Effect of the adrenoreactive structures of the anterior hypothalamus on blood coagulation

In the chronic experiment stimulation of alpha- and beta-adrenoreactive structures of the anterior hypothalamus by adrenolytic substances is carried out before and after the blockade. The results of the experiments show specificity of the influence of alpha- and beta-adrenoreactive structures of the anterior hypothalamus on different phases of the process of blood coagulability.     

Plasma growth hormone responses to microinfusion of noradrenergic agents into or electrical stimulation of the hypothalamus and amygdala in baboons

In nine baboons (Papio papio) guide cannulae and electrodes were stereotaxically implanted into the medial basal or lateral hypothalamus, the anterior hypothalamus or the dorsal amygdala. Plasma GH responses were measured after microinfusion (1 microliter) of the alpha2 adrenergic agonist, clonidine, or the beta adrenergic antagonist, propranolol, or electrical stimulation, in each of these sites. Clonidine, 100 nmol/microliter, infused into the medial basal or lateral hypothalamus elevated plasma GH levels by 5-30 ng/ml, 30-45 min post-infusion. Plasma GH responses to clonidine infused into the anterior hypothalamus or the dorsal amygdala were all less than 10 ng/ml. The prior, intravenous, administration of piperoxane, 1.0 mg/kg prevented GH responses to clonidine. Propranolol, 50 nmol/microliter, infused into the dorsal amygdala consistently increased plasma GH levels by 5-15 ng/ml. Electrical stimulation of the medial basal or lateral hypothalamus elevated plasma GH levels by 7-35 ng/ml, 15-45 min post stimulation. Electrical stimulation of anterior hypothalamus or dorsal amygdala did not alter plasma GH levels. The stimulation of alpha 2 adrenergic receptors in the medial basal or lateral hypothalamus of the baboons appears to facilitate GH release.     

The role of adrenergic structures of the posterior hypothalamus in the regulation of the blood coagulation system functions

Under conditions of chronic experiment, the stimulation of alpha- and beta-adrenergic structures of the posterior hypothalamus was performed. The same procedure was repeated after inactivation of these structures. The results of experiments have shown a specificity of the influence of alpha- and beta- adrenergic structures upon the separate blood coagulation phases and the heterogeneity of those structures distribution in the posterior hypothalamic region.     

Distribution of delta sleep-inducing peptide in the newborn and infant human hypothalamus: an immunohistochemical study

The distribution of delta sleep-inducing peptide immunoreactive cell bodies, fibers, and terminal-like structures was investigated in the normal human hypothalamus during the first postnatal year, using immunohistofluorescence and peroxidase anti-peroxidase techniques. Immunolabeled perikarya were relatively few and were mostly scattered through the anterior (preoptic) and mediobasal regions (infundibular nucleus) of the hypothalamus. DSIP-immunoreactive fibers and terminal-like fibers were observed throughout the entire rostrocaudal extent of the hypothalamus. They exhibit high densities in the preoptic region, the organum vasculosum of lamina terminalis, infundibular nucleus and median eminence. Moderate to low densities of DSIP-immunoreactive fibers were observed in the other hypothalamic structures, located in the anterior and mediobasal regions of hypothalamus, such as periventricular, paraventricular, suprachiasmatic, ventromedial, dorsomedial and parafornical nuclei. In the present study, the analysis of the immunohistochemical pattern of DSIP-immunoreactive neuronal elements in the human infant hypothalamus during the first postnatal year provided evidence of the presence of several differences. We have found qualitative age-related changes in the density of DSIP immunoreactivity in several hypothalamic structures such as the anterior region and the median eminence.     

Participation of hypothalamic adrenergic and cholinergic systems in the regulation of pituitary adrenocorticotropic function]

Experiments were conducted on male rats; a study was made of the activity of pituitary-adrenal cortex system under conditions of electrolyte destruction of various hypothalamic areas. Pharmacological analysis pointed to the irregular distribution in the hypothalamus of the cholinergic and adrenergic systems controlling the secretion of ACTH-glucocorticoids. As suggested, the cholinergic systems are situated in the mammillary region, alpha-adrenergic ones--in the anterior or the posterior regions of the hypothalamus, and beta-adrenergic receptors--in the ventromedial nuclei of the hypothalamus. The latter possibly play an inhibitory role.     

