Influence of environmental enrichment on hypothalamic-pituitary-adrenal (HPA) responses to single-dose nicotine, continuous nicotine by osmotic mini-pumps, and nicotine withdrawal by mecamylamine in male and female rats.

In the present study, we determined the effects of environmental enrichment (EE; Kong Toys and Nestlets) on sexually diergic HPA axis responses to single-dose nicotine (NIC), single-dose NIC following continuous NIC administration for two weeks, and NIC withdrawal by single-dose mecamylamine (MEC) in male and female rats. Blood sampling occurred before and after MEC and NIC administrations for the determination of adrenocorticotropic hormone (ACTH) and corticosterone (CORT). Supporting and extending our previous findings, EE appeared to produce anxiolytic effects by reducing hormone responses: Male and female rats housed with EE had lower baseline ACTH and significantly lower HPA axis responses to the mild stress of saline (SAL) injection than did those housed without EE. The sexually diergic responses to single dose NIC, continuous NIC, and MEC-induced NIC withdrawal were reduced by EE in many male and female groups. ACTH responses to continuous NIC and MEC-induced NIC withdrawal were blunted to a greater extent in female EE groups than in male EE groups, suggesting that females are more sensitive to the anxiolytic effects of EE. Because EE lowered stress-responsive hormones of the HPA axis in most groups, EE may be a useful intervention for stress reduction in animal models of NIC addiction. As well, the effectiveness of EE in animal studies of NIC withdrawal may enlighten human studies addressing coping styles and tobacco cessation in men and women.

The adult suicide-prone patient: a review of the medical literature and implications for oral and maxillofacial surgeons.

PURPOSE: Suicide is the 11th most common cause of death among American adults. Some individuals who commit suicide may have been treated by oral and maxillofacial surgeons in the days preceding the event. Because suicide often is preventable, in this report we review methods that are useful in identifying individuals at risk of imminent suicide and give suggestions for obtaining interventional assistance. METHODS: A Medline search using the key terms "suicide," "adult," and "oral surgery" was conducted. Articles selected were published in peer-reviewed journals. RESULTS: Individuals who have told their surgeon they have no further reason to live, have developed a suicide plan, have secured a lethal device, and have previously made such an attempt are at extreme risk and require immediate intervention. Additional risk factors include being white, aged older than 45 years, and unemployed; living alone, with poor social supports; having a current mental illness or history of mental illness, including substance abuse; and having a family history of suicide. Specialty-specific patients at highest risk are those treated for oral cancer and cosmetic issues and those with adverse surgical outcomes. With regard to assessment of these individuals, the modified SAD PERSONS acronym can assist surgeons in documenting the presence of major risk factors associated with adult suicide and in facilitating communication with emergency personnel. CONCLUSIONS: Suicide is a potentially preventable public health problem. Oral and maxillofacial surgeons can be key in elucidating clinically significant suicide potential in their patients and referring them for timely intervention.

Sexually diergic hypothalamic-pituitary-adrenal (HPA) responses to single-dose nicotine, continuous nicotine infusion, and nicotine withdrawal by mecamylamine in rats.

Hypothalamic-pituitary-adrenal (HPA) responses to single-dose nicotine (NIC) are sexually diergic: Female rats have higher adrenocorticotropic hormone (ACTH) and corticosterone (CORT) responses than do males. In the present study we determined HPA responses in male and female rats following single doses of NIC, a single-dose of NIC immediately following continuous NIC for two weeks, and NIC withdrawal by single-dose mecamylamine (MEC) following continuous NIC infusion for two weeks. Blood sampling occurred before and after MEC and NIC administrations for the determination of ACTH and CORT. In accordance with our previous findings, female ACTH and CORT responses to single-dose NIC were greater than male responses. This sex difference remained after single-dose NIC followed continuous NIC infusion, but HPA responses in both sexes were significantly lower in magnitude and duration than in the single-dose NIC alone groups. Sex differences also were observed following NIC withdrawal by MEC: the HPA responses to pretreatment with MEC were significantly higher in magnitude and duration in the continuous NIC groups than in the single-dose NIC groups. These results demonstrate that HPA responses to NIC are reduced and transient following continuous NIC infusion but are enhanced and sustained following NIC withdrawal by MEC after continuous NIC, suggesting that NIC habituation and withdrawal influence the stress responses in a diergic manner. These findings highlight the importance of sex differences in the effect of NIC on HPA axis activity and stress responsiveness, which may have implications for directing NIC-addiction treatment specifically towards men and women.

