The pineal gland in sudden infant death syndrome: preliminary observations

Exploration of the white matter bundles connected to the pineal gland: A DTI study

PURPOSE

Pineal gland (PG) is a structure located in the midline of the brain, and is considered as a main part of the epithalamus. There are reports on the role of this area for brain function by hormone secretion, as well as few reports on its role in brain cognition. However, little knowledge is available on the PG, and in particular on the structural connectivity of this region with the other brain structures.

METHODS

Using diffusion-weighted images collected by a 3T MRI scanner, and using a sample of 61 (29 F) mentally and physically healthy young individuals in the age range of 20-30 years old, we tried to extract the white matter bundles connected to the PG. Based on prior knowledge, seven target bundles were suggested to be between the PG body and the PG roots, Pons, Periventricular region, thalamus, caudate, lentiform, suprachiasmatic nuclei, and the supercervical ganglia.

RESULTS

Nearly all the target bundles were successfully extracted, with the exception of the lentiform. Rate of identification of the tracts was different, with the bundle between the PG body and roots having the highest identification rate (97%); then it was with the Pons (70%), Periventricular region (57%), SCN (55%), left thalamus (52%), right thalamus (47%), left caudate (27%) and right caudate (22%).

CONCLUSION

This study is an attempt to expand our knowledge on the neuroanatomy of the PG, which might help for identifying further roles for it in brain functionality, and also be a help for the treatment of some disorders in the future.

Sudden infant death syndrome: Melatonin, serotonin, and CD34 factor as possible diagnostic markers and prophylactic targets

Sudden infant death syndrome (SIDS) is one of the primary causes of death of infants in the first year of life. According to the WHO's data, the global infant mortality rate is 0.64-2 per 1,000 live-born children. Molecular and cellular aspects of SIDS development have not been identified so far. The purpose of this paper is to verify and analyze the expression of melatonin 1 and 2 receptors, serotonin (as a melatonin precursor), and CD34 molecules (as hematopoietic and endothelial markers of cardiovascular damage) in the medulla, heart, and aorta in infants who died from SIDS. An immunohistochemical method was used to investigate samples of medulla, heart, and aorta tissues of infants 3 to 9 months of age who died from SIDS. The control group included children who died from accidents. It has been shown that the expression of melatonin receptors as well as serotonin and CD34 angiogenesis markers in tissues of the medulla, heart, and aorta of infants who died from SIDS is statistically lower as compared with their expression in the same tissues in children who died from accidents. The obtained data help to clarify in detail the role of melatonin and such signaling molecules as serotonin and CD34 in SIDS pathogenesis, which can open new prospects for devising novel methods for predictive diagnosis of development and targeted prophylaxis of SIDS.

A Probabilistic Atlas of the Pineal Gland in the Standard Space

Pineal gland (PG) is a structure located in the midline of the brain, and is considered as a main part of the epithalamus. There are numerous reports on the facilitatory role of this area for brain function; hormone secretion and its role in sleep cycle are the major reports. However, reports are rarely available on the direct role of this structure in brain cognition and in information processing. A suggestion for the limited number of such studies is the lack of a standard atlas for the PG; none of the available MRI templates and atlases has provided parcellations for this structure. In this study, we used the three-dimensional (3D) T1-weighted MRI data of 152 healthy young volunteers, and provided a probabilistic map of the PG in the standard Montreal Neurologic Institute (MNI) space. The methods included collecting the data using a 64-channel head coil on a 3-Tesla Prisma MRI Scanner, manual delineation of the PG by two experts, and robust template and atlas construction algorithms. This atlas is freely accessible, and we hope importing this atlas in the well-known neuroimaging software packages would help to identify other probable roles of the PG in brain function. It could also be used to study pineal cysts, for volumetric analyses, and to test any associations between the cognitive abilities of the human and the structure of the PG.

Exome-Wide Rare Variant Analyses in Sudden Infant Death Syndrome

OBJECTIVE

To determine whether a monogenic basis explains sudden infant death syndrome (SIDS) using an exome-wide focus.

