The Neuroendocrine brain

25.04.2026, Saturday, 12:00-13:30

Chair: Savani Anbalagan
Institute of Molecular Biology & Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland

General focus of the symposium:

In this symposium, the overall theme will be about the neuroendocrine brain with a large focus on the hypothalamus and neurohypophysis, two inter-connected and major evolutionarily conserved brain regions with multiple functions in reproduction and water balance. The speakers are chosen in such a way - that each talk will touch an important aspect of the neuroendocrine brain and using four different model organisms. The axonal oxytocin signaling in rat and human brain will be presented by Prof. Valery Grinevich (Central Institute of Mental Health, Heidelberg University, Germany), the spatial transcriptomics of mice neurohypophysis by Dr Ewelina Kałużna (Institute of Bioorganic Chemistry, PAS, Poznań), the cell signaling mechanisms underlying vascular permeability in the zebrafish neurohypophysis by Athul R Ramesh (Institute of Molecular Biology & Biotechnology, Adam Mickiewicz University, Poznań). The symposium will unite researchers using different model organisms, questions, techniques and functions. Valery and Ewelina are PhD holders, while Athul is a PhD student.

12:00 Valery Grinevich

Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Heidelberg University, Germany & International Joint Laboratory for Translational Research on Neuromodulation, Shenzhen Institutes ofAdvanced Technology, Chinese Academy of Sciences, Shenzhen, China

"Axonal Oxytocin Signaling in Rat and Human Brain"

Over the past decade, major advances have deepened our understanding of the oxytocin (OT) system, yet a central question remains: how can a single neuropeptide mediate such diverse actions in the brain? I propose that this diversity arises from distinct types of OT neurons, their widespread axonal projections, and the variety of OT-responsive cell populations across brain regions. In this talk, I will focus on axonal OT projections to the medial prefrontal cortex (mPFC) in rats, demonstrating OT action on local interneurons and its profound facilitation of social interactions. I will also present complementary findings from human stem cell-derived OT neurons, which extend axons toward cortical assembloids and, when integrated into the rat hypothalamus, form functional connections with multiple brain regions and the pituitary. Together, these results reveal conserved principles of axonal OT signaling across species, shedding light on the mechanisms underlying the peptide’s diverse functions in the mammalian brain.

12:40 Ewelina Kałużna

Department of Non-coding RNAs, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland

"Mapping the mouse pituitary gland in space: a transcriptomic view of the posterior lobe"

The pituitary gland is a central neuroendocrine interface, integrating hypothalamic inputs to regulate systemic physiology. Using spatial transcriptomics on adult mice pituitary sections, we mapped gene expression across all pituitary gland lobes. Visium (10x Genomics) platform enabled characterization of the less densely packed posterior lobe (PL). Dimensionality reduction of the transcriptomic output revealed nine spatial clusters. Further, marker gene expression analysis and cell-type deconvolution showed that cluster number 6 comprised pituicytes in about ~50% of cells, in addition to pericytes, endothelial cells, macrophages. Importantly, we detected magnocellular neuron-specific axonal transcripts in high abundance, namely Avp and Oxt-encoded mRNAs. This observation supports the hypothesis that arginine vasopressin and oxytocin are not only transported, stored and released as peptides from the pituitary, but also actively synthetized there, perhaps on demand. Overall, this dataset provides the first spatially resolved transcriptomic framework of the mouse posterior pituitary and a resource for future studies of pituitary organization and cell-cell signaling within it.

12:53 Athul R Ramesh

Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University in Poznań

"Role of glial pituicytes in regulating neurohypophyseal vascular permeability"

The blood-brain barrier (BBB) serves as a critical safeguard for the central nervous system (CNS), but it also presents a formidable obstacle to effective therapeutic drug delivery. Neurohypophysis (NH), a circumventricular organ, circumvents the BBB due to its specialized fenestrated vasculature, which allows selective molecular permeability. The molecular mechanisms that regulate vascular permeability in the NH are relatively unknown. Our research investigates the genetic and molecular pathways underlying NH vascular permeability, with the aim of identifying key regulators that could be leveraged to modulate BBB permeability. Through transcriptomic datamining, we have identified Sfrp5, a WNT regulator as a potential candidate genes and signaling pathways that may govern NH-specific vascular fenestrations and permeability. Towards this goal, we have been employing pharmacological and genetic perturbations on larval zebrafish to explore the roles of Sfrp5 and WNT signaling in the regulation of neurohypophyseal vascular permeability. Our studies are expected to reveal a novel role of Sfrp5 in the vascular development of a key neuroendocrine interface conserved in vertebrates.

