Pineal serotonin-N-acetyltransferase activity in four mammalian species

Rudeen, P. K.; Reíter, Russel J.; Vaughan, Mary K.

doi:10.1016/0304-3940(75)90065-8

Cited by 94 publications

(29 citation statements)

References 10 publications

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“…NAT and HIOMT are not lacking in the pig pineal gland. Indeed, the daytime activities of these two enzymes in the pineal gland of the pig are equivalent to those in other species; however, NAT simply does not increase during darkness as is the usual case [18].…”

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confidence: 84%

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Absence of a nocturnal rise in either norepinephrine, N-acetyltransferase, hydroxyindole-O-methyltransferase or melatonin in the pineal gland of the domestic pig kept under natural environment photoperiods

Reíter

Britt

Armstrong

1987

Neuroscience Letters

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Castrated male and intact female pigs were kept under natural photoperiodic and temperature condi tions and were killed over a 24 h period in either May (under long days) or in December (under short days). Neither the pineal norepinephrine (NE) concentration nor the melatonin content rose at night: like wise, neither the activities of N-acetyltransferase (NAT) nor hydroxyindole-O-methyltransferasc (HIOMT) increased during darkness. In May pineal melatonin content actually decreased (P<0.05) at night while in December NAT activity fell (P < 0.05) at night. Daytime levels of each of these variables were equivalent to those measured in other species. The absence of a nocturnal increase in pineal melato nin production in either Mayor December raises the possibility that pineal melatonin may be involved in regulating seasonal breeding in the pig in a manner different from other mammals. Alternatively, pineal melatonin production may be unrelated to seasonal reproduction in the pig.Few reports have examined levels of melatonin in the blood of the wild boar and domestic pig. Kennaway et al. [8] measured melatonin in the plasma of one boar and found that the midnight level was about 3 times higher than the midday value. The photoperiodic conditions under which the boar was kept were not specified. Accord ing to McConnell and Ellendorff [10], the plasma melatonin profile in domestic adult German Landrace sows is determined by the photoperiod environment to which the animals are exposed. Thus, under photoperiodic conditions of LD 12: 12 they found that 3 of 4 sows exhibited a nighttime rise in plasma melatonin (the increase ranged from 2 to 5-fold). However, when the animals were shifted to a summer photoperiod,

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confidence: 84%

“…Also, the fact that HIOMT values in the pig pineal did not exhibit a 24-h cycle is not unique inasmuch as the activity of this enzyme typically does not exhibit a rhythm in the pineal gland [6]. NAT activity, however, shows a nocturnal increase in all animals where it has been examined although the magnitude of the 24-h rhythm varies widely [18].…”

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confidence: 99%

Absence of a nocturnal rise in either norepinephrine, N-acetyltransferase, hydroxyindole-O-methyltransferase or melatonin in the pineal gland of the domestic pig kept under natural environment photoperiods

Reíter

Britt

Armstrong

1987

Neuroscience Letters

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“…The times o f injection o f N E were 08.00 h (early light phase). 16.00 h (late light phase), 22.00 h (early dark phase). 24.00 h (early to mid dark phase), 02.00 h (mid to late dark phase), and 04.00 h (late dark phase).…”

Section: Methodsmentioning

confidence: 99%

Norepinephrine or Isoproterenol Stimulation of Pineal N-Acetyltransferase Activity and Melatonin Content in the Syrian Hamster Is Restricted to the Second Half of the Daily Dark Phase

