Sex differences in brain and behavior: emphasis on nicotine, nitric oxide and place learning

Avoidance biases for vaping stimuli among college students with electronic-cigarette use

Previous research has suggested that individuals who smoke demonstrate a behavioral tendency to approach rather than avoid smoking-related stimuli (i.e., approach bias). This study assessed whether 149 undergraduates with varying levels of e-cigarette use demonstrated an approach bias for vaping-related stimuli on an Approach-Avoidance Task (AAT). In contrast to our hypotheses, participants with e-cigarette use demonstrated a significant avoidance bias to vaping-related stimuli, and this effect appeared to be primarily driven by female e-cigarette users. Further, we found that more severe e-cigarette use was associated with numerous adverse outcomes, including reduced quality of life and increased vaping cravings, depressive symptoms, perceived stress, and cannabis use severity. Overall, our findings elucidate various negative impacts of e-cigarette use and suggest a potential role for sex differences in approach-avoidance tendencies toward vaping-related stimuli among young adults.

Sex differences in dopamine release regulation in the striatum

The mesolimbic dopamine system-which originates in the ventral tegmental area and projects to the striatum-has been shown to be involved in the expression of sex-specific behavior and is thought to be a critical mediator of many psychiatric diseases. While substantial work has focused on sex differences in the anatomy of dopamine neurons and relative dopamine levels between males and females, an important characteristic of dopamine release from axon terminals in the striatum is that it is rapidly modulated by local regulatory mechanisms independent of somatic activity. These processes can occur via homosynaptic mechanisms-such as presynaptic dopamine autoreceptors and dopamine transporters-as well as heterosynaptic mechanisms, such as retrograde signaling from postsynaptic cholinergic and GABAergic systems, among others. These regulators serve as potential targets for the expression of sex differences in dopamine regulation in both ovarian hormone-dependent and independent fashions. This review describes how sex differences in microcircuit regulatory mechanisms can alter dopamine dynamics between males and females. We then describe what is known about the hormonal mechanisms controlling/regulating these processes. Finally, we highlight the missing gaps in our knowledge of these systems in females. Together, a more comprehensive and mechanistic understanding of how sex differences in dopamine function manifest will be particularly important in developing evidence-based therapeutics that target this system and show efficacy in both sexes.

Assessment of individual differences in response to acute bupropion or varenicline treatment using a long-access nicotine self-administration model and behavioral economics in female rats

Bupropion and varenicline are widely prescribed pharmacological treatments for smoking cessation. These treatments are only marginally effective in clinical populations but most preclinical studies show that they are effective in decreasing self-administration in rats on a group level. The present study investigated individual differences in responding to bupropion or varenicline in a preclinical model of long-access to nicotine (0.03 mg/kg/inf; 12 h/day) in female rats. Rats were first assessed for their individual economic demand for nicotine and for their individual performance in open field and elevated plus maze prior to nicotine access and during withdrawal. Rats were then tested for the acute effects of bupropion, varenicline, and yohimbine. We found that neither bupropion nor varenicline decreased responding for nicotine on test days. On the contrary, a moderate dose of bupropion (30 mg/kg) significantly increased responding for nicotine. We also found that rats with higher demand for nicotine were more sensitive to pretreatment with yohimbine which resulted in increased responding for nicotine during the dose-effect tests. Finally, we show that rats that had a higher demand for nicotine also were more persistent in seeking nicotine during extinction and reinstatement tests with nicotine or yohimbine as triggers. Our findings suggest that the length of access to daily nicotine may be an important factor underlying the response to pharmacological treatments like bupropion or varenicline. Future studies modeling chronic treatment approaches that include both sexes will be needed to further extend our findings.

Overexpression of corticotropin-releasing factor in the nucleus accumbens enhances the reinforcing effects of nicotine in intact female versus male and ovariectomized female rats

This study assessed the role of stress systems in the nucleus accumbens (NAc) in promoting sex differences in the reinforcing effects of nicotine. Intravenous self-administration (IVSA) of various doses of nicotine was compared following overexpression of corticotropin-releasing factor (CRF) in the NAc of female and male rats. Ovariectomized (OVX) females were also included to assess the role of ovarian hormones in promoting nicotine reinforcement. Rats received intra-NAc administration of an adeno-associated vector that overexpressed CRF (AAV2/5-CRF) or green fluorescent protein (AAV2/5-GFP). All rats were then given extended access (23 h/day) to an inactive and an active lever that delivered nicotine. Separate groups of rats received intra-NAc AAV2/5-CRF and saline IVSA. Rats were also allowed to nose-poke for food and water during IVSA testing. At the end of the study, the NAc was dissected and rt-qPCR methods were used to estimate CRF overexpression and changes in CRF receptors (CRFr1, CRFr2) and the CRF receptor internalizing protein, β-arrestin2 (Arrb2). Overexpression of CRF in the NAc increased nicotine IVSA to a larger extent in intact female versus male and OVX females. Food intake was increased to a larger extent in intact and OVX females as compared to males. The increase in CRF gene expression was similar across all groups; however, in females, overexpression of CRF resulted in a larger increase in CRFr1 and CRFr2 relative to males. In males, overexpression of CRF produced a larger increase in Arrb2 than females, suggesting greater CRF receptor internalization. Our results suggest that stress systems in the NAc promote the reinforcing effectiveness of nicotine in female rats in an ovarian hormone-dependent manner.

