Endogenous opiates: 1998

This paper is the twenty-first installment of our annual review of research concerning the opiate system. during 1998 that studied the behavioral effe cts of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; eating and dri nking; alcohol; gastrointestinal, renal, and hepatic function; mental illne ss and mood; learning, memory, and reward; cardiovascular responses; respir ation and thermoregulation; seizures and other neurologic disorders; electr ical-related activity; general activity and locomotion; sex, pregnancy, and development; immunologic responses; and other behaviors. (C) 1999 Elsevier Science Inc. All rights reserved.