Effect of testosterone on the distribution of vasotocin immunoreactivity in the brain of the zebra finch, Taeniopygia guttata castanotis

The distribution of vasopressin or vasotocin immunoreactive cells and fibers in the lateral septum and the bed nucleus of the stria terminalis are sexually dimorphic in many vertebrates including several species of birds examined to date. We examined the vasotocin-like immunoreactivity in the zebra finch brain. Male birds had a higher level of immunoreactive staining in some telencephalic and diencephalic regions. The density of immunostaining increased in the testosterone-treated females to levels typically seen in males. The sexual dimorphism and testosterone dependence of the vasotocin-like immunoreactivity are similar to that found in the canary. Thus this pattern of vasotocin localization and testosterone dependence may be a general feature in brains of passerine songbirds.     

The effect of dopaminergic nigrostriatal system on sleep deprivation in rats

The analysis of the electrophysiological features of sleep-wakefulness cycle in Wistar rats for 9h after a 6h sleep deprivation was carried out. The delay of sleep rebound (since 2.5-3 h after deprivation) was found in the form of moderate increasing of slow-wave sleep and fast-wave sleep phases. According to these sleep-wakefulness cycle changes, a quantitative immunohistochemical study of tyrosine hydroxylase: a key enzyme of dopamine synthesis--and D1 and D2 receptors in nigro-striatal projections has been performed. After sleep, an elevation of D1 receptors immunoreactivity in caudate nucleus and reduction of tyrosine hydroxylase immunoreactivity in compact part of substancia nigra was found. After postdeprivation sleep, a decrease of D1 receptors immunoreactivity and increase of D2 receptors immunoreactivity in caudate nucleus together some increase of tyrosine hydroxilase immunoreactivity in substancia nigra compacta has been observed. These data can testify about active role of dopaminergic nigrostriatal system which provide at the same time with another neurotransmitters of the central nervous system the telencephalo-diencephalic interaction in sleep-wakefulness-sleep cycle.     

Morphofunctional interaction of CART peptide and dopaminergic brain neurons

In Wistar rats, after 6 h of sleep deprivation and subsequent 2 h postdeprivation sleep, we found significant changes in optical density of CART peptide in neurons of nucleus accumbens and hypothalamic nucleus arcuatus as well as in processes coming into substantia nigra from nucleus accumbens. The obtained data revealed unidirectional changes of optical density of CART and tyrosine hydroxylase in the studied structures: a decrease after sleep deprivation (p < 0.05) and, on the contrary, an increase after postdeprivation sleep (p < 0.05). Confocal laser microscopy showed morphological connections of CART and dopaminergic neurons and possible colocalization of these both substances in the same neuron at the postdeprivation sleep. In experiments in vitro, after 1 h of incubation of surviving brain sections from the substantia nigra area in the medium with CART peptide there was revealed a rise of optical density of tyrosine hydroxylase in the substantia nigra pars compacta by 55% (p < 0.05). The obtained data indicate an activating effect of CART peptide on brain dopaminergic neurons and its role as a modulator of their functional activity.     

Study of protective effects of exogenous heat shock protein 70 kDa in model of sleep deprivation in pigeon <Emphasis Type="Italic">Columba livia</Emphasis>

Electroencephalographic methods were used to study effects of preparation of the exogenous heat shock protein with molecular mass of 70 kDa (Hsp70i/Hsc70) on time characteristics of sleep and wakefulness, brain temperature, peripheral vasomotor reactions, and thoracic muscle contractile activity after the 5-hour forceful sleep deprivation in the pigeon Columba livia. Administration of Hsp70i/Hsc70 into the third brain ventricle at once after the end of sleep deprivation eliminated disturbances in the sleep-wakefulness cycle organization and decreased the thoracic muscle contractile activity and the brain temperature as early as for the first hour of postdeprivation period. For the subsequent hours, the Hsp70i/Hsc70 action was characterized by an increase of the total time of deep sleep and a decrease of the total time of the rapid eye movement sleep. We suggest that the protective effects of the exogenous Hsp70i/Hsc70 preparation are associated with its ability to decrease activity of the hypothalamo-pituitary-adrenal axis and to enhance the stress-limiting function of the slow eye movement sleep.     

