Investigation of Some Amino Acid Analogues and Metabolites as Inhibitors of Wool and Hair Growth

Reis, PJ; Tunks, DA; Rigby, R. D. G.; Morton, TC; Munro, SG

doi:10.1071/bi9830157

Cited by 6 publications

(4 citation statements)

References 27 publications

(26 reference statements)

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“…The specific effects of methionine on wool growth may well be related to some function of S-adenosylmethionine, which acts as a methyl donor for many important reactions and which is required for the synthesis of the polyamines spermidine and spermine (Pegg & McCann 1982). Experiments with analogues of methionine (ethionine and methoxinine) have supported the view that some effects of methionine on wool growth are mediated via S-adenosylmethionine (Reis & Tunks 1982;Reis et al 1983Reis et al , 1986).…”

Section: Discussionmentioning

confidence: 99%

Effects of the infusion of amino acids into the abomasum of sheep, with emphasis on the relative value of methionine, cysteine and homocysteine for wool growth

1990

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SUMMARYMerino sheep were given abomasal infusions of various amino acids or mixtures of amino acids. Effects on wool growth were measured using autoradiography or a clipping procedure and changes in the concentration of amino acids in plasma were measured in some experiments.Mixtures of five (28 g/day) or ten (45 g/day) essential amino acids (both mixtures containing 3 g methionine) stimulated wool growth of sheep receiving a maintenance ration; on average, the volume of wool grown increased 48% and 86%, respectively. When cysteine completely replaced methionine in these mixtures, wool growth was markedly reduced, but two-thirds of the methionine could be replaced by cysteine without affecting wool growth. Homocysteine was partially effective in replacing methionine and, when supplemented with betaine, folic acid and vitamin B12, the mixture was still significantly inferior to that containing methionine. In contrast, abomasal supplements of methionine or homocysteine alone were equivalent as supplements for wool growth. The results indicated a specific role for methionine in the control of wool growth, other than the provision of cysteine. This role was postulated to be related to some function of S-adenosylmethionine.Infusion often essential amino acids caused appreciable increases in the concentrations of cystine, methionine, cystathionine and taurine in plasma; total essential amino acids increased threefold whereas nonessential amino acids decreased in concentration. The replacement of methionine in the infusion by cysteine or homocysteine significantly altered the concentration of cystine, methionine and cystathionine in plasma.Evidence was obtained that the adverse effects on wool growth of high abomasal doses of methionine (10g/day) could not be reduced or prevented by provision of additional glycine and were not related to the supposed toxic effects of 3-methylthiopropionic acid, a metabolite of the transamination pathway.

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Section: Discussionmentioning

confidence: 99%

Effects of the infusion of amino acids into the abomasum of sheep, with emphasis on the relative value of methionine, cysteine and homocysteine for wool growth

1990

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“…However, the manner in which methoxinine produces its various effects is a matter of speculation. It has previously been pointed out (Reis et al 1983) that, in the absence of a sulfur or selenium atom, methoxinine would not act as a substrate for methionine adenosyltransferase (Lombardini et al 1970) and therefore would not act on wool fibres in the manner postulated for another methionine analogue, ethionine (Reis and Tunks 1982). Nevertheless, it is possible that methoxinine could interfere with the transulfuration pathway of methionine metabolism by virtue of the fact that L-methoxininechas been shown to be an inhibitor of methionine adenosyltransferase (Sufrin et al 1982).…”

Section: Discussionmentioning

confidence: 99%

“…Methoxinine was synthesized as described by Reis et al (1983). DL-Methionine was obtained from BDH Chemicals Ltd, Poole, England and L-cysteine hydrochloride monohydrate from Ajinomoto Co. Inc., Tokyo, Japan.…”

Section: Chemicals and Dosingmentioning

confidence: 99%

Effects of Methoxinine, an Analogue of Methionine, on the Growth and Morphology of Wool Fibres

Reis¹,

Tunks²,

Rigby³

et al. 1986

Aust. Jnl. Of Bio. Sci.

