Other rodent studies have determined that (a) chronic morphine use accelerates the progression of LPS-induced sepsis to septic shock [226]; (b) both chronic morphine and morphine withdrawal lower host immune defense against IM bacteria (reviewed in [225]); and (c) the opioid antagonist naltrexone (i.e., a prescription drug used in the management of alcohol and opioid dependence) blocks acute endotoxic shock in mice by inhibiting TNF-α production [227]. Here, TNF is linked to Shock.