Pineal hydroxyindole - o - methyl transferase and n- acetyl transferase during sexual maturation of coturnix quail

Preslock, James P.

doi:10.1016/0024-3205(74)90182-9

Cited by 5 publications

(9 citation statements)

References 20 publications

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“…This feedback inhibition of melatonin upon its synthesizing enzymes may be of particular significance during rapid sexual maturation when pineal enzymes of Coturnix undergo dramatic changes in activities [A lexander et al, 1970;Preslock, 1974a], If the pineal of Coturnix is progonadotrophic during sexual maturation [Sayler and W olfson, 1967], it is possible that during rapid sexual maturation the pineal, through increased synthesis and secretion of melatonin, may act to promote gonadal maturation. However, at a critical pineal level of melatonin, the enzymes responsible for melatonin synthesis may be decreased by feedback-inhibition of melatonin, resulting in lowered enzymic activities during this stage.…”

Section: Discussionmentioning

confidence: 99%

“…[1965], as modified in our laboratory for microdeterminations [Preslock, 1974a]. This assay involves the incubation of 5.0 //I of pineal homogenate in 15-ml glassstoppered centrifuge tubes containing 50 /<g N-acetyl serotonin and 50 ni/<Ci of S-adenosyl-L-methionine (methyl-C14) in 295 tú 0.05 m phosphate buffer, pH 7.9.…”

Section: Methodsmentioning

confidence: 99%

“…(2) N-acetyl transferase: The assay for NAT was modified as a micromethod [Preslock, 1974a] from the procedure described by Dequchi and Axelrod [1972]. Pineal homogenate (5.0 /tl) was added to conical centrifuge tubes containing tryptamine hydrochloride (0.1 /jmol), acetyl-l-C14 coenzyme A (3.4 nM) and potassium phosphate (2.5 /zmol) in 62 /ú 0.05 m phosphate buffer, pH 6.9.…”

Section: Methodsmentioning

confidence: 99%

“…Although the biologically-active pineal substance has not been identified in this species, it is generally assumed to be melatonin since melatonin has been determined in the chicken pineal [A xelrod et al, 1964; Binkley et ai., 1973], and the enzymes responsible for its synthesis are present in Coturnix and fluctuate in response to photoperiodic [A lexa nder et al, 1970;Backstrom et al, 1972; O ishi and Lauber, 1973;Preslock, 1974a] and hormonal [P reslo ck , 1974b, c] manipulations. N-acetyl transferase (NAT) acetylates serotonin to Nacetyl serotonin, while hydroxyindole-O-methyl transferase (HIOMT) Omethylates N-acetyl serotonin to melatonin.It has been recently reported [Preslock, 1974a] that pineal HIOMT activity is decreased, and NAT increased, during the rapid sexual maturation …”

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confidence: 99%

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Melatonin Inhibition of Pineal Enzymes in <i>Coturnix </i>Quail

Wright¹,

Preslock²

1975

Neuroendocrinology

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The activities of the melatonin-forming enzymes hydroxyindole-O-methyl transferase (HIOMT) and N-acetyl transferase (NAT) were determined in pineals of mature female Coturnix quail receiving implants of melatonin (10 µg, 1 µg, 0.1 µg) weekly for 4 weeks. Both HIOMT and NAT were significantly decreased by implants of 10 and 1 µg melatonin compared to vehicle and intact controls. Oviductal weights tended to be higher with increasing quantities of melatonin. These results suggest that melatonin exerts a feedback inhibition upon its synthesizing enzymes which may be of particular importance during the rapid sexual maturation of this species.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Melatonin Inhibition of Pineal Enzymes in <i>Coturnix </i>Quail

Wright¹,

Preslock²

1975

Neuroendocrinology

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“…The enzymes responsible for the synthesis of melatonin, a pineal indoleamine thought to mediate this response, have been demonstrated in pineals of Coturnix quail (2,5,18,20,(22)(23)(24). N-Acetyl transferase (NAT) acetylates serotonin to N-acetyl serotonin, while hydroxy indole-O-methyl transferase (HIOMT) O-methylates N-acetyl serotonin to melatonin.…”

mentioning

confidence: 99%

Regulation of Pineal Enzymes by Photoperiod, Gonadal Hormones and Melatonin in Coturnix Quail

Preslock¹

1976

Horm Res

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The photoperiodic and hormonal regulation of melatonin-synthesizing enzymes was determined in pineals of Coturnix quail. N-Acetyl transferase (NAT) and hydroxyindole-O-methyl transferase (HIOMT) were twofold higher in pineals of female and male Coturnix quail during exposure to darkness (16L:8D). Castration decreased pineal HIOMT activity in both female and male Coturnix, while selective gonadal steroids restored activity. NAT was not affected by castration or gonadal steroids. Implantation of melatonin into female Coturnix decreased both HIOMT and NAT activities. These results suggest that NAT is regulated primarily by photoperiodicity, while HIOMT activity is a consequence of the external perceptive environment and the internal hormonal milieu, with both enzymic activities modulated by the feedback inhibitory influence of endogenous melatonin.

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Effect of steroid hormones on serotonin, norepinephrine and epinephrine contents in the pineal-paraphyseal complex of the soft-shelled turtle (Lissemys punctata punctata)

Mahata

1992

J Comp Physiol B

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Steroids (testosterone, oestrogen, progesterone, corticosterone, dexamethasone and deoxycorticosterone) were administered intramuscularly (0.1 mg.100 g bw-1) on seven consecutive days to juvenile male soft-shelled turtles. Serotonin, norepinephrine and epinephrine contents of the pineal-paraphyseal complex were measured spectrofluorometrically 24 h after the last injection. Testosterone and oestrogen decreased serotonin, norepinephrine and epinephrine levels. Progesterone treatment resulted in an increase of serotonin level and a fall in norepinephrine and epinephrine levels. Corticosterone treatment caused an increase of serotonin level and a decrease of norepinephrine and epinephrine levels. Dexamethasone failed to alter serotonin content, increased norepinephrine and decreased epinephrine levels. Deoxycorticosterone decreased serotonin and elevated epinephrine content.

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Pineal hydroxyindole - o - methyl transferase and n- acetyl transferase during sexual maturation of coturnix quail

Cited by 5 publications

References 20 publications

Melatonin Inhibition of Pineal Enzymes in <i>Coturnix </i>Quail

Melatonin Inhibition of Pineal Enzymes in <i>Coturnix </i>Quail

Regulation of Pineal Enzymes by Photoperiod, Gonadal Hormones and Melatonin in Coturnix Quail

Effect of steroid hormones on serotonin, norepinephrine and epinephrine contents in the pineal-paraphyseal complex of the soft-shelled turtle (Lissemys punctata punctata)

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