Differential regulation of prodynophin, c-fos, and serotonin transporter mRNA following withdrawal from a chronic, escalating dose regimen of D-amphetamine.

Several lines of evidence suggest that D-amphetamine (D-AMPH) withdrawal induces a syndrome with symptoms similar to major depressive disorder (MDD). Upregulation of dynorphin (DYN) may underlie the symptoms of MDD and contribute to the negative emotional symptoms associated with psychostimulant withdrawal. Changes in the serotonin transporter (SERT) have also been reported in MDD, and changes in the immediate early gene c-fos have been observed in the context of psychostimulant withdrawal. This study examined the effects of chronic, escalating doses of D-AMPH followed by 24 h of withdrawal on the expression of prodynorphin (PD) and c-fos mRNA in limbic regions of the brain, caudate putamen (CPu), and brainstem and SERT mRNA expression in the dorsal raphe nucleus (DRN). Male Sprague-Dawley rats were treated three times a day for 4 days with escalating doses of D-AMPH (1-10 mg/kg) and sacrificed 24 h after the last injection. Following 24 h of withdrawal, there was an increase in PD and c-fos mRNA expression in the CPu and nucleus accumbens (NAc), and a decrease in PD and c-fos expression in hippocampus and amygdala. SERT mRNA expression was decreased in the DRN, and PD mRNA expression was increased in the adjacent ventrolateral periaqueductal gray (VLPAG) following D-AMPH withdrawal. These data indicate that region-specific changes in PD and c-fos expression occur after withdrawal, while SERT mRNA expression is suppressed, similar to what has been reported in MDD. Alterations in PD, c-fos, and SERT expression could contribute to the depression-like syndrome associated with psychostimulant withdrawal.

Central memory CD4 T cells are the predominant cell subset resistant to anergy in SIV disease resistant sooty mangabeys.

OBJECTIVE: HIV infection in humans and experimental SIV infection in rhesus macaques leads to the loss of recall antigen responses, immunological anergy in CD4 T cells and AIDS. In contrast, natural infection in sooty mangabeys with SIV does not lead to disease despite high viral loads accompanied by resistance of their CD4 T cells to undergo immunological anergy. The objective of the study was to further elucidate the mechanisms that contribute to anergy resistance in CD4 T cells from sooty mangabeys and identify whether the anergy resistance is a function of a specific subset or the entire cell population. MATERIALS AND METHODS: Susceptibility or resistance to anergy was analyzed in antigen specific and defined CD4 T cell subsets from peripheral blood of sooty mangabeys and rhesus macaques by using an in vitro anergy inducing protocol; expression of the anergy associated gene GRAIL was measured. RESULTS: Antigen specific CD4 T cells from SIV disease resistant sooty mangabey are relatively resistant to the development of anergy. This resistance is associated with a lack of an upregulation of GRAIL. Conversely, rhesus macaque CD4 T cells are sensitive to anergy induction associated with upregulation of GRAIL. Furthermore the anergy resistant phenotype of sooty mangabey CD4 T cells predominantly resides in central memory cells defined either as CD4+CD45RA-CD62L+ or CD4+CD28+CD95+CCR7+. CONCLUSIONS: The maintenance of recall responses in sooty mangabeys is associated with the resistance of central memory CD4 T cells to the induction of anergy which may represent an important mechanism underlying SIV disease resistance in this species.

Pathogenic and apathogenic courses of SIV infection are associated with distinct and characteristic regulatory patterns of G1/S and G2/M cell cycle checkpoints in CD4+ T cells.

Dysregulation of both the cell cycle within the CD4(+) T cells and T cell responses is characteristic for pathogenic HIV infection in humans and experimental SIV infection in rhesus macaques. However, SIV infection in sooty mangabeys does not lead to either an AIDS-like disease or such CD4(+) T cell dysregulation. A previous study has highlighted a potential role for cell cycle regulatory proteins in these distinct clinical outcomes. This study was performed to characterize the effect of SIV infection on the expression of cell cycle-related molecules in CD4(+) T cells of rhesus macaques and sooty mangabeys in attempts to define activation-induced gene expression patterns associated with disease resistance or susceptibility. First, T cell receptor (TCR)-mediated cell activation induced gene expression profiles that were unique to CD4(+) T cells from SIV-naive sooty mangabeys and rhesus macaques. More importantly, distinct and reproducible gene expression patterns were detected in CD4(+) T cells as a result of in vivo SIV infection in animals from each of the two species. In addition, SIV infection in both species showed significant differential effects on TCR activation-induced expression with a reproducible alteration of 10 genes highlighted by discordant effects on expression of Cyclin D3, Cyclin B, and RAD17. Therefore SIV infection in rhesus macaques and sooty mangabeys exhibits distinct and reproducible effects on cell cycle regulation in CD4(+) T cells during T cell activation that may be the basis for disease susceptibility vs. resistance in these two species, respectively.

Differential regulation of 5-HT2A receptor mRNA expression following withdrawal from a chronic escalating dose regimen of D-amphetamine.

Several lines of evidence indicate that psychostimulant withdrawal can induce negative emotional symptoms, such as anhedonia and dysphoria, which may be due in part, to dysfunction of the serotonin (5-HT) system, including alterations in 5-HT receptors. For example, changes in 5-HT(2A) receptor function in prefrontal cortex (PFC) have been reported in association with psychostimulant withdrawal. However, it is not known if alterations in 5-HT(2A) receptor mRNA expression occur in the PFC or other limbic-associated areas following withdrawal from chronic psychostimulant treatment. The goal of the current study was to determine the effects of chronic, escalating doses of D-amphetamine (D-AMPH) and withdrawal on the expression of 5-HT(2A) receptors in the cortex, caudate putamen, NAc and hippocampus of rat brain. Animals were treated three times a day for 4 days with escalating doses of D-AMPH (1-10 mg/kg). Twenty-four hours after the final dose of D-AMPH, animals were sacrificed and the tissue processed for in situ hybridization histochemistry. Chronic, escalating doses of D-AMPH, followed by a 24 h withdrawal period, significantly decreased 5-HT(2A) receptor mRNA expression in the prefrontal, motor and cingulate cortices, while 5-HT(2A) receptor mRNA expression in the NAc, caudal CPu and hippocampus were significantly increased. These data indicate that region-specific changes in 5-HT(2A) receptor mRNA expression occur in limbic system and associated areas following chronic D-AMPH treatment, supporting the notion that alterations in the 5-HT system may contribute to the negative emotional aspects of psychostimulant withdrawal.

Methamphetamine-induced stereotypy correlates negatively with patch-enhanced prodynorphin and arc mRNA expression in the rat caudate putamen: the role of mu opioid receptor activation.

Amphetamines induce stereotypy, which correlates with patch-enhanced c-Fos expression the patch compartment of caudate putamen (CPu). Methamphetamine (METH) treatment also induces patch-enhanced expression of prodynorphin (PD), arc and zif/268 in the CPu. Whether patch-enhanced activation of any of these genes correlates with METH-induced stereotypy is unknown, and the factors that contribute to this pattern of expression are poorly understood. Activation of mu opioid receptors, which are expressed by the neurons of the patch compartment, may underlie METH-induced patch-enhanced gene expression and stereotypy. The current study examined whether striatal mu opioid receptor blockade altered METH-induced stereotypy and patch-enhanced gene expression, and if there was a correlation between the two responses. Animals were intrastriatally infused with the mu antagonist CTAP (10 microg/microl), treated with METH (7.5 mg/kg, s.c.), placed in activity chambers for 3h, and then sacrificed. CTAP pretreatment attenuated METH-induced increases in PD, arc and zif/268 mRNA expression and significantly reduced METH-induced stereotypy. Patch-enhanced PD and arc mRNA expression in the dorsolateral CPu correlated negatively with METH-induced stereotypy. These data indicate that mu opioid receptor activation contributes to METH-induced gene expression in the CPu and stereotypy, and that patch-enhanced PD and arc expression may be a homeostatic response to METH treatment.

CD4+ T cells from simian immunodeficiency virus disease-resistant sooty mangabeys produce more IL-2 than cells from disease-susceptible species: involvement of p300 and CREB at the proximal IL-2 promoter in IL-2 up-regulation.

IL-2 is an important cytokine required for the physiological function of CD4(+) T cells. Immunological unresponsiveness-anergy- of CD4(+) T cells is characterized by the inability of these cells to synthesize IL-2. Both progressive HIV infection leading to AIDS in humans and SIV infection in rhesus macaques (RM) are associated with dysregulation of IL-2 synthesis. In certain nonhuman primate species, such as sooty mangabeys (SM), SIV infection does not lead to AIDS. We have shown that this is associated with the resistance of the CD4(+) T cells from SM to undergo anergy in vitro. In this study, we show that CD4(+) T cells from SM spontaneously synthesize 2- to 3-fold higher levels of IL-2 than corresponding cells from RM. Proximal IL-2 promoter constructs derived from SM show significantly higher activity than the RM-derived constructs in primary CD4(+) T cells, which is associated with an element at approximately nt -200. Activity of both constructs was up-regulated by p300 and down-regulated by CREB to a similar degree. Chromatin immunoprecipitation analysis showed significantly higher binding of p300 and lower binding of CREB to the SM promoter in vivo. Two single nucleotide substitutions present in the SM sequence around position -200 and -180 seem to increase the affinity of these sites for the binding of transcription factors, one of which was identified as Oct-1. These unique characteristics of the proximal IL-2 promoter in SM therefore can represent one of the mechanisms contributing to the resistance of these cells to undergo anergy.