Ovarian hormones and drug abuse

Sex differences in addiction

Women exhibit more rapid escalation from casual drug taking to addiction, exhibit a greater withdrawal response with abstinence, and tend to exhibit greater vulnerability than men in terms of treatment outcome. In rodents, short-term estradiol intake in female rats enhances acquisition and escalation of drug taking, motivation for drugs of abuse, and relapse-like behaviors. There is also a sex difference in the dopamine response in the nucleus accumbens. Ovariectomized female rats exhibit a smaller initial dopamine increase after cocaine treatment than castrated males. Estradiol treatment of ovariectomized female rats enhances stimulated dopamine release in the dorsolateral striatum, but not in the nucleus accumbens, resulting in a sex difference in the balance between these two dopaminergic projections. In the situation where drug-taking behavior becomes habitual, dopamine release has been reported to be enhanced in the dorsolateral striatum and attenuated in the nucleus accumbens. The sex difference in the balance between these neural systems is proposed to underlie sex differences in addiction.

The association between cannabis use and suicidality among men and women: A population-based longitudinal study

BACKGROUND

Evidence regarding the role of sex differences in the association between cannabis use and suicidality is lacking. We explored sex differences in the bidirectional association between cannabis use and suicidality in a 3-year longitudinal study.

METHODS

Data were drawn from waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Bidirectional analyses were conducted separately by sex, exploring incidence of suicidality among cannabis users (n=963 vs. 30,586 non-users) as well as initiation of cannabis use among suicidal individuals (n=1805 vs. 25,729 non-suicidal). Cannabis use was categorized based on frequency of use. Multivariate logistic regression analyses controlling for multiple covariates were conducted.

RESULTS

Cannabis use was significantly associated with increased incidence of suicidality among men (Adjusted Odds Ratio [AOR] for any cannabis use =1.91[1.02-3.56]) but not among women (AOR=1.19[0.64-2.20]). Daily cannabis use was significantly associated with increased incidence of suicidality among men (AOR=4.28[1.32-13.82]) but not among women (AOR=0.75[0.28-2.05]). Conversely, baseline suicidality was associated with initiation of cannabis use among women (AOR=2.34[1.42-3.87]) but not among men (AOR=1.10[0.57-2.15]). Separate analyses of suicidal ideation and suicide attempts demonstrated a significant association between cannabis use and subsequent incidence of suicidal ideation in men, and a significant association between baseline suicidal ideation and subsequent initiation of cannabis use in women. No significant association was found for the bidirectional association between cannabis use and suicide attempts in either sex.

LIMITATIONS

Suicidality was assessed only in individuals reporting depressed mood and/or anhedonia.

CONCLUSIONS

Our findings support a longitudinal association between heavy cannabis use and the incidence of suicidality in men, but not in women. Conversely, baseline suicidality is longitudinally associated with the initiation of cannabis use in women, but not in men. This may have implications on clinical and social aspects of cannabis use and merit further research into the unique effects of sex differences on cannabis induced psychopathology.

Estradiol impacts the endocannabinoid system in female rats to influence behavioral and structural responses to cocaine

Compared with men, women show enhanced responses to drugs of abuse, and consequently are thought to be more vulnerable to addiction. The ovarian hormone estradiol has emerged as a key facilitator in the heightened development of addiction in females. These actions of estradiol appear mediated by estrogen receptor (ER) activation of metabotropic glutamate receptor type 5 (mGluR5). However, the downstream effectors of this ER/mGluR5 signaling pathway are unknown. Here we investigate whether cannabinoid 1 receptor (CB1R) activation is a part of the mechanism whereby estradiol influences behavioral and synaptic correlates of addiction. Following repeated cocaine administration, estradiol-treated ovariectomized rats exhibited both sensitized locomotor responses and decreases in the dendritic spine density of nucleus accumbens core medium-spiny neurons in comparison to oil-treated controls. Both effects of estradiol were blocked by AM251, a CB1R inverse agonist. These results indicate that part of the signaling mechanism through which estradiol impacts behavioral and synaptic correlates of addiction in female rats requires activation of CB1Rs.