Study of the innervation of blood vessels of the digestive organs by fluorescence microscopy]

The blood vessels of the samll intestine and the gallbladder were shown to possess a great amount of adrenergic nerve fibres which, when penetrating the thickness of the wall of the above organs, become thinner and the distributed between the tissue structures of the organs as the thinnest monoaxonal network. The method of Falck--Hillarp--Krokhina was used. Among the vessel nerves there are perivascular nerves accompanying the vessels along their total legnth, juxtavascular and intramural nervous bundles of the sumpathetic nature detected by the fluorescent-microscopy method. Large arteries are disposed in a considerably thicker network of specifically fluorescing fibres than veins and small arteries.     

Sympathetic innervation of blood vessels in rats with aortic constriction hypertension

The adrenergic innervation of blood vessel wall was studied in various vascular beds of adult rats with experimental hypertension induced by the constriction of the aorta between the origins of both renal arteries. A moderate expansion of body fluids was demonstrated in this hypertensive model. The decrease of the density of adrenergic plexus in the vessel wall as well as the diminished catecholamine fluorescence were found only in renal vessels. These changes were pronounced in the left renal artery and vein even if the left kidney was not subjected to elevated blood pressure. Thus the alteration of vascular adrenergic innervation in hypertensive rats is not a consequence of high blood pressure but it seems to be a part of neurohumoral pathogenetic mechanisms.     

Neurotensin-like immunoreactivity in the diencephalon of the adult male cat

Using an indirect immunoperoxidase technique, the location of neurotensin-like fibers and cell bodies was studied in the diencephalon of the cat. The findings showed that the hypothalamus is richer in neurotensin-like-immunoreactive structures than the thalamus, and that neurotensin-like-immunoreactive structures are more widely distributed in the hypothalamus than in the thalamus. A high density of immunoreactive fibers was observed in the hypothalamic regions, area hypothalamica dorsalis, hypothalamus posterior, nucleus (n.) filiformis and n. arcuatus, whereas a moderate density was found in the n. parafascicularis, n. paraventricularis anterior, hypothalamus lateralis, median eminence and n. paraventricularis hypothalami. Other diencephalic regions such as n. lateralis posterior, n. lateralis dorsalis, n. medialis dorsalis, n. habenularis lateralis, n. centrum medianum, n. rhomboidens, n. reuniens, hypothalamus anterior, n. supra chiasmaticus, hypothalamus ventromedialis, n. supraopticus and hypothalamus dorsomedialis had the lowest density of immunoreactive fibers. In addition, the densest clusters of neurotensin-like perikarya were found in the n. arcuatus, n. centralis medialis and hypothalamus posterior, whereas the n. medialis dorsalis, n. paraventricularis anterior, n. reuniens, hypothalamus lateralis and hypothalamus ventromedialis had the lowest density. In the n. lateralis dorsalis, n. supraopticus, area hypothalamica dorsalis and n. supra chiasmaticus the density of immunoreactive perikarya was moderate.     

Effect of N-stearoylethanolamine(NSE) on activity of angiotensine-converting enzyme in the brain structures and blood plasma of rats with streptozotocine-induced diabetes

The influence of saturated N-acylethanolamine--N-stearoylethanolamine (NSE) on the activity of angiotensine-converting enzyme (ACE) in the brain structures of rats with streptozotocine-induced diabetes was studied. It was shown that decreased activity of ACE was observed in the hypothalamus, increased--in the anterior pituitary. The NSE suspension administration to rats with experimental diabetes in a dose 50 mg/kg of body weight during 10 days caused a decrease in ACE activity in the anterior pituitary, whereas in the hypothalamus and hippocampus ACE activity did not change significantly. At the same time, introduction of NSE to intact animals led to the reduction of activity of ACE in the hippocampus, anterior pituitary and blood plasma. It is known that the highest amount of ACE in the brain structures is located in the membrane-bound state. Thus, the changes we have found in the activity of ACE in the control rats and in animals with induced diabetes may be related to the ability of NSE to the modulation of cell membranes lipid profile. Changes in the activity of ACE under the action of N-acylethanolamines may be one of the mechanisms for implementation of anti-hypertensive and anti-inflammatory action of these compounds.     