Sex differences in the effect of acute administration of nicotine on MRS-measured metabolic profile of the rat brain

Women are less able to stop smoking than men. Elucidation of sex differences in the tobacco addiction could facilitate personalized treatment. Specialized brain reward systems are controlling the behavior through reinforcement using specific neuromediators. Using non-invasive magnetic resonance spectroscopy (MRS) to ascertain addiction/harm biomarkers could lead to better management of public health through advancements in regulatory and translational research. Proton MRS was used to monitor changes of specific neurometabolites in hippocampus (HC), nucleus accumbens (NAC), and anterior cingulate cortex (ACC) of rats of both sexes after single intraperitoneal injection of nicotine. At the baseline, male rats showed higher level of GABA, taurine, N-acetyl aspartate, and creatine in HC, and taurine in NAC. Also, there were stronger correlations between neurometabolites in females than in males at the baseline. Nicotine administration changed taurine, GABA, myo-inositol, choline, and N-acetyl aspartate in HC, and taurine in NAC. Significant interactions between time, treatment, and sex were detected for taurine and choline in HC. The number of inter-metabolite correlations increased significantly in ACC and decreased in NAC and HC in females after nicotine administration, while in males it was unchanged. There are distinct sex differences in neurometabolic profiles at the baseline and after acute nicotine administration. Nicotine changes inter-metabolite correlations in females more than in males.

Effects of nicotine and stress exposure across generations in C57BL/6 mice

Chronic administration of nicotine or exposure to stress can produce long-lasting behavioral and physiological changes in humans and animals alike. Further, the impact of nicotine and stress exposure can be inherited by offspring to produce persistent changes in physiology and behavior. To determine if nicotine and stress interact across generations to influence offspring behavior we exposed F0 male mice to nicotine and F1 male and female mice to chronic unpredictable stress during adolescence. We then measured locomotor sensitization to repeated nicotine injections in the subsequent F2 and F3 generations. Stress exposure alone (F1) did not influence locomotor sensitization in any lineage. However, in the F1 male lineage, F0 nicotine exposure abrogated locomotor sensitization in F2 male and transiently enhanced locomotor sensitization in F2 female offspring. These effects were not passed down to the F3 generations or observed in the F1 female lineage. F1 stress exposure modulated the effects of prior F0 nicotine exposure in a sex-dependent manner. Specifically, stress blunted the nicotine-induced enhancement in locomotor sensitization observed in F2 female offspring of F1 males. The effect of F0 nicotine and F1 stress exposure in females appears to have skipped a generation and enhanced nicotine sensitization only in the F3 generation, and only in females. This novel multigenerational exposure paradigm examining the inheritance of two different environmental exposures demonstrates that nicotine responses can be modified by nicotine and stress exposure from previous generations, and these effects are strongly influenced by sex.

Do cortical plasticity mechanisms differ between males and females?

The difference between male and female behavior and male and female susceptibility to a number of neuropsychiatric conditions is not controversial. From a biological perspective, one might expect to see at least some of these differences underpinned by identifiable physical differences in the brain. This Mini‐Review focuses on evidence that plasticity mechanisms differ between males and females and ask at what scale of organization the differences might exist, at the systems level, the circuits level, or the synaptic level. Emerging evidence suggests that plasticity differences may extend to the scale of synaptic mechanisms. In particular, the CaMKK, NOS1 and estrogen receptor pathways show sexual dimorphisms with implications for plasticity in the hippocampus and cerebral cortex. © 2016 The Authors. Journal of Neuroscience Research Published by Wiley Periodicals, Inc.

Sex differences in neurotensin and substance P following nicotine self-administration in rats

Investigator-administered nicotine alters neurotensin and substance P levels in Sprague-Dawley rats. This finding suggested a role of the dopamine-related endogenous neuropeptides in nicotine addiction. We sought to extend this observation by determining the responses of neurotensin and substance P systems (assessed using radioimmunoassay) in male and female rats following nicotine self-administration (SA). Male and female Sprague-Dawley were trained to self-administer nicotine, or receive saline infusions yoked to a nicotine-administering rat during daily sessions (1-h; 21 days). Brains were extracted 3 h after the last SA session. Nicotine SA increased tissue levels of neurotensin in the males in the anterior and posterior caudate, globus pallidus, frontal cortex, nucleus accumbens core and shell, and ventral tegmental area. Nicotine SA also increased tissue levels of neurotensin in the females in the anterior caudate, globus pallidus, nucleus accumbens core and shell, but not in the posterior caudate, frontal cortex, or ventral tegmental area. There were fewer sex differences observed in the substance P systems. Nicotine SA increased tissue levels of substance P in both the males and females in the posterior caudate, globus pallidus, frontal cortex, nucleus accumbens shell, and ventral tegmental area. A sex difference was observed in the nucleus accumbens core, where nicotine SA increased tissue levels of substance P in the males, yet decreased levels in the females. The regulation of neuropeptides following nicotine SA may play a role in the susceptibility to nicotine dependence in females and males. Synapse 70:336-346, 2016. © 2016 Wiley Periodicals, Inc.

Striatal NOS1 has dimorphic expression and activity under stress and nicotine sensitization

Nicotine exerts its addictive influence through the meso-cortico-limbic reward system, where the striatum is essential. Nicotine addiction involves different neurotransmitters, nitric oxide (NO) being especially important, since it triggers the release of the others by positive feedback. In the nervous system, NO is mainly produced by nitric oxide synthase 1 (NOS1). However, other subtypes of synthases can also synthesize NO, and little is known about the specific role of each isoform in the process of addiction. In parallel, NOS activity and nicotine addiction are also affected by stress and sexual dimorphism. To determine the specific role of this enzyme, we analyzed both NOS expression and NO synthesis in the striatum of wild-type and NOS1-knocked out (KO) mice of both sexes in situations of nicotine sensitization and stress. Our results demonstrated differences between the caudate-putamen (CP) and nucleus accumbens (NA). With respect to NOS1 expression, the CP is a dimorphic region (27.5% lower cell density in males), but with a stable production of NO, exclusively due to this isoform. Thus, the nitrergic system of CP may not be involved in stress or nicotine addiction. Conversely, the NA is much more variable and strongly involved in both situations: its NO synthesis displays dimorphic variations at both basal (68.5% reduction in females) and stress levels (65.9% reduction in males), which disappear when nicotine is infused. Thus, the KO animals showed an increase in NO production (21.7%) in the NA, probably by NOS3, in an attempt to compensate the lack of NOS1.

A mechanistic hypothesis of the factors that enhance vulnerability to nicotine use in females

Women are particularly more vulnerable to tobacco use than men. This review proposes a unifying hypothesis that females experience greater rewarding effects of nicotine and more intense stress produced by withdrawal than males. We also provide a neural framework whereby estrogen promotes greater rewarding effects of nicotine in females via enhanced dopamine release in the nucleus accumbens (NAcc). During withdrawal, we suggest that corticotropin-releasing factor (CRF) stress systems are sensitized and promote a greater suppression of dopamine release in the NAcc of females versus males. Taken together, females display enhanced nicotine reward via estrogen and amplified effects of withdrawal via stress systems. Although this framework focuses on sex differences in adult rats, it is also applied to adolescent females who display enhanced rewarding effects of nicotine, but reduced effects of withdrawal from this drug. Since females experience strong rewarding effects of nicotine, a clinical implication of our hypothesis is that specific strategies to prevent smoking initiation among females are critical. Also, anxiolytic medications may be more effective in females that experience intense stress during withdrawal. Furthermore, medications that target withdrawal should not be applied in a unilateral manner across age and sex, given that nicotine withdrawal is lower during adolescence. This review highlights key factors that promote nicotine use in females, and future studies on sex-dependent interactions of stress and reward systems are needed to test our mechanistic hypotheses. Future studies in this area will have important translational value toward reducing health disparities produced by nicotine use in females. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Brain nitric oxide metabolites in rats preselected for nicotine preference and intake

Nicotine addiction is a serious health problem resulting in millions of preventable deaths worldwide. The gas messenger molecule nitric oxide (NO) plays a critical role in addiction, and nicotine increases nitric oxide metabolites (NOx) in the brain. Understanding the factors which underlie individual differences in nicotine preference and intake is important for developing effective therapeutic strategies for smoking cessation. The present study aimed to assess NO activity, by measuring its stable metabolites, in three brain regions that express high levels of nicotinic acetylcholine receptors in rats preselected for nicotine preference. Rats (n=88) were exposed to two-bottle, free choice of oral nicotine/water starting either as adolescents or adults; control animals received only water under identical conditions. Following 12 or six weeks of exposure, levels of NOx (nitrite+nitrate), were determined in the hippocampus, frontal cortex, and amygdala. Since the rats were singly housed during oral nicotine treatment, naïve rats were also included in the study to evaluate the effect of isolation stress. Isolation stress increased NOx in the hippocampus. Nicotine preference did not have a significant effect on NO activity, but rats with adolescent exposure had higher NOx levels in the frontal cortex compared to adult-onset rats. Our findings suggest that nicotine exposure during adolescence, regardless of the amount of nicotine consumed, results in higher NO activity in the frontal cortex of rats, which persists through adulthood.

The role of estrogen receptor β and nicotinic cholinergic receptors in postpartum depression

Postpartum depression (PPD) is a devastating disease occurring in approximately 20% of women. Women who suffer from PPD appear to be more sensitive to postpartum hormonal changes than women who do not experience this form of depression. Furthermore, women who quit smoking prior to or during pregnancy, and who develop PPD, are at an increased risk of smoking relapse. Unfortunately, the mechanistic relationship between the pathophysiology of PPD and smoking relapse is unknown. Here we review the roles of both estrogen receptor beta (ERβ) and cholinergic nicotinic receptors (nAChRs) in the pathogenesis of depression and propose a mechanistic rationale to explain the high rate of smoking relapse exhibited by women who develop PPD.

Gambling-related cognitive biases and pathological gambling among youths, young adults, and mature adults in Chinese societies

This study investigated the extent to which gambling-related cognitive biases would associate with various levels of gambling pathology among 2,835 youths, 934 young adults, and 162 mature adults in Chinese societies. Results showed that gambling cognitive biases, especially biases in perceived inability to stop gambling and positive gambling expectancy, were salient correlates of pathological gambling across the three age cohorts. Analyses of variances on total cognitive biases also showed a gambling pathology main effect and an age cohort × gambling pathology 2-way interaction effect. It was noted that the probable pathological gambling group had greater cognitive biases than the probable problem gambling group, which in turn had greater cognitive biases than the non-problem gambling group. In the non-problem gambling group, mature adults had greater cognitive biases than youths and young adults, but this pattern was reversed in the probable problem gambling group. In the probable pathological gambling group, youths had greater cognitive biases than young and mature adults. Specific categories of cognitive biases also varied according to gender and gambling pathology. While men as compared to women in the non-problem and probable problem gambling groups reported a greater bias in their perceived inability to stop gambling, no significant gender difference in this bias was found in the probable pathological gambling group. Men generally had greater perceived gambling expectancy bias than women.

