APVV-15-0388

Principal Investigator: Ľubica Lacinová

Duration: July 2016 – June 2020
Coordinating Organization: Centre of Biosciences – Institute of Molecular Physiology and Genetics SAS, Bratislava

Annotation:

Ligands of opioid receptors δ (DOR) and μ opioid receptors (MOR) are commonly used in treatment of severe acute and chronic pain. DORs are involved also in mood disorders like depression and anxiety, which are related to the hippocampal function. Treatment with DOR ligands does not result in adverse effects including addiction, which are common with MOR ligands. However, much less is known about DOR – activated signaling pathways than about MOR – activated pathways. We will analyze the effect of acute (seconds to minutes) and chronic (hours to days) in in vitro and in vivo (prenatal and postnatal) administration of DOR ligands on the morphological and electrophysiological properties of rat hippocampal neurons and compare them with effects of MOR ligands and with effects of ligands specific for MOR-DOR heteromers. Further, involvement of calcium transporting proteins in signal transduction pathways activated by DORs and MORs ligands will be addressed by molecular biology methods. Possible remodeling of the dendritic spines will be investigated using transmission electron microscopy. Effect of DOR ligands on hippocampal plasticity in control and stressed rats will be examined using behavioral tests and molecular neuroscience techniques. Excitability will be investigated in primary culture of hippocampal neurons by patch clamp and in situ by in vivo electrophysiology. Both models enable to follow effects of acute and chronic drug application as well as possible receptor desensitization and offer complementary advantages. Primary neuronal culture is the possibility to visually identify neurons, characterize in details both action potentials and underlying ionic currents and to correlate electrophysiology and molecular biology on the same batch of neurons. In vivo electrophysiology offers the possibility to measure neuronal activity within its normal environment including all interactions with other brain parts. Finalz, behavioral studies enable investigation of an intact animal.

Keywords:

μ and δ opioid receptors, hippocampal excitability, voltage-dependent ion channels, transport proteins, patch clamp, in vivo electrophysiology, hippocampal plasticity, stress, depression, aldosterone, dendritic spines, electron microscopy

Objectives:

We will investigate effects of acute and chronic in vitro and in vivo (prenatal and postnatal) administration of μ and δ opioid receptor ligands on the morphology and excitability of hippocampal neurons and on hippocampal plasticity in control and stressed rats. In primary culture of neonatal rat hippocampal neurons we will analyze: i) changes in both depolarization-evoked and spontaneous generation of action potentials; ii) underlying alterations of voltage-dependent ion channel activity; iii) altered expression of transport proteins; iv) remodeling of dendritic spines. In intact brain of anesthetized animal we will analyze changes in action potential firing of single hippocampal neuron in its natural environment with preserved interaction networks. Further, we will examine the effect of δ opioid receptor ligands on the hippocampal plasticity in control, stressed, and aldosterone-administered arts (a rat model of depression), using the specific neurochemical markers and behavioral tests.

Publications: