Opioid dependence is accompanied by neuroplastic changes in reward circuitry leading to a negative affective state contributing to addictive behaviors and risk of relapse. The current study presents a neuroimmune mechanism through which chronic opioids disrupt the ventral tegmental area (VTA) dopaminergic circuitry that contributes to impaired reward behavior. Opioid dependence was induced in rodents by treatment with escalating doses of morphine. Microglial activation was observed in the VTA following spontaneous withdrawal from chronic morphine treatment. Opioid-induced microglial activation resulted in an increase in brain-derived neurotrophic factor (BDNF) expression and a reduction in the expression and function of the K+Cl− co-transporter KCC2 within VTA GABAergic neurons. Inhibition of microglial activation or interfering with BDNF signaling prevented the loss of Cl− extrusion capacity and restored the rewarding effects of cocaine in opioid-dependent animals. Consistent with a microglial-derived BDNF-induced disruption of reward, intra-VTA injection of BDNF or a KCC2 inhibitor resulted in a loss of cocaine-induced place preference in opioid-naïve animals. The loss of the extracellular Cl− gradient undermines GABAA-mediated inhibition, and represents a mechanism by which chronic opioid treatments can result in blunted reward circuitry. This study directly implicates microglial-derived BDNF as a negative regulator of reward in opioid-dependent states, identifying new therapeutic targets for opiate addictive behaviors.

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OBJECTIVEKlippel-Feil syndrome (KFS) is characterized by congenital fusion of the cervical vertebrae. Due to its rarity, minimal research has been done to assess the quality and management of pain associated with this disorder. Using a large global database, the authors report a detailed analysis of the type, location, and treatment of pain in patients with KFS.METHODSData were obtained from the Coordination of Rare Diseases at Stanford registry and Klippel-Feil Syndrome Freedom registry. The cervical fusions were categorized into Samartzis type I, II, or III. The independent-sample t-test, Wilcoxon rank-sum test, and Friedman test were conducted, with significance set at p < 0.05.RESULTSSeventy-five patients (60 female, 14 male, and 1 unknown) were identified and classified as having the following types of Samartzis fusion: type I, n = 21 (28%); type II, n = 15 (20%); type III, n = 39 (52%). Seventy participants (93.3%) experienced pain associated with their KFS. The median age of patients at pain onset was 16.0 years (IQR 6.75–24.0 years), and the median age when pain worsened was 28.0 years (IQR 15.25–41.5 years). Muscle, joint, and nerve pain was primarily located in the shoulders/upper back (76%), neck (72%), and back of head (50.7%) and was characterized as tightness (73%), dull/aching (67%), and tingling/pins and needles (49%). Type III fusions were significantly associated with greater nerve pain (p = 0.02), headache/migraine pain (p = 0.02), and joint pain (p = 0.03) compared to other types of fusion. Patients with cervical fusions in the middle region (C2–6) tended to report greater muscle, joint, and nerve pain (p = 0.06). Participants rated the effectiveness of oral over-the-counter medications as 3 of 5 (IQR 1–3), oral prescribed medications as 3 of 5 (IQR 2–4), injections as 2 of 5 (IQR 1–4), and surgery as 3 of 5 (IQR 1–4), with 0 indicating the least pain relief and 5 the most pain relief. Participants who pursued surgical treatment reported significantly more comorbidities (p = 0.02) and neurological symptoms (p = 0.01) than nonsurgically treated participants and were significantly older when pain worsened (p = 0.03), but there was no difference in levels of muscle, joint, or nerve pain (p = 0.32); headache/migraine pain (p = 0.35); total number of cervical fusions (p = 0.77); location of fusions; or age at pain onset (p = 0.16).CONCLUSIONSMore than 90% of participants experienced pain. Participants with an increased number of overall cervical fusions or multilevel, contiguous fusions reported greater levels of muscle, joint, and nerve pain. Participants who pursued surgery had more comorbidities and neurological symptoms, such as balance and gait disturbances, but did not report more significant pain than nonsurgically treated participants.

Neurosurgery as a distinct speciality has been around for 100 years. Some of the earliest women neurosurgeons were European, emerging from the 1920 0 s onwards. Here we detail the rise of women in neurosurgery across Europe with a decade by decade account of big events and firsts across the continent. The emerging themes are seen in stories of pioneers with enormous resilience, camaraderie, trailblazing and triumphing in a system with great obstacles and challenges. Our journey through this chronology brings us to the modern day, where most European countries have or have had a woman neurosurgeon and the future for women in neurosurgery in the continent is very bright.