Biology subjects

Wood, S. K.

Publications and source records attributed to Wood, S. K..

4 recordsLinked to original sources

bioRxiv2022

Matrix Metalloproteinase Activity During Methamphetamine Cued Relapse

Relapse to drug seeking involves transient synaptic remodeling that occurs in response to drug associated cues. This remodeling includes activation of matrix metalloproteinases (MMPs) to initiate catalytic signaling in the extracellular matrix (ECM) in the nucleus accumbens core (NAcore). We hypothesized that MMP activity would be increased in the NAcore during cue-induced methamphetamine (meth) seeking in a rat model of meth use and relapse. Male and female rats had indwelling jugular catheters and bilateral intracranial cannula targeting the NAcore surgically implanted. Following recovery, rats underwent meth or saline self-administration (6hr/day for 15 days) in which active lever responding was paired with a light+tone stimulus complex, followed by home cage abstinence. Testing occurred after 7 or 30 days of abstinence. On test day, rats were microinjected with a FITC-quenched gelatin substrate that fluoresces following cleavage by MMPs, allowing for the quantification of gelatinase activity by MMP-2 and -9 during cued relapse testing. MMP-2,9 activity was significantly increased in the NAcore by meth cues presentation after 7 and 30 days of abstinence, indicating that remodeling by MMPs occurs during presentation of meth associated cues. Surprisingly, while cue-induced seeking increased between days 7 and 30, suggesting behavioral incubation, MMP-2,9 activity did not increase. These findings indicate that while MMP activation is elicited during meth cue-induced seeking, MMP activation did not parallel the behavioral incubation that occurs during extended drug abstinence.

neuroscience↗

bioRxiv2022

Site-Specific Knockdown of Microglia in the Locus Coeruleus Regulates Hypervigilant Responses to Social Stress in Female Rats

BackgroundWomen are at increased risk for psychosocial stress-related anxiety disorders, yet mechanisms regulating this risk are unknown. Psychosocial stressors activate microglia, and the resulting neuroimmune responses that females exhibit heightened sensitivity to may serve as an etiological factor in their elevated risk. However, studies examining the role of microglia during stress in females are lacking. MethodsMicroglia were manipulated in the stress-sensitive locus coeruleus (LC) of female rats in the context of social stress in two ways. First, intra-LC lipopolysaccharide (LPS; 0 or 3g/side, n=5-6/group), a potent TLR4 agonist and microglial activator, was administered. One hour later, rats were exposed to control or an aggressive social defeat encounter between two males (WS, 15-min). In a separate study, females were treated with intra-LC or intra-central amygdala mannosylated liposomes containing clodronate (m-CLD; 0 or 25g/side, n=13-14/group), a compound toxic to microglia. WS-evoked burying, cardiovascular responses, and sucrose preference were measured. Brain and plasma cytokines were quantified, and cardiovascular telemetry assessed autonomic balance. ResultsIntra-LC LPS augmented the WS-induced burying response and increased plasma corticosterone and interleukin-1{beta} (IL-1{beta}). Further, the efficacy and selectivity of microinjected m-CLD was determined. In the context of WS, intra-LC m-CLD attenuated the hypervigilant burying response during WS as well as the accumulation of intra-LC IL-1{beta}. Intra-central amygdala m-CLD had no effect on witness stress-evoked behavior. ConclusionsThese studies highlight an innovative method for depleting microglia in a brain region specific manner and indicate that microglia in the LC differentially regulate hypervigilant WS-evoked behavioral and autonomic responses. HIGHLIGHTSO_LIIntra-LC LPS augments behavioral and physiological responses to social stress C_LIO_LIMannosylated liposomal clodronate site-specifically reduces microglial expression C_LIO_LIMicroglia within the locus coeruleus regulate stress-evoked behavior in female rats C_LI

neuroscience↗

bioRxiv2022

Estrogen receptor beta in the central amygdala regulates the deleterious behavioral and neuronal consequences of repeated social stress in female rats

While over 95% of the population has reported experiencing extreme stress or trauma, females of reproductive age develop stress-induced neuropsychiatric disorders at twice the rate of males. This suggests that estrogen may facilitate neural processes that increase stress susceptibility and underlie the heightened rates of these disorders, like depression and anxiety, that result from stress exposure in females. However, there is contradicting evidence in the literature regarding estrogens role in stress-related behavioral outcomes. Estrogen signaling through estrogen receptor beta (ER{beta}) has been traditionally thought of as anxiolytic, but recent studies suggest estrogen exhibits distinct effects in the context of stress. Furthermore, ER{beta} is found abundantly in many stress-sensitive brain loci, including the central amygdala (CeA), in which transcription of the vital stress hormone, corticotropin releasing factor (CRF), can be regulated by an estrogen response element. Therefore, these experiments sought to identify the role of CeA ER{beta} activity during stress on behavioral outcomes in naturally cycling, adult, female Sprague-Dawley rats. Rats were exposed to an ethological model of vicarious social stress, witness stress (WS), in which they experienced the sensory and psychological aspects of an aggressive social defeat encounter between two males. Following stress, rats exhibited stress-induced anxiety-like behaviors in the marble burying task, and, finally, brain analysis revealed increased ER{beta} and CRF specifically within the CeA following exposure to stress cues. Subsequent experiments were designed to target this receptor in the CeA using microinjections of the ER{beta} antagonist, PHTPP, prior to each stress session. Sucrose preference, acoustic startle, and marble burying tasks determined that blocking ER{beta} in the CeA during WS prevented the development of depressive-,anxiety-like, and hypervigilant behaviors. Additionally, brain analysis revealed a long-term decrease of intra-CeA CRF expression in PHTPP-treated WS rats compared to vehicle. These experiments indicate that ER{beta} signaling in the CeA, through its effects on CRF, contribute to the development of negative valence behaviors that result from exposure to repeated social stress in female rats.

neuroscience↗

bioRxiv2022

Neuronal, Affective, and Sensory Correlates of Targeted Helping Behavior in Male and Female Sprague Dawley Rats

Empathy is an innate ability to understand the emotional states of others along with the motivation to improve it. It has evolved over time into highly complex behaviors, the basis of which can be described using the Perception Action Model (PAM), where shared affect promotes an action that eliminates the distress of both the passive "Target" and, by extension, the active "Observer." There are myriad biological variables that may modulate empathic behavior, including sex, sensory modalities, and neural activity. In the following studies, using our labs model of social contact-independent targeted helping, we first tested whether sex differences exist in helping behavior. Next, we explored sex differences in sensory and affective signaling, including the impact of direct visualization of a distressed conspecific and the type of ultrasonic vocalizations (USV) made between animal pairs during the task. Finally, we examined the neural activity of multiple cortical and subcortical regions of interest across time during targeted helping between males and females. We show both sexes exhibit similar helping behavior, but sensory and affective signaling differs between sexes. Further, changes in neural activity exhibited distinct sex-specific patterns across time. Our results indicate sex differences are not a ubiquitous presence in targeted helping. Instead, it is likely sex differences may be a convergent phenomenon in which the behavior is similar, but the underlying biological mechanisms are distinct. These results lay the groundwork for future studies to explore the similarities and differences that drive empathic behavior in both males and females.

animal behavior and cognition↗