Individual Variation in the Motivational and Neurobiological Effects of an Opioid Cue

A discrete cue associated with intravenous injections of cocaine acquires greater control over motivated behavior in some rats (‘sign-trackers'', STs) than others (‘goal-trackers'', GTs). It is not known, however, if such variation generalizes to cues associated with other drugs. We asked, therefore, whether a discrete cue (a light) associated with the intravenous administration of an opioid drug (the short-acting mu receptor agonist, remifentanil) acquires incentive motivational properties differently in STs and GTs, as indicated by tests of Pavlovian conditioned approach and conditioned reinforcement. Consistent with studies using cocaine, STs approached a classically conditioned opioid cue more readily than GTs, and in a test of conditioned reinforcement worked more avidly to get it. Interestingly, STs and GTs did not differ in the acquisition of a conditioned orienting response. In addition, the performance of conditioned approach behavior, but not conditioned orientation, was attenuated by pretreatment with the dopamine receptor antagonist, flupenthixol, into the core of the nucleus accumbens. Lastly, food and opioid cues engaged similar amygdalo–striatal–thalamic circuitry to a much greater extent in STs than GTs, as indicated by Fos expression. Taken together, these data demonstrate that, similar to food and cocaine cues: (1) a discrete opioid cue attains greater incentive motivational value in STs than GTs; (2) the attribution of incentive motivational properties to an opioid cue is dopamine dependent; and (3) an opioid cue engages the so-called ‘motive circuit'' only if it is imbued with incentive salience.     

Can Specialized Pro-resolving Mediators Deliver Benefit Originally Expected from Fish Oil?

Purpose of the Review

Fish oil (FO) supplementation has historically been used by individuals suffering from cardiovascular disease and other inflammatory processes. However, a meta-analysis of several large randomized control trials (RCTs) suggested FO conferred no benefit in reducing cardiovascular risk. Skeptics surmised that the lack of benefit was related to FO dose or drug interactions; therefore, the widely accepted practice of FO consumption was brought into question.

Recent Findings

Thereafter, Serhan et al. identified specialized pro-resolving mediators (SPMs) to be one of the bioactive components and mechanisms of action of FO. SPMs are thought to enhance resolution of inflammation, as opposed to classic anti-inflammatory agents which inhibit inflammatory pathways. Numerous diseases, including persistent Inflammation, immunosuppression, and catabolic syndrome (PICS), are rooted in a burden of chronic inflammation. SPMs are gaining traction as potential therapeutic agents used to resolve inflammation in cardiovascular disorders, inflammatory bowel disease, sepsis, pancreatitis, and acute respiratory distress syndrome (ARDS).

Summary

This narrative reviews the history of FO and the various studies that made the health benefits of FO inconclusive, as well as an overview of SPMs and their use in specific disease states.

     

Distribution of vesicular glutamate transporter-2 messenger ribonucleic Acid and protein in the septum-hypothalamus of the rat

The excitatory neurotransmitter glutamate is involved in the control of most, perhaps all, neuroendocrine systems, yet the sites of glutamatergic neurons and their processes are unknown. Here, we used in situ hybridization and immunohistochemistry for the neuron-specific vesicular glutamate transporter-2 (VGLUT2) to identify the neurons in female rats that synthesize the neurotransmitter glutamate as well as their projections throughout the septum-hypothalamus. The results show that glutamatergic neurons are present in the septum-diagonal band complex and throughout the hypothalamus. The preoptic area and ventromedial and dorsomedial nuclei are particularly rich in glutamatergic neurons, followed by the supraoptic, paraventricular, and arcuate nuclei, whereas the suprachiasmatic nucleus does not express detectable amounts of VGLUT2 mRNA. Immunoreactive neurites are seen in very high densities in all regions analyzed, particularly in the preoptic region, followed by the ventromedial, dorsomedial, and arcuate nuclei as well as the external layer of the median eminence, whereas the mammillary complex does not exhibit VGLUT2 immunoreactivity. Many VGLUT2 immunoreactive fibers also contained synaptophysin, suggesting that the transporter is indeed localized to presynaptic terminals. Together, the results identify glutamatergic cell bodies throughout the septum-hypothalamus in region-specific patterns and show that glutamatergic nerve terminals are present in very large numbers such that most neurons in these brain regions can receive glutamatergic input. We examined the GnRH system as an example of a typical neuroendocrine system and could show that the GnRH perikarya are closely apposed by many VGLUT2-immunoreactive boutons, some of which also contained synaptophysin. The presence of VGLUT2 mRNA-containing cells in specific nuclei of the hypothalamus indicates that many neuroendocrine neurons coexpress glutamate as neurotransmitter, in addition to neuropeptides. These systems include the oxytocin, vasopressin, or CRH neurons as well as many others in the periventricular and mediobasal hypothalamus. The presence of VGLUT2 mRNA in steroid-sensitive regions of the hypothalamus, such as the anteroventral periventricular, paraventricular, or ventromedial nuclei indicates that gonadal and adrenal steroid can directly alter the functions of these glutamatergic neurons.     

