DOI: 10.5061/dryad.h9w0vt4tb
title: Exploring the effects of adolescent social isolation stress on the serotonin system and ethanol-motivated behaviors

description: Rationale: Alcohol is one of the most frequently used drugs of abuse and
 has a major impact on human health worldwide. People assigned female at
 birth and those with adverse childhood experiences are stress-vulnerable
 and more likely to report drinking as a means of “self-medication.” Prior
 studies in our laboratory showed that adolescent social isolation stress
 (SIS) increases vulnerability to ethanol (EtOH) intake and consumption
 despite negative consequences in female rats. Objectives: Here, we
 explored modulation of the dorsal raphe nucleus (DRN)-serotonin (5-HT)
 system, a sexually dimorphic neurotransmitter system involved in
 stress-reward interactions, to determine its contribution to
 EtOH-motivated behaviors in rats that have undergone SIS. Results: We
 employed electrophysiological and functional neuroanatomy strategies to
 show that both SIS and EtOH exposure induce persistent hypofunction of the
 DRN 5-HT system, particularly in females. Chemogenetic activation of DRN
 5-HT neurons attenuated reward value for both EtOH and sucrose and
 elevated punished responding for EtOH in a stress-dependent manner.
 Conclusions: Our results highlight an inverse relationship between EtOH
 consumption and the 5-HT system, the sex- and stress-dependent nature of
 this relationship, and a connection between DRN 5-HT signaling and acute
 responding to rewards and punishment. These data support the DRN 5-HT
 system as a potential target to treat aberrant alcohol consumption and
 drinking despite negative consequences in stress-vulnerable populations.
description: # Exploring the Effects of Adolescent Social Isolation Stress on the
 Serotonin System and Ethanol-Motivated Behaviors
 [https://doi.org/10.5061/dryad.h9w0vt4tb](https://doi.org/10.5061/dryad.h9w0vt4tb) ## Description of the data and file structure Figure 1 panels c-e contain ex vivo brain slice electrophysiology data (number of action potentials that are elicited by a range of current pulses (0-160 pA)) showing excitability in 5-HT dorsal raphe nucleus neurons across experimental groups: group housed (GH) males, social isolation stress (SIS) males, GH females and SIS females. The number of cells in each experimental group ranges from 6 to 8. Brain slices are all from ethanol naive subjects. Missing cells due to unequal numbers of animals or cells in different experimental groups are indicated by an ‘x’. Figure 2 panels b-c contain ex vivo brain slice electrophysiology data (number of action potentials that are elicited by a range of current pulses (0-160 pA)) showing excitability in 5-HT dorsal raphe nucleus neurons across experimental groups (panel b: ethanol (EtOH)-exposed group housed (GH) females and EtOH-exposed social isolation stress (SIS) females; panel c: lower EtOH drinking and higher EtOH drinking females). The number of cells in each experimental group is 5 in panel b and ranges from 4 to 6 in panel c. Panel d correlates ethanol intake (g/kg) with neuronal excitability from the subjects shown in panel c. Missing cells due to unequal numbers of animals or cells in different experimental groups are indicated by an ‘x’. Figure 3 panel b shows ethanol intake (average number of reinforcers earned) at different ethanol concentrations (10-50%) for 5 group housed (GH) females; panels c-d show effects of chemogenetically activating 5-HT dorsal raphe neuronal activity with the drug clozapine-N-oxide (CNO) on intake (reinforcers earned) of 20% EtOH (panel c) and 50% EtOH (panel d) in 4 GH females; panel e shows effects of of chemogenetically activating 5-HT dorsal raphe neuronal activity with the drug CNO on intake (reinforcers earned) of 20% sucrose in 4 GH females. Missing cells due to unequal numbers of animals or cells in different experimental groups are indicated by an ‘x’. Figure 4 panels b-c show effects of chemogenetically activating 5-HT dorsal raphe neuronal activity with the drug clozapine-N-oxide (CNO) on ethanol intake consumed despite footshock punishment, a model of compulsive consumption of ethanol. Panel b shows average punishment resistance scores (punished ethanol intake divided by unpunished ethanol intake) across three days. Panel c shows punishement resistance scores for each of the three days of punished responding. Experimental groups are either group housed (GH) or social isolation stress (SIS) female rats exposed to vehicle (no chemogenetic activation) or CNO (chemogenetic activation) and the animal numbers range from 3 to 7. Missing cells due to unequal numbers of animals or cells in different experimental groups are indicated by an ‘x’. Supplemental figure 1 panels a-c compares select membrane characteristics from electrophysiological recordings of 5-HT dorsal raphe nucleus neurons across experimental groups: group housed (GH) males, social isolation stress (SIS) males, GH females and SIS females. Panels a-b shows the action potential (AP) firing threshold (panel a) and the difference between AP threshold and the resing membrane potential (RMP) (panel b) in ethanol-naive subjects. Panel c shows the latency (ms) to AP threshold in high ethanol intake vs low ethanol intake subjects. Each data point in the figure represents an individual subject. Missing cells due to unequal numbers of animals or cells in different experimental groups are indicated by an ‘x’. ## Code/software Microsoft Excel is needed to access these data.