Individual Differences in Volitional Social Self-Administration and Motivation in Male and Female Mice Following Social Stress

BACKGROUND

A key challenge in developing treatments for neuropsychiatric illness is the disconnect between preclinical models and the complexity of human social behavior. We integrate voluntary social self-administration into a rodent model of social stress as a platform for the identification of fundamental brain and behavior mechanisms underlying stress-induced individual differences in social motivation.

METHODS

Here, we introduced an operant social stress procedure in male and female mice composed of 3 phases: 1) social self-administration training, 2) social stress exposure concurrent with reinforced self-administration testing, and 3) poststress operant testing under nonreinforced and reinforced conditions. We used social-defeat and witness-defeat stress in male and female mice.

RESULTS

Social defeat attenuated social reward seeking in males but not females, whereas witness defeat had no effect in males but promoted seeking behavior in females. We resolved social stress-induced changes to social motivation by aggregating z-scored operant metrics into a cumulative social index score to describe the spectrum of individual differences exhibited during operant social stress. Clustering does not adequately describe the relative distributions of social motivation following stress and is better described as a nonbinary behavioral distribution defined by the social index score, capturing a dynamic range of stress-related alterations in social motivation inclusive of sex as a biological variable.

CONCLUSIONS

We demonstrated that operant social stress can detect stable individual differences in stress-induced changes to social motivation. The inclusion of volitional behavior in social procedures may enhance the understanding of behavioral adaptations that promote stress resiliency and their mechanisms under more naturalistic conditions.

Sex differences in appetitive and reactive aggression

Aggression is an evolutionarily conserved, adaptive component of social behavior. Studies in male mice illustrate that aggression is influenced by numerous factors including the degree to which an individual finds aggression rewarding and will work for access to attack and subordinate mice. While such studies have expanded our understanding of the molecular and circuit mechanisms of male aggression very little is known about female aggression, within these established contexts. Here we use an ethologically relevant model of male vs. female aggression by pair housing adult male and female outbred CFW mice with opposite sex cage mates. We assess reactive (defensive) aggression in the resident intruder (RI) test and appetitive (rewarding) aggression in the aggression conditioned place preference (CPP) and operant self-administration (SA) tests. Our results show dramatic sex differences in both qualitative and quantitative aspects of reactive vs. appetitive aggression. Males exhibit more wrestling and less investigative behavior during RI, find aggression rewarding, and will work for access to a subordinate to attack. Females exhibit more bites, alternate between aggressive behaviors and investigative behaviors more readily during RI, however, they do not find aggression to be rewarding or reinforcing. These results establish sex differences in aggression in mice, providing an important resource for the field to better understand the circuit and molecular mechanisms of aggression in both sexes.

Binge ethanol drinking associated with sex-dependent plasticity of neurons in the insula that project to the bed nucleus of the stria terminalis

Modifications in brain regions that govern reward-seeking are thought to contribute to persistent behaviors that are heavily associated with alcohol-use disorder (AUD) including binge ethanol drinking. The bed nucleus of the stria terminalis (BNST) is a critical node linked to both alcohol consumption and the onset, maintenance and progression of adaptive anxiety and stress-related disorders. Differences in anatomy, connectivity and receptor subpopulations, make the BNST a sexually dimorphic region. Previous work indicates that the ventral BNST (vBNST) receives input from the insular cortex (IC), a brain region involved in processing the body's internal state. This IC-vBNST projection has also been implicated in emotional and reward-seeking processes. Therefore, we examined the functional properties of vBNST-projecting, IC neurons in male and female mice that have undergone short-term ethanol exposure and abstinence using a voluntary Drinking in the Dark paradigm (DID) paired with whole-cell slice electrophysiology. First we show that IC neurons projected predominantly to the vBNST. Next, our data show that short-term ethanol exposure and abstinence enhanced excitatory synaptic strength onto vBNST-projecting, IC neurons in both sexes. However, we observed diametrically opposing modifications in excitability across sexes. In particular, short-term ethanol exposure resulted in increased intrinsic excitability of vBNST-projecting, IC neurons in females but not in males. Furthermore, in females, abstinence decreased the excitability of these same neurons. Taken together these findings show that short-term ethanol exposure, as well as the abstinence cause sex-related adaptations in BNST-projecting, IC neurons.

Glutamatergic input from the insula to the ventral bed nucleus of the stria terminalis controls reward-related behavior

Individuals suffering from substance use disorder often experience relapse events that are attributed to drug craving. Insular cortex (IC) function is implicated in processing drug-predictive cues and is thought to be a critical substrate for drug craving, but the downstream neural circuit effectors of the IC that mediate reward processing are poorly described. Here, we uncover the functional connectivity of an IC projection to the ventral bed nucleus of the stria terminalis (vBNST), a portion of the extended amygdala that has been previously shown to modulate dopaminergic activity within the ventral tegmental area (VTA), and investigate the role of this pathway in reward-related behaviors. We utilized ex vivo slice electrophysiology and in vivo optogenetics to examine the functional connectivity of the IC-vBNST projection and bidirectionally control IC-vBNST terminals in various reward-related behavioral paradigms. We hypothesized that the IC recruits mesolimbic dopamine signaling by activating VTA-projecting, vBNST neurons. Using slice electrophysiology, we found that the IC sends a glutamatergic projection onto vBNST-VTA neurons. Photoactivation of IC-vBNST terminals was sufficient to reinforce behavior in a dopamine-dependent manner. Moreover, silencing the IC-vBNST projection was aversive and resulted in anxiety-like behavior without affecting food consumption. This work provides a potential mechanism by which the IC processes exteroceptive triggers that are predictive of reward.

Need-based prioritization of behavior

When presented with a choice, organisms need to assimilate internal information with external stimuli and past experiences to rapidly and flexibly optimize decisions on a moment-to-moment basis. We hypothesized that increasing hunger intensity would curb expression of social behaviors such as mating or territorial aggression; we further hypothesized social interactions, reciprocally, would influence food consumption. We assessed competition between these motivations from both perspectives of mice within a resident-intruder paradigm. We found that as hunger state escalated, resident animal social interactions with either a female or male intruder decreased. Furthermore, intense hunger states, especially those evoked via AgRP photoactivation, fundamentally altered sequences of behavioral choice; effects dependent on food availibility. Additionally, female, but not male, intrusion attenuated resident mouse feeding. Lastly, we noted environmental context-dependent gating of food intake in intruding mice, suggesting a dynamic influence of context cues on the expression of feeding behaviors.

East-West Flap After Mohs Micrographic Surgery

Repair of distal nasal defects resulting from Mohs micrographic surgery is a challenge, but surgeons can choose from a number of techniques. We present 3 cases in which an east-west flap was used to close the defect. The east-west flap is an easily conceived advancement flap that consists of a superior triangle used to cover the defect and an inferior triangle whose base is located along the advancement line. The flap results in an optimal cosmetic outcome and involves minimum movement of tissue (preserving the nasal architecture) and well-camouflaged suture lines.

Quorum sensing activity in Ophiostoma ulmi: effects of fusel oils and branched chain amino acids on yeast-mycelial dimorphism

AIMS

  For Ophiostoma (Ceratocystis) ulmi, the ability to undergo morphological change is a crucial factor for its virulence. To gain an understanding of quorum-sensing activity in O. ulmi as it relates to yeast-mycelium dimorphism control, this study examines the effects of branched-chain amino acids as well as their fusel alcohols and fusel acids as quorum sensing molecules.

METHODS AND RESULTS

  In a defined medium containing glucose, proline and salts, O. ulmi grew as yeasts when the culture was inoculated with a high density of spores (2 × 10(7)  CFU ml(-1) ) and as mycelia when inoculated with a low spore density (4 × 10(5)  CFU ml(-1) ). The cultures displaying yeast morphology secreted a quorum-sensing factor that shifted the morphology from mycelia to yeast. This quorum-sensing molecule was lipophilic and extractable by organic solvents from the spent medium. Using GC/MS analysis, it was determined that the major compound in the extract was 2-methyl-1-butanol. A similar effect was observed when the branched-chain amino acids (fusel alcohol precursors) were used as the nitrogen source. E, E-farnesol had no effect on the morphology of O. ulmi.

CONCLUSIONS

  Addition of the branched-chain amino acids or one of the compounds detected in the spent medium, 2-methyl-1-butanol or 4-hydroxyphenylacetic acid, or methylvaleric acid, decreased germ tube formation by more than 50%, thus demonstrating a quorum sensing molecule behaviour in O. ulmi cultures.

SIGNIFICANCE AND IMPACT OF THE STUDY

  This study presents advances in the investigation of dimorphism in O. ulmi, complementing the existing scientific basis, for studying, understanding and controlling this phenomenon.

Influence of the Synthesis Parameters on Textural and Structural Properties of MCM-41 Mesoporous Materials

MCM-41 mesoporous materials were synthesized under different hydrothermal conditions using organic templates, i.e. CTMA-Br, DTMA-Br. Reaction temperature (120 to 195 °C) and reaction time (24 to 120 hr) varied and their influence on the structure properties of MCM-41 was sought i.e. d = 36 to 41.6 Å for distinct micelles diameters. Also, insertion of polyaromatics into the surfactant micelles was determinant in the final pore diameter, i.e d = 35.4 to 48.6 Å.

Molecular vibrational analysis and MAS-NMR spectroscopy study of epilepsy drugs encapsulated in TiO2-sol–gel reservoirs

A nanostructured matrix, consisting of titania, was designed in such a way that an antiepileptic drug could be encapsulated and released according to a well-defined time release schedule. The titania was synthesized by a sol-gel method in which titanium n-butoxide was used as the precursor for the formation of the sol. The synthesis was optimized to yield a homogeneous particle size with a high porosity and an anatase crystal structure. The antiepilectic drugs, phenytoine or valproic acid, were added during the gelation stage in order to obtain a homogeneous gel phase. The resulting nanostructured matrix including the drug showed only weak attractive forces, such as London forces, dipole-dipole coupling, and in some cases hydrogen bonds. The resulting assembly, referred to as a reservoir, was characterized using conventional FTIR and NMR spectroscopic techniques. Theoretical simulation studies were performed so as to obtain an understanding of the equilibrium electrostatic potential distribution and the relative charges on the titania and the anticonvulsants.

Differences in cholesterol incorporation into mitochondria from hepatoma AS-30D and human term placenta

Cholesterol transport for steroidogenesis in the human placental mitochondria is an enigma as, contrary to other steroidogenic tissues, the human placenta does not express steroidogenic acute regulatory protein (StAR), a protein known to be required for efficient utilization of cholesterol by adrenal and gonadal mitochondria. These observations suggest the possibility that cholesterol transport in human placental mitochondria involves a similar system to that present in other non-steroidogenic tissues. We studied cholesterol incorporation into mitochondria isolated from AS-30D hepatoma cells and the human placenta. Mitochondria from both sources incorporated cholesterol in vitro. There were no differences in cholesterol incorporation into hepatoma mitochondria treated with or without trypsin. In contrast, the human placental mitochondria treated with trypsin did not incorporate exogenous cholesterol. The presence of ATP increased the uptake of cholesterol by human placental mitochondria. This increase was inhibited by vanadate. These results suggest that cholesterol incorporation into human placental mitochondria is mediated by protein(s).

Higher milk intake during pregnancy is associated with lower maternal and umbilical cord lead levels in postpartum women

Lead exposure and its deleterious effects continue to be a problem in many countries. The lack of effective and safe treatments for low-level intoxication has promoted environmental interventions to control different sources of lead. In this study we evaluated the effect of milk consumption in 1849 mother-and-child pairs participating in the lead surveillance program in Mexico City. The mean lead levels were 11.2 micrograms/dL for maternal blood lead (MBL) and 10.8 micrograms/dL in umbilical cord. The correlation between blood lead and umbilical cord lead was r = 0.74. Forty-eight percent of the MBL exceeded 10 micrograms/dL and 9.5% exceeded 20 micrograms/dL. Maternal blood lead was positively related to the use of lead-glazed ceramic were and to traffic exposure and was inversely related to the consumption of milk and orange juice. Women who reported the consumption of more than 7 glasses of milk per week had a blood lead level of 8.7 micrograms/dL; in comparison, those women who reported a consumption of less than 7 glasses per week had a blood lead level of 11.1 micrograms/dL. Similar findings were observed for lead measured in umbilical cord. The association between lead levels and milk intake remained unchanged after taking in consideration other predictors of blood lead. This study suggests that a simple intervention could reduce lead burden among women and their newborns.

[Colorectal cancer: study on 365 cases]

We report a clinic-endoscopical study about 365 patients, both of sex, between 26-95 years old, with colonoscopic diagnosis of colorectal cancer. Results showed that 61,92% were men and 38,08% women; in 92,60% the disease ocurred over 40 years old. 13,42% had malignant personal history -colorectal cancer, uterus and breast cancer, and others-; 13,97% had bening personal history-colorectal adenoma, cholecystectomy, and others-; Abdomina pain, change in intestinal habits, and bleeding were the moist frequent symptoms, with differences depending of the tumors localization in the colon or rectum. 62,57% of patients had anemia under 10g% of hernoglobin; in 85,23% the fecal occult blood test was positive. On 199 patients, the simple barium enema diagnosed the tumor in 66,33% only; but in the same group, colonoscopy diagnosed the cancer in 96,49% at first examination. In all patients, colonoscopywas excellent for diagnosis of the principal lesion, and for the identification of synchronous neoplasia. On 365 patients, colonoscopy diagnosed the cancer in 98,08% at first examination. The localization of tumors was: 57,63% in left colon (49,47% in rectum and sigmoid colon); 34,21% in the right colon; and 8,16% in transverse. Pathology showed that adenocarcinoma was the most frequent tumor 95,23%; 1,06% mucoid carcinoma; 1,06% epidermoid carcinoma; and 2,65% lymphorna. In 32,05% of cases there were synchronous lesions; 3,01% had other cancer, and 54 patients had 112 polyps (62,50% adenomatous polyp, 6,25% adenoma with non invasive or invasive adenocarcinoma, and 31,25% hiperplastic polyp. Authors emphasize the value of the detection and early diagnosis to decrese the colorectal cancer mortality.

[Adenoma of the colon and rectum]

318 adenomatous polyps were removed by colonoscopic polypectomy, from two hundred patients, between 25 to 88 years old; 60.50% men, and 39.50% women. 86.50% of patients were older than 50 years old. In 64.50% of patients the adenomatous polyp was single, and 35.50% had "multiple adenoma"; the lesions distribution was 72.64% in the rectum-sigmoid colon. The grade of dysplasia was severe in adenomas over 20mm, and in those of villous type. The malignant percentage was: 1.61% in the adenomatous polyp under 10mm in diameter, 8.49% in those of 10mm to 19mm, and 30.68% in the adenomas of 20mm or more. The adenocarcinomatous focus increased from 1.69% in the adenomas under 10mm to 58.33% in those of 40mm or more in diameter. The relationship between type of adenomatous polyp and his adenocarcinoma incidence was 7.66% in tubular type, 22.22% in tubular-villous, and 26.32% in villous type. The carcinoma incidence in all of the adenomas of this series was 11.95%.

[Therapeutic colonoscopy in patients with colonic and rectal polyps]

598 colorectal polyps were removed by therapeutic colonoscopy from 377 patients, of both sexes, between 1 and 88 years old, most of them with lower digestive symptoms. The polyps were unique in 67.37% and multiple in 32.63% of patients, and mostly located in rectum and sigmoid colon; 42.14% were pedunculated, 33.95% sessile++/sub-pedunculated, and 23.91% sessile in shape. In 51% the size was over 10 mm in diameter. Histologically, 68.68% were of epithelial neoplastic type: 60.91% adenoma; 6.42% adenoma with adenocarcinoma, and 1.35% polypoid carcinoma. 30.64 were epithelial non-neoplastic type: 20.32% hyperplastic polyp, and 0.51% hyperplastic polyp with tubular adenoma. Two patients (0.53%) had lower digestive hemorrhage immediately after the polypectomy. The complications were controlled with conservative measures without blood transfusion.

Laparoscopic inguinal herniorrhaphy. Techniques and controversies

Because of the remarkable success of laparoscopic cholecystectomy, numerous investigators have attempted to duplicate this success with laparoscopic herniorrhaphy. This article presents a different view of the preperitoneal anatomy, reviews the rationale behind the various laparoscopic approaches, and presents, in detail, the laparoscopic preperitoneal repair with mesh, including complications and early recurrences. An attempt is made to put the new laparoscopic procedures into perspective with regard to economic issues and safety.