Corticotropin-releasing hormone-like immunoreactivity in the brain of the snake Bothrops jararaca

The distribution of corticotropin-releasing hormone in the brain of the snake Bothrops jararaca was studied immunohistochemically. Immunoreactive neurons were detected in telencephalic, diencephalic and mesencephalic areas such as dorsal cortex, subfornical organ, paraventricular nucleus, recessus infundibular nucleus, nucleus of the oculomotor nerve and nucleus of the trigeminal nerve. Immunoreactive fibres ran along the hypothalamo-hypophysial tract to end in the outer layer of the median eminence and the neural lobe of the hypophysis. In general, immunoreactive fibres occurred in the same places of immunoreactive neurons. In addition, immunoreactive fibres were observed in the septum, amygdala, lamina terminalis, supraoptic nucleus, nucleus of the paraventricular organ, ventromedial hypothalamic nucleus and interpeduncular nucleus. These results indicate that, as for other vertebrates, corticotropin-releasing hormone in B. jararaca brain, besides being a releasing hormone, may also act as a central neurotransmitter and/or neuromodulator.     

Quantitative changes in the total proteins of the cells of the hypothalamic supraoptic nucleus after extreme exposures: acute immobilization and deprivation of the paradoxical sleep phase

It has been shown that 1-hour acute immobilization of rats resulted in a decrease of total protein content (per 1 cell) in neurones (by 17% in cytoplasm and 22% in nucleus) of the supraoptic nucleus of the hypothalamus and in their glial satellite cells (by 10%), mainly at the expense of the nuclei of the latter. These changes remained at the same level in the neuronal cytoplasm and satellite cells within 6 hours after cessation of acute immobilization, being abolished in the neuronal nuclei. Deprivation of REM sleep for 24 hours affected these parameters to the same extent as acute immobilization. However, 6-hour rest was sufficient for normalisation in satellite cells and for decrease in protein deficiency in the neuronal nuclei; yet protein deficiency still sustained in the neuronal cytoplasm. REM sleep deprivation was also accompanied by a decrease in tritium incorporation into satellite cell proteins (by 18%); after 3-hour rest, incorporation of the label into satellite cells was restored to the initial level being increased by 20% in neuronal nuclei; another 3-hour rest resulted in normalisation of labeling in the neuronal nuclei and in 27% increase of labeling in the satellite cells.     

The ultrastructural reorganization of the neurons in some brain formations during the deprivation of paradoxical sleep]

Electron microscopy was used to study intracellular changes in the dorsal hippocampus, lateral hypothalamic nucleus and pontine reticular formation of rats after 96-hour paradoxical sleep deprivation. It was found that compensative-accommodative processes predominate in the majority of neurons. At the same time destructive changes are detected in some cells. In changed neurons the ultrastructural signs of damage to protein-synthesizing apparatus were observed. These changes can be as a result of disturbances of protein biosynthesis.     

Serotonin Turnover in Discrete Regions of Young Rat Brain After 24 h REM Sleep Deprivation

The present study has attempted to elucidate the alteration of serotonin turnover after 24 h REM sleep deprivation in different regions in brain of young rat. Sleep deprivation was induced by the inverted flowerpot technique. Results of this study show increased serotonin turnover after 24 h REM sleep deprivation in all the brain regions except in the hypothalamus. The decreased 5-HT ratio shows increased serotonin in the hypothalamus after 24 h sleep deprivation. This study indicates increased activity of serotonergic neurons in the hypothalamus after 24 h sleep deprivation. This also indicates that the hypothalamus plays a role in the immediate compensatory mechanism during 24 h REM sleep deprivation in young rats.     