et al. 1987

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Seven experiments were performed to investigate the sensitivity of the hamster pineal gland to exogenously administered norepinephrine (NE). In these studies NE (1 mg/kg) administration was preceded (10 min earlier) by the injection of the catecholamine uptake inhibitor desmethylimipramine (DM I; 5 mg/kg). When DMIand NE were given at night, the hamsters were exposed to light to depress pineal N-acetyltransferase activity and melatonin values to low levels; the drugs were then given 20 (DMI) and 30 (NE) min later, and the subsequent changes in pineal N-acetyltransferase and melatonin were monitored. The combination of DMI and NE administration anytime during the normal light period or during the first 4 h of the normal dark period failed to stimulate either pineal N-acetyltransferase activity or melatonin levels. Conversely, DMI followed by NE (injected either intraperitoneally or subcutaneously) in the second half of the dark phase typically stimulated pineal melatonin production. Likewise, the NE agonist isoproterenol promoted pineal melatonin production only in the latter half of the dark phase. If hamsters were exposed to continual light at night or if they were superior cervical ganglionectomized, a procedure which sympathetically denervates the pineal gland, the stimulatory effect of NE on melatonin production was significantly suppressed. Thus, the hamster pineal gland is sensitive to NE only during the latter half of the normal dark period and both darkness and an intact sympathetic innervation to the pineal gland are required for the gland to develop maximal sensitivity to the catecholamine. Also, the hamster pineal seems not to exhibit a supersensitivity response to NE following a period of reduced exposure to the catecholamine. The normal nocturnal rise in melatonin production in the hamster pineal gland seems to be determined by two parameters: an increased production and secretion of NE by sympathetic nerve endings in the pineal at night and (2) an increased sensitivity of the β-receptors on the pinealocyte membranes to NE during the late dark phase.

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“…Titus the delay is much shorter in the guinea pig: whether mRNA synthesis is required is not known. In this spe cies, the night time elevation of NAT activity commences much earlier than in the rat, gerbil or golden hamster [21 ]. MT prod uction in the sheep in vivo also commences rapidly after the onset of darkness [37].…”

Section: Discussionmentioning

confidence: 71%

“…Neural connections with the habenula were demonstrated [19], and light-related alterations in firing patterns were observed [20], Other aspects of the physiology and biochemistry of the guinea pig pineal gland have received less attention. It is known that the night/day ratio of NAT activ ity is much smaller in the guinea pig than in the rat, golden hamster or gerbil [21], though in the case of the last two this is due to a higher day time level in the guinea pig, and not a lower level at night.…”

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Melatonin Production by the Guinea Pig Pineal Gland in vitro

McCance¹,

Parkington²,

Coleman³

1990

Neuroendocrinology

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The fluid bathing pineal glands isolated from guinea pigs was collected serially and its melatonin content was estimated. Production was found to be high (500 pg/5 min) soon after isolation of the gland: it declined exponentially to a maintained lower level (50 pg/5 min) with a half-time of 16–20 min. A rapid increase could be produced by exposure of the gland to the β-adrenoceptor agonist orciprenaline or by stimulating it electrically. The time course and the extent of the responses to either form of stimulation were similar in glands that had been taken in the morning, at dusk or in mid-dark: the prestimulation peak was lower from glands taken at dusk. Thus the pineal gland of the guinea pig is capable of responding rapidly to stimulation of its β-adrenoceptors at any time. These responses parallel the depolarization observed intracellularly in this species when the pineal gland is stimulated electrically or exposed to β-adrenoceptor agonists.

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Pineal serotonin-N-acetyltransferase activity in four mammalian species

Cited by 94 publications

References 10 publications

Absence of a nocturnal rise in either norepinephrine, N-acetyltransferase, hydroxyindole-O-methyltransferase or melatonin in the pineal gland of the domestic pig kept under natural environment photoperiods

Absence of a nocturnal rise in either norepinephrine, N-acetyltransferase, hydroxyindole-O-methyltransferase or melatonin in the pineal gland of the domestic pig kept under natural environment photoperiods

Norepinephrine or Isoproterenol Stimulation of Pineal N-Acetyltransferase Activity and Melatonin Content in the Syrian Hamster Is Restricted to the Second Half of the Daily Dark Phase

Melatonin Production by the Guinea Pig Pineal Gland in vitro

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