Modulation of spiking of neurons of the cat anterior hypothalamus induced by experimental shifts in the osmolarity of the blood plasma

We examined changes in the impulse activity (IA) generated by neurons of the anterior hypothalamus (including the preoptic region) resulting from infusions of hyper-and hypotonic NaCl solutions (3.0 and 0.2%, respectively; hyper-and hypoosmotic stimulations, respectively); the infused volumes did not exceed 200 μl. The effects of hyper-and hypoosmotic stimulations were studied in detail in 83 and 88 neurons, respectively. In 31.2% (26 cells) and 29.6% (26 cells) of the neurons of the above groups, these stimulations evoked changes in the IA frequency greater than +40 or −40% of the mean background IA frequency. In approximately 50% of the responding neurons in each group, such shifts in the IA frequency were observed in the course of infusions of test solutions (5 sec long) and within the subsequent 5 min after termination of the infusion. In another 50% of the neurons, changes in the IA frequency occurred within the afterperiod (30 sec long); these shifts could develop exclusively within the latter interval, or these changes accompanied an initial early reaction. In general, activating responses dominated (they were observed in 65% of the cases where test stimulations of both modalities were used). The possible aspects of the involvement of neurons of the anterior hypothalamus in the control of the water/salt balance in the organism are discussed. Neirofiziologiya/Neurophysiology, Vol. 38, No. 1, pp. 40–45, January–February, 2006.     

Expression of the GnRH and GnRH receptor (GnRH-R) genes in the hypothalamus and of the GnRH-R gene in the anterior pituitary gland of anestrous and luteal phase ewes

Data exists showing that seasonal changes in the innervations of GnRH cells in the hypothalamus and functions of some neural systems affecting GnRH neurons are associated with GnRH release in ewes. Consequently, we put the question as to how the expression of GnRH gene and GnRH-R gene in the hypothalamus and GnRH-R gene in the anterior pituitary gland is reflected with LH secretion in anestrous and luteal phase ewes. Analysis of GnRH gene expression by RT-PCR in anestrous ewes indicated comparable levels of GnRH mRNA in the preoptic area, anterior and ventromedial hypothalamus. GnRH-R mRNA at different concentrations was found throughout the preoptic area, anterior and ventromedial hypothalamus, stalk/median eminence and in the anterior pituitary gland. The highest GnRH-R mRNA levels were detected in the stalk/median eminence and in the anterior pituitary gland.During the luteal phase of the estrous cycle in ewes, the levels of GnRH mRNA and GnRH-R mRNA in all structures were significantly higher than in anestrous ewes. Also LH concentrations in blood plasma of luteal phase ewes were significantly higher than those of anestrous ewes.In conclusion, results from this study suggest that low expression of the GnRH and GnRH-R genes in the hypothalamus and of the GnRH-R gene in the anterior pituitary gland, amongst others, may be responsible for a decrease in LH secretion and the anovulatory state in ewes during the long photoperiod.     

Eating or Drinking Elicited by Direct Adrenergic or Cholinergic Stimulation of Hypothalamus

A double cannula system, allowing repeated stimulation of central structures with crystalline chemicals, was developed. This technique was employed to study the effects of adrenergic and cholinergic stimulation of the lateral hypothalamus of rats. Drug-specific effects on the feeding and drinking mechanisms, respectively, were observed.     

Adrenergic and cholinergic components of the innervation of the arteries of the base of the bird brain

By means of Falck's and Koelle's methods adrenergic and cholinergic structures were studied in the arteries in the cerebral basis of blue rock pigeons and of hens, white leghorn stock. The number of nerve transmitters was estimated per 1 mm2 of the vessel surface. The arteries of the basis in pigeon brain are surrounded with developed adrenergic and cholinergic nerve plexuses, their density decreasing in the following order: nasal branch of the internal carotid artery, middle, nasal cerebral and basilar arteries. A little more cholinergic transmitters occur on the middle cerebral artery, while on the other vessels, concentration of cholinergic and adrenergic fibers is equal. In hens, the density in the arrangement of adrenergic nerve transmitters is higher in the nasal branch of the internal carotid and in the nasal cerebral arteries than in the basilar artery. At the same time, chromaffin cells forming numerous conglomerations in some places are found on the latter. In pigeons, the density of adrenergic fibers arrangement on the arteries of the cerebral basis is higher than in hens.     