Sexually diergic, dose-dependent hypothalamic-pituitary-adrenal axis responses to nicotine in a dynamic in vitro perfusion system.

INTRODUCTION: The hypothalamic-pituitary-adrenal cortical (HPA) axis modulates physiological responses to stress. We previously reported sexually diergic, dose-dependent HPA responses in vivo following nicotine administration: Male rats had greater arginine vasopressin (AVP) responses than females, and female rats had greater adrenocorticotropic hormone (ACTH) and corticosterone (CORT) responses than males. The goal of the present study was to further investigate sexually diergic, dose-dependent HPA responses following nicotine addition to an in vitro model of the HPA axis, so that hormone output could be determined at each level of the axis. METHODS: Hypothalami, pituitaries, and adrenal glands were harvested from male and female rats. One-half hypothalamus, one-half pituitary, and one adrenal gland were placed individually into three jacketed tissue baths connected by tubing and perfused in series with physiological medium. Sampling ports between tissue baths were used to collect buffer before and after addition of various doses of nicotine, for measurement of AVP and corticotropin-releasing hormone (CRH) from the hypothalamus bath, ACTH from the pituitary bath, and CORT from the adrenal bath. Hormones were measured by highly specific immunoassays. RESULTS: Stable temperatures, flow rates, pH, and hormone baselines were achieved in the in vitro system. Consistent with our in vivo and earlier in vitro studies, nicotine added to the hypothalamus tissue bath significantly increased HPA responses in a sex- and dose-dependent manner: Males had greater AVP responses than did females, and females had greater CRH responses than did males. Sexually diergic ACTH and CORT responses were less apparent and were higher in females. DISCUSSION: Our in vitro system accurately models in vivo HPA responses to nicotine in both sexes and thus represents a reliable method for investigating the effects of nicotine on components of the HPA axis. These studies may be pertinent to understanding the biological differences to nicotine between men and women smokers.

A role for cell sex in stem cell-mediated skeletal muscle regeneration: female cells have higher muscle regeneration efficiency.

We have shown that muscle-derived stem cells (MDSCs) transplanted into dystrophic (mdx) mice efficiently regenerate skeletal muscle. However, MDSC populations exhibit heterogeneity in marker profiles and variability in regeneration abilities. We show here that cell sex is a variable that considerably influences MDSCs' regeneration abilities. We found that the female MDSCs (F-MDSCs) regenerated skeletal muscle more efficiently. Despite using additional isolation techniques and cell cloning, we could not obtain a male subfraction with a regeneration capacity similar to that of their female counterparts. Rather than being directly hormonal or caused by host immune response, this difference in MDSCs' regeneration potential may arise from innate sex-related differences in the cells' stress responses. In comparison with F-MDSCs, male MDSCs have increased differentiation after exposure to oxidative stress induced by hydrogen peroxide, which may lead to in vivo donor cell depletion, and a proliferative advantage for F-MDSCs that eventually increases muscle regeneration. These findings should persuade researchers to report cell sex, which is a largely unexplored variable, and consider the implications of relying on cells of one sex.

Adrenal androgen and gonadal hormone levels in adolescent girls with conduct disorder.

There are few data on the biological correlates of female antisocial behavior. This study compared adrenal androgen and gonadal hormone levels in adolescent girls with conduct disorder (CD) to girls without any psychiatric disorder (NC). We studied 87 girls, (47 CD; 36 NC), ages 15-17 years, obtaining three blood samples, drawn 20 min apart between 8 and 9 AM in the first 72 h of the onset of menstrual flow. Plasma was assayed for testosterone, estradiol, androstenedione, dehydroepiandrosterone (DHEA), dehydroepiandrosterone-sulfate (DHEA-S), sex hormone binding globulin (SHBG), and cortisol; area under the curve (AUC) for each of the three samples was used in the data analysis. We also calculated the Free Testosterone Index, Free Estrogen Index, Index of Hyperandrogenism and cortisol to DHEA ratio. In addition to receiving a full psychiatric interview, each girl completed a self-report questionnaire on general aggression. Main hormone analyses controlled for potentially confounding variables such as psychiatric comorbidity and race. Girls with CD had significantly lower cortisol to DHEA ratios, but did not differ from NC girls on any other hormone variable. Girls with symptoms of aggressive CD had significantly higher mean free testosterone indexes, lower SHBG levels, and lower cortisol to DHEA ratios than girls with non-aggressive CD. Girls with CD scored higher on the aggression questionnaire, but there was no association between general aggression and any hormone variable for the sample. Our data suggest that girls with CD, particularly aggressive CD, have lower cortisol to DHEA ratios, higher levels of free testosterone, and lower levels of SHBG. Clinical and research implications of these findings are discussed.