STUDY DESIGN

A cohort of 427 unrelated cases of SIDS (257 male; average age = 2.7 ± 1.9 months) underwent whole-exome sequencing. Exome-wide rare variant analyses were carried out with 278 SIDS cases of European ancestry (173 male; average age = 2.7 ± 1.98 months) and 973 ethnic-matched controls based on 6 genetic models. Ingenuity Pathway Analysis also was performed. The cohort was collected in collaboration with coroners, medical examiners, and pathologists by St George's University of London, United Kingdom, and Mayo Clinic, Rochester, Minnesota. Whole-exome sequencing was performed at the Genomic Laboratory, Kings College London, United Kingdom, or Mayo Clinic's Medical Genome Facility, Rochester, Minnesota.

RESULTS

Although no exome-wide significant (P < 2.5 × 10-6) difference in burden of ultra-rare variants was detected for any gene, 405 genes had a greater prevalence (P < .05) of ultra-rare nonsynonymous variants among cases with 17 genes at P < .005. Some of these potentially overrepresented genes may represent biologically plausible novel candidate genes for a monogenic basis for a portion of patients with SIDS. The top canonical pathway identified was glucocorticoid biosynthesis (P = .01).

CONCLUSIONS

The lack of exome-wide significant genetic associations indicates an extreme heterogeneity of etiologies underlying SIDS. Our approach to understanding the genetic mechanisms of SIDS has far reaching implications for the SIDS research community as a whole and may catalyze new evidence-based SIDS research across multiple disciplines. Perturbations in glucocorticoid biosynthesis may represent a novel SIDS-associated biological pathway for future SIDS investigative research.

Critical diaphragm failure in sudden infant death syndrome

Sudden infant death syndrome (SIDS) is the leading cause of death in infants between the ages of 1 and 12 months in developed countries. SIDS is by definition a diagnosis of exclusion, and its mechanism of action is unknown. The SIDS-Critical Diaphragm Failure (CDF) hypothesis postulates that the cause of death in SIDS is respiratory failure caused by CDF. Four principal risk factors contribute to CDF in young infants: undeveloped respiratory muscles, non-lethal infections, prone resting position, and REM sleep. Even relatively minor infections can cause an acute and significant reduction in diaphragm force generation capacity that in conjunction with other risk factors can precipitate CDF. CDF-induced acute muscle weakness leaves few, if any pathological marks on the affected tissue.Understanding the underlying mechanism of SIDS may help in formulating new approaches to child care that can help to further reduce the incidence of SIDS.

Update on the use of melatonin in pediatrics

Melatonin, an endogenously produced indoleamine, is a highly effective antioxidant, free radical scavenger, and a primary circadian regulator. Melatonin has important antioxidant properties owing to direct and indirect effects. It directly scavenges reactive oxygen and reactive nitrogen species, prevents molecular oxidation, improves mitochondrial physiology, and restores glutathione homeostasis. Its indirect antioxidant effects stem from its ability to stimulate the activities of the enzymes involved in the glutathione cycling and production. Melatonin, by reducing free radical damage, may be an effective protective agent for the fetus as it is in adults. Several clinical studies on melatonin have shown that it reduces oxidative stress in human newborns with sepsis, hypoxic distress, or other conditions, where there is excessive free radical generation. A role of melatonin in infant development has also been suggested. Pineal dysfunction may be associated with deleterious outcomes in infants and may contribute to an increased prevalence of sudden infant death syndrome. Delayed melatonin production is evident in infants who had experienced an apparent life-threatening event. Melatonin has been used as a pharmacologic treatment for insomnias associated with shift work, jet lag, and delayed sleep onset in adults for decades. In children as well, melatonin has value as a sleep-promoting agent. Evidence suggests that melatonin has utility as an analgesic agent presumably related to its ability to release β-endorphin. The data support the notion that melatonin, or one of its analogs, might find use as an anesthetic agent in children.

Cardiovascular protective effect of melatonin in sudden unexpected death in epilepsy: A hypothesis

Epilepsy is the most common neurological disorder, approximately 1% of the population worldwide have epilepsy. Moreover, sudden unexpected death in epilepsy (SUDEP) is the most important direct epilepsy-related cause of death. Information concerning risk factors for SUDEP is conflicting, but potential risk factors include: age, early onset of epilepsy, duration of epilepsy, uncontrolled seizures, seizure frequency, AED number and winter temperatures. Additionally, the cause of SUDEP is still unknown; however, the most commonly suggested mechanisms are cardiac abnormalities during and between seizures. Furthermore, the evidence from the last 10 years suggests that melatonin has an important role in the epileptogenesis process and influences the cardiovascular system as well. The positive effect of melatonin has been demonstrated against different convulsive stimuli in several rodents, including seizures induced by pentylenetetrazole kainate, glutamate, maximal electrical shock and electrically kindled stimulation of amygdala. Clinical studies have also demonstrated a positive role of melatonin on the seizure frequency in children and reduced spiking activity and seizure frequency in patients with intractable epilepsy. In the rat hearts, studies in vivo and in vitro using pharmacological concentrations of melatonin confirmed an anti-arrhythmic effect of this hormone and studies in humans have been shown that chronic heart disease patients have significantly lower melatonin levels in their blood stream than do normal individuals. Thus, caution should be taken in generalization of these findings to epileptic population. Moreover, it is important to note that when dealing with intractable epilepsy that do not respond to any conventional treatment, the additional of melatonin may be evaluated. Taken together, in this paper we suggested a possible relationship between cardiac abnormalities, melatonin and SUDEP.

Melatonin production in infants

This study investigated the relationships of the excretion of the melatonin metabolite, 6-sulfatoxymelatonin, to prenatal, natal, and postnatal variables and its possible relation to psychomotor development. nocturnal urinary excretion of 6-sulfatoxymelatonin was studied over a 13-hour period in 355 term infants at 8 weeks of age (n = 320) and 16 weeks of age (n = 96). data on a variety of perinatal factors including pregnancy course, delivery, early postnatal course, birth weight, medical problems, growth (length, weight, and head circumference), and psychomotor development were collected at 1, 3, 6, 9, 12, and 18 months. the relationship between nocturnal 6-sulfatoxymelatonin excretion at 8 and 16 weeks of age and these factors was investigated and analyzed. 6-sulfatoxymelatonin levels at 16 weeks of age were significantly lower in infants with abnormal vs normal development at 3 months of age (7.27 + 1.44 vs 7.97 + 1.06, p = 0.05) as well as at 6 months of age (7.15 + 1.29 vs 7.95 + 1.10, p = 0.04). no other significant relation was evident among growth, perinatal complications, medical problems, and 6-sulfatoxymelatonin excretion at 8 weeks of age and at 16 weeks of age. low melatonin excretion in the first weeks of life correlates with delayed psychomotor achievements at 3 and 6 months of age. this association suggests a causal or predictive link between melatonin and neurodevelopment in infants.

Review of risk factors for sudden infant death syndrome

Sudden infant death syndrome (SIDS) accounts for the largest number of deaths during the first year of life in developed countries. The possible causes of SIDS are numerous and, to date, there is no adequate unifying pathological explanation for SIDS. Epidemiological studies have played a key role in identifying risk factors, knowledge of which has underpinned successful preventive programmes. This review critically assesses information on the main risk factors and causal hypotheses put forward for SIDS, focusing on research published since 1994. The overall picture that emerges from this review is that affected infants are not completely normal in development, but possess some inherent weakness, which may only become obvious when the infant is subjected to stress. Initially there may be some minor impairment or delay in development of respiratory, cardiovascular or neuromuscular function. None of these is likely to be sufficient, in isolation, to cause death and, provided the infant survives the first year of life, may no longer be of any significance. However, when a compromised infant is confronted with one or more stressful situations, several of which are now clearly identified as risk factors, and from which the majority of infants would normally escape, the combination may prove fatal.