Aromatase and 5β-reductase activity in cultures of developing zebra finch brain: An investigation of sex and regional differences

Estrogen treatment of hatchling female zebra finches causes the masculine development of singing behavior and of the telencephalic brain regions involved in the control of song. However, early estrogen treatment of males also blocks masculine development of copulatory behavior, presumably controlled by diencephalic regions. In an effort to determine whether the differences in estrogen action are related to sex and regional differences in androgen metabolism (estrogen synthesis or androgen inactivation), we measured aromatase and 5β-reductase activity in dissociated-cell cultures made separately from the telencephalon, diencephalon, and also cerebellum of hatching zebra finches under a variety of conditions. Cultures from all three brain regions express high levels of aromatase and 5β-reductase activity. Comparisons between telencephalic and diencephalic cultures of the activity and kinetics of aromatase suggest that the telencephalic cultures convert androgen to estrogen more efficiently than diencephalic cultures, which might be important in the differential action of estrogen in the two brain regions. However, the activity of neither aromatase nor 5β-reductase was significantly different between the sexes in either telencephalic or diencephalic cultures. Thus, comparisons between the sexes do not support the idea that differences in posthatching aromatase or 5β-reductase activity account for the pattern of sexual differentiation of the song and copulatory systems. © 1995 John Wiley & Sons, Inc.     

Neuropeptide Y localization in telencephalic and diencephalic structures of the ground squirrel brain

The distribution of neuropeptide Y-immunoreactive (NPY-IR) perikarya, fibers, and terminals was investigated in the brain of two species of hibernatory ground squirrels, Spermophilus tridecemlineatus and S. richardsonii, by means of immunohistochemistry. In the telencephalic and diencephalic structures studied, distinct patterns of NPY-IR were observed which were essentially identical in male and female animals of both species. No differences in amount or distribution of NPY-IR structures were observed between animals which had been in induced hibernation for several months before sacrifice in March/April and those sacrificed one week after their capture in May. In some brain structures (e.g., the hypothalamic arcuate nucleus), IR cell bodies were observed only after pretreatment with colchicine. NPY-IR perikarya and fibers were found in the cerebral cortex, caudate nucleus-putamen, and dorsal part of the lateral septal nucleus. Dense fiber plexuses were seen in the lateral and medial parts of the bed nucleus of the stria terminalis. The numbers of IR perikarya observed in the medial part of the nucleus increased following intraventricular colchicine injections. The accumbens nucleus exhibited few IR cells and many fibers. Claustrum and endopiriform nuclei showed a considerable number of stained cells and fibers that increased in number and staining intensity in colchicine-treated ground squirrels. The induseum griseum showed a small band of IR cell bodies and varicose fibers. Bipolar of multipolar IR cells and varicose fibers were found in the basal nucleus of the amygdala. Dense fiber plexuses as well as IR terminals were seen in the median, medial, and lateral preoptic areas of the hypothalamus. Terminals and relatively few fibers were located in the periventricular, paraventricular, and supraoptic nuclei. The anterior, lateral, dorsomedial, and ventromedial hypothalamic nuclei contained relatively large numbers of terminals and fibers. In the suprachiasmatic nuclei, dense terminals were distributed mainly in the ventromedial subdivision. In the median eminence, immunoreactive terminals were concentrated in the external layer, with fibers predominant in the internal layer. NPY-IR perikarya were observed only in the arcuate nucleus of the hypothalamus and only following colchicine treatment. In the epithalamus (superficial part of the pineal gland and habenular nuclei), varicose fibers appeared mainly in perivascular locations (pineal) or as a dense plexus (habenular nuclei). These results from ground squirrels are discussed in comparison to those obtained in other species and with regard to considerations of the physiological role of NPY.     

