Pinealocytes can not transport neurotropic viruses. Pinealo-to-retinal connection in prepubertal rats originates from pineal neurons: Light and electron microscopic immunohistochemical studies.

It is well established that the adult mammalian pineal body (PB), with the exception of rodents, contains nerve cell bodies. Based on our previous results we have proposed that there is a pinealo-to-retinal neuronal connection in adult hamsters and in prebubertal rats. By the time the animals reached puberty, labeled cells in the PB were not observed in rats. In the present experiment, we provide light and electron microscopic immunohistochemical evidence that the labeled cells in the PB of prepubertal rats are neurons. Pinealocytes cannot transport neurotropic viruses. Virus labeled cells do not show S-antigen immunoreactivity typical for pinealocytes of six-day-old rats. Electron microscopic investigation confirmed the neuronal nature of virus labeled cells. These neurons, similarly to that of hamsters, also establish pinealo-to-retinal connections in prepubertal rats.

Thymus-Pineal Gland Axis: Revisiting Its Role in Human Life and Ageing.

For years the thymus gland (TG) and the pineal gland (PG) have been subject of increasingly in-depth studies, but only recently a link that can associate the activities of the two organs has been identified. Considering, on the one hand, the well-known immune activity of thymus and, on the other, the increasingly emerging immunological roles of circadian oscillators and the rhythmically secreted main pineal product, melatonin, many studies aimed to analyse the possible existence of an interaction between these two systems. Moreover, data confirmed that the immune system is functionally associated with the nervous and endocrine systems determining an integrated dynamic network. In addition, recent researches showed a similar, characteristic involution process both in TG and PG. Since the second half of the 20th century, evidence led to the definition of an effectively interacting thymus-pineal axis (TG-PG axis), but much has to be done. In this sense, the aim of this review is to summarize what is actually known about this topic, focusing on the impact of the TG-PG axis on human life and ageing. We would like to give more emphasis to the implications of this dynamical interaction in a possible therapeutic strategy for human health. Moreover, we focused on all the products of TG and PG in order to collect what is known about the role of peptides other than melatonin. The results available today are often unclear and not linear. These peptides have not been well studied and defined over the years. In this review we hope to awake the interest of the scientific community in them and in their future pharmacological applications.

Developmental morphology of the turkey pineal organ. Immunocytochemical and ultrastructural studies.

Our previous study showed that the turkey pineal organ, in contrast to that of the chicken, is characterized by a follicular structure throughout the entire period of post-hatching life. Despite the preservation of the follicular organization, the histological structure of the pineal follicles in turkeys changes prominently with age. The present research was performed to investigate the cellular composition and organization of the follicle wall as well as the ultrastructure of parenchymal cells in the turkey pineal organ during the period of post-hatching development. Pineal organs were collected from female turkeys at 2 days, 2 weeks, 4 weeks, 10 weeks, 20 weeks, 30 weeks, 40 weeks, and 56 weeks post-hatching. The organs were prepared for immunocytochemical studies using antibodies against N-acetylserotonin O-methyltransferase (ASMT), glial fibrillary acidic protein (GFAP) and proliferating cell nuclear antigen (PCNA) and for ultrastructural examination. The results showed that regardless of age, the pineal follicle was formed by ASMT-immunopositive cells, among which rudimentary photoreceptor and secretory pinealocytes were identified. The second component of the follicle wall consisted of GFAP-immunopositive cells, as represented by ependymal-like and astrocyte-like cells. Rudimentary photoreceptor pinealocytes and ependymal-like cells formed the inner part of the follicle wall, while secretory pinealocytes and astrocyte-like cells created the outer part. Three forms of the pineal follicle structure characteristic of young (two days to ten weeks), young adult (20-30 weeks) and adult (40-56 weeks) turkeys were distinguished. These forms primarily differed in the relative dimensions of the inner and outer parts of the follicle wall. Ultrastructural studies showed prominent changes in the organization of rudimentary receptor pinealocytes during the investigated period of life. These cells developed until the age of 20 weeks, at which time they appeared as strongly elongated cells with a stratified, highly regular distribution of organelles. In adult turkeys, rudimentary receptor pinealocytes showed pronounced regressive changes; however, we never observed their transformation into cells of the secretory type. Secretory pinealocytes increased in number and size during the post-hatching period, which was especially pronounced after 20 weeks of age. The most prominent changes in the supporting cells included the intensification of GFAP-immunoreactivity due to the accumulation of filaments in the cytoplasm and the development of astrocyte-like cells. The increase in the number of secretory pinealocytes and astrocyte-like supporting cells resulted in the formation of two distinct parts of the follicle wall in the pineal organs of young adult and adult turkeys.

Pineal gland calcification under hypoxic conditions.

The pineal gland (glandula pinealis) is neuroendocrine gland located at the epithalamus of the brain secreting melatonin. The aim of this study was to explore effects of prenatal hypoxia in rats at the age of 33 weeks on the occurrence of pineal gland calcification. Distribution and chemical composition of calcerous material by light, scanning and transmission electron microscopy was investigated. Melatonin concentrations in blood plasma by direct radioimmunoassay were measured. Rats were exposed to prenatal hypoxia for 12 h at day 20 of development and second group to prenatal hypoxia for 2x8 h at days 19 and 20 of development. Vacuoles of intracellular edema in the pineal samples after 12 h hypoxia were found. Their size ranges up to 30 µm. Some of them were filled with the flocculent and fibrous material. Samples of pineal glands after 2 x 8 h hypoxia revealed the pericellular edema of pinealocytes. The amount of calcium rich particles in 2 x 8 h hypoxia group was lower than in 12 h hypoxia group. Plasma melatonin levels did not differ between control and both hypoxia groups. We concluded that calcification is a process induced by osteoblasts and osteocytes with melatonin as a promotor and it is favored under hypoxic conditions.

The pineal gland of the shrew (Blarina brevicauda and Blarina carolinensis): a light and electron microscopic study of pinealocytes.

The pineal gland structure and ultrastructure in the Northern (Blarina brevicauda) and Southern short-tailed shrew (Blarina carolinensis) are described by light and electron microscopy. Results observed were similar to other mammals of Insectivora described previously, specifically, the hedgehog (Erinaceus europaeus) and the Old World mole (Talpa europea). Two different types of pinealocytes were noticed by electron microscopy, in addition to relatively few glial cells. Granular vesicles were not noticed in abundance. The granular endoplasmic reticulum was observed and studded with vesicles. The golgi apparatus was well developed and appeared often. Synaptic ribbons were observed in several different formations consisting of ribbons and/or rods. The ciliary derivative, the rudimentary photoreceptor structures found in the pinealocytes of population I, was noticed in a 9 + 0 tubular pattern. Within these semifossorial shrews, the relationship between specific intracellular organelles and their function was discussed.

Morphologic variations in the pineal gland of the albino rat after a chronic alcoholisation process.

We studied the effect of alcohol on the pineal gland of 48 male Wistar rats. Animals were divided into control and experimental groups. The experimental group underwent a previous progressive alcoholisation period with ethanol diluted in water at a concentration of 40%. Animals were sacrificed at 3, 6, 9 and 12 months, and the ultrastructure, karyometric indices, and number of synaptic bodies in the pineal gland were analysed. The results showed progressive morphologic alterations in the ethanol-treated animals, which culminated in fatty degeneration of the pineal parenchyma after 6 months. The karyometric indices decreased in both the central and peripheral areas compared with the control group. Moreover, the seasonal rhythmicity observed in the controls disappeared in the experimental groups, whose number of different populations of synaptic bodies (synaptic ribbons and synaptic spherules) considerably lowered with inversion of their normal seasonal rhythm. These results support that chronic alcoholisation leads to fatty degeneration of the pineal parenchyma, and a considerable alteration in nuclear functional rhythms and synaptic bodies.

Arecoline cannot alter testicular dysfunction and pineal activation caused by noise in wistar rat.

Millions of people consume betel nut for increased capacity to work and for stress reduction. The nut contains arecoline, which has multiple side effects on endocrine functions. Objective of the work is to investigate pineal-testicular responses to noise and after arecoline treatment in noise in rats. Noise exposure (100 dB, 6 h daily, 10 days) caused pineal stimulation ultrastructurally and at indoleamines level. Leydig cell dysfunction with fall of testosterone level and suppression of sex accessories were noticed. In contrast, pineal activity was inhibited and reproductive functions were stimulated after arecoline administration, confirmed from reversed changes to those of noise. Arecoline treatment in noise exposure showed same results as in noise both in pineal and in reproductive functions. It is concluded that noise causes testicular dysfunction probably by gonadotropin suppression induced by pineal melatonin in noise. Furthermore, arecoline cannot prevent it in noise in rats.

Adrenergic regulation of cytoplasmic structures related to secretory processes in pig pinealocytes-an ultrastructural, quantitative study.

Two structures, considered as secretory in nature, are present in the pinealocytes in of the domestic pig show the presence of two structures, which are considered as secretory in nature - the dense core vesicles (DCV) and the membrane bounded (dense) bodies (MBB). The latter are extremely numerous in pig pinealocytes (they occupy 6-20% of the cytoplasm), and the number of MBB changes under different physiological and experimental conditions. Norepinephrine is the main neurotransmitter that regulates the secretion of pineal melatonin. The present study was carried out to 1) clarify whether the DCV and their source - the Golgi apparatus (GA) - as well as the MBB are controlled by norepinephrine, 2) determine the effect of adrenergic stimulation on these structures, and 3) identify the receptors involved in the regulation of these structures. The studies were performed using a static organ culture of pig pineal explants. The explants were incubated in a control medium between 08:00 and 20:00 and in a medium with 10µM norepinephrine or alpha- or beta-adrenoceptor agonists between 20:00 and 08:00 on five consecutive days. The tissues were subsequently prepared for ultrastructural analysis. The results distinctly showed that the DCV, GA and MBB in pig pinealocytes are under adrenergic control. The stimulation of the beta-adrenoceptors resulted in an increase in the numerical density of the DCV and a decrease in the relative volume of the GA in the perikarya, while the incubation with agonists of the alpha1-adrenoceptors was ineffective. The relative volume of the MBB in the perikarya significantly decreased after treatment with both beta-agonists and alpha1-agonists, which suggested the involvement of two types of adrenoceptors in the regulation of these structures.

Connexin36 localization to pinealocytes in the pineal gland of mouse and rat.

Several cell types in the pineal gland are known to establish intercellular gap junctions, but the connexin constituents of those junctions have not been fully characterized. Specifically, the expression of connexin36 (Cx36) protein and mRNA has been examined in the pineal, but the identity of cells that produce Cx36 and that form Cx36-containing gap junctions has not been determined. We used immunofluorescence and freeze fracture replica immunogold labelling (FRIL) of Cx36 to investigate the cellular and subcellular localization of Cx36 in the pineal gland of adult mouse and rat. Immunofluorescence labelling of Cx36 was visualized exclusively as puncta or short immunopositive strands that were distributed throughout the pineal, and which were absent in pineal sections from Cx36 null mice. By double immunofluorescence labelling, Cx36 was localized to tryptophan hydroxylase-positive and 5-hydroxytryptamine-positive pinealocyte cell bodies and their large initial processes, including at intersections of those processes and at sites displaying a confluence of processes. Labelling for the cell junction marker zonula occludens-1 (ZO-1) either overlapped or was closely associated with labelling for Cx36. Pinealocytes thus form Cx36-containing gap junctions that also incorporate the scaffolding protein ZO-1. FRIL revealed labelling of Cx36 at ultrastructurally defined gap junctions between pinealocytes, most of which was at gap junctions having reticular, ribbon or string configurations. The results suggest that the endocrine functions of pinealocytes and their secretion of melatonin is supported by their intercellular communication via Cx36-containing gap junctions, which may now be tested by the use of Cx36 null mice.

Adrenergic control of pinealocyte chondriome - an in vitro study.

Norepinephrine released from sympathetic innervation plays the main role in the regulation of melatonin secretion in mammalian pinealocytes. The present study was conducted for the following reasons: 1) to establish whether the pinealocyte chondriome is controlled by norepinephrine, 2) to determine the effect of adrenergic stimulation on mitochondria, and 3) to characterize adrenoceptors involved in the regulation of the chondriome. The static organ culture of the pineal gland was used. The explants were incubated for 5 consecutive days in control medium and between 20:00 and 08:00 in medium with the presence of 10 µM norepinephrine - adrenergic agonist; isoproterenol - beta-adrenoceptor agonist; cirazoline, methoxamine, M-6364 - alfa1 - adrenoceptors agonists or PMA - activator of PKC. The explants were then subjected to ultrastructural examination and morphometric analysis. The incubation of explants in the presence of norepinephrine or isoproterenol caused a decrease in the relative volume and the numerical density of mitochondria and induced an increase in the percentage of free mitochondria in pinealocytes. Significant changes in these parameters were not observed after treatment with methoxamine, cirazoline, M-6463 and PMA. The results obtained show that the chondriome of pig pinealocytes is controlled by norepinephrine acting via beta-adrenoceptors. Adrenergic stimulation, repeated for five consecutive days of organ culture, causes a decrease in the number of mitochondria and a shift in the distribution of mitochondria from the form of networks and filaments into the form of single particles. This indicates the intensive remodeling of the mitochondria network, which is closely linked to the metabolic status of the cell.

Nucleolus-like bodies in the pineal gland of the adult yak (Bos grunniens).

The pineal glands of adult yak were studied electron microscopically. Nucleolus-like bodies (NLBs) were found mostly in the pinealocytes and the interstitial cells of the pineal glands of the yak. The NLBs were electron-dense, round or ovoid bodies with a diameter of 50 nm - 500 nm. Two types of granules were identified as melanin. These may correspond to different stages of a progressive storage of melanin. Rough endoplasmic reticula with abundant ribosomes were observed. There was no correlation between the number of NLBs and the sex of the animals.

Growth patterns for acervuli in human pineal gland.

Acervuli are calcified concretions in the pineal gland (PG). Particularly interesting are their incidence and size, which are believed to affect neurological disorders and many physiological functions of PG such as regulating circadian rhythm. Despite long investigations for a century, detailed growth mechanism of acervuli has yet to be studied. Here we study the growth morphology of acervuli in human PGs by a direct visualization in 3-dimension (3-D) using a synchrotron X-ray imaging method. For an entire PG, non-aggregated acervuli show Gaussian distribution in size with 47±28 µm. The 3-D volume rendered images of acervuli reveal that the bumpy surfaces developed by lamination result in the mulberry-like structure. In addition, coalescence of multiple acervuli leads to large-scale lamination on the whole aggregate. We suggest a novel hypothesis on the growth patterns of acervuli by their nucleation density (N(d)): i) mulberry-like structure at low N(d), and ii) large-scale lamination on an aggregate at high N(d).

NeuroD1 is required for survival of photoreceptors but not pinealocytes: results from targeted gene deletion studies.

NeuroD1 encodes a basic helix-loop-helix transcription factor involved in the development of neural and endocrine structures, including the retina and pineal gland. To determine the effect of NeuroD1 knockout in these tissues, a Cre/loxP recombination strategy was used to target a NeuroD1 floxed gene and generate NeuroD1 conditional knockout (cKO) mice. Tissue specificity was conferred using Cre recombinase expressed under the control of the promoter of Crx, which is selectively expressed in the pineal gland and retina. At 2 months of age, NeuroD1 cKO retinas have a dramatic reduction in rod- and cone-driven electroretinograms and contain shortened and disorganized outer segments; by 4 months, NeuroD1 cKO retinas are devoid of photoreceptors. In contrast, the NeuroD1 cKO pineal gland appears histologically normal. Microarray analysis of 2-month-old NeuroD1 cKO retina and pineal gland identified a subset of genes that were affected 2-100-fold; in addition, a small group of genes exhibit altered differential night/day expression. Included in the down-regulated genes are Aipl1, which is necessary to prevent retinal degeneration, and Ankrd33, whose protein product is selectively expressed in the outer segments. These findings suggest that NeuroD1 may act through Aipl1 and other genes to maintain photoreceptor homeostasis.

Morphological studies of the pineal gland in the common gull (Larus canus) reveal uncommon features of pinealocytes.

The avian pineal is a directly photosensory organ taking part in the organization of the circadian and seasonal rhythms. It plays an important role in regulation of many behavior and physiological phenomena including migration. The aim of the study was to investigate morphology of the pineal organ in the common gull (Larus canus). The light and electron microscopic studies were performed on the pineals of juvenile birds living in natural conditions of the Baltic Sea coast, which have been untreatably injured during strong storms in autumn and qualified for euthanasia. The investigated pineals consisted of a wide, triangular, superficially localized distal part and a narrow, elongated proximal part, attached via the choroid plexus to the intercommissural region of the diencephalon. The accessory pineal tissue was localized caudally to the choroid plexus. Based on the histological criteria, the organ was classified as the solid-follicular type. Two types of cells of fotoreceptory line were distinguished: rudimentary-receptor pinealocytes and secretory pinealocytes. Both types of cells were characterized by unusual features, which have been not previously described in avian pinealocytes: the presence of paracrystalline structures in the basal processes and their endings, the storage of glycogen in the form of large accumulations and the arrangement of mitochondria in clusters. Further studies on other species of wild water birds dwelling in condition of cold seas are necessary to explain if the described features of pinealocytes are specific for genus Larus, family Laridae or a larger group of water birds living in similar environmental conditions.

Pineocytoma in a lowland anoa (Bubalus depressicornis).

This report describes the first case of a pineocytoma in an 18-year-old female lowland anoa (Bubalus depressicornis). The tumour grossly appeared as a focal, non-infiltrative, yellow-tan, encapsulated mass occupying the normal anatomical location of the pineal gland. Microscopical, immunohistochemical and electron microscopical findings were consistent with a diagnosis of pineocytoma an entity not previously described in this member of the buffalo subgenus species.

Pineal-adrenal interactions in domestic male pigeon exposed to variable circadian light regimes and exogenous melatonin.

OBJECTIVE: This study was aimed to see the histophysiological changes of the pineal and adrenal glands under altered photoperiodic conditions due to the administration of melatonin in the male domestic pigeon, Columba livia Gmelin. METHODS: Young adult male domestic pigeons were exposed to long photoperiod (LP; 20 hr light: 4 hr dark), short photoperiod (SP; 4 hr light: 20 hr dark) exogenous melatonin (MEL; 20 microg/100 g body weight/day) was administered for 60 days in the primary breeding and regressive phase. At the end of experiment, adrenal and pineal glands were quickly dissected and processed for histology, ultrastructure study, biochemical, histochemical and immunohistochemical analysis. RESULTS: In the primary breeding phase, the number of mitochondria and rough endoplasmic reticulum were increased in the adrenal gland in MEL-LP group, while lipid granules were also increased in the subcapsular zone. In MEL-SP treated group, however, the number of mitochondria decreased. Pinealocytes were increased in size and well-developed Golgi complexes were present near the cell nucleus after induction with MEL-LP treatment during the primary breeding phase. No remarkable changes were noticed in the number of mitochondria. In the regressive phase-I, the adrenocortical cytoplasm showed similar morphological features both in MEL-LP treatment and control groups. In pinealocytes, few rough endoplasmic reticulum and lipid droplets and moderate number of mitochondria were present. In MEL-SP treatment, increased number of mitochondria in the adrenocortical cells and decreased nuclear diameter of the pinealocytes were noticed. Few mitochondria were observed within the pinealocyte cytoplasm. Side chain cleavage enzyme (immunocytochemical) activity was increased in the subcapsular zone in MEL-LP treated group. CONCLUSIONS: The present data indicates that the changes in pineal and adrenocortical tissue histophysiology might be due to melatonin rhythm and light/dark regime which act as a modulator in the male domestic pigeon.

Changes in concentrations of cortisol and melatonin in plasma, expression of synaptophysin, and ultrastructural properties of pinealocytes in goat kids in situations of stress due to early weaning: the effect of melatonin.

AIM: To analyse the changes in some histo-physiological parameters of the pineal gland of goat kids in situations of stress due to early weaning, and the effect of exogenous treatment with melatonin. METHODS: Twenty-four 6-day-old Verata goat kids were used; 12 suckled their dams throughout the study (non-weaned groups), and the other 12 were removed from their dams and fed a milk replacer (weaned groups). Six goat kids in each group were treated with melatonin, and the other six with double-distilled pyrogen-free water (Day 0). On Days 28-29, blood samples were collected at 0600, 1000, 1400, 1800, 2200, 0200 and 0600 hours, to determine concentrations of cortisol and melatonin in plasma. On Days 29 and 30, six animals per group (three at 1400 and three at 0200 hours, respectively) were subject to euthanasia and the weight of their pineal glands determined. The structural immunocytochemistry, morphometric analysis, ultrastructural analysis and immunotransmission electron microscopy of the pineal glands were established. RESULTS: Concentrations of cortisol in plasma were significantly higher in weaned than in non-weaned goat kids (p<0.05), and treatment with melatonin reduced the concentrations in weaned kids (p<0.05). Concentrations of melatonin in plasma showed a similar pattern in the four groups, with peak values at 0200 and troughs at 1400 hours. Mean concentrations of melatonin in plasma in weaned goat kids were significantly lower than those in the other groups (p<0.05). In weaned goat kids not treated with melatonin, the weight and volume of the pineal gland, and number of pinealocytes, were significantly lower when compared with those from non-weaned kids (p<0.05). Quantitative ultrastructural analysis of pinealocytes showed the relative volume of mitochondria, rough endoplasmic reticulum and Golgi complex was significantly lower in weaned than non-weaned goat kids (p<0.05); treatment with melatonin significantly increased these parameters in weaned kids. CONCLUSIONS: Taken together, these results indicate that treatment with melatonin in goat kids in situations of stress due to premature weaning could play an important role in the improvement of histo-physiological function of the pineal gland.