Melatonin production in healthy infants: evidence for seasonal variations

The objective of this study was to determine the normal range of nocturnal urinary excretion of the major melatonin metabolite, 6-sulfatoxymelatonin (6SMT) in a large sample of healthy full-term infants (8 and 16 wk old) and assess whether the endogenous production of melatonin changes with season. 6SMT was assessed in urine samples extracted from disposable diapers removed from full-term, 8- (n = 317) and 16-wk-old (n = 93) infants over the nocturnal period (19:00-08:00 h). In addition, 6SMT was assessed in 8-wk-old (n = 35) healthy infants over the entire 24-h period. 6SMT was determined by an ELISA assay. 6SMT excretion at 8 wk of age exhibited diurnal variations with (mean +/- SD) 61 +/- 18% of the daily production excreted during the nocturnal period regardless of season. The nocturnal 6SMT values in the entire cohort (at 8 as well as 16 wk of age) were found to significantly depart from normal distribution (Kolmogorov-Smirnov test). A normal distribution was obtained using a natural base logarithmic (ln) transformation of the data. The normal range (2.5-97.5 percentile of the ln 6SMT excretion per night) was thus defined as 4.66-8.64 (106-5646 ng/night) for 8-wk-old and 5.19-9.67 (180-15,820 ng/night) for 16-wk-old infants. A significant effect of the month of birth on 6SMT production at the age of 8 wk was found (ANOVA, p < 0.002) with maximal levels produced by infants born in June (summer solstice) and minimal excretion in infants born in December (winter solstice). Short-photoperiod-born infants excreted on average about threefold less 6SMT compared with long-photoperiod-born infants (t test, p = 0. 01). The seasonal variations were no longer present at 16 wk of age. No effect of breast-feeding at the time of sampling on seasonality of 6SMT was found. Normal ranges for the nocturnal urinary excretion of 6SMT in full-term infants at 8 and 16 wk of age are defined. This enables the evaluation of nocturnal 6SMT excretion as a prognostic and diagnostic factor for child development. The strong effect of season on the normal excretion of nocturnal 6SMT at 8 but not 16 wk of age suggests prenatal influence of the photoperiod on the ontogeny of melatonin.

Melatonin and development: physiology and pharmacology

This review discusses the development of melatonin rhythmicity in humans and the factors that may alter the appearance of melatonin rhythms. The literature on the possible consequences of disordered melatonin production in relation to Sudden Infant Death Syndrome, fetal origins of adult disease, and scoliosis is critically reviewed. Finally, the emerging use of melatonin to correct sleep disorders in infants and children is reviewed.

Optimality of the birth population reduces learning and behaviour disorders and sudden infant death after the first month

The weight distribution pattern of all births can be divided into a "skewing to the left" to lower weights and high neonatal mortality, a "skewing to the right" to higher weights (>3500g) and minimum neonatal and postneonatal mortality, and a "symmetrical distribution" with mortality in between. This study was initiated with the hypothesis that a deficit in newborns of more than 3500 g would adversely affect postneonatal death. Higher and rising postneonatal mortality solely attributable to sudden infant death of unknown cause (sudden infant death syndrome; SIDS) was observed in the Nordic countries with a lower proportion of heavy newborns. Minor environmental intervention almost eliminated excess mortality from this cause, supporting raised susceptibility with a depressed birthweight in postneonatal SIDS. This contrasts with classical neonatal low birthweight SIDS, which is stable despite numerous attempts at reduction, supporting a multi-factorial aetiology: low maternal age, low education, low socioeconomic status, maternal smoking, infection, etc. The postneonatal SIDS epidemic associated with a deficit in heavy newborns is thought to be a result of changing behaviour in pregnancy: moderate iatrogenic dietary restriction and young women favouring a low-calorie, low-fat diet, especially in the third trimester when the foetus is most vulnerable, which delays myelination and somatic growth and renders the infant susceptible to minor morbidity and irregularity. The timing of death and neuropathological findings suggestive of repeated hypoxic episodes in more than 80% of cases of SIDS prior to death support this theory. The similar weight distribution patterns in SIDS and all births in Denmark, the UK and the USA suggest a substantial proportion of the neonates in these countries could be growth-retarded and at risk of hypoxic episodes in infancy. A few cases, particularly males (sex-ratio = 1.7), suffer SIDS, the majority survive. Many, mostly males, present minor CNS signs and learning and behaviour problems. The male predominance accords with males more than 500 g higher optimal birthweight than females and susceptibility to a depressed weight at birth. In order to prevent postneonatal dying, SIDS and reduce learning/behaviour disorders it is necessary to raise the proportion of heavy newborns by promoting foetal growth rate equal to the maternal intrinsic rate by eating to one's appetite a balanced diet, favouring a diet high in marine fat, especially in third trimester, in order to ensure maturation of the CNS and prolong gestation, thereby increasing birthweight. Although the increased survival of some very low birthweight neonates confounds the issue, a division between SIDS in neonatal and postneonatal death is recommended in order to assess the proportion of "avoidable infant death" as opposed to persistent classical neonatal SIDS.

Anatomy of a new paired tract of the pineal gland in humans

The human pineal gland and it anterior attachments were investigated grossly in the fresh state and microscopically in the sagittal plane and 25 degrees tangential to the coronal plane of sectioning. Fiber stains of tissue samples from the midline commissural attachments of the pineal gland indicated the presence of both myelinated and non-myelinated fibers connecting the pineal gland and the pre-tectal area. A previously unreported paired fiber tract was observed associated with the anterior inferio-ventro-lateral pineal gland. This paired tract appears to be physically separate and distinct from the posterior commissure. These tracts form a structural component of the wall of the pineal recess. The fibers coursing in this paired tract are myelinated, and are of two different sizes (1-3 microm diameter and 5-8 microm diameter) as determined by electron microscopy. Fibers from these tracts invade the pineal gland, and can be traced a short distance into the lateral pre-tectal area. The precise point of origin and termination for this paired tract is unknown.

Melatonin and human reproduction

In photoperiodic nonhuman mammals the secretion of melatonin from the pineal gland plays a major role in regulating reproductive physiology; in humans these relationships are less clear. The melatonin rhythm changes throughout life with the first substantial change in nocturnal melatonin secretion being reportedly associated with puberty. The transition from Tanner stage 1 to Tanner stage 5 of sexual maturation is associated with a significant reduction in nocturnal melatonin levels, but a cause-effect relationship has not been established. Menstrual cyclicity has been reported to be associated with fluctuations in melatonin production but whether they are related to, eg ovulation or menstruation is not established. At high latitudes the quantity of melatonin produced by the pineal gland varies with season (changes in the light-dark cycle), and there is some evidence that this changes reproductive efficiency accordingly. Menopause is associated with a reduction in melatonin which may relate to the changing gonadotropin levels. In males of the same age melatonin levels also drop with no significant alteration in reproductive physiology. While correlations between melatonin and the status of the reproductive system in humans have been noted, whether they are functionally related remains to be determined.

Could exogenous melatonin prevent sudden infant death syndrome?

Hypoplastic pineal glands and decreased melatonin levels are found in sudden infant death syndrome. Excess oxygen radical production and inadequate radical quenching is suggested to cause oxidative stress in the brain of sudden infant death syndrome victims. Loss of intraventricular cerebrospinal fluid melatonin could play an important role in the disease process. Infants at risk might be protected by exogenous melatonin.

Geophysical variables and behavior: LXXXII. A strong association between sudden infant death syndrome and increments of global geomagnetic activity--possible support for the melatonin hypothesis

A significant subpopulation of young infants who die suddenly (SIDS) often exhibit anomalies consistent with disruptions within the pineal-limbic system. We have hypothesized that sudden decreases in nocturnal melatonin by a specific range of geomagnetic activity would precipitate sudden infant death. A correlation of .90 was found between the numbers of cases of Sudden Infant Death Syndrome per month during the years 1960 and 1961 in Ontario and an increase (primarily) in numbers of days per month with average geomagnetic activity between 11 and 20 nT and 31 through 40 nT but a decrease in the numbers of days with values between 21 and 30 nT. This nonlinear sensitivity, presumably associated with specific ripple frequencies within the geomagnetic field, may explain the failure by other researchers to detect linear associations between the numbers of these types of deaths and gross, scalar indicators of geomagnetic activity.

Comparison of [125I]iodomelatonin binding sites in infant cerebellum of sudden infant death syndrome and non-sudden infant death syndrome

[125I]Iodomelatonin bindings sites in human infant cerebellum were studied by radioligand receptor binding assay and in vitro quantitative autoradiography. The binding sites characterized in membrane preparations revealed saturable, reversible and highly specific binding sites with a Kd value of 21.2 +/- 8.33 pM and a Bmax value of 2.02 +/- 0.52 fmol/mg protein. 10 microM of GTP gamma S significantly reduced the binding capacity, suggesting the possible G-protein coupling of the binding sites. Autoradiographic study showed that the labelling was mainly located in the cerebellar cortex. On comparison of the binding parameters from cerebellum of sudden infant death syndrome (SIDS) and non-SIDS infants, no significant change in binding capacity and binding affinity was detected. These findings suggest that the binding sites in cerebellum may not be related to the etiology of SIDS.

Human hydroxyindole-O-methyltransferase: presence of LINE-1 fragment in a cDNA clone and pineal mRNA

Hydroxyindole-O-methyltransferase (HIOMT) catalyzes the last step in the synthesis of the pineal hormone melatonin. In this study, an HIOMT clone was isolated from a human pineal cDNA library using synthetic oligonucleotide probes based on the bovine HIOMT sequence. The human sequence is unusual because it contains a 3' fragment (84 bp) of the LINE-1 sequence, a highly repetitive sequence in the human genome and the genome of some primates and rodents. Exclusive of this LINE-1 fragment, the human HIOMT clone is 75% and 63% homologous to bovine and avian HIOMT sequences, respectively. The deduced amino acid sequence of the human cDNA clone encodes a 41.6-kD protein. In addition, the sequence is 70% and 57% identical and 81% and 73% similar to bovine and avian HIOMT, respectively. In agreement with the results of earlier studies, it was found that vertebrate HIOMT amino acid sequences are not homologous to any other vertebrate proteins, including several methyltransferases. However, HIOMT exhibits homology with a plant O-methyltransferase and an internal 120-amino-acid region is approximately 35% identical to a region of four bacterial O-methyltransferases. The results of PCR and Southern blot analysis indicate that three species of HIOMT mRNA are typically present in the human pineal gland, only one of which contains the LINE-1 fragment. An antiserum was raised against a mixture of three synthetic peptides, corresponding to three regions of the deduced amino acid sequence of human HIOMT. This antiserum detected a single immunoreactive protein in Western blot analysis of human pineal glands. The size of the protein (approximately 42 kD) is identical to that predicted from the HIOMT clone, including the LINE-1 fragment. The human HIOMT sequence should be useful in further studies of this enzyme and will also be of special importance in evaluating the functional significance of the inclusion of a fragment of the LINE-1 in an mRNA.

Synaptic neurochemistry of human striatum during development: changes in sudden infant death syndrome