Participation of agouti-related peptide in the regulation of the wakefulness-sleep cycle

Agouti-related peptide is expressed in the hypothalamic neurons in humans and animals. Immunohistochemical studies in Wistar rats shows significant changes in the optical density of agouti-related peptide in the neurons of the arcuate hypothalamic nucleus, as well as in their processes in the hypothalamus and nucleus accumbens after 6 h of sleep deprivation (an increase) and after 2 h of post-deprivative sleep (a decrease). Comparison of these findings with the earlier results shows the opposite trends in the changes in the optical density of agouti-related peptide and the speed of the limiting enzyme of dopamine synthesis, tyrosine hydroxylase, in the hypothalamus and in the striatonigral system. An increase in the agouti-related peptide level was accompanied by a decrease in tyrosine hydroxylase, while a decrease in agouti-related peptide, on the contrary, was accompanied by an increase in the tyrosine hydroxylase activity. Our data show the role played by agouti-related peptide as a modulator of the functional activity of the dopaminergic brain neurons. The interrelation between various functions of the body, such as food behavior, sleep, and stress, is considered to be mediated by the participation of the same neurotransmitter systems in their regulation.     

Localization of GRF-like immunoreactive neurons in the rat brain

The localization of human GRF1-44-immunoreactive neurons was studied in the rat brain. A dense accumulation of GRF-containing fibers was noted in the external layer of the median eminence. Cell bodies were observed in colchicine-treated rats. The most intensely fluorescent cluster of cells was contained in the arcuate nucleus. Other cells were seen on the base of the hypothalamus, within the median forebrain bundle, dorsal and ventral aspects of the ventromedial nucleus, zona incerta and dorsal part of the dorsomedial nucleus. These cells may influence the pulsatile release of pituitary growth hormone.     

THE EFFECT OF SLEEP DEPRIVATION UPON THE IN VIVO AND IN VITRO INCORPORATION OF TRITIATED AMINO ACIDS INTO BRAIN PROTEINS IN THE RAT AT THREE DIFFERENT AGE LEVELS

Abstract— The effect of sleep deprivation on the in vivo and in vitro tritiated amino acid incorporation into brain proteins was studied in the rat at three age levels. Sleep deprivation was induced either by water tank or handling methods. Three experimental groups of animals were used: control, sleep deprived and post deprivation sleeping rats.
A significant decrease of protein synthesis was found in the cerebellum, telencephalon and in crude subcellular fractions of brainstem of adult rats selectively deprived of paradoxical sleep. However, no alteration of protein synthesis was observed either in vivo or in vitro , in the same brain regions or in the liver after the rebound of paradoxical sleep following deprivation.
In four crude subcellular protein fractions a specific increase of the in vitro labelled amino acid incorporation was observed in the brain stem of 24-day-old rats allowed to recuperate after sleep deprivation as compared with the deprived rats. No significant changes were seen in the telencephalon.
No alteration of incorporation was found in 7-day-old rats deprived of sleep.
The possible functional significance of these results is discussed in relation to stress and to variations in the size of the precursor pool for protein synthesis.     

Enzymes of adenosine metabolism in the brain: diurnal rhythm and the effect of sleep deprivation

Adenosine plays a role in promoting sleep, an effect that is thought to be mediated in the basal forebrain. Adenosine levels vary in this region with prolonged wakefulness in a unique way. The basis for this is unknown. We examined, in rats, the activity of the major metabolic enzymes for adenosine - adenosine deaminase, adenosine kinase, ecto- and cytosolic 5'-nucleotidase - in sleep/wake regulatory regions as well as cerebral cortex, and how the activity varies across the day and with sleep deprivation. There were robust spatial differences for the activity of adenosine deaminase, adenosine kinase, and cytosolic and ecto-5'-nucleotidase. However, the basal forebrain was not different from other sleep/wake regulatory regions apart from the tuberomammillary nucleus. All adenosine metabolic enzymes exhibited diurnal variations in their activity, albeit not in all brain regions. Activity of adenosine deaminase increased during the active period in the ventrolateral pre-optic area but decreased significantly in the basal forebrain. Enzymatic activity of adenosine kinase and cytosolic-5'-nucleotidase was higher during the active period in all brain regions tested. However, the activity of ecto-5'-nucleotidase was augmented during the active period only in the cerebral cortex. This diurnal variation may play a role in the regulation of adenosine in relationship to sleep and wakefulness across the day. In contrast, we found no changes specifically with sleep deprivation in the activity of any enzyme in any brain region. Thus, changes in adenosine with sleep deprivation are not a consequence of alterations in adenosine enzyme activity.     