Binge drinking +/- chronic nicotine administration alters extracellular glutamate and arginine levels in the nucleus accumbens of adult male and female Wistar rats

AIMS

The effect of 'binge drinking' coupled or not with chronic nicotine administration on nucleus accumbens (NAc) glutamate, arginine, taurine and hydroxyl radical levels has been investigated in these present studies.

METHODS AND RESULTS

Ethanol, 2 or 3 g/kg, has been administered to male or female adult rats in a 'binge-type' regime for 3 weeks, +/- nicotine, and changes in glutamate, arginine and taurine content in the NAc, assayed by microdialysis after a further dose of ethanol. The basal concentration of NAc glutamate increased 8-fold in the female adult rats but did not change significantly after further doses of ethanol. In contrast, the male adult rats showed no changes in basal glutamate content but exhibited a dose-dependent increase in NAc glutamate after further doses of ethanol. NAc arginine basal levels decreased significantly in both male and female adult rats after further doses of ethanol. Co-administration of nicotine modified the toxicity of ethanol as exemplified by diminishment of both the basal NAc glutamate release as well as modifying the release of this excitatory amino acid after further ethanol doses, particularly in female rats. In addition, the marked changes in arginine release after further ethanol doses were less evident. There was no evidence for increased hydroxyl radical production in the NAc after 'binge drinking' +/- nicotine.

CONCLUSION

There appeared to be a greater vulnerability to ethanol toxicity in female adult rats after 'binge drinking'. It remains unclear whether the increased release of glutamate during the microdialysis evokes activation of inducible nitric oxide synthase (iNOS), which would utilize arginine in the formation of nitric oxide.

Different isoforms of nitric oxide synthase are involved in angiotensin-(1-7)-mediated plasticity changes in the amygdala in a gender-dependent manner

BACKGROUND

The amygdala receives afferent sensory input and processes information related to hydromineral balance. Angiotensin acts on and through the amygdala to stimulate thirst and sodium appetite. In addition, different angiotensins seem to play a role in cognition and learning mechanisms by acting on and through the amygdala. Recently, we showed that angiotensin-(1-7) (Ang-(1-7)) enhances the magnitude of long-term potentiation (LTP) in the lateral nucleus of the amygdala (LA) via the Mas receptor.

METHODS

Extracellular field potentials were measured in the LA.

RESULTS

LA-LTP induced by stimulation of the external capsule was nitric oxide (NO)-dependent because the NO synthase (NOS) inhibitor L-NAME reduced LA-LTP. The LA-LTP was also reduced in both male and female nNOS and eNOS knockout mice. In male eNOS(-/-) mice, Ang-(1-7) enhanced LA-LTP, whereas the LTP-enhancing effect of Ang-(1-7) was missing in female eNOS(-/-) mice. Therefore, the LTP-enhancing effect of Ang-(1-7) was mediated by eNOS in females. In contrast, Ang-(1-7) strongly enhanced the LTP in nNOS(-/-) females, whereas the effect of Ang-(1-7) was missing in nNOS(-/-) males. Thus, Ang-(1-7) induced an increase in the magnitude of LTP via the involvement of nNOS in males.

CONCLUSION

Our data support not only the hypothesis that NO contributes to plasticity changes in the lateral amygdala, but also show for the first time a gender-dependent involvement of different isoforms of NOS in the mediation of Ang-(1-7) on LTP in the amygdala.

Sex Differences in Verbal and Visual-Spatial Tasks under Different Hemispheric Visual-Field Presentation Conditions

This paper reports sex differences in cognitive task performance that emerged when 39 Australian university undergraduates (19 men, 20 women) were asked to solve verbal (lexical) and visual-spatial cognitive matching tasks which varied in difficulty and visual field of presentation. Sex significantly interacted with task type, task difficulty, laterality, and changes in performance across trials. The results revealed that the significant individual-differences' variable of sex does not always emerge as a significant main effect, but instead in terms of significant interactions with other variables manipulated experimentally. Our results show that sex differences must be taken into account when conducting experiments into human cognitive-task performance.

The effects of strain and prenatal nicotine exposure on ethanol consumption by adolescent male and female rats

Two studies of variables affecting voluntary ethanol consumption by adolescent male and female rats are reported. Sprague-Dawley (SD) and spontaneously hypertensive rats (SHRs) were compared in Experiment 1. Starting on postnatal day 30 all had 24-h access to 2%, then 4%, and then 6% ethanol, followed by 1-h access to the 6% until intake stabilized. During the 1-h access SHR females consumed more ethanol than all other groups. In Experiment 2, the same procedure was used to compare SD groups prenatally exposed to nicotine, with controls. Nicotine-exposed females consumed more ethanol during 1-h access than both nicotine-exposed and control males; but after using water intake as a covariate, the differences were not significant. These data show that deprivation conditions need to be considered when generalizing the results of voluntary consumption studies, and that estrogens may be a modulator of addictive behavior.

Dimensions of impulsive behavior in adolescent smokers and nonsmokers

Robust associations have been identified between impulsive personality characteristics and cigarette smoking during adolescents, indicating that impulsive behavior may play an important role in the initiation of cigarette smoking. The present study extended this research by using laboratory behavioral assessments to explore relationships between three specific dimensions of impulsive behavior (impulsive decision-making, inattention, and disinhibition) and adolescent cigarette smoking. Participants were male and female adolescent smokers (n = 50) and nonsmokers (n = 50). Adolescent smokers were more impulsive on a measure of decision-making; however, there were significant smoking status by gender interaction effects for impulsive inattention and disinhibition. Male smokers were most impulsive on the measure of inattention, but male smokers were least impulsive on the measure of disinhibition. Correlations between biomarkers of smoking and impulsive inattention and disinhibition were found for females but not males. The current findings, coupled with previous findings (Reynolds et al., 2007), indicate there may be robust gender difference in associations between certain types of impulsive behavior and cigarette smoking during adolescence.

