γ-Amino-β-Hydroxy Butyric Acid Stimulates Prolactin and Growth Hormone Release in Normal Women*

Abstract

The influence of gamma-amino-beta-hydroxy butyric acid (GABOB) treatment on pituitary function has been investigated in this study. Different doses (50 x 100 mg) of GABOB were iv injected into three and six normal women, respectively. PRL and GH plasma levels were measured before and after the injection. The treatment with 150 mg GABOB, performed in another two normal women, was interrupted because of side-effects (loss of consciousness etc.) due to the treatment. The treatment with 50 mg GABOB did not induce significant variations of the two hormones; however, significant increases of PRL (P less than 0.05) and GH (P less than 0.01) plasma levels were observed after injection with 100 mg GABOB. The present data suggest that gamma-amino butyric acid (GABA) itself of GABAergic drugs might play an important role in the control of hypothalamic-pituitary function.

A Possible Role for λ-Aminobutyric Acid in the Control of the Endocrine Pancreas*

“…As it concerns GH, there are at least five drugs affecting GABAergic mechanisms (y-hydroxybutyric acid, yamino-/Miydroxybutyric acid, muscimol, baclofen, and diazepam) (5,6,(19)(20)(21) that are able to stimulate GH secretion. However, baclofen has been shown to exert opposite effects (decreased GH response to insulin-induced hypoglycemia and arginine) after chronic treatment (22).…”

“…Evidence for GABAergic control of ACTH, LH, PRL, and GH release has been reported (3)(4)(5)(6). Recently, GABA has been found in a variety of tissues outside of the central nervous system (CNS), with its highest concentration localized in the islets of Langerhans (7,8).…”

Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man

“…Recent studies have clearly shown that GABA-ergic compounds are capable of stimulating growth hor¬ mone secretion Fioretti et al 1978;Takahara et al 1977;Abe et al 1977;Vijayan & McCann 1978a;Tamminga et al 1978).…”

“…In contrast, reports on the effects of these com¬ pounds on prolactin release are controversial (In¬ vitti et al 1977;Fioretti et al 1978;Takahara et al 1977;Tamminga et al 1978;Vijayan & McCann 1978b;Mioduszewski et al 1976;Ondo & Pass 1976;Libertun & McCann 1976;Pass & Ondo 1977;Schally et al 1977;Rivier & Vale 1977;Hall et al 1977;Lamberts 8c MacLeod 1978;Locatelliet al 1978). The above investigations were carried out under conditions of acute drug administration and, to our knowledge, no information is at present available on the influence of protracted GABA treatment on growth hormone and prolactin secre¬ tion.…”

“…Its high concentra¬ tion in the hypothalamus (Baldessarini & Karobath 1973) and the existence in this part of the brain of cell bodies and nerve endings that concentrate [3H]GABA (Makara et al 1975) actively, make it likely that this amino acid plays a role in the control of hypothalamic-pitutary function. In fact, GABA and a number of GABA-ergic compounds have been shown to promote growth hormone release in laboratory animals and in man Fioretti et al 1978;Takahara et al 1977;Abe et al 1977;Vijayan & McCann 1978a;Tamminga et al 1978). The influence of these compounds on pro¬ lactin secretion is not clearly established: stimula¬ tion, inhibition and no change of prolactin secre¬ tion have all been reported Fioretti et al 1978;Takahara et …”