Knowledge of sexual consent as a protective factor against sexual violence perpetration among first-year college men: a moderation analysis.

This study examined whether knowledge of sexual consent buffers the relationship between risk factors for sexual violence (SV) and SV perpetration among first-year college men. The study data were drawn from a longitudinal study with 1144 first-year college men. A series of generalized linear models were conducted to examine whether knowledge of sexual consent moderated the relationship between SV risk factors and SV perpetration. Knowledge of sexual consent moderated the effect of hypermasculinity (P < 0.001), binge drinking (P < 0.001), rape-supportive social norms (P = 0.007) and peer support for SV (P < 0.001) such that there was a positive association between risk factors and SV perpetration among those with lower, but not higher, knowledge of sexual consent. Knowledge of sexual consent did not significantly moderate the relationship between SV perpetration and outcome expectancies for non-consensual sex (P = 0.387) and pornography use (P = 0.494). Knowledge of sexual consent may counteract risk factors for SV perpetration among young college men. The findings highlight the need for consent education to be incorporated in youth comprehensive sexual education to increase knowledge of sexual consent prior to college and campus-based SV prevention programming delivered to college students.

The mass spectrometric analysis of the urinary metabolites of melatonin and its deuterated analogues, confirming their identity as N-acetylserotonin and 6-hydroxymelatonin.

In a recent study, we showed that melatonin could be metabolized to N-acetylserotonin and 6-hydroxymelatonin. To confirm this finding rats were administered three different forms of deuterated melatonin intraperitoneally. Their urines were analysed by gas chromatography/mass spectrometry and the results showed, in each case, that the appropriate deuterated (or non-deuterated) metabolite had been formed. From these data it is clear that N-acetylserotonin is a urinary metabolite of melatonin.

An investigation of demethylation in the metabolism of methoxytryptamine and methoxytryptophol.

Though melatonin is primarily metabolised to 6-hydroxy-melatonin, we have recently shown that it can also be demethylated to form N-acetyl-serotonin. The question therefore arises as to whether demethylation is a general metabolic pathway that can apply to other pineal methoxyindoles. To investigate this possibility we administered deuterated methoxy-tryptophol (dML) and deuterated methoxy-tryptamine (dMT) to rats and analysed the urine for the presence of deuterated methoxyindole acetic acid (dMIAA) and deuterated hydroxyindole acetic acid (dHIAA). The method of analysis was gas chromatography mass spectrometry (GCMS), where the relevant molecular ion and fragment ions were monitored. The results showed that the major metabolite in all cases was dMIAA. There was no evidence to suggest that the compounds had been demethylated to form dHIAA. The study therefore indicates that the demethylation of melatonin is a specific metabolic pathway that does not apply to other methoxyindoles.

Melatonin is metabolized to N-acetyl serotonin and 6-hydroxymelatonin in man.

To investigate whether melatonin (aMT) can be metabolized to N-acetyl serotonin (NAS), a low dose of deuterated aMT was administered to four normal subjects, and their urine samples were analyzed for the presence of deuterated NAS and deuterated 6-hydroxymelatonin (6-HaMT). In one set of experiments, the urine samples were subjected to column chromatography to separate the glucuronide and sulfate conjugates for independent analysis. In another, an internal standard (NAS-sulfate) was used for quantification and total conjugate analysis. Measurement was by gas chromatography-mass spectrometry, and the molecular ions of deuterated and nondeuterated NAS and 6-HaMT were monitored. Deuterated aMT was metabolized to deuterated NAS and deuterated 6-HaMT. The proportion of NAS was less in the sulfate than in the glucuronide conjugates and, overall, represented 15% of the total. Since demethylation is not a pathway that occurs with other pineal methoxyindoles, even at a much larger dose, it seems to be a significant finding with regard to aMT. Thus, it may be important to elucidate the differential metabolism of aMT at different time points and in different age groups.

Melatonin can be differentially metabolized in the rat to produce N-acetylserotonin in addition to 6-hydroxy-melatonin.

It has been generally agreed that the metabolism of the pineal hormone melatonin (aMT) consists of 6-hydroxylation followed by sulfate or glucuronide conjugation. The urinary assay of 6-hydroxy-melatonin (6-HaMT) is valued as a means of providing integrated information on aMT production. However, we show, in this study, that aMT has two principal urinary metabolites, N-acetylserotonin (NAS) as well as 6-HaMT. Rats were administered varying doses of aMT and their urines were collected and analyzed by thin layer chromatography and gas chromatography-mass spectrometry (GCMS). Thin layer chromatography of the urinary metabolites showed the expected pattern, a major spot at Rf 46%, the position of 6-sulfatoxy-melatonin, a less intense spot at Rf 32%, the position of 6-glucuronide-melatonin and a weak spot at Rf 78%, the unconjugated metabolite. However, after deconjugation and derivitization, GCMS analysis of the urines, or of the spot at Rf 46%, showed two products, one of which had the same GC retention time and mass spectrum as 6-HaMT, whereas the other had the GC retention time and mass spectrum of NAS. When deuterated aMT was administered, GCMS analysis showed the presence of deuterated 6-HaMT and deuterated NAS, proving that NAS was metabolized directly from aMT and not produced somewhere else in the body in response to aMT. Finally, GCMS analysis of urines after the administration of 6-HaMT or of NAS showed only one metabolic product in each case, i.e. 6-HaMT and NAS, respectively. This suggested that the conversion of aMT to 6-HaMT and NAS resulted from two independent metabolic pathways. It is understandable that research workers who relied entirely on chromatography should have failed to distinguish NAS and its conjugates from 6-HaMT and its conjugates since the chromatographic and staining properties of the two indoles are almost indistinguishable.

