Reference

Isolation of gamma-amino butyric acid from pig hypothalami and demonstration of its prolactin release-inhibiting (PIF) activity in vivo and in vitro

Isolation of gamma-amino butyric acid from pig hypothalami and demonstration of its prolactin release-inhibiting (PIF) activity in vivo and in vitro. Schally, Andrew V.; Redding, Tommie W.; Arimura, Akira; Dupont, Andre; Linthicum, George L. (Sch. Med., Tulane Univ., New Orleans, La., USA). Endocrinology (Philadelphia), 100(3), 681-91 (English) 1977. CODEN: ENDOAO. 9002-62-4 and 56-12-2 are cas registry numbers. These chemicals are also mentioned in this article. DOCUMENT TYPE: Journal CA Section: 2 (Hormone Pharmacology) Section cross-reference(s): 13 A non-retarded fraction with prolactin [9002-62-4]-release inhibiting factor (PIF) activity obtained by chromatog. of a conc. of porcine hypothalami on carboxymethyl-cellulose was chromatog. distinct from catecholamines. This fraction was purified further by 6 steps involving chromatog. on Sephadex G-25, countercurrent distribution, free-flow electrophoresis, and chromatog. on triethylaminoethyl cellulose. The PIF-active substance was isolated and identified as GABA [56-12-2] by: amino acid analyses using Na as well as Li-based buffers for resoln. of biol. fluids, thin-layer chromatog. of underivatized material as well as phenylthiocarbamyl derivs., and mass spectroscopy. Natural and synthetic GABA inhibited prolactin, but not LH release in vitro from isolated rat pituitary halves at doses as low as 0.1 .mu.g/L. The inhibition was proportional to the dose; natural and synthetic GABA possessed identical PIF activity. Synthetic GABA also decreased prolactin release in monolayer cultures of rat pituitary cells and inhibited TSH-releasing hormone [9015-91-2]-stimulated prolactin release. The inhibition of prolactin release in vitro by GABA was blocked by perphenazine, which inhibits PIF activity of catecholamines. GABA also suppressed prolactin release in vivo, although large doses were needed. Either rapid i.v. injection or infusion of GABA in doses of 1-100 mg in rats decreased serum prolactin levels, which were previously elevated by pretreatment with monoiodotyrosine, perphenazine, chlorpromazine, haloperidol, or sulpiride. .beta.-Hydroxy-GABA [13477-53-7] depressed prolactin release, but .beta.-(p-chlorophenyl)-GABA and 4 other analogs of GABA were not effective in vivo and(or) in vitro. Apparently, GABA can inhibit prolactin release by a direct action on the pituitary gland, but whether this effect is physiol. meaningful still remains to be detd. .

Study of the effect of free nitrogenous substances

Study of the effect of free nitrogenous substances. Koucky, M. (Anim. Prod. Res. Inst., Prague, Czech.). Zivocisna Vyroba, 22(7), 533-8 (Czech) 1977. CODEN: ZIVYAY. DOCUMENT TYPE: Journal CA Section: 18 (Animal Nutrition) Five expts. were performed to examine the action of 2 nonprotein N compds. (at 0.05-0.15% of the diet) fed to broilers. Administration of GABA [56-12-2] did not have a significant effect on the basic performance indexes. The best results were obtained at 0.10% GABA, the live wt. being increased by 3.9-4.2% and feed consumption reduced by 1.2-4.7%. Graded GABA doses did not have a significant effect on the protein content of the broiler muscle analyzed. Similarly, HABA (hydroxyaminobutyric acid) [13477-53-7] administration did not have a significant effect on live wt. at 0.05%. The remaining results were not clear. The effect of HABA on muscle protein content was not significant. There was no significant trend toward a decrease in the meat prodn. and no depressive effect on performance, health, and meat quality.