Vasotocin release from the pineal gland of newborn mammals: the involvement of GABA mechanisms.
The arginine vasotocin (AVT) levels were bioassayed in the pineal extracts from 20-day-old kittens and from 10-day-old rat pups and in the cerebrospinal (CSF) samples taken from 20-day-old kittens. The animals received daily (between the postnatal day 2 and the day of sacrifice) the selective GABA receptor antagonist picrotoxin (5 X 10(-7) mg) or the specific GABA agonist valproic acid (10(-5) mg). Picrotoxin was found to produce a decrease of the pineal AVT levels in newborn kittens and rats, and an increase of the AVT amount of the CSF samples from kittens. Valproic acid had opposite effects, producing an increase of pineal AVT in both species and a decrease of AVT levels in the kittens CSF samples below the sensitivity limit of the bioassay method. The result suggests that not only in adult, but also in newborn mammals, the inhibitory feed-back loop between the brain and the pineal gland is GABA-mediated and that the GABA-ergic mechanisms are involved in regulating the release of AVT from the pineal gland.
D000818:Animals; D000831:Animals, Newborn; D002415:Cats; D010852:Picrotoxin / Q000494:pharmacology; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000502:physiology*; D014635:Valproic Acid / Q000494:pharmacology; D014668:Vasotocin / Q000134:cerebrospinal fluid / Q000378:metabolism*
D010852:Picrotoxin; D011963:Receptors, GABA-A; D014635:Valproic Acid; D014668:Vasotocin