Lee J. Grota

Determination of N-acetylserotonin and Melatonin Activities in the Pineal Gland, Retina, Harderian Gland, Brain and Serum of Rats and Chickens

An N-acetylserotonin/melatonin radioimmunoassay (NAS/Mel RIA) and a Mel RIA were developed to measure NAS and Mel contents in tissues of rats and chickens. Anti-NAS and anti-Mel sera were produced by immunization of rabbits with NAS-M-bovine serum albumin (BSA) and Mel-M-BSA, respectively. Anti-NAS serum used in the NAS/Mel RIA reacts equally well with NAS and Mel, while anti-Mel serum used in the Mel/RIA reacts specifically with Mel. The NAS and Mel levels in the pineal and Harderian gland, the retina and the brain of rats and chickens and Mel levels in chicken serum were determined using these RIAs. Levels of NAS and Mel in the rat pineal demonstrated diurnal rhythms with high levels during the dark period and low levels during the light period. The indole levels determined in this study correlate well with those obtained by other methods.

Continuous recording of maternal behaviour in Rattus norvegicus

Summary It was assumed that the time a lactating rat spends with its litter can be taken as a reflection of maternal behaviour. This was measured continuously in a dual-chambered apparatus which permitted the female to be with or away from its litter for any amount of time at any time of the day. It was found that the total time and the duration of each period that the mother spends with its litter shows an orderly decrease over the 21 days post-partum. Further analyses of these data indicated that there is a 24-hr rhythm in maternal behaviour. The rhythm appears to be inversely related to and may be a direct reflection of the rats characteristic 24-hr activity cycle. A comparison of the time spent with the litter with data obtained from a modified version of Seitzs maternal-behaviour scale yielded similar changes over time for those tests of the scale which did not involve any disruption of the ongoing behaviour of the mother or litter. Otherwise, there was no consistent relationship between these two measures or within the scale itself. Administration of the maternal-behaviour scale to females rearing litters in a single cage indicated that the above findings could be attributed to the use of the dual-chambered apparatus. These data further suggested that some aspects of the maternal-behaviour scale may be artifacts of the conditions of housing or method of administration, and may reflect emotional reactivity rather than maternal behaviour, per se. The continuous recording of maternal behaviour was also found to differentiate between females rearing large and small litters. The time spent with the litter over the 21-day post-partum period decreased more rapidly in females rearing litters of twelve than in females rearing litters of four animals. The data are interpreted as support for the assumption that the time that a lactating rat spends with its litter can be taken as a reflection of maternal behaviour. The main advantages of this procedure are that it provides a continuous recording that is not subject to sampling error or experimenter bias, and it takes advantage of the ongoing mother-litter interactions which are initiated by the animals themselves rather than forced by the proximity of a single cage or by the intervention of an experimenter.

Melatonin in the retina and the Harderian gland. Ontogeny, diurnal variations and melatonin treatment.

Abstract Using highly specific antibodies, melatonin has been identified immunohistologically in the rat retina, and the Harderian gland. The first truly significant amount of retinal melatonin was already detected in the 2 day old pups. The amount of melatonin progressively increased with age reaching adult levels around the 20th day. Diurnal variations with higher night levels of melatonin have been found in the adult in both retina and Harderian gland. Intraperitoneal injection or subcutaneous implantation of melatonin in beeswax (150 μg/rat) resulted in a vast increase in melatonin content in the retina and the Harderian gland of the juvenile and adult rats. No sexual differences have been registered in any experimental group. The concept of melatonin synthesis at peripheral sites independent of pineal production, the involvement of light-dark rhythm in the regulation of pineal and extrapineal melatonin content and the possibility of uptake mechanisms or receptors for melatonin in the retina and Harderian gland are discussed.

Effects of early experience on adrenocortical reactivity

Abstract Unmanipulated control animals and rats that were exposed to handling or electric shock either pre- or post-weaning were subsequently stimulated by being placed into a novel environment for 5 sec or 3 min. Plasma corticosterone levels were sampled 5, 15, or 30 min following the cessation of this stimulation and in animals that received no such stimulation. The handled and shocked animals did not differ. As a group, however, the corticosterone response of the manipulated animals showed them to be less reactive than controls irrespective of the duration of stimulation.