Heavy chain diseases

Heavy chain diseases (HCDs) are rare B-cell lymphoplasma-cell proliferative disorders characterized by production of truncated monoclonal immunoglobulin heavy chains without associated light chains. HCDs involving the three main immunoglobulin classes have been described; alpha-HCD is the most common and has the most uniform presentation, gamma- and mu-HCDs have variable clinical presentations and histopathologic features. HCDs can be thought of as variant types of non-Hodgkin lymphoma: alpha-HCD presents as an extranodal marginal-zone lymphoma of mucosa-associated lymph-node tissue, gamma-HCD as lymphoplasmacytoid non-Hodgkin lymphoma, and mu-HCD as small lymphocytic non-Hodgkin lymphoma or chronic lymphocytic leukemia. Diagnosis of HCD requires documentation of a deleted immunoglobulin heavy chain without a bound light chain in the serum or urine. Prognosis is variable, and no standardized effective treatment programs are available except for alpha-HCD, which in its early stage may respond to antibiotics.     

Hepatic iron overload in blacks and whites: a comparative autopsy study

OBJECTIVE: Genetic susceptibility to iron loading is an important factor in the development of iron overload in Africans. This suggests that persons of African descent may be at risk to develop iron overload with its attendant complications, but relatively little is known about hepatic iron overload among blacks. The aim of this study was to compare the prevalence, histological features, and clinical correlates of hepatic iron overload in a group of autopsied black and white veterans. METHODS: Hepatic iron concentrations (HIC) were determined on liver tissue from autopsies performed at the John Cochran Veterans Affairs Medical Center during the period 1993 to 1996. Clinical information was obtained from autopsy protocols. Sections from livers in which the HIC exceeded the upper limit of normal were examined histologically. RESULTS: Of 256 specimens, 99 were from blacks (39%), whereas 157 were from whites (61%). Thirty-one blacks (31%) had an elevated HIC versus 44 whites (28%) (ns). In the majority of these cases (18 blacks, 30 whites), the HIC was less than twice the upper limit of normal. Nine of 15 subjects with an HIC greater than twice the upper limit of normal and no evident cause of secondary iron overload were black. CONCLUSIONS: The prevalence of mild-to-moderate hepatic iron overload was similar in this group of black and white veterans. Because of the inherent limitations of autopsy studies, prospective assessment of iron stores in healthy blacks is needed to determine more accurately the prevalence and clinical significance of iron overload in this population.     

IgD multiple myeloma: a cure at 21 years

A 52-year-old man with a plasmacytoma of the body of T-10 in February 1965 returned 6 months later with multiple myeloma characterized by bone pain, osteolytic lesions, and IgD lambda monoclonal protein in the serum, 6.1 g of Bence Jones protein in the urine, and 21% plasma cells in the bone marrow. The M-protein and bone pain disappeared within 6 weeks after therapy with melphalan and prednisone was started. Therapy was discontinued in December 1974. Immunoelectrophoreses and immunofixations of the serum and urine over the years revealed no monoclonal protein. A mediastinal tumor developed, and the patient died of respiratory insufficiency on October 23, 1986. Autopsy revealed a large bronchogenic carcinoma of the right lung extending to the mediastinum, trachea, and esophagus. There was no evidence of multiple myeloma. This patient had responded rapidly to chemotherapy and had no recurrence of myeloma during a 21-year follow-up.     

Control of systemic capillary leak syndrome with aminophylline and terbutaline.

PURPOSE: Patients with systemic capillary leak syndrome have a characteristic triad of hypotension, hemoconcentration, and monoclonal gammopathy. They have frequent and severe attacks of hemoconcentration and hypotension accompanied by marked plasma shifts. The exact role of this monoclonal protein is unknown, but it probably leads, in some way, to an increase in capillary permeability. Despite efforts to resuscitate the patients during an acute attack, the syndrome is often fatal. Some success has been obtained in preventing the attacks with the beta-adrenergic-stimulating agent terbutaline. The purpose of this study was to determine the effectiveness of aminophylline and terbutaline in the treatment of systemic capillary leak syndrome. METHODS: Over a decade, three patients with systemic capillary leak syndrome presented at our institution. All three patients were treated with terbutaline and aminophylline. Prednisone was used during the course of treatment in each of the three patients. RESULTS: In contrast to previous reports of partial or temporary control of episodes, all three patients are alive with almost complete resolution of their recurrent attacks and have been able to return to their normal lifestyles. CONCLUSION: The regimen of terbutaline and aminophylline effectively prevents the attacks of hypotension and hemoconcentration that occur in systemic capillary leak syndrome. The role of prednisone is not clear. Until more is known about the pathophysiology of the disorder, treatment must remain empiric and supportive.     

Acute leukemia and cytogenetic abnormalities complicating melphalan treatment of primary systemic amyloidosis

We followed up 153 patients with biopsy-proven primary systemic amyloidosis to determine their risk for acute nonlymphocytic leukemia or a dysmyelopoietic syndrome. In 10 patients cytogenetic abnormalities developed consistent with alkylator-induced damage to hematopoietic cells. In this group, the total melphalan dose ranged from 476 to 2450 mg (median, 1764 mg) administered over 21 to 92 months (median, 38 months). Eight of the 10 patients died as a direct result of pancytopenia, 1 died of progressive renal amyloid, and 1 remains alive with persistent complex cytogenetic abnormalities. Four patients had acute nonlymphocytic leukemia; 5 had a dysmyelopoietic syndrome; and 1 had a nondiagnostic bone marrow examination. Although only 6.5% of the entire group had leukemia or a dysmyelopoietic syndrome, the actuarial risk in patients surviving 3.5 years was 21%. Median survival from onset of dysmyelopoietic syndrome or acute leukemia was 8.1 months.