Sex differences in response to nicotine in C57Bl/6:129SvEv mice

INTRODUCTION

Human studies suggest that smoking behavior in men may depend more on the pharmacological effects of nicotine, whereas in women, this behavior may rely more on nonpharmacological factors associated with smoking. Investigation of these parameters in mice may also reveal sex differences.

METHODS

Male and female C57Bl/6:129SvEv hybrid mice were exposed to increasing concentrations of nicotine in a voluntary oral nicotine consumption paradigm in which we measured fluid consumption over time and dose. Separate cohorts of mice were exposed to nicotine in a place-conditioning paradigm, and preference was determined. These behavioral models were used to examine sex differences in mice as they rely on pharmacological as well as nonpharmacological factors. Mice exposed to nicotine or saline also were tested for sex differences in locomotor-activating effects of nicotine and in analgesia using standard activity monitoring and hot-plate tests.

RESULTS

Females responded more to the conditioned rewarding effects of nicotine compared with males. Males, however, seemed more responsive to the pharmacological aspects of nicotine by reducing nicotine drinking at higher concentrations; females maintained consistent levels of intake over several doses of nicotine. Male and female mice demonstrated similar locomotor and antinociceptive responses to nicotine.

DISCUSSION

These data suggest that place-conditioning and two-bottle choice paradigms may be more sensitive measures of sexual dimorphism in the C57BL/6:129SvEv hybrid mouse than are locomotor or nociception assays.

Sex differences in nicotine action

Accumulating evidence suggests that the antecedents, consequences, and mechanisms of drug abuse and dependence are not identical in males and females and that gender may be an important variable in treatment and prevention. Although there has been a decline in smoking prevalence in developed countries, females are less successful in quitting. Tobacco use is accepted to be a form of addiction, which manifests sex differences. There is also evidence for sex differences in the central effects of nicotine in laboratory animals. Although social factors impact smoking substantially in humans, findings from nonhuman subjects in controlled experiments provide support that sex differences in nicotine/tobacco addiction have a biological basis. Differences in the pharmacokinetic properties of nicotine or the effect of gonadal hormones may underlie some but not all sex differences observed. Laboratory-based information is very important in developing treatment strategies. Literature findings suggest that including sex as a factor in nicotine/tobacco-related studies will improve our success rates in individually tailored smoking cessation programs.

Gender effects on mood and cigarette craving during early abstinence and resumption of smoking

Women are more likely than men to relapse after initiating abstinence from cigarette smoking. The reasons for this phenomenon are unclear but may relate to negative mood, cigarette craving, or other symptoms of nicotine withdrawal. We addressed this issue in a study of 26 female and 38 male smokers. The Profile of Mood States, Shiffman-Jarvik Withdrawal Scale, and Urge to Smoke Scale were administered twice in each of two test sessions on different days. One session began within 1 hr after smoking ad libitum and the other followed overnight abstinence (>13 hr). On each test day, the two assessment blocks were separated by a 5-10-min break, during which each participant smoked one cigarette. In the first test block, both men and women reported higher scores after >13 hr abstinence than after <1 hr abstinence on the tension-anxiety and anger-hostility subscales of the Profile of Mood States, and for the craving and psychological symptoms of the Shiffman-Jarvik Withdrawal Scale. Scores of female subjects showed significantly larger differences between sessions on the tension-anxiety subscale and a trend toward significance (p = .050) on the anger-hostility subscale of Profile of Mood States than those of males. Moreover, on the tension-anxiety subscale, women also reported a greater reduction than men from smoking one cigarette after overnight abstinence. The findings indicate that overnight abstinence produces more negative mood symptoms and cigarette craving in female smokers than in males, and that resumption of smoking produces greater relief from these symptoms in female smokers. These differences may contribute to the greater likelihood of relapse when women try to quit smoking.

Transdermal nicotine modulates strategy-based attentional semantic processing in non-smokers

Nicotine has been shown to improve various aspects of cognitive processing such as attention and memory, however, its effects on lexical-semantic processing are relatively uncharted. Recent investigations of mnemonic processing in minimally deprived smokers suggest that nicotine might selectively modulate processes concerned with associative memory. This study investigated the effects of nicotine on lexical-semantic processing in non-smokers using a strategy-based lexical-decision priming paradigm. Transdermal nicotine patches (7 mg/24 h) were administered within a double-blind, placebo-controlled, cross-over design. Participants were trained to expect target words to come from a specified semantic category based on the prime word, although in some instances trained expectations were not met. Participants were presented with the stimuli at either a short or long stimulus onset asynchrony (SOA) to target automatic and attentional processing, respectively (n=12 and 17 for the short and long SOAs, respectively). Nicotine was found to selectively affect priming condition reaction times at the long SOA, indicating a nicotinic modulation of attentional mechanisms. Specifically, facilitation effects were dominant under placebo compared to a dominance of inhibition effects under nicotine. These results suggest that nicotine supports inhibitory attentional mechanisms in cognitively demanding semantic processing paradigms.

