Sex Differences in Addiction: The Effects of Cocaine Self-Administration and Abstinence on Astrocytes in the Nucleus Accumbens of Female Rats

Astrocytes are the most numerous glial cell of the brain, and are implicated in various psychiatric disorders including addiction. Previous research on male rats demonstrates cocaine-induced changes in surface area, volume, and synaptic colocalization in astrocytes of the nucleus accumbens (NAc), a reward center of the brain. However, it is unknown whether the effects of cocaine on astrocytes in male rats are also observed in females. Thus, the goal of my Honors Thesis was to test the hypothesis that prolonged abstinence following cocaine self-administration (SA) would lead to a reduction in morphometric features and synaptic colocalization of NAc astrocytes in female rats. Twenty-four female Sprague-Dawley rats underwent 10-days of long-access (6 h/day) self-administration of cocaine or saline, followed by 45 days of abstinence. Fluorescently-labelled astrocytes in the NAc were imaged and analyzed for morphological properties and synaptic colocalization. My results revealed no significant differences between saline and cocaine groups in astrocyte morphology and synaptic contact, suggesting the effects of cocaine on astrocytes in male rats do not extend to females. This study demonstrates a sex difference in the cellular effects of cocaine self-administration, and indicates that female astrocytes may display protective factors against cocaine-induced astrocyte retraction.Bachelor of Scienc

Application of optogenetic glial cells to neuron–glial communication

Optogenetic techniques combine optics and genetics to enable cell-specific targeting and precise spatiotemporal control of excitable cells, and they are increasingly being employed. One of the most significant advantages of the optogenetic approach is that it allows for the modulation of nearby cells or circuits with millisecond precision, enabling researchers to gain a better understanding of the complex nervous system. Furthermore, optogenetic neuron activation permits the regulation of information processing in the brain, including synaptic activity and transmission, and also promotes nerve structure development. However, the optimal conditions remain unclear, and further research is required to identify the types of cells that can most effectively and precisely control nerve function. Recent studies have described optogenetic glial manipulation for coordinating the reciprocal communication between neurons and glia. Optogenetically stimulated glial cells can modulate information processing in the central nervous system and provide structural support for nerve fibers in the peripheral nervous system. These advances promote the effective use of optogenetics, although further experiments are needed. This review describes the critical role of glial cells in the nervous system and reviews the optogenetic applications of several types of glial cells, as well as their significance in neuron–glia interactions. Together, it briefly discusses the therapeutic potential and feasibility of optogenetics

Arrays of MicroLEDs and Astrocytes: Biological Amplifiers to Optogenetically Modulate Neuronal Networks Reducing Light Requirement

<div><p>In the modern view of synaptic transmission, astrocytes are no longer confined to the role of merely supportive cells. Although they do not generate action potentials, they nonetheless exhibit electrical activity and can influence surrounding neurons through gliotransmitter release. In this work, we explored whether optogenetic activation of glial cells could act as an amplification mechanism to optical neural stimulation via gliotransmission to the neural network. We studied the modulation of gliotransmission by selective photo-activation of channelrhodopsin-2 (ChR2) and by means of a matrix of individually addressable super-bright microLEDs (μLEDs) with an excitation peak at 470 nm. We combined Ca²⁺ imaging techniques and concurrent patch-clamp electrophysiology to obtain subsequent glia/neural activity. First, we tested the μLEDs efficacy in stimulating ChR2-transfected astrocyte. ChR2-induced astrocytic current did not desensitize overtime, and was linearly increased and prolonged by increasing μLED irradiance in terms of intensity and surface illumination. Subsequently, ChR2 astrocytic stimulation by broad-field LED illumination with the same spectral profile, increased both glial cells and neuronal calcium transient frequency and sEPSCs suggesting that few ChR2-transfected astrocytes were able to excite surrounding not-ChR2-transfected astrocytes and neurons. Finally, by using the μLEDs array to selectively light stimulate ChR2 positive astrocytes we were able to increase the synaptic activity of single neurons surrounding it. In conclusion, ChR2-transfected astrocytes and μLEDs system were shown to be an amplifier of synaptic activity in mixed corticalneuronal and glial cells culture.</p></div