There is evidence of abnormalities in the brain-stem monoamine-containing neurons in infants with sudden infant death syndrome (SIDS). By taking advantage of the rich innervation of the human basal ganglia by monoaminergic afferents from cell bodies in the brainstem, we studied the synaptic chemistry of catecholamine and associated neurons of the putamen obtained postmortem from 14 SIDS infants, eight age-matched control infants, and older control subjects of various ages. We found significantly lower concentrations of dopamine and higher homovanillic acid/DA ratios in samples from SIDS infants compared with age-matched control infants. Noradrenaline and 5-hydroxytryptamine were lower in SIDS compared with control subjects, but the difference did not reach statistical significance. There was no clear evidence that dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid were altered. Immunoblot analysis of striatal tissue showed that samples from infants with SIDS, which exhibited lower DA, also had lower tyrosine hydroxylase protein. Other transmitter-specific neuronal markers were also assessed, including enzymes associated with cholinergic and GABA-containing neurons. We found significantly decreased choline acetyltransferase activities. However, GABA, glutamate, or somatostatin concentrations or monoamine oxidase activities were unchanged in SIDS. We also noted age-dependent changes in brain weights and some synaptic markers by comparing the age-matched infants with older control subjects. Analysis of variance revealed that homovanillic acid, dihydroxyphenylacetic acid, and monoamine oxidase B activities were increased with age. DA and choline acetyltransferase were also found to be positively correlated in putamen. Our findings suggest developmental changes in some transmitter-specific neurons in SIDS that may result from apneic episodes or chronic hypoxia induced before death.

Ontogeny of peptides in human hypothalamus in relation to sudden infant death syndrome (SIDS)

The brains of mammals are not mature at birth, in particular in humans. Growth and brain development are influenced by the hormonal state in which the hypothalamus plays the major regulatory role. The maturation of the hormonal patterns leads to the physiological establishment of chronological variations as revealed by the circadian variations of both hypothalamic peptides and pituitary hormones (as illustrated for hypothalamic-pituitary-thyroid axis by the determination of thyro-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH) circadian rhythms in the rat (Jordan et al., 1989)). It has been established that hypothalamic peptide variations are regulated by hormonal feed-back and amine systems, with the maturation of the latter also being dependent upon the whole functional maturation of the brain. Though these systems have been studied in the rat, very little information is currently available with regard to the human brain. The only biochemical or immunohistochemical information published to date concerns either the fetus or the adult. We have studied four main peptidergic systems (somatostatin-releasing inhibiting factor (SRIF), thyrotropin-releasing hormone (TRH), luteinizing hormone-releasing hormone (LHRH) and delta sleep inducing peptide (DSIP) in post-mortem adults and infants and in sudden infant death syndrome (SIDS) brains either by autoradiography and/or immunochemistry of radioimmunology. From a technical point of view, human brain studies display certain pitfalls not present in animal studies. These may be divided into two subclasses: ante- and post-mortem. Ante-mortem problems concern mainly sex, laterality, nutritional and treatment patterns while post-mortem problems concern post-mortem delay and conditions before autopsy and hypothalamic dissection. This might induce dramatic changes in morphological, immunochemical and autoradiographic evaluations. The matching of pathological subjects with controls is particularly difficult in the case of SIDS because of the rapid changes which take place in physiological regulatory processes during the first year of life. Thus, the treatment of hypothalamic tissue samples both for immunochemistry, radioimmunology and autoradiographic studies required techniques which must be rigorously controlled. For example, SRIF studies were carried out with three different antibodies, which gave similar results. The use of different technical procedures as well as different antibodies is discussed. These types of differences might explain, at least in part, the discrepancy observed until now. As previously described in the fetus (Bugnon et al., 1977b; Bouras et al., 1987), we confirmed that in the infant hypothalamic SRIF immunoreactive cell bodies are present in the paraventricular and suprachiasmatic nuclei and in the periventricular area.(ABSTRACT TRUNCATED AT 400 WORDS)

Sudden infant death syndrome: altered aminergic-cholinergic synaptic markers in hypothalamus

Alterations of sleep are reported to occur in sudden infant death syndrome (SIDS). It is well established that the hypothalamus mediates the onset, maintenance, and timing of sleep, and does so via serotonergic and cholinergic mechanisms. We have investigated serotonergic and cholinergic synaptic markers in the hypothalamus from eight SIDS infants and six age-matched non-SIDS infants between 3 and 7 months of age. By use of established methods, we observed a number of chemical alterations in SIDS hypothalamus: (1) tryptophan content was increased and serotonin content was decreased, (2) serotonin binding was increased and imipramine binding was unchanged, (3) monoamine oxidase-A activity was increased without an effect on monoamine oxidase-B, and (4) choline acetyltransferase activity was decreased and acetylcholinesterase activity was unchanged.