Sexually dimorphic effects of acute nicotine administration on arousal and visual-spatial ability in non-smoking human volunteers

The effect of an acute administration of nicotine on arousal and visual-spatial ability in healthy non-smoking participants was investigated. Healthy adult volunteers with a mean age of 19.98 years received a transdermal nicotine or placebo patch prior to completing a water-level task and two mental rotation tasks while concurrent psychophysiological recordings were taken. Nicotine administration showed a sexually dimorphic effect on arousal (skin conductance level and heart rate). Evidence of superior performance in males compared to females was found in reaction time and accuracy measures for the visual-spatial tasks. However, performance reflected the interaction between sex and nicotine. Nicotine slowed reaction times in the mental rotation tasks more extensively in females than males. Nicotine also reduced confidence in performance during the water-level task in males, but not in females. The effects of nicotine on visual-spatial ability may reflect the interactive effects of sex and changes in arousal levels induced by nicotine administration.

Sex differences in modulating blood brain barrier permeability by NO in pentylenetetrazol-induced epileptic seizures

Susceptibility to epilepsy as well as BBB dysfunction in some pathological conditions varies depending on sex difference. It has recently been shown that systemically given NO donor and antagonists modify the nature of seizures induced by PTZ (pentylenetetrazol) differently in male and female rats. This study investigates the role of NO on BBB permeability in PTZ seizures with sex differences using NO donor, sodium nitroprusside (SNP), and NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). Nitrite+nitrate levels as indices of NO generation in the brain were also assessed. L-NAME prolonged seizure latency in male rats, seizure intensity and seizure duration were lessened. L-NAME depicted opposite effects in seizure nature in female rats. SNP prolonged seizure latency, while seizure intensity and duration were lessened only in female rats. L-NAME in male rats increased L-NAME use in female rats (not in male rats) which resulted in a more leaky BBB especially in midbrain, thalamus, hippocampus, corpus striatum and cerebellum whereas SNP use in male rats and not in female rats resulted in pronounced BBB opening in all brain regions studied than PTZ per se. L-NAME while decreasing nitrite+nitrate levels in male rat brains, acted in an opposite fashion in females. SNP use depicted an inverse picture with respect to L-NAME, with an opposite action in different sexes. This study reveals that NO effect on BBB in PTZ-induced seizures depends unequivocally on sex difference. The sex-dependent action of NO in seizures and in CNS pathologies warrants further investigation.

Sex differences in the regulation of cocaine and amphetamine-regulated transcript expression in hypothalamic nuclei of rats by forced swim stress

Cocaine and amphetamine-regulated transcript (CART) peptides are suggested to play a role in several physiological processes including feeding, reward, neuroendocrine modulation, and the stress response. Although some studies implicate the modulation of CART peptide expression by glucocorticoids, direct evidence relating CART to the stress response is limited. The present study was undertaken to evaluate the possible involvement of CART peptides during acute stress in male and female rats. Forced swim was used as the stress procedure. Following stress, serum adrenocorticotropic hormone (ACTH), and corticosterone (CORT) levels were determined, and CART immunocytochemistry was performed in the paraventricular (PVN) and arcuate (ARC) nuclei of the hypothalamus. Our results depict the following changes: (1) Serum ACTH and CORT levels were increased by stress and CORT levels were higher in female rats than males. (2) Stress modulated the number of CART expressing neurons. The degree and direction of this modulation varied according to the hypothalamic region and the sex of the subject. Forced swim stress increased CART peptide expression significantly in the PVN of female rats. In males, although there was a tendency for an increase in CART-immunoreactive cells by forced swim stress, the difference was not statistically significant. In the ARC nucleus, forced swim stress did not affect CART peptide expression in either sex. Our results suggest differential and sexually dimorphic modulation of CART expression in the PVN and ARC by forced swim stress.

Cocaine and amphetamine regulated transcript (CART) and the stress response

CART is expressed abundantly in the hypothalamic paraventricular nucleus and locus coeruleus, major corticotropin releasing factor (CRF) and noradrenaline sources, respectively. There is a bidirectional relation between CART and hypothalamo-pituitary-adrenal axis activity. CART stimulates CRF, adrenocorticotropic hormone and glucocorticoid secretion, whereas CRF and glucocorticoids increase the transcriptional activity of the CART gene; adrenalectomy declines CART expression in the hypothalamus. Stress exposure modulates CART expression in hypothalamus and amygdala in rat brain in a region and sex specific manner. CART may be a mediator peptide in the interaction between stress, drug abuse, and feeding. The review discusses the established role of CART as it relates to the stress response.

Are there sex and gender differences in acute exposure to chemicals in the same setting?

We have little understanding of the influence that sex and gender may have on exposure to and measurement of occupational chemicals. If men and women are in the same physical environment, whether that be an occupational or an environmental setting, researchers need to question whether their acute exposure, as measured by administered and/or biologically effective dose, is the same. Not doing so may result in incorrect inferences being made about the risks associated with that exposure. Three critical questions arise specifically, do men and women differ in (1) their personal environments (immediate physical environments and personal attributes), (2) their absorption of the substance across the various biological barriers, and (3) the amount of active substance that reaches the target sites? Both contextual (e.g., smoking habits, diet, use of personal care products and jewellery, hobbies, stress, and use of medications) and biological (e.g., endocrine status) factors should be considered in answering these questions. Examples from the literature are provided to show that, depending on the chemical compound, there may be sex and gender differences in exposure to chemicals which can be manifested in sex differences in absorption, distribution, metabolism, storage, and excretion. An argument is developed to support the need to make information available, such as pharmacokinetic modeling studies in both men and women including appropriate age groups representing the spectrum of life stages and reproductive status.

Differential effects of nicotine on alcohol consumption in men and women

RATIONALE

Nicotine and alcohol are frequently co-used, suggesting that use of one drug may facilitate use of the other. Furthermore, because men and women differ in their responses to both drugs, it is possible that men and women also differ in their responses to the combination of nicotine and alcohol.

