Prolactin secretion seems to be regulated by central as well as by peripheral GABA receptors, the latter receptors being located dimctly on the anterior pituitary?2 Activation of the central and peripheral GABA receptors stimulates and inhibits, respectively, prolactin release?2 suggesting that GABA agonists like P4S and isoguvacine, which do not pass the BBB, have therapeutic interest in this clinical situation.In agreement with the involvement of GABA in feeding behavior, THIP (PO) has anorexigenic actions stronger than those of cocaine (PO) but ten times weaker than those of This action of THIP may be relevant for the treatment of human obesity.GABA Uptake Inhibitors as Potential Antiepileptics. The pharmacology of a number of GABA uptake inhibitors on single cells in vivo has been investigated using microelectrophoretic techniques. In experiments where inhibitor and GABA were administered simultaneously to cells in the spinal cord or in the cerebellum of cats,- all types of inhibitors, namely, DABA (neuronal) THPO (glial), and nipecotic acid, and guvacine (glial/neuronal) (Figure 2) enhanced the depressant action of GABA on neuronal firing. However, marked differences between different types of inhibitors were observed after intracerebroventricular (icv) injection into mice.73 DABA and ACHC provoked generalized seizures, whereas THPO and nipecotic acid protected the animals against audiogenic seizures, and systemic administration of THPO or prodrugs of nipecotic acid (Figure 4) effectively protected the animals against Why are inhibitors of neuronal GABA uptake convulsants and selective glial uptake inhibitors anticonvulsants? Intramuscular injections of THPO or nipecotic acid ethyl ester into mice elevate the concentration of GABA in the nerve terminals of the probably because blockade of the glial uptake system results in a preferential reuptake of synaptically released GABA into the nerve terminals. This increase of the releasable pool of GABA may facilitate the GABA neurotransmission process and in this way produce anticonvulsant effecks2The neuronal GABA uptake process seems to be coupled to the release system by an as yet unknown mechanism, and ACHC and related amino acids have been shown to be effective inducers of GABA release.B4 Thus, the convulsant effects of ACHC and DABA (icv) may be the consequence of interruption of GABA-mediated inhibition by depletion of GABA from the terminals. Nipecotic acid also has some effect on neuronal GABA uptake (Figure 2), although weaker than the effect on the glial system.33 Nipecotic acid does not, however, stimulate GABA release from synaptosomes in vitro, suggesting that the mechanism of interaction of this uptake inhibitor with the neuronal transport carrier is different from that of ACHC and DABA.B4 Such a difference may contribute to the difference between the pharmacology of these amino acids and nipecotic acid. In any case, the present investigations have brought glial GABA uptake inhibitors into focus as potential antiepileptic drugs.