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Sex chromosome complement and mechanisms of escalating ethanol intake in adolescence
PI: J. David Jentsch (jjentsch@binghamton.edu)

It is increasingly appreciated that multiple biological, psychological and sociocultural factors contribute to sex differences in alcohol consumption and associated health consequences in humans. The three main sex biasing biological factors, including sex chromosome complement and organizational and activational effects of gonadal hormones, can independently and interactively influence behavior, including ethanol consumption and preference. In work using the four core genotypes mice, in which sex chromosome complement and gonadal type segregate independently, we found that these two factors interact on ethanol intake during a limited access period when assessed in early adolescence. In this renewal period, we seek to test the hypothesis that sex chromosome complement affects the escalation of ethanol consumption that occurs across a chronic adolescent intermittent access period in a manner that depends upon the gonadal milieu. Additionally, we will assess the contributions of sex differences in ethanol pharmacokinetics and pharmacodynamics in these effects. Based upon recent work from our group demonstrating sexually dimorphic consequences of adolescent intermittent ethanol exposure on nucleus accumbens dopamine release, we will additionally examine how adolescent ethanol drinking affects this neurotransmitter system, and whether dysregulation of extrahypothalamic oxytocin release contributes to these observed effects. Finally, we will measure the impact of adolescent ethanol drinking on expression of X-chromosome genes that escape inactivation and that may causally contribute to sex chromosome complement effects on ethanol responsiveness. By conducting this integrated set of behavioral, neurochemical and genetic studies, we will develop a more comprehensive understanding of the mechanisms by which the major sex biasing biological factors regulate escalated ethanol drinking during adolescence and its consequences for brain and behavior.

Main Project 2

Sex-specific effects in the acceleration of pathological aging and dementia following AIE
PI: Lisa Savage (lsavage@binghamton.edu)

Excessive alcohol use can increase the risk of alcohol-related brain damage and cognitive decline, including an increased risk for the development of dementia. Converging data from human studies and preclinical animal models have revealed that extreme alcohol binge drinking/exposure during adolescence is associated with long-term changes in brain structure and connectivity. Persistent brain damage after adolescent intermittent ethanol exposure (AIE) in rodents, a model of binge drinking, entails reduced hippocampal neurogenesis, suppression of the cholinergic neuronal phenotype, and alterations in the ratio between pro and mature neurotrophins. This brain profile is also seen in patients with Alzheimer’s Disease and Related Dementias (ADRD), as well as in preclinical models of such disorders. Subclinical neuropathology and/or alteration in neurotrophins following AIE likely makes the brain more vulnerable to the aging process, and normal compensatory aging responses may fail, leading to the behavioral sequelae of dementia. The goal of this proposal is to reveal how intermittent alcohol exposure during adolescence alters the normal age-related trajectory (loss of cholinergic phenotype, reduced neurogenesis) in the F344 rat, as well as the onset of additional AD-pathological markers (plaque load, hyper tau phosphorylation,) in the TgF344-AD model. Specifically, we will (a) reveal AIE-induced sex-specific neurotrophic mediators of resilience and susceptibility to compromised cognitive aging and AD-related pathology (AIM 1); (b) rescue sex-specific AIE-induced acceleration of pathological age-related cognitive decline and AD pathology by inhibiting the p75NTR cell death pathway (AIM 2). Finally, we will determine if exercise load drives the sex-dependent recovery of AIE/AD-associated spatial memory impairment and neuropathology (AIM 3). Our preliminary data revealed a profile that AIE accelerates age-related cognitive impairment in male rats, and amplifies pathological aging in female rats with AD transgenes. Ultimately, this proposal will determine the sex-specific drivers of accelerated age-related pathology associated with alcohol use disorders to inform effective therapeutic approaches to halt the progressive development of dementia.

Main Project 3

AIE, Blood-Brain Barrier regulation, and neurovascular integrity in amyloidopathy
PI: Terrence Deak (tdeak@binghamton.edu)

The Blood-Brain Barrier (BBB) plays an indispensable role in protecting the Central Nervous System (CNS) by restricting the ability of blood-borne pathogens, circulating immune cells, and macromolecules from passing into the brain parenchyma where these agents can exert a disruptive influence on CNS function. Recent studies have shown that BBB integrity waxes and wanes in response to psychological distress and immunological challenge, contributing to anxiety, depression, and even heightened suicidality. Importantly, human post-mortem studies showed BBB disruption among deceased males with Alcohol Use Disorder (AUD). Our lab recently revealed long-lasting effects of Adolescent Intermittent Ethanol (AIE) on BBB integrity that were sex-specific and brain region-selective. In males, AIE-induced BBB alterations were evident in early adulthood after a three-week period of forced abstinence, whereas females were largely unaffected. These findings call for comprehensive studies of sex-specific neurovascular dysfunction associated with AIE. One biological mechanism known to compensate for compromised BBB integrity is through increased deposition of Amyloid-β (Aβ) protein in perivascular regions, which, as a “sticky” protein, attempts to seal the BBB and prevent enhanced permeability. Importantly, AIE has recently been shown to increase Aβ(1-42) deposition and tau hyperphosphorylation in 3X transgenic mouse model of Alzheimer’s Disease (AD), exclusively in females when tested at 6-7 months of age. Consistent with this, we recently reported that long-term ethanol consumption later in life increased co-localization of Aβ(1-42) in iba1+ cells (microglia) that were located in close proximity to the neurovasculature exclusively in female rats, and in the absence of transgenes that promote vulnerability to familial AD. Thus, emerging evidence suggests that chronic intermittent ethanol exposure produces distinctive patterns of neurovascular dysfunction in males and females, contributing to sex-specific outcomes later in life. The over-arching goal of this proposal, therefore, is to determine the sex-specific mechanisms by which AIE produces long-lasting changes in neurovascular integrity, with male-specific increases in BBB permeability and female-specific increases in Aâ(1-42) deposition playing major roles in AIE-associated neurovascular dysfunction. Studies proposed in three Specific Aims will (i) fill critical gaps in our knowledge regarding natural development of the BBB during adolescence, (ii) provide new insight into reactivity of the BBB to acute ethanol challenge during adolescence and adulthood; (iii) establish distinct and separable paths of AIE-induced neurovascular dysfunction in male and female rats across adulthood; and (iv) test novel hypotheses regarding loss of BBB integrity as a harbinger of neurovascular dysfunction. These studies will provide much needed information about contributions of early life alcohol exposure to the development of Alzheimer’s Disease and Related Dementias (ADRD), including vascular dementia, Cerebral Amyloid Angiopathy (CAA), and Vascular contributions to Cognitive Impairment and Dementia (VCID).

