[Neuropeptides and behavior. Methodologic and critical reflections]

Relations between a peptide, hormone or neurotransmitter and behavior involve a molecule and a frequently complex process. The psychobiologist suggest the need for caution against extensive, operative and pharmacologic use of the notion of behavior. Multifactorial organization of adaptive behavior lends itself poorly to a reductionism leading to the equation molecule-behavior; however, neuropeptides do modulate behavior, sometimes potently. These subjects are discussed from a methodologic and critical point of view. Neurobiologists and endocrinologists have too often neglected the organizational and controlling roles of behavior on global neurobiologic and neuroendocrine reactions. Several examples are given to illustrate these various propositions.