Offspring control of cerebrospinal fluid GABA concentrations in lactating rats.

The concentrations of gamma-aminobutyric acid (GABA) and its metabolic precursors glutamate (Glu) and ornithine (Orn) were measured in cerebrospinal fluid (CSF) samples obtained from the cisterna magna of freely moving lactating rats on: postpartum day 5 when the rats were with their pups, day 6, 6 h after removal of the pups, and day 7, 24 h after mother-pup reunion. The concentration of GABA was non-detectable in the absence of pups (condition 2) but forty-fold above the limit of detection whenever the rats and the pups were together (conditions 1 and 3). Glu and Orn were low in but increased in and still more so in. Thus, the CSF concentration of GABA, an inhibitory neurotransmitter which profoundly influences behavior and hormone secretion is markedly increased by the pup-related stimuli, which control the behavior and the endocrine secretions of the lactating rat.