Main Project 4

Sex-specific mechanisms of ethanol withdrawal during adolescence
PI: David Werner (dwerner@binghamton.edu)

Early initiation of alcohol use during adolescence and subsequent binge drinking put young individuals at high risk for developing alcohol use disorder (AUD), with young girls more likely to escalate alcohol consumption over boys. Similar to these human studies, our current work in the DEARC demonstrated enhanced sensitivity  of female rats to ethanol withdrawal-related negative affective-like behavioral alterations during early adolescence relative to males. Both sexes were equally affected by withdrawal from chronic exposure when tested in late adolescence. The central amygdala (CeA) is primarily composed of a GABAergic cell population that is sensitive to acute and chronic ethanol and is highly implicated in withdrawal-associated anxiety. The CeA is also responsive to input from sexually dimorphic oxytocin and vasopressin neuropeptide systems. The current proposal will address critical gaps in our understanding of sex differences in sensitivity to ethanol withdrawal during adolescence. Aim 1 will assess withdrawal effects during early or late adolescence, focusing on sex differences in CeA function, connectivity and CeA GABAergic cell activity in adolescent rats. Aim 2 will similarly investigate CeA function, connectivity and CeA GABAergic cell activity in both sexes during withdrawal from chronic ethanol exposure. Finally, Aim 3 will test whether vasopressin and/or oxytocin neuropeptide systems sex-dependently contribute to withdrawal-related negative affect and CeA dysfunction in adolescents.

Main Project 5

Anterior cingulate dysfunction in a PAE-AIE combined model during protracted abstinence
PI: Marvin Diaz (mdiaz@binghamton.edu)

Alcohol consumption during early pregnancy is a common occurrence in our society. Unfortunately, prenatal alcohol exposure increases the risk of onset of alcohol consumption to problematic levels earlier in adolescence. Both prenatal and adolescence periods are critical windows for neurodevelopment and insults to the developing nervous system, such as alcohol exposure, may dysregulate typical neurogenesis and synapse formation, ultimately resulting in behavioral maladaptations such as augmented anxiety-like behavior and pathological pain perception. The pain and the addiction circuit overlap with many mesocortical interactions. The anterior cingulate cortex (ACC) is at the intersection of addiction and pain circuit and receives dopamine projections from the ventral tegmental area. Dopamine in the ACC contributes to the excitation/inhibition balance within layer 2/3 in the ACC and is affected by chronic ethanol exposure during adolescence in the nucleus accumbens in a sex- and age of exposure-dependent manner. Interestingly however, changes in cortical dopamine and the resulting shift in excitation/inhibition balance is unknown following prenatal ethanol exposure (PAE), adolescent intermittent ethanol exposure (AIE), or double-hit with PAE+AIE exposure. Therefore in Main Project 5, we will elucidate the effect of PAE alone, AIE alone, and the combination of the two (PAE+AIE) on the interplay between dopamine and glutamate and the resulting changes in affective behavior and mechanical nociception. Our overarching hypothesis is that PAE+AIE exposure synergistically augments anxiety-like behaviors and mechanical allodynia in male and female rats via altered interactions between glutamate and dopamine in the ACC. Specifically, in Aim 1 we will examine the excitability of glutamate neurons and dopamine terminal excitability in the ACC during protracted abstinence from PAE, AIE, and PAE+AIE exposures using electrophysiology and fast scan cyclic voltammetry (FSCV), respectively. We predict that PAE+AIE with reduce glutamate and dopamine transmission significantly more than either PAE or AIE alone. In Aim 2, we will determine the impact of subsequent ethanol exposure on overall neural activity and glutamate and dopamine transmission in ACC layer 2/3 using electrophysiology and FSCV, respectively. We expect to find a sensitized response to acute ethanol with respect to glutamate and dopamine transmission in PAE+AIE exposed rats compared to rats with single (PAE or AIE) exposure. Finally, in Aim 3 we will determine a causal link between ACC layer 2/3 neuron activity and/or dopamine and anxiety-like behavior and mechanical allodynia using chemogenetics. We predict that dysregulation in both glutamate and dopamine will contribute to the pathological pain perception and augmented anxiety-like behavior in PAE+AIE exposed rats. Collectively, this proposal will identify the impact of alcohol exposure during two developmentally critical windows on interactions between glutamate and dopamine in the ACC resulting in augmented anxiety-like behavior and mechanical allodynia.