be regulated by changing prolactin/placental lactogen during pregnancy and lactation. First, to investigate the degree of PACAP neurons that express Prlr we used a transgenic mouse line (PACAPCre/Prlrlox/lox) in which cells that express both Prlr and PACAP produce green fluorescence protein (GFP). We observed GFP in various hypothalamic nuclei, including the preoptic area (POA), ventromedial nucleus, paraventricular nucleus and the retrochiasmatic area, indicating that these nuclei have populations of neurons that co-express Prlr and PACAP. Within the POA, where high levels of Prlr and PACAP colocalization was observed, PACAP is expressed in warm-sensitive neurons (WSNs) which are involved in the regulation of body temperature. To assess Prlr expression in WSNs during pregnancy and lactation, when core temperature is more tightly regulated, we performed RNAscope in situ hybridisation for Prlr and PACAP in the POA of virgin, pregnant and lactating C57BL/6 mice. Overall, our data indicates colocation of PACAP and Prlr in a variety of neuronal populations, and hence PACAP neurons may be a key target for prolactin-induced adaptations in the maternal brain.