Investigation of cell-specific projections of neurons in Posterior intralaminar thalamus related to maternal behaviour
01/30/2020
Szilvia Oláh1, Bence Haller1, Vivien Csikós1, Erzsébet Oszwald2, Gina Puska1, 3, Péter Lőw3, Árpád Dobolyi1
1 MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Hungarian Academy of Sciences and Eötvös Loránd University, Budapest
2 Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest
3 Department of Anatomy, Cell and Developmental Biology, Institute of Biology, Eötvös Loránd University, Budapest
The Posterior intralaminar thalamic nucleus (PIL) was suggested to relay somatosensory information on suckling to the forebrain. Tuberoinfundibular peptide 39 (TIP39)-expressing neurons in the PIL were activated in response to suckling based on Fos experiments. In addition, the distribution of Fos-expressing neurons overlap with the distribution of TIP39-positive fibres in the medial preoptic area. The objective of the present study was to identify the targets and functions of TIP39 neurons in the PIL. TIP39 neurons all express calbindin in the PIL. Therefore, we injected an adeno-associated virus (AAV) into the PIL of Calbindin-Cre mice to transfer Cre-dependent expression of designer receptors exclusively activated by designer drugs (DREADDs) for behavioural studies and a fluorescent protein for tract tracing of TIP39/calbindin neurons. Anterogradely labelled fibres were observed in a variety of different limbic and hypothalamic regions, including around dopaminergic cells in the medial preoptic area. Using double immunolabelling coupled with electron microscopy, we demonstrated that TIP39 terminals indeed synapse on cell bodies of dopaminergic neurons. In conclusion, TIP39 neurons in the PIL are activated in response to suckling and they have a relatively wide projection profile to limbic and hypothalamic brain areas. The targets of TIP39 neurons include the dopaminergic neurons in the medial preoptic area, which are known to be involved in the control of maternal behaviours. The work was supported by the Hungarian National Research, Development and Innovation Office NKFIH-4300-1/2017-NKP_17 and OTKA K116538 research grants