13:09 John C. Oyem

UiT The Arctic University of Norway, Tromso, Norway

"Neurobiological Application of Temporal Copulatory Patterns of Female Rat Sexual Behavior"

Female rat sexual behavior is a rewarding activity essential for reproduction and species continuity. However, previous studies have been limited by relying on a set of specific parameters, leaving significant gaps in our understanding of female rats' temporal copulatory patterns. Additionally, the neural mechanisms underlying reproductive behaviors remain fully unraveled.

Our study developed a new behavioral tool for analyzing female rats' copulatory patterns. We applied this tool to enhance the interpretation of intervention studies, particularly those targeting the ventral tegmental area (VTA), a brain region implicated in reward and motivation.

We examined two groups of female rats (fully receptive vs. less receptive), that hormonally primed with estradiol benzoate (EB) alone or EB + progesterone (P) across six paced mating tests. This design allowed us to compare the effects of hormonal priming on female rats' copulatory patterns. Based on this experiment, we organized female copulatory behavior into bouts and then combined fiber photometry with a behavioral reward paradigm to investigate VTA neural responses during female rat sexual behavior.

Our findings revealed that female rats exhibit structured patterns of sexual bouts and time-outs. Fully receptive females displayed more frequent sexual bouts and shorter time-outs. Furthermore, neural activity in the VTA increased during the onset of paracopulatory behavior and at the end of the copulatory stimulation received by the female, indicating its role in regulating sexual bouts rather than time-out.

This demonstrated that copulatory patterns are organized into sexual bouts and time-outs. While sexual bouts reflect copulatory speed, time-outs indicate motivation to continue mating. Our findings further highlight the crucial role of the VTA in regulating distinct aspects of female rat sexual behavior, emphasizing the importance of detailed behavioral assessments in behavioral neuroscience research.

13:22 Aleksandra Rzeszut

Department of Molecular Neuropharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Cracow, Poland

"Second time is the charm: κ - opioid receptors control expression of social memory"

The κ-opioid receptor (KOR), activated by endogenous dynorphin peptides, is widely expressed across the brain and regulates transmitter release within areas relevant to emotional processing, thereby shaping social cognition and behavior. Previous studies have linked the dynorphin/KOR system to social memory, a core component of social cognition in group-living species. It was observed that inhibition of KOR signaling enhances partner recognition and KOR activation weakens it. However, the specific KOR-expressing neuronal populations that underlie these effects remain unknown.

We hypothesized that KOR signaling constrains social recognition by suppressing oxytocinergic or serotonergic circuits, such that loss of KOR signaling within these neuronal populations would improve social recognition and be associated with altered baseline monoamine levels.

Social memory was assessed in both sexes using a two-trial social recognition paradigm in mice with global prodynorphin deletion (Pdyn⁻/⁻) or selective KOR removal from oxytocinergic (Oprk1OxtCre) or serotonergic (Oprk1Tph2CreERT2) neurons. Neurochemical analyses were performed in male and female mice by quantifying total tissue concentrations of NA, 5-HT, DA, and their metabolites (5-HIAA, DOPAC, HVA) in the striatum and prefrontal cortex using high-performance liquid chromatography.

Consistent with previous reports, male Pdyn (-/-) mice exhibited enhanced social memory; notably, this phenotype was also observed in female Pdyn (-/-). Selective deletion of KORs from oxytocinergic neurons enhanced social memory in females but not males, whereas serotonergic KOR deletion had no impact. Additionally, female Oprk1OxtCre mice displayed increased baseline 5-HIAA/5-HT ratios in the prefrontal cortex and elevated baseline striatal NA levels.

Together, these findings demonstrate that dynorphin/KOR signaling constrains social recognition memory, and that in females, this effect is mediated through KORs on oxytocinergic neurons.

FINANCIAL SUPPORT: National Science Centre, Poland OPUS 2019/35/B/NZ7/03477