Pineal ribbon synapses: regulated by the gland's central innervation.

OBJECTIVE: The pineal gland is part of the circadian clock system and is under the predominant influence of the endogenous oscillator located in the suprachiasmatic nucleus. A polysynaptic pathway involving hypothalamus, spinal cord and sympathetic system regulates the so far best-studied aspect of its neuroendocrine output, i.e., the synthesis and secretion of melatonin. This parameter increases dramatically at night upon sympathetic activation in rats and many other mammals including man. In addition, parasympathetic, trigeminal, diencephalic and other sites or mechanisms connect the gland, mainly via its stalk, to the nervous system. However, their function for pineal metabolic or morphological features are hardly known. An interesting ultrastructural attribute of the pineal gland are ribbon synapses. These presynaptic structures in pinealocytes are composed of a ribbon and vesicles. They are thought to regulate and facilitate multivesicular release, and display a circadian rhythm with higher levels at night paralleling melatonin synthesis but regulated differently. METHODS: To gain more insight into the roles of both, the non-sympathetic ("central") innervation and the regulation of pineal ribbon synapses, a surgical transection of the pineal stalk was conducted in rats and the number of synaptic ribbons (SR) were determined by electron microscopy from experimental, sham-operated and control animals. RESULTS: The transection resulted in normal daytime levels but diminished the nocturnal increase of SR numbers when compared to controls or sham-operated rats. CONCLUSION: These data provide first evidence that the central innervation of this neuroendocrine organ plays an important role in SR (up)regulation, and that this pathway is antagonistic to the sympathetic innervation.

Pineal concretions in turkey (Meleagris gallopavo) as a result of collagen-mediated calcification.

The intra-pineal calcification is a well-known phenomenon in mammals, however it is almost completely unknown in birds. The aim of the present work was to analyze morphology and genesis of the pineal concretions in the turkey. The studies were performed on the pineals collected from one-year-old turkeys (Meleagris gallopavo). In addition to standard morphological methods, the alizarin red S and potassium pyroantimonate methods were employed for localization of calcium at the light and electron microscopy level. In light microscopy, calcified concretions with diameters from 300 microm to 2 mm and quantities from 3 to 6 per gland were observed in all the examined pineals. They were stained red with alizarin S and showed the presence of collagen in Mallory's staining. Two types of cells were noted inside the concretion: polygonal and elongated ones. Using electron microscopy, three parts were distinguished within the calcification area. The peripheral part contained densely packed collagen fibrils, some elongated cells and numerous pyroantimonate precipitates demonstrating the presence of calcium ions. In the intermediate part, the fibrils were covered by almost continuous sheets of pyroantimonate precipitates and fused side by side. The central part showed an appearance of calcified hard tissue and contained some polygonal (osteocyte-like) cells. The obtained data demonstrated that the formation of the pineal concretions in the turkey is associated with the mineralization of collagen. This process is completely different from the mechanisms responsible for the formation of the concretions in the mammalian pineal.

[The morphological response of the pineal gland of old animals on course of melatonin injections].

On the old (18-20 months) male rats of Wistar population the influence of the 10 days evening melatonin injections in physiological rang doses on morphological state pineal gland, was studied. It has been shown, that the course of melatonin injections to old rats brings appearance of histological pattern of pineal gland activation: increasing of area of pinealocytes nuclear and density of nuclear and cytoplasm with stein by hallocyanine on total nucleic acid that means stimulation to material both indole, and peptide nature production. Using of melatonin in dose 0.05 mg/kg mass of the body is sparing for pinealocytes of the old rats and slows the apoptosis processes on background of polyploidization. Using of melatonin in dose 0,5 mg/kg mass of the body causes cell's overstrain and induces the forced apoptosis. It's possible to suppose that the geroprotective effect of the evening injections of melatonin is increased due to stimulation of the biosynthesis of neuropeptides in pineal gland.