Novel in vitro perfusion system for the determination of hypothalamic-pituitary-adrenal axis responses.

INTRODUCTION: The hypothalamic-pituitary-adrenal (HPA) axis is a three-gland component of the endocrine system and a key modulator of the stress response. We have developed a novel in vitro perfusion system to enable the study of pharmacological and hormonal challenges to tissue components of the HPA axis. In vivo studies have shown functional sex differences (sexual diergism) in HPA responses to cholinergic drugs, and in the present in vitro study, we examine these differences at several levels of the HPA axis. METHODS: Hypothalami, pituitaries, and adrenal glands were collected from male and female rats (n=3 per sex). One-half hypothalamus, one-half pituitary, and one adrenal gland were placed individually into three Erlenmeyer flasks connected by tubing. Flasks were perfused with medium (pH 7.4) at 37 degrees C. Sampling ports between the flasks were used to collect buffer for determination of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and corticosterone (CORT) release from the hypothalamus, pituitary, and adrenal flasks, respectively, over an extended baseline period, to determine stability of the system, and after nicotine administration. RESULTS: The perfusion system produced steady CRH, ACTH, and CORT baselines, the ACTH and CORT values being comparable to in vivo basal ACTH and CORT values in jugular-vein-cannulated rats. In vitro CRH, ACTH, and CORT responses to nicotine were significantly increased at 10 min and returned to baseline by 30 min, the CRH and ACTH responses from female tissues being greater than responses from male tissues. These sex differences were similar to those following nicotine administration in vivo. DISCUSSION: The ability of this novel, dynamic in vitro system to replicate in vivo HPA axis responses supports its potential as a new method for pharmacological and toxicological studies.

Rat estrous cycle influences the sexual diergism of HPA axis stimulation by nicotine.

We previously reported that female rats had significantly greater hypothalamic-pituitary-adrenal (HPA) axis responses to cholinergic stimulation by nicotine (NIC) than did male rats. Females in defined estrous cycle stages, however, were not studied because of sample size limitations. We further explored this finding by determining HPA axis responses to two doses of NIC in female rats (N = 101) during different estrous cycle stages, and in males (N = 69). NIC doses were: 0.3 mg/kg, which provided the greatest female-male difference in the earlier study, and 0.5 mg/kg, which stimulated the HPA axis similarly in the two sexes. Plasma AVP, ACTH, and corticosterone were measured. Proestrous and estrous females had higher ACTH responses to NIC (0.3 mg/kg) compared to metestrous and diestrous females, and compared to males. ACTH responses to NIC (0.5 mg/kg) were similar, regardless of estrous cycle stage or sex. Males had higher AVP responses to both NIC doses compared to females in all estrous cycle stages. Corticosterone responses followed the ACTH responses, except that females in all estrous stages started from a higher corticosterone baseline compared to males. These results are similar to our earlier findings across the estrous cycle with non-specific cholinergic stimulation by physostigmine and suggest that the nicotinic system contributes to the differential HPA axis responses to cholinergic challenge across the estrous cycle.

Detection and management of cognitive impairment in primary care: The Steel Valley Seniors Survey.