The assessment of a plasma melatonin assay using gas chromatography negative ion chemical ionization mass spectrometry.

It has been shown that negative ion chemical ionization can increase the sensitivity of the mass spectrometric assay of the pineal hormone melatonin. However, it is an exacting assay requiring extensive sample preparation which precludes its use as a general research tool. We have investigated different derivatizing reagents and reaction conditions to demonstrate that a simple negative ion chemical ionization assay can be developed which will measure low picogram or even femtogram levels of the hormone in samples where the data have been ambiguous.

Identification of O-acetyl-5-methoxytryptophenol in the pineal gland by gas chromatography-mass spectrometry.

The presence of O-acetyl-5-methoxytryptophol in the pineal glands of rats kept in the dark for 8 h, but not in the light, has been shown by means of g.l.c.-mass spectrometry. It is suggested that this compound may be the biologically active precursor of circulating methoxytryptophol.

Immediate response of 5-methoxytryptophol in the circulation to hypoglycaemic stress induced by insulin.

Pineal indoles have been shown to affect the release of anterior pituitary hormones but details of the interrelationships are lacking. Using a new gas chromatography-mass spectrometry (g.c.-m.s.) assay the concentration of 5-methoxytryptophol (ML) was measured in plasma samples obtained from 16 children undergoing investigation of pituitary function for delayed growth. All the children received an insulin tolerance test (ITT) to study their endocrine response to stress. Some children received luteinizing hormone releasing hormone (LH-RH) and/or thyrotrophin releasing hormone (TRH). The change in concentration of ML during an ITT was similar to the change in concentration of blood sugar; a drop at 20 min followed by a rise at 30 min. This was not significantly altered by the administration of LH-RH or TRH, nor was there a different pattern of response in children who were deficient in growth hormone as opposed to those with idiopathic delayed growth. The fall in concentration of ML with stress may mediate the increased secretion of pituitary hormones. Alternatively, the pineal gland may respond directly to insulin.

Melatonin, the pineal gland and human puberty.

Animal experiments have suggested that the pineal gland produces an anti-gonadotropic hormone. The hamster, for example, undergoes reproductive collapse when kept in short-day periods, an effect which is abolished by pinealectomy. Although there is little direct evidence about the endocrine role of the pineal gland in man, it has been noted that tumours of the pineal gland in young boys are associated with precocious puberty and the human pineal gland has been suggested to produce a substance that holds sexual maturation in check. This observation has been extended by Kitay, who has shown that destructive tumours are associated with precocious puberty whereas hyperactive tumours are associated with delayed puberty. However, no studies have described any change of pineal function with normal puberty. Because two pineal indoles, melatonin and methoxytryptophol, have been shown to be antigonadotropic when administered to animals, we have now measured them in schoolchildren. Our findings show that in young boys there is an abrupt fall in the concentration of melatonin with advancing development suggesting that it may play an important physiological role in the control of human puberty.

Concentration of 5-methoxytryptophol in pineal gland and plasma of the rat.

5-Methoxytryptophol, a serotonin metabolite, was measured by gas chromatography-mass spectrometry in pineal glands, plasma and control tissues (cerebral cortex and salivary glands) from male rats kept in a controlled lighting environment. In the pineal gland the level of 5-methoxytryptophol was significantly higher during the dark period than during the light, the absolute levels being an order of magnitude less than those of melatonin. In the plasma, the levels showed a reverse situation with respect to lighting conditions. No correlation was found between the 5-methoxytryptophol levels in plasma and the pineal gland in individual animals. These results suggest that there is no obvious correlation between pineal content and pineal activity. This may be due to a combination of rapid turnover, secretion and/or peripheral conversion of another 5-methoxyindole to 5-methoxytryptophol.

A sensitive and specific assay for 5-methoxytryptophol in plasma.

5-Methoxytryptophol (ML) is found in the pineal gland and is known to have biological activity especially as an antigonadotrophic agent, but methods have been lacking for its measurement in the circulation. A gas chromatography-mass spectrometry assay using a trimethylsilyl derivative has been developed for the routine measurement of ML in plasma. The assay is of great specificity and has a sensitivity of 20 pmol/l. Studies on the levels of pineal indoles in the circulation, however, have been hampered by the possibility that extraneous compounds are being cross-measured. Thus the specificity of the routine assay has been further validated by comparing it with an alternative assay system where all the major parameters were changed, i.e. derivatizing reagent, internal standard and mass number. Results that were obtained using both assay systems were closely comparable.

Changes in the concentration of 5-methoxytryptophol in the circulation at different phases of the human menstrual cycle.

The pineal indole 5-methoxytryptophol (ML) has been shown to have an antigonadal activity when administered to experimental animals, but data on its normal pattern of secretion have been lacking. Using a new gas chromatography-mass spectrometry assay, the concentration of ML at various phases of the human menstrual cycle has been studied. Daily samples were obtained throughout the month from five women with a normal cycle and two women taking an oral contraceptive. In women with a normal cycle levels of ML were found to be significantly lower in the last third of their cycle; this change was not seen in women taking an oral contraceptive who had low levels throughout the month. The changes in concentration of ML did not correlate with the changes in concentration of gonadotrophins.