Changes in hypothalamic and extra-hypothalamic vasopressin content of water-deprived rats

A correlative radioimmunoassay (RIA) and immunocytochemical (ICC) study was carried out on vasopressin (VP) distribution and content in brains of normal and 3-day water-deprived rats. By RIA there were statistically significant differences in brain VP per pg/mg between normal and osmotically stressed specimens in hypothalamus (338.4 versus 134.4), thalamus (4.8 versus 0.9), septum (18.0 versus 3.4), striatum (1.6 versus 0.7) and amygdala (17.3 versus 1.3), but not in other brain regions measured. Pituitary VP decreased from 71.1 to 8.7 ng/mg, and plasma VP rose from 3.6 to 19.3 pg/ml during water deprivation. Application of the peroxidase-anti-peroxidase ICC method of Sternberger to vibratome sections showed that VP-immunoreactivity in dehydrated specimens decreased in perikarya of paraventricular nucleus and suprachiasmatic nucleus, while intrahypothalamic immunoreactive magnocellular fibers appeared more conspicuous due to proliferation of large Herring bodies. In extrahypothalamic sites VP-immunoreactivity in water-deprived rats was visibly reduced in periventricular thalamus and septum. Thus it is apparent that both intra- and extrahypothalamic VP are affected by osmotic stress, and these results are discussed within the context of current ideas relating to co-activation of neurosecretory cells that project to different sites.     

NT-4 protein is localized in neuronal cells in the brain stem as well as the dorsal root ganglion of embryonic and adult rats

We have newly established a sensitive, two-site enzyme immunoassay system for neurotrophin-4 (NT-4) and investigated its tissue distribution in the rat nervous system. The minimal limit of detection of the assay is 0.3 pg/0.2 mL of assay mixture. Concentrations of NT-4 were found to be extremely low in all brain regions, irrespective of the animal age, the highest level being found in the brain stem of 40-day-old rats, at 0.12 ng/g wet weight. NT-4 levels in young adult rats were significantly lower in the thalamus and higher in the olfactory bulb, neocortex, hypothalamus and brain stem than respective levels in 1-week-old rats. NT-4 immunoreactivity was strong in large neurons of the red nucleus and pontine reticular nucleus as well as the locus coeruleus, and moderate in cells in the mesencephalic trigeminal nucleus and interstitial nucleus of the medial longitudinal fasciculus. In the rat embryo, stong staining of NT-4 was detected in cells of regions corresponding to the midbrain/pons from E11.5 through E15.5. The intensity was decreased after E13.5 when the cytoplasm of cells in the medulla oblongata, fibers of the cerebellar primordium, and both cells and fibers of the dorsal root ganglion were also stained. Concentrations of NT-4 were detected in regions including the hindbrain and the dorsal root ganglion. Immunoblotting of NT-4-immunoreactive proteins extracted from these two regions revealed a band corresponding to mature NT-4 with a molecular mass of approximately 14 kDa. Kainic acid and another glutamte agonist, (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid did not affect NT-4 levels in the hippocampus. The present results show NT-4 to be localized in very limited brain cells and fibers from the embyonic period through to the young adult, suggesting specific roles in brain functions.     

Morphofunctional Analysis of Effect of Short-Term Sleep Deprivation on the Wakefulness–Sleep Cycle in Young and Adult Rats

