Pharmaco~gicalResea~hCommunication~VoL 20 No.~ 1988 THE BIOINACTIVATION OF CEREBRAL TRH~ BY A SPECIFIC ANTISERUM AFFECTS NEONATAL AND ADULTBEHAVIOROF THE RAT F. Spadaro, F. Drago and U. Scapagnini Institute of Pharmacology, University of Catania Medical. School, Italy TRH-antiserum neonatal behavior - adult behavior -~ open field - grooming A great evide,;ce seems to suggest that TRH may have a role in the neurobiology of the newborn rat. It is present in rat and human placenta, in the amniotJc fluid and in human breast milk (Baram et al., 1977; Gibbons.et aI., 1975; Schambaugh et al., 1978). Furthermore, its concentration increases with gestational, age. It has also been observed that in spite of a very high concentration in the systemic circulation in the first days of life, TRH seems to be devoid of any endocrine activity (Oliver et a]., 1981).1nconsideration of these:findings, we investigated the possible role of TRH as a factor involved in,the process of brain maturation, by using a specific TRH antiserum in 3-day old rats and evaluating the consequent behavioral changes. Pregnant female rats of th6 Wistar strain were used. After the delivery, the pups were maintened in the same cage of the mother until they were 1 month old. They were successively caged separetely. TRH antiserum ~as raised in rabbits against synthetic rat TRH using Keyhole Lumpet hemocianine as a carrier protein and gluteraldehyde as a coupling agent. TR~ antiserum was injected i.p. in a single administration at day 3 of lie, and normal rabbit serum was injected in control animals. No significant difference was observed between animals treated with TRH antiserum and controls in the development of the neonatal reflexes, 21.7 0031-6989/88/030217-2/$03.00/0 © 1988 The Italian Pharmacological Society