Voluntary and forced exposure to ethanol vapor produces similar escalation of alcohol drinking but differential recruitment of brain regions related to stress, habit, and reward in male rats.

A major limitation of the most widely used current animal models of alcohol dependence is that they use forced exposure to ethanol including ethanol-containing liquid diet and chronic intermittent ethanol (CIE) vapor to produce clinically relevant blood alcohol levels (BAL) and addiction-like behaviors. We recently developed a novel animal model of voluntary induction of alcohol dependence using ethanol vapor self-administration (EVSA). However, it is unknown whether EVSA leads to an escalation of alcohol drinking per se, and whether such escalation is associated with neuroadaptations in brain regions related to stress, reward, and habit. To address these issues, we compared the levels of alcohol drinking during withdrawal between rats passively exposed to alcohol (CIE) or voluntarily exposed to EVSA and measured the number of Fos+ neurons during acute withdrawal (16 h) in key brain regions important for stress, reward, and habit-related processes. CIE and EVSA rats exhibited similar BAL and similar escalation of alcohol drinking and motivation for alcohol during withdrawal. Acute withdrawal from EVSA and CIE recruited a similar number of Fos+ neurons in the Central Amygdala (CeA), however, acute withdrawal from EVSA recruited a higher number of Fos+ neurons in every other brain region analyzed compared to acute withdrawal from CIE. In summary, while the behavioral measures of alcohol dependence between the voluntary (EVSA) and passive (CIE) model were similar, the recruitment of neuronal ensembles during acute withdrawal was very different. The EVSA model may be particularly useful to unveil the neuronal networks and pharmacology responsible for the voluntary induction and maintenance of alcohol dependence and may improve translational studies by providing preclinical researchers with an animal model that highlights the volitional aspects of alcohol use disorder.

Ankle Power and Endurance Outcomes Following Isolated Gastrocnemius Recession for Achilles Tendinopathy.

BACKGROUND: Studies have demonstrated improved ankle dorsiflexion and pain reduction following a gastrocnemius recession (GR) procedure. However, changes in muscle performance during functional activities are not known. The purpose of this study was to determine the effect of an isolated GR on ankle power and endurance in patients with Achilles tendinopathy. METHODS: Fourteen patients with chronic unilateral Achilles tendinopathy and 10 healthy controls participated in this study. Patient group data were collected 18 months following GR. Pain was compared to preoperative values using a 10-cm visual analog scale (VAS). Patient-reported outcomes for activities of daily living (ADL) and sports were assessed using the Foot and Ankle Ability Measure (FAAM). Kinematic and kinetic data were collected during gait, stair ascent (standard and high step), and repetitive single-limb heel raises. Between-group and side-to-side differences in ankle plantarflexor muscle power and endurance were evaluated with appropriate t tests. RESULTS: Compared with preoperative data, VAS pain scores were reduced (pre 6.8, post 1.6, P < .05). Significant differences were observed between GR and Control groups for FAAM scores for both ADL (GR 90.0, Control 98.3, P = .01) and Sports subscales (GR 70.6, Control 94.6, P = .01). When compared to controls, ankle power was reduced in the involved limb of the GR group for all activities (all P < .05). Between-group and side-to-side deficits (GR group only) were also found for ankle endurance. CONCLUSION: The gastrocnemius recession procedure provided significant pain reduction that was maintained at the 18-month follow-up for patients with chronic Achilles tendinopathy who failed nonoperative interventions. There were good patient-reported outcomes for activities of daily living. However, compared to controls, ankle plantarflexion power and endurance deficits in the GR group were noted. The functional implications of the muscle performance deficits are unclear, but may be reflective of patients' self-reported difficulty during more challenging activities. LEVEL OF EVIDENCE: Level III, comparative study.