Central and peripheral alpha adrenergic activity of imidazoline derivatives

Intravenous injection of a number of imidazoline derivatives into rats induced an increase in blood pressure due to peripheral alpha adrenergic receptor stimulation. Some of these compounds, however, caused a secondary, long lasting decrease which was caused by central nervous system alpha adrenergic receptor stimulation. This central hypotensive action was only observed in the case of 2-amino-imidazolines such as clonidine, tramazoline and St 600, a clonidine analogue. Imidazolines lacking the nitrogen between the imidazoline and the benzene or naphtalene group such as oxymetazoline, xylometazoline and naphazoline were found to exert no central hypotensive action.Within the series of 2-amino-imidazolines lipid solubility turned out to be a major factor in the potency of a drug's central hypotensive action.Oxymetazoline — peripherally a very potent alpha adrenergic receptor stimulating agent — did not even cause hypotension when injected into the anterior hypothalamus, a brain structure where alpha adrenergic receptors mediating depressor effects have been localized. These data show that the hypothalamic alpha adrenergic receptors differ from peripheral alpha receptors and that only imidazolines with 2-amino substitution show affinity for these central hypotensive alpha adrenergic receptors.     

Electrophysiological study of the functional connections of the hypothalamus with the forebrain in the tortoise Emys orbicularis

During stimulation of the posterior hypothalamus, the evoked potentials with short latent periods, high amplitude and poor exhaustion by rhythmic stimulation were recorded in the hippocampal cortex. In the piriform cortex, the evoked potentials exhibited longer latent periods and complex configuration. Less readily the evoked potentials appeared in the neocortex, their latency being very large. During stimulation of the anterior hypothalamus, maximum activity was also localized in the hippocampal cortex. The data obtained indicate close connection between hypothalamic structures and the hippocampal cortex. The latter is presumably the main projectional area for the ascending afferentation from the hypothalamus.     

Study of human cerebral blood flow by corrosion casts of the carotid system

20 corrosion casts of human anterior cerebral arteries and middle cerebral arteries were analyzed. In 588 vessel sections in between 2 bifurcations, the relation of vessel length and vessel diameter was investigated. Measurements were taken starting from the arterial trunk down to vessels with a diameter of 0.4 mm. The mean values of the lengths show that both the anterior cerebral artery and the middle cerebral artery can be grouped into 5 diameter ranges with significant different lengths. With decreasing diameter there are short vessels in the groups 1, 3 and 5 and long vessels in the groups 2 and 4. However, the long branches in the groups 2 and 4 of the middle cerebral artery are longer and thinner than in the anterior cerebral artery. Due to the higher pressure loss in thin and long vessels, blood pressure drop occurs earlier in the branches of the middle cerebral artery than in those of the anterior cerebral artery.     

Fate of the anterior neural ridge and the morphogenesis of the xenopus forebrain

The fate of the anterior neural ridge was studied by following the relative movements of simultaneous spot applications of DiI and DiO from stage 15 through stage 45. These dye movements were mapped onto the neuroepithelium of the developing brain whose shape was gleaned from whole-mount in situs to neural cell adhesion molecule and dissections of the developing nervous system. The result is a model of the cell movements that drive the morphogenesis of the forebrain. The midanterior ridge moves inside and drops down along the most anterior wall of the neural tube. It then pushes forward a bit, rotates ventrally during forebrain flexing, and gives rise to the chiasmatic ridge and anterior hypothalamus. The midanterior plate drops, forming the floor of the forebrain ventricle, and, keeping its place behind the ridge, it gives rise to the posterior hypothalamus or infundibulum. The midlateral anterior ridge slides into the lateral anterior wall of the neural tube and stretches laterally into the optic stalk and retina, and then rotates into a ventral position. The lateral anterior ridge converges to the most anterior part of the dorsal midline during neural tube closure, then rotates anteriorly, and gives rise to telencephalic structures. Whole-mount bromodeoxyuridine labeling at these stages showed that cell division is widespread and relatively uniform throughout the brain during the late neurula and early tailbud stages, but that during late tailbud stages cell division becomes restricted to specific proliferative zones. We conclude that the early morphogenesis of the brain is carried out largely by choreographed cell movements and that later morphogenesis depends on spatially restricted patterns of cell division. © 1995 John Wiley & Sons, Inc.     

The mechanisms of the influence of the anterior and posterior hypothalamus on the electrical activity of the large hemispheres of the forebrain and on autonomic reactions in hