cues remains very high in individuals, even after many years of abstinence and after the last withdrawal symptom has receded. 7-9 Most of our knowledge and comprehension of drug habits and chronic relapse to drug-intake behaviors is based on the several decades of devoted search for the neurobiological mechanisms of motivation and choice for biological rewards, such as food and sex, as well as the understanding of the cognitive and experientially social-produced rewards (i.e., friendship, family and social status). 7,10 Moreover, the physiological mechanisms of the neural pathways and neuroplasticity events that underlie the generation of adaptive behavioral responses to motivationally relevant events and natural rewards, have led to a significant understanding of the pathological deregulation of cellular and molecular mechanisms and circuitry functions induced by drug addiction. 1,7,10 These altered changes in cellular and molecular mechanisms in drug addiction led researchers to postulate that "Addiction represents a pathological usurpation of the neural mechanisms of learning and memory that under normal circumstances serve to shape survival behaviors related to the pursuit of rewards and the cues that predict them." 1 In addition to this postulate, the advances in the search of the neural mechanisms of drug addiction showed that persistence vulnerability to drug-relapse in addicts after prolonged drug-free periods is caused by enduring, long-lasting changes in brain function (i.e., neuroadaptative plastic mechanisms) as a result of repeated drug use, genetic disposition and environmental associations learned with continuous drug use. 7 It has long been recognized that reward-processing depends on mesocorticolimbic dopamine (DA) system, comprising DA neurons in the ventral tegmental area (VTA) and their projections to the nucleus accumbens (NAc), amygdala, prefrontal cortex (PFCx) and other forebrain regions. 1,7,11 Addictive drugs act on the DA reward system, although the brain evolved to respond not to drugs but to natural rewards, such as food and sex. Appropriate responses to natural rewards have been evolutionarily important for survival, reproduction and for shaping several functions and behaviors. In the turn of the evolutionary ladder, humans discovered how to stimulate this system artificially with drugs. 12,13 The chemicals that the human abuse are structurally diverse and produce different behavioral effects in the user. However all share the common feature that they can interact, modulate Current pharmacotherapies for treating morphine/heroin dependence are designed to substitute or block addiction by targeting the drug itself rather than the brain. The heroin addict is still being exposed to addictive opiates, and consequently may develop tolerance to and experience withdrawal and drug's toxic effects from the treatment with high incidence of relapse to addictive drug consumption. As for other drugs of abuse, an alternative approach for morphine/heroin addiction is an antibody-based antagonism of...

Nociceptin/orphanin FQ (N/OFQ), added in vitro to murine spleen cells in the picomolar range, suppressed antibody formation to sheep red blood cells in a primary and a secondary plaque-forming cell (PFC) assay. The activity of the peptide was maximal at 10−12 M, with an asymmetric U-shaped dose response curve that extended activity to 10−14 M. Suppression was not blocked by pretreatment with naloxone. Specificity of the suppressive response was shown using affinity purified rabbit antibodies against two N/OFQ peptides, and with a pharmacological antagonist. Antisera against both peptides were active, in a dose related manner, in neutralizing N/OFQ -mediated immunosuppression, when the peptide was used at concentrations from 10−12.3 to 10−11.6 M. In addition, nociceptin given in vivo by osmotic pump for 48 hr suppressed the capacity of spleen cells placed ex vivo to make an anti-sheep red blood cell response. These studies show that nociceptin directly inhibits an adaptive immune response, i.e. antibody formation, both in vitro and in vivo.

The scaffold protein SH2B1, a major regulator of body weight, is recruited to the receptors of multiple cytokines and growth factors, including nerve growth factor (NGF). The β isoform, but not the α isoform, of SH2B1 greatly enhances NGF-dependent neurite outgrowth of PC12 cells. Here we asked how the unique C-terminal tails of the α and β isoforms modulate SH2B1 function. We compared the actions of SH2B1α and SH2B1β to those of the N-terminal 631 amino acids shared by both isoforms. In contrast to the β-tail, the α-tail inhibited the ability of SH2B1 to both cycle through the nucleus and enhance NGF-mediated neurite outgrowth, gene expression, phosphorylation of Akt and PLCγ and autophosphorylation of the NGF receptor TrkA. These functions were restored when Tyr753 in the α-tail was mutated to phenylalanine. We provide evidence that TrkA phosphorylates Tyr753 in SH2B1α, as well as tyrosines 439 and 55 in both SH2B1α and SH2B1β. Finally, co-expression of SH2B1α, but not SH2B1α Y753F, inhibited the ability of SH2B1β to enhance neurite outgrowth. These results suggest that the C-terminal tails of SH2B1 isoforms are key determinants of the cellular role of SH2B1. Furthermore, the function of SH2B1α is regulated by phosphorylation of the α-tail.

Disruption of the adaptor protein SH2B1 (SH2-B, PSM) is associated with severe obesity, insulin resistance, and neurobehavioral abnormalities in mice and humans. Here, we identify 15 SH2B1 variants in severely obese children. Four obesity-associated human SH2B1 variants lie in the Pleckstrin homology (PH) domain, suggesting that the PH domain is essential for SH2B1’s function. We generated a mouse model of a human variant in this domain (P322S). P322S/P322S mice exhibited substantial prenatal lethality. Examination of the P322S/+ metabolic phenotype revealed late-onset glucose intolerance. To circumvent P322S/P322S lethality, mice containing a two-amino acid deletion within the SH2B1 PH domain (ΔP317, R318 [ΔPR]) were studied. Mice homozygous for ΔPR were born at the expected Mendelian ratio and exhibited obesity plus insulin resistance and glucose intolerance beyond that attributable to their increased adiposity. These studies demonstrate that the PH domain plays a crucial role in how SH2B1 controls energy balance and glucose homeostasis.

Human variants of the adapter protein SH2B1 are associated with severe childhood obesity, hyperphagia, and insulin resistance - phenotypes mimicked by mice lacking Sh2b1. SH2B1β and γ isoforms are expressed ubiquitously, whereas SH2B1α and δ isoforms are expressed primarily in the brain. Restoring SH2B1β driven by the neuron-specific enolase promoter largely reverses the metabolic phenotype of Sh2b1-null mice, suggesting crucial roles for neuronal SH2B1β in energy balance control. Here we test this hypothesis by using CRISPR/Cas9 gene editing to delete the β and γ isoforms from the neurons of mice (SH2B1βγ NKO mice) or throughout the body (SH2B1βγ KO mice). While parameters of energy balance were normal in both male and female SH2B1βγ NKO mice, food intake, body weight, and adiposity were increased in male (but not female) SH2B1βγ KO mice. Analysis of long-read single cell RNA seq data from wild-type mouse brain revealed that neurons express almost exclusively the α and δ isoforms, whereas neuroglial cells express almost exclusively the β and γ isoforms. Our work suggests that neuronal SH2B1β and γ are not primary regulators of energy balance. Rather, non-neuronal SH2B1β and γ in combination with neuronal SH2B1α and δ suffice for body weight maintenance. While SH2B1β/γ and SH2B1α/δ share some functionality, SH2B1β/γ appears to play a larger role in promoting leanness.