OBJECTIVE

This experiment was designed to investigate the effects of nicotine on consumption and subjective and physiological effects of alcohol in healthy male and female social drinkers.

MATERIALS AND METHODS

Healthy light smoking, social drinkers (22 men and 12 women) participated in a three-session, double-blind within-subject study. They were pretreated with transdermal nicotine (7 or 14 mg) or placebo, followed two h later by an alcoholic beverage, and subsequent opportunities to "purchase" and consume more of the same drink. Outcome measures included the number of alcoholic beverages consumed and subjective and physiological effects.

RESULTS

Nicotine increased alcohol consumption in men, whereas it decreased alcohol consumption in women. These effects were even more pronounced after excluding participants reporting nausea after nicotine administration. Nicotine alone increased subjective arousal in men but decreased positive mood in women. Nicotine increased the sedative-like effects of alcohol in both sexes.

CONCLUSIONS

These findings indicate that both the subjective effects of nicotine and the effects of nicotine on alcohol consumption differ markedly in men and women. The findings extend existing data on sex differences in the effects of either nicotine or cigarette smoking on alcohol consumption, and support the idea that the pharmacological effects of nicotine may differ in men and women.

Effects of transdermal nicotine on attention in adult non-smokers with and without attentional deficits

Extant evidence suggests a possibility of self-medication to account for greater prevalence of cigarette smoking among adults with ADHD as they tend to show improvements on affective and cognitive measures, particularly on measures of sustained attention following nicotine administration. The present study was conducted to evaluate whether adult non-smokers with low attentiveness might exhibit greater improvements on measures of sustained attention than those with higher attentiveness using neuropsychological tests that had previously shown sensitivity to ADHD. On the basis of their scores on attention scales used in the diagnosis of adult ADHD, 62 male non-smokers were divided into 2 groups of either low or high attentiveness and treated with either a placebo or 7 mg nicotine patch. After 6 h of patch application each participant completed the Wisconsin Card Sorting Test (WCST), classic Stroop task, and Conners' Continuous Performance Test (CPT), which were administered in a counterbalanced order and a double-blind manner. No significant drug or group differences were observed on the Stroop task. On the Conners' CPT participants in the low attention group treated with nicotine committed significantly fewer errors of commission, showed improved stimulus detectability and fewer perseverations than those in the low attention placebo group. On the WCST nicotine significantly impaired the ability of participants in the high attention group to learn effective strategies to complete the test with fewer trials. The results showed nicotine-induced improvement on some measures of sustained attention in the low attention group and some decrement in working memory in the high attention group, which suggests that nicotine tends to optimize rather than improve performance on cognitive tasks.

Effects of laterality and sex on cognitive strategy in a water maze place learning task and modification by nicotine and nitric oxide synthase inhibition in rats

The aim of the present study was to investigate sex differences in learning strategies and to elucidate the mechanisms, which may underlie these differences. In two separate experiments, rats were presented with different strategies that could be employed to learn the position of a platform in a water maze (WM); furthermore, rats received treatments that could influence these strategies. In the first experiment, we demonstrated that the response-learning paradigm can be applied to the WM and can be compared with visually cued learning and reversal learning. Naïve rats of either sex could acquire this protocol relatively easily. On the probe trial, where the rats are presented with a choice between using response versus visually cued learning, initially response learning was preferred, however, during these experiments, laterality emerged as a significant factor and rats trained to turn right had difficulty in reversing the learned pattern to find the platform. The second part of our study evaluated the effects of nicotine and nitric oxide synthase (NOS) inhibition on the aforementioned parameters. Drug treatments impaired acquisition compared to saline treatments and the effect was more pronounced with NOS inhibition. During the probe trial, while NOS inhibition enhanced the right-side bias in both sexes, nicotine treatment had the same effect only in males. In conclusion, naïve rats can acquire place learning using visible cues or response learning; however, there is a right side bias in both sexes and the laterality effect is more pronounced in male rats. In drug-treated animals, while NOS inhibition enhances laterality (right bias) in both sexes similarly, nicotine modifies the cognitive strategy in a sexually dimorphic manner by augmenting the right bias only in male rats.

Sex differences in the contribution of nicotine and nonpharmacological stimuli to nicotine self-administration in rats

RATIONALE

Sex differences have been reported for the impact of nicotine and nonpharmacological cues on smoking. While nonpharmacological environmental stimuli have also been shown to influence nicotine self-administration in rats, there have been no attempts to examine the impact of sex differences in the contributions of nicotine and nondrug stimuli to this behavior.

OBJECTIVES

This experiment investigated sex differences in operant responding for nicotine in rats when drug infusions were delivered either in the absence of, or in combination with, a nonpharmacological stimulus.

METHODS

Initially, male and female rats acquired self-administration for nicotine alone across a range of doses (0.03, 0.06, and 0.15 mg kg(-1) inf(-1), freebase). After stable acquisition, nicotine infusions were combined with a weakly reinforcing, compound visual stimulus.

RESULTS

While there was no overall effect of dose on active lever responding for nicotine in the absence of the visual stimulus, female rats responded more on the reinforced lever than males at 0.06 and 0.15 mg kg(-1) inf(-1) on an FR5 schedule. However, they also showed increased responding on the nonreinforced lever compared to males at the same doses. Combining nicotine infusions with the visual stimulus doubled responding compared to nicotine alone at 0.03 and 0.06, but not at 0.15 mg kg(-1) inf(-1): this effect was significantly greater for female rats.