Sex Differences in Animal Models: Focus on Addiction

The purpose of this review is to discuss ways to think about and study sex differences in preclinical animal models. We use the framework of addiction, in which animal models have excellent face and construct validity, to illustrate the importance of considering sex differences. There are four types of sex differences: qualitative, quantitative, population, and mechanistic. A better understanding of the ways males and females can differ will help scientists design experiments to characterize better the presence or absence of sex differences in new phenomena that they are investigating. We have outlined major quantitative, population, and mechanistic sex differences in the addiction domain using a heuristic framework of the three established stages of the addiction cycle: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Female rats, in general, acquire the self-administration of drugs and alcohol more rapidly, escalate their drug taking with extended access more rapidly, show more motivational withdrawal, and (where tested in animal models of "craving") show greater reinstatement. The one exception is that female rats show less motivational withdrawal to alcohol. The bases for these quantitative sex differences appear to be both organizational, in that estradiol-treated neonatal animals show the male phenotype, and activational, in that the female phenotype depends on the effects of gonadal hormones. In animals, differences within the estrous cycle can be observed but are relatively minor. Such hormonal effects seem to be most prevalent during the acquisition of drug taking and less influential once compulsive drug taking is established and are linked largely to progesterone and estradiol. This review emphasizes not only significant differences in the phenotypes of females and males in the domain of addiction but emphasizes the paucity of data to date in our understanding of those differences.

Toll-like Receptors in the Vascular System: Sensing the Dangers Within

Toll-like receptors (TLRs) are components of the innate immune system that respond to exogenous infectious ligands (pathogen-associated molecular patterns, PAMPs) and endogenous molecules that are released during host tissue injury/death (damage-associated molecular patterns, DAMPs). Interaction of TLRs with their ligands leads to activation of downstream signaling pathways that induce an immune response by producing inflammatory cytokines, type I interferons (IFN), and other inflammatory mediators. TLR activation affects vascular function and remodeling, and these molecular events prime antigen-specific adaptive immune responses. Despite the presence of TLRs in vascular cells, the exact mechanisms whereby TLR signaling affects the function of vascular tissues are largely unknown. Cardiovascular diseases are considered chronic inflammatory conditions, and accumulating data show that TLRs and the innate immune system play a determinant role in the initiation and development of cardiovascular diseases. This evidence unfolds a possibility that targeting TLRs and the innate immune system may be a novel therapeutic goal for these conditions. TLR inhibitors and agonists are already in clinical trials for inflammatory conditions such as asthma, cancer, and autoimmune diseases, but their study in the context of cardiovascular diseases is in its infancy. In this article, we review the current knowledge of TLR signaling in the cardiovascular system with an emphasis on atherosclerosis, hypertension, and cerebrovascular injury. Furthermore, we address the therapeutic potential of TLR as pharmacological targets in cardiovascular disease and consider intriguing research questions for future study.

PBOV1 correlates with progression of ovarian cancer and inhibits proliferation of ovarian cancer cells

Prostate and breast cancer overexpressed 1 (PBOV1) is significantly upregulated in prostate, breast and bladder cancer, while its expression status in ovarian cancer and its clinical significance are unclear. We examined the expression levels of PBOV1 mRNA and protein in ovarian cancer cell lines and primary tissues using real-time PCR and western blotting. Immunohistochemistry was employed to analyze PBOV1 expression in 17 normal ovaries, 13 cystadenoma tissues, 14 borderline tumor tissues, and 165 clinicopathologically characterized ovarian cancers. There was negative PBOV1 expression in the 17 normal ovarian epithelial tissues. Compared to the normal ovarian epithelial cells, PBOV1 mRNA and protein were overexpressed in ovarian cancer cell lines. There was high PBOV1 protein expression in the ovarian cancer tissues from 59 of the 165 (35.8%) patients; PBOV1 expression was weak in 106 (64.2%) patients. Notably, there were significant negative associations between high PBOV1 expression and ascending histological grade, late pT/pN/pM, and International Federation of Gynecology and Obstetrics (FIGO) stage (P<0.05). Patients with high PBOV1 expression had longer overall survival; patients with low PBOV1 expression had shorter survival. Multivariate analysis revealed that PBOV1 upregulation is an independent prognostic indicator for ovarian cancer and might serve as a tumor-suppressor gene. Furthermore, PBOV1 overexpression inhibited ovarian cancer cell proliferation and tumorigenesis in vitro and in a tumor transplantation nude mouse model. In conclusion, our results suggest that PBOV1 may play an important role in suppressing ovarian cancer proliferation and carcinogenesis. PBOV1 may be a novel and useful prognostic marker and potential target for treating human ovarian cancer.