Maternal deprivation and prolonged suckling in the absence of milk alter the frequency and intensity of sucking responses in neonatal rat pups

Jaw-muscle EMG recordings reveal that 3–5-day-old rat pups suckling an anesthetized non-lactating dam emit one of three different sucking responses every 20–25 sec. The frequency and intensity of two of these responses increase if preceded by lengthy maternal deprivation and decrease during extended suckling in the absence of milk. Sucking in neonatal rats is pervasive, complex in structure, and unlike most other measures of suckling at this age, is affected by deprivation.