OBJECTIVES: To identify characteristics of older primary care patients who were cognitively impaired and who underwent mental status testing by their physicians. DESIGN: Cross-sectional and retrospective analysis. SETTING: Seven small-town primary care practices. PARTICIPANTS: A total of 1,107 patients with a mean+/-standard deviation age of 76.3+/-6.6, screened using the Mini-Mental State Examination (MMSE); medical records reviewed. MEASUREMENTS: Demographics, MMSE, medical record information. Odds ratios (OR) with 95% confidence intervals (CI), adjusted for age, sex, and education. RESULTS: Thirty-one percent of the sample had MMSE scores of less than 25. Among these patients, physicians documented memory loss in only 23% which was significantly more often than in the higher scoring group (OR=1.9, 95% CI=1.3-2.8), basic activity of daily living (ADL) impairment in 7.9% (OR=2.4, 95% CI=1.3-4.4), instrumental ADL (IADL) impairment in 6.7% (OR=2.2, 95% CI=1.1=4.2), dementia in 12.2% (OR=3.7, 95% CI=2.0-6.8), and prescription of cholinesterase inhibitors in 7.6% (OR=4.4, 95% CI=1.9-10.2). Physicians recorded mental status testing largely in patients with research MMSE scores of 24 to 28, significantly more often when they also documented memory loss (OR=3.8, 95% CI=2.5-5.6) or impaired IADLs (OR=2.7, 95% CI=1.4-5.2), diagnosed dementia (OR=4.9, 95% CI=2.8-8.6), referred to specialists (OR=6.3, 95% CI=2.5-16.2) or social services (OR=3.6, 95% CI=1.8-7.3), or prescribed cholinesterase inhibitors (OR=8.5, 95% CI=4.2-17.5). CONCLUSION: Physicians noted impairment in a minority of impaired patients. They tested mental status in those with documented cognitive and functional difficulties, in very mildly impaired patients, and in those for whom they intervened.

Plasma leptin suppression by arginine vasopressin in normal women and men.

Leptin inhibits appetite by activating several neuroendocrine systems, including the hypothalamo-pituitary-adrenal cortical (HPA) axis. In turn, elevated glucocorticoids can increase circulating leptin. We therefore measured plasma leptin in 12 normal women and eight normal men administered low-dose physostigmine (PHYSO) and arginine vasopressin (AVP) to stimulate the HPA axis. The subjects underwent four test sessions 5-7 days apart: PHYSO (8 microg/kg IV), AVP (0.08 U/kg IM), PHYSO + AVP, and saline control. Serial blood samples were taken before and after pharmacologic challenge and analyzed for leptin, adrenocorticotropin (ACTH)1-39, cortisol, and AVP. Estradiol and testosterone also were measured at each test session. PHYSO and AVP produced no side effects in about half the subjects and predominantly mild side effects in the other half, with no significant female-male differences. Correlations between side effects (absent or present) after PHYSO or AVP and the corresponding leptin responses were nonsignificant. Baseline plasma leptin concentrations were significantly higher in the women than in the men (p < 0.003). Leptin concentrations following PHYSO remained unchanged from baseline, indicating that the short-lived ACTH and cortisol increases produced by PHYSO did not affect leptin secretion. In contrast, AVP administration, while also increasing ACTH and cortisol, suppressed leptin, to a significantly greater degree in the women than in the men (p = 0.01). This significant suppression of leptin by AVP has not been previously described; physiologically, it may be part of a negative feedback regulatory system between central leptin and its activation of the HPA axis, by inhibition of leptin production or acceleration of its clearance.

Estrous cycle influences on sexual diergism of HPA axis responses to cholinergic stimulation in rats.

Central cholinergic systems differentially modulate hypothalamic-pituitary-adrenal (HPA) axis activity in female and male animals (sexual diergism). We previously reported that male rats had significantly greater HPA axis responses to stimulation by physostigmine (PHYSO), an acetylcholinesterase (AChE) inhibitor, compared to females. Females in defined estrous cycle stages, however, were not studied because of sample size limitations. We, therefore, determined HPA axis responses to stimulation by PHYSO in females during all estrous cycle stages (n = 78), and in male rats (n = 75). Plasma arginine vasopressin (AVP), adrenocorticotropic hormone (ACTH), and corticosterone (CORT) were measured. Estrous cycle stage was determined by light microscopy of vaginal smears. Proestrous and estrous females had higher ACTH and CORT responses compared to metestrous and diestrous females. Males had higher ACTH and AVP responses compared to females in all cycle stages. CORT responses followed the ACTH responses, except that females started from a higher baseline in all estrous stages, compared to males. These results suggest that cholinergic regulation of the HPA axis differs among females across stages of the estrous cycle, as well as between males and females. These effects are likely due to differences in circulating sex steroids and their actions within the brain.