CONCLUSIONS

These data highlight the prominent contribution of nonpharmacological stimuli to nicotine-reinforced behavior across a range of doses in both male and female rats. They also reveal sex differences in operant responding for nicotine under conditions where a nonpharmacological stimulus is either absent, or combined with drug delivery.

Sex differences in mouse behavior following pyrilamine treatment: role of histamine 1 receptors in arousal

Arousal, the activation of brain and behavior, is a fundamental component of behavior. While sex differences in behavior are pervasive, it is unknown whether they could be due to an underlying dimorphism in arousal mechanisms. Because histamine (HA) acting through histamine 1 (H1) receptors is one essential component of arousal neural circuitry, the aim of the current experiment was to measure sex differences in behavioral arousal following treatment with the H1 receptor antagonist, pyrilamine (PYRL). Castrated male and ovariectomized female Swiss-Webster mice were treated subcutaneously with either 15 or 35 mg/kg of PYRL. The effect of drug treatment was determined in an array of behaviors: sensory responsiveness, running wheel activity, and fearfulness. Surprisingly, the lower dose of PYRL increased some aspects of arousal, sensory responsiveness, and anxiety-like behavior, while the higher dose of PYRL resulted in decreases in arousal across tests, indicating that antagonism of histamine receptors does not have a linear relationship with arousal. Females were more sensitive to the arousal-reducing effects of PYRL than males in sensory and running wheel tasks but not in tests of emotion. In conclusion, antagonism of H1 receptors can alter arousal in a sex-dependent manner, independent of circulating gonadal steroids, in mice.

The Gambling Related Cognitions Scale (GRCS): development, confirmatory factor validation and psychometric properties

AIMS

The aims of this study are to develop and validate a measure to screen for a range of gambling-related cognitions (GRC) in gamblers.

DESIGN AND PARTICIPANTS

A total of 968 volunteers were recruited from a community-based population. They were divided randomly into two groups. Principal axis factoring with varimax rotation was performed on group one and confirmatory factor analysis (CFA) was used on group two to confirm the best-fitted solution.

MEASUREMENTS

The Gambling Related Cognition Scale (GRCS) was developed for this study and the South Oaks Gambling Screen (SOGS), the Motivation Towards Gambling Scale (MTGS) and the Depression Anxiety Stress Scale (DASS-21) were used for validation.

FINDINGS

Exploratory factor analysis performed using half the sample indicated five factors, which included interpretative control/bias (GRCS-IB), illusion of control (GRCS-IC), predictive control (GRCS-PC), gambling-related expectancies (GRCS-GE) and a perceived inability to stop gambling (GRCS-IS). These accounted for 70% of the total variance. Using the other half of the sample, CFA confirmed that the five-factor solution fitted the data most effectively. Cronbach's alpha coefficients for the factors ranged from 0.77 to 0.91, and 0.93 for the overall scale.

CONCLUSIONS

This paper demonstrated that the 23-item GRCS has good psychometric properties and thus is a useful instrument for identifying GRC among non-clinical gamblers. It provides the first step towards devising/adapting similar tools for problem gamblers as well as developing more specialized instruments to assess particular domains of GRC.

The effect of nitric oxide synthase inhibition on cognitive ability and strategies employed for place learning in the water maze: sex differences

Male and female rats use different cognitive strategies in the solution of place-learning problems in the water maze despite similar abilities. The female-type strategy has been negatively correlated with cortical nitric oxide (NO) metabolites. The present study aimed to examine the effect of NO synthase (NOS) inhibition (N(omega)-nitro-L-arginine, L-NA) on cognitive ability and strategy in the water maze, and to evaluate possible sex differences. In a 2 (male versus female) x2 (L-NA versus saline) factorial design, rats were trained to find the platform (visible or hidden), always in the same position, for 12 days. L-NA impaired acquisition, during the earlier phases and more prominently in females. This impairment was quite dramatic and unique to females during the first day that the platform was hidden following 3 days of visible-platform conditions. After acquisition, the visible platform's position was shifted, thereby presenting the rats with a choice (searching for the hidden platform in the previous location, i.e. adopting a conceptual cognitive style, or escaping to the visible platform in a new position, i.e. adopting a perceptual style). On the first of the four shift trials (where the newly positioned platform was proximal to the rat's starting position), female rats showed the previously found tendency to adopt a perceptual style escape directly in clear contrast to saline-treated males. The L-NA-treated males tended to manifest female-like perceptual style, suggesting that inhibition of NO synthesis in males weakened the tendency to choose a conceptual style in this shifted-platform task. The role of NO in both cognitive and non-cognitive psychological functions is discussed.

Pavlov's methodological behaviorism as a pre-Socratic contribution of the melding of the differential and experimental psychology

The differential/experimental distinction that Cronbach specified is important because any adequate account of psychological phenomena requires the recognition of the validity of both approaches, and a meaningful melding of the two. This paper suggests that Pavlov's work in psychology, based on earlier traditions of inquiry that can be traced back to the pre-Socratics, provides a potential way of achieving this melding, although such features as systematic rather than anecdotal methods of observation need to be added. Pavlov's methodological behaviorist approach is contrasted with metaphysical behaviorism (as exemplified explicitly in Watson and Skinner, and implicitly in the computer-metaphorical, information-processing explanations employed by current "cognitive" psychology). A common feature of the metaphysical approach is that individual-differences variables like sex are essentially ignored, or relegated to ideological categories such as the treatment of sex as merely a "social construction." Examples of research both before and after the "cognitive revolution" are presented where experimental and differential methods are melded, and individual differences are treated as phenomena worthy of investigation rather than as nuisance factors that merely add to experimental error.