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Methoxinine (O-methyl-DL-homoserine) was given to 18 Merino sheep by intravenous infusion or injection in amounts of 52-100 mg/kg body weight. Effects on strength, morphology and growth rate of wool fibres were studied.On average, methoxinine reduced the strength of bundles of wool fibres to about one-third of pretreatment values, but the magnitude of the effect varied considerably between sheep. Methoxinine also reduced the staple crimp frequency over a distance of c. 5-30 mm. A loss of cuticle scale pattern on wool fibres was observed following dosing; other abnormalities included grooved cuticle scales, degraded sections of fibre and distorted fibres . ..wool growth was temporarily reduced after methoxinine administration to c. 60% of the pretreatment rate. Effects were greater and more rapid on length growth rate than on fibre diameter.None of the above effects of methoxinine was prevented by the concurrent administration of cysteine and the efficacy of the concurrent administration of methionine was equivocal. A continuation of the infusion of methionine for 4 weeks following methoxinine administration prevented the depression of wool growth and either prevented or reduced the effects on wool fibres.Following a dose of methoxinine (60 mg/kg) the concentration of methoxinine in blood plasma was 500-800 {lmolll, at the end of a 2-day infusion or 5 h after an injection. The concentration in plasma declined slowly thereafter and was 50-80 {lmolll after 5 weeks. The effects of methoxinine were not mediated via copper deficiency as judged by plasma copper concentrations and the failure to cause depigmentation of black wool.

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“…The distance along wool fibres between individual bands of [35S1cystine incorporation was measured using an image analyser (Ernst Leitz, Gmbh, Wexlar, West Germany); the diameter at each point was calculated from the fibre length and diameter measurements, assuming the fibres were cylindrical (Reis et al 1983).…”

Section: Wool Growthmentioning

confidence: 99%

Effects of Growth Hormone Administration on Wool Growth in Merino Sheep

Wynn

Wallace²,

Ac³

et al. 1988

Aust. Jnl. Of Bio. Sci.

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The effects of daily administration of 10 mg of highly purified ovine growth hormone (GH) for a period of 4 weeks on wool growth have been measured in 12 Merino ewes fed either a calculated maintenance energy intake or 1·6 times this amount (six on each ration). Concentrations of hormones, glucose, urea, a-amino N and amino acids in the blood were monitored and faeces and urine collected for measurement of nitrogen balance.Wool growth rate decreased by 200/0 during the 4 weeks of GH treatment in sheep fed the high energy diet, largely because of reduced wool fibre diameter. This was followed by restoration of normal growth and then an increase of up to 20% above control levels, a response which persisted for 12 weeks following cessation of GH administration, and which was due to increases in both fibre length and diameter. GH administration caused marked increases in plasma concentrations of GH, insulin and somatomedin C, glucose and free fatty acids, all of which returned to basal levels following cessation of GH administration. No consistent changes in plasma concentration of T 3 , T 4 , cortisol, prolactin or a amino N were detected. Plasma urea and methionine levels decreased during GH treatment and returned to, or were raised above, basal levels after the GH treatment period. GH injection also resulted in a net retention of N during treatment, followed by a transient period of net N loss.The GH-induced changes in wool growth may be caused by a change in the partitioning of amino acids between the muscle mass and the skin. No other contributing factor(s) were identified.

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Investigation of Some Amino Acid Analogues and Metabolites as Inhibitors of Wool and Hair Growth

Cited by 6 publications

References 27 publications

Effects of the infusion of amino acids into the abomasum of sheep, with emphasis on the relative value of methionine, cysteine and homocysteine for wool growth

Effects of the infusion of amino acids into the abomasum of sheep, with emphasis on the relative value of methionine, cysteine and homocysteine for wool growth

Effects of Methoxinine, an Analogue of Methionine, on the Growth and Morphology of Wool Fibres

Effects of Growth Hormone Administration on Wool Growth in Merino Sheep

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