Increased ALZ-50-reactive neurons in the brains of SIDS infants: an indicator of greater neuronal death?

Brain tissue from 15 infants who had died from sudden infant death syndrome (SIDS) and 15 age-matched control infants was investigated for the presence of degenerating neurons using ALZ-50 immunocytochemical methods. Significantly increased numbers (P less than .0001) of ALZ-50-reactive neurons were found in SIDS infants compared to infants dying of known causes. The location and appearance of such ALZ-50-reactive neurons in SIDS may indicate that the initial degeneration of the central nervous system occurs early in the development of affected infants.

Neural maturational delay as a link in the chain of events leading to SIDS

Although numerous etiological or triggering factors have been suggested in sudden infant death syndrome (SIDS), the underlying mechanism of death is ultimately cardiac and/or respiratory in nature. As there is no evidence of lung or heart abnormalities, attention has focussed on the neural control of respiration and cardiac function. It is important to appreciate the methodological limitations involved in utilizing autopsy material and the criteria for selection of appropriate controls. This report reviews the pathological evidence for developmental delay in SIDS emphasizing delay of neural maturation of both myelination and synapses. Other abnormalities of the nervous system apparently associated with hypoxia-ischemia such as brainstem astrogliosis are also discussed. The occurrence of SIDS at a precise age together with our preliminary studies indicate that neural development delay is an important link in the chain of events leading to SIDS.

Melatonin concentrations in the sudden infant death syndrome

To examine a possible relationship between pineal function and the sudden infant death syndrome (SIDS), samples of whole blood, ventricular cerebrospinal fluid (CSF) and/or vitreous humor (VH) were obtained at autopsy from 68 infants (45 male, 23 female) whose deaths were attributed to either SIDS (n = 32, 0.5-5.0 months of age; mean +/- S.E.M., 2.6 +/- 0.2 months) or other causes (non-SIDS, n = 36, 0.3-8.0 months of age 4.3 +/- 0.3 months). The melatonin concentrations were measured by radioimmunoassay. A significant correlation was observed for melatonin levels in different body fluids from the same individual. After adjusting for age differences, CSF melatonin levels were significantly lower among the SIDS infants (91 +/- 29 pmol/l; n = 32) than among those dying of other causes (180 +/- 27; n = 35, P less than 0.05). A similar, but non-significant trend was also noted in blood (97 +/- 23, n = 30 vs. 144 +/- 22 pmol/l, n = 33) and vitreous humor (68 +/- 21, n = 10 vs. 81 +/- 17 pmol/l, n = 15). These differences do not appear to be explainable in terms of the interval between death and autopsy, gender, premortem infection or therapeutic measures instituted prior to death. Diminished melatonin production may be characteristic of SIDS and could represent an impairment in the maturation of physiologic circadian organization.

Sudden infant death syndrome and hibernation: is there a link?

Two very large bodies of information seem to overlap, one being the epidemiological and pathological studies on sudden infant death syndrome (SIDS), the other being the research on hibernation. Until now, these two phenomena have been studied independently; however, it will be argued here that the role of the pineal gland, that of brown adipose tissue (BAT) and sleep patterns in both endothermic hibernating mammals and those babies presenting as SIDS provide clues and support for the hypothesis that SIDS is pathoplastic to the hibernatory response.

A study of heart-pineal interactions: atrial natriuretic peptide response to melatonin administration in healthy humans

It is known that the pineal hormone melatonin plays a role in the regulation of several biological functions. In an attempt to investigate interactions between the pineal and the cardiac endocrine activity, in this preliminary study we have evaluated the effect of melatonin on the secretion of the cardiac hormone, atrial natriuretic peptide (ANP). The study included five healthy volunteers, and melatonin was given orally at a dose of 30 mg at 17:00. The results of the study show that the administration of melatonin does not influence ANP plasma concentrations. Further studies will be required to better define the cardiac-pineal interaction.