The work presents comparative data on changes of neurophysiological, time characteristics of the wakefulness–sleep cycle (WSC) and morphofunctional state of neurosecretory cells in supraoptic nucleus of the hypothalamus, which develop under influence of a 6-h long sleep deprivation in adult and one-month old rats. It is shown that the rebound of sleep develops in adult animals with a delay, after the 3rd hour and is characterized by a moderate increase of portions of slow-wave (SSP) and fast-wave (FSP) sleep phases in WSC and by a decrease of the wakefulness portion. Morphological analysis of the hypothalamus nonapeptidergic system has revealed a rise of content of neurosecretory material in fibers of supraoptic nucleus cells an in area of supraoptic-pituitary tract, as well as marked hyperemia that indicates activation of processes of secretion of neurohormones into the general blood flow; these reactions are similar to reactions of this system to stress. In rat pups the sleep rebound develops in 0.5 h after the end of the deprivation procedure and is characterized by more pronounced, statistically significant changes in WSC. Individual WSC become very short and almost all of them are completed with episodes of FSP. A statistically significant rise of power of the -wave band in electrogram spectra of hippocampus and somatosensory cortex in SSP, whereas peak of the activity in FSP is shifted to -waves. Ratios of SSP and FSP to wakefulness in individual WSC in mature animals increase after the deprivation 1.53 and 1.85 times, while they are elevated in one-month old animals 5.25 and 6.75 times, respectively. The obtained morphofunctional data allow believing that deprivation is the stress factor of low intensity for adult animals, whereas it may be considered as the stress action of intermediate and even high intensity for rat pups, which changes essentially the interrelations in WSC. Participation of central mechanisms of regulation of sleep and vigilance, which provide processes of compensation of damaging action of deprivation on WSC in the maturing animals, is discussed.     

Different somatostatin receptor subtypes are operating in the brain of the teleost fish, Coris julis

Characterization of somatostatinergic (sst) neuronal activity through the application of nonpeptidyl agonists L-779,976 and L-817,818 which are highly specific for the sst receptors (sstr) sstr(2) and sstr(5), respectively, shows for the first time that sstr2, 5-like subtypes are the two major sstr subtypes operating in the brain of the teleost sea wrasse, Coris julis. A somewhat high but heterogeneous distribution pattern (> 30 < 180 fmol/mg wet tissue weight) of neurons expressing sstr2, 5 was reported in the different diencephalic regions plus in mesencephalon and telencephalon while low values were obtained in the cerebellum. Application of the above nonpeptidyl agonists permitted us to identify sstr2-like as the predominant subtype in telencephalic areas such as the entopeduncular nucleus (E) and postcommissural nucleus of the ventral telencephalon (Vp) as well as in hypothalamic and thalamic areas. At the same time high levels of neurons expressing sstr5-like, that greatly overlap those of sstr2-like in the diencephalic areas such as the anteroventral part of the preoptic nucleus (NPOav), the dorsal habenular nucleus (NHd) and the ventrolateral thalamic nucleus (VL), indicate that sstr2-like is very likely not the only sstr subtype acting in this fish brain. The predominance of sstr5-like in other brain areas is confirmed by the high quantities of this subtype in mesencephalic areas such as the torus longitudinalis (TLo). Overall, the discriminately differing densities of neurons expressing both subtypes seem to point to this system as a key molecular basis accounting for the distinct neurophysiological and behavioral sst-dependent activities in Coris julis.     

Electrical stimulation of the preoptic area in Eigenmannia: evoked interruptions in the electric organ discharge

The functional role of the basal forebrain and preoptic regions in modulating the normally regular electric organ discharge was determined by focal brain stimulation in the weakly electric fish, Eigenmannia. The rostral preoptic area, which is connected with the diencephalic prepacemaker nucleus, was examined physiologically by electrical stimulation in a curarized fish. Electrical stimulation of the most rostral region of the preoptic area with trains of relatively low intensity current elicits discrete bursts of electric organ discharge interruptions in contrast to other forebrain loci. These responses were observed primarily as after-responses following the termination of the stimulus train and were relatively immune to variations in the stimulus parameters. As the duration and rate of these preoptic-evoked bursts of electric organ discharge interruptions (approximately 100 ms at 2 per s) are similar to duration and rate of natural interruptions, it is proposed that these bursts might be precursors to natural interruptions. These data suggest that the preoptic area, consistent with its role in controlling reproductive behaviors in vertebrates, may be influencing the occurrence of electric organ discharge courtship signals by either direct actions on the prepacemaker nucleus or through other regions that are connected with the diencephalic prepacemaker nucleus. Accepted: 16 October 1999