F., MacDonald, S.W.S, Hunter, M., sildenafil daily use LevyBenecheton, J., & Strauss, E. (1999). Recovery after severe injury to the head sildenafil daily use. Intraindividual variability in cognitive performance in older adults.
Publication of the Massachusetts Medical Society, 4, 377–406.
Enhanced interstitial collagenase (matrix metalloproteinase-12) production of Kupffer cell by gadolinium sildenafil daily use chloride prevents pig serum–induced rat liver ﬁbrosis. Expression patterns of matrix Nonparenchymal Cells and Macrophages 231 378. Biochem Biophys Res Commun sildenafil daily use 2001. Knittel T, Mehde M, Kobold D, Saile B, Dinter C, Ramadori G.
2001), manstch sildenafil daily use et al.. This escalation is correlated with a dramatic elevation in basal reward thresholds. And decreased release of dopamine in the striatum , perhaps equally problematic for the neural sensitization hypothesis are data from imaging studies in human cocaine addicts showing tolerance to the ‘high’ associated with intravenous methylphenidate challenge in cocaine addicts actively using cocaine.
In fact, it was metabolic activity in the rectal gyrus (medial orbitofrontal cortex) that increased with methylphenidate challenge and correlated with cocaine craving (Volkow et al., 1999, 2002). The evidence from human studies of addiction is overwhelmingly one of tolerance to the pleasurable or hedonic sildenafil daily use effects of drugs. From a theoretical perspective, an allostatic decrease in reward function provides the most parsimonious explanation of escalated levels of cocaine self-administration and associated vertical shifts upward in the dose–injection function observed with extended access to the drug (Ahmed and Koob, 1997, 1999, 2001, 2003.
Indeed, with psychostimulants such tolerance is readily observable within one self-administration session (see Psychostimulants, Opioids, and Alcohol chapters). Similarly in animal models of escalation in drug intake there is evidence of upward shifts in the dose–effect function for cocaine self-administration in the animals showing escalation in drug intake compared to controls.
Curr Mol Med sildenafil daily use 1999. Mechanisms of liver injury. An overview.  Sahai A, Malladi P, Melin-Aldana H, Green RM, Whitington PF.
Upregulation of osteopontin expression is involved in the development of nonalcoholic steatohepatitis in a diatary murine model.
1986. Crowell and Burgess 1997. Den Herder and Redner 1989.
Gelles and Straus 1988.