Immunohistological localization of N-acetylindolealkylamines in pineal gland, retina and cerebellum

Abstract An immunohistological method has been used for visualization of N-acetylindolealkylamines (N-acetylindoles) in the pineal gland, retina and cerebellum using antibody highly specific for two N-acetylindoles; namely, N-acetylserotonin and melatonin. Staining by a double antibody technique using fluorescein or peroxidase labeling revealed that N-acetylindole is present not only in the parenchymal cells of the pineal gland but also in the outer nuclear layer of the retina and in the granule and Golgi II cells of cerebellum. Because N-acetylindole was found in the retina and cerebellum even after pinealectomy, we can speculate that extrapineal biosynthesis of N-acetylindole may occur. The observation of staining for N-acetylindole in cerebellum of rat, rhesus monkey and man suggests that N-acetylindolealkylamines may be present in the central nervous tissue of all mammals.

Plasma Corticosterone Response to Parameters of Electric Shock Stimulation in the Rat

&NA; Rats were subjected to one of six intensities of electric shock administered for 30, 60, 120, or 240 sec., and then sacrificed immediately or 5, 15, or 60 min. later. Plasma corticosterone levels were determined and compared to values obtained from both unmanipulated controls and “handled” rats. It was found that merely placing the animals in the experimental cage increased corticosterone levels, and these levels were further elevated as shock intensity and duration were increased.

Effects of Bright Incandescent Light on Seasonal and Nonseasonal Major Depressive Disorder

Previous research has indicated that exposure to bright fluorescent light can benefit clinically depressed individuals. The present study, a 1- to 2-week open trial of bright (greater than or equal to 2,000 lux) incandescent light with seasonal (fall/winter) and nonseasonal depressives, produced a therapeutic effect on seasonal depression, as measured by three criteria for recovery: final score on the Hamilton Rating Scale for Depression (HRSD) less than 10; final HRSD score less than or equal to 50% of pretreatment HRSD score; no longer meets DSM-III criteria for major depressive disorder. Phototherapy was not effective in the nonseasonal patients, whose functioning was more impaired than that of the seasonal subjects even before the trial. No adverse effects were observed in any patient.

Adrenal involvement in conditioned immunosuppression.

Abstract A taste aversion was induced in rats by pairing cyclophosphamide, an immunosuppressive drug, with the consumption of saccharin, a novel drinking solution. Three days after conditioning, animals were injected with sheep erythrocytes; hemagglutinating antibody titers were determined 6 days later. Relative to control groups, conditioned animals provided with saccharin at the time of antigen injection showed an attenuated antibody response, confirming the results of previous studies. The injection of LiCl to elicit an adrenocortical response or the exogenous administration of corticosterone in place of the conditioned stimulus (saccharin) at the time of antigen injection did not lower antibody titer significantly. The results provide no support for the hypothesis of an adrenocortical mediation of conditioned immunosuppressive effects.

Serum Melatonin Response to Melatonin Administration in the Syrian Hamster

Chronic daily administration of melatonin (MT) can have potent effects on reproduction in the hamster. Various theories have been elaborated to explain these effects but little information has been available on circulating levels of MT following MT administration. We have examined the serum MT response in the male hamster to a single dose of 25 micrograms MT administered in the morning or in the afternoon--the same timing and dose used by others to produce reproductive effects. With both morning and afternoon administration, serum MT increased above 1,000 pg/ml and remained above the highest basal levels during most of the 24-hour cycle. These levels are clearly supraphysiologic ones. The decline in serum MT showed two distinct components following morning administration. Half-life of the initial component which probably represents rapid distribution into tissues was 17.3 min. A half-life of 25.1 h was calculated for the second component. We conclude that use of a 25-micrograms dose of melatonin to study pineal effects may be misleading.

Melatonin in human cerebrospinal fluid in daytime; Its origin and variation with age

Abstract Melatonin was measured in human daytime CSF samples originating in the lumbar sac and basal cisterns. No gradient was found for melatonin, although significantly more 5-hydroxyindoleacetic acid was found in the cisternal samples. This suggests that, in the daytime, melatonin is not released directly from the pineal into the third ventricle, as that would produce a CSF gradient. Presumably daytime CSF melatonin is derived from blood and the original sources may include the retina, intestine and pineal. Daytime human CSF melatonin showed a significant negative correlation with age over the age range 8 to 70 years.