Chronic nicotine exposure during adolescence differentially influences calcium-binding proteins in rat anterior cingulate cortex.

We have recently shown that chronic amphetamine exposure selectively up-regulates parvalbumin (PV) calcium-binding proteins in the anterior cingulate cortex (ACC). In this study, we evaluated the effects of chronic nicotine (NIC) exposure on PV, calbindin D28k (CB) and calretinin (CR) calcium-binding protein immunostaining in ACC GABAergic interneurons. Chronic NIC exposure for 3 weeks in adolescent rats, either via drinking water (the oral group) or by twice daily subcutaneous injections (the injection group), resulted in the expression of high levels of CR proteins in the ACC but not in the parietal cortex. Larger increases in the density of CR-immunoreactive (ir) neurons were noted in the NIC-injected rats at 0-day withdrawal (45% increase) compared with the oral group (26% increase). The larger increases in CR-ir neuron density in the NIC-injected rats were also reflected by prominent CR-ir processes across cortical layers. The density of PV-ir neurons was also increased (37%) at 0-day withdrawal but only in the oral NIC group and no changes in CB-ir neuron density were observed in either NIC group. Combined dual-immunofluorescence and confocal microscopy revealed that somatodendritic alpha4 nicotinic acetylcholine receptors colocalized with cortical neurons stained positively for CR, PV or CB. These results suggest that CR- and/or PV-ir-containing GABA interneurons may be involved in channeling the effects of NIC in the ACC, which is closely associated with the ventral basal ganglia circuit that is linked to brain reward function.

Plasminogen activator inhibitor-1 deficiency retards diabetic nephropathy.

BACKGROUND: Plasminogen activator inhibitor-1 (PAI-1) is increased in kidneys of humans and animals with diabetic nephropathy and is associated with extracellular matrix (ECM) accumulation. PAI-1 may promote ECM buildup by preventing plasmin and matrix metalloproteinase (MMP) activation. However, the importance and mechanism of PAI-1 action in the pathogenesis of diabetic nephropathy is unknown. METHODS: We investigated the effect of streptozotocin (STZ)-induced diabetes in wild-type (PAI-1(+/+)) mice and mice null for PAI-1 (PAI-1(-/-)). After 1 month of diabetes, animals were placed in metabolic cages for 24-hour urine collection. Total RNA was isolated from kidney cortex for reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis, and Western blots were quantitated from cortical protein. Primary mesangial cells were grown from Sprague-Dawley rats and used in signal transduction studies. RESULTS: Urinary albumin excretion (UAE) in diabetic PAI-1(+/+) mice increased >threefold, but remained unchanged in PAI-1(-/-) mice. Transforming growth factor-beta (TGF-beta) and fibronectin message and protein levels were lower in diabetic PAI-1(-/-) vs. PAI-1(+/+) mice, suggesting that PAI-1 deficiency impaired TGF-beta expression despite diabetes. Indeed, recombinant PAI-1 directly stimulated TGF-beta message and protein via mitogen-activated protein kinase (MAPK) signal transduction in cultured mesangial cells. Urokinase plasminogen activator (uPA) inhibited this PAI-1 action in a dose-dependent manner. The inhibitory effect of antibody to uPA receptor (uPAR) on PAI-1-induced TGF-beta function suggested that uPAR mediated the cellular effect of PAI-1. CONCLUSION: PAI-1 can regulate TGF-beta expression by binding to uPAR and activating the extracellular-regulated signal kinase (ERK)/MAPK pathway. Therefore, PAI-1 contributes to diabetic nephropathy by regulating TGF-beta and renal ECM production and may be a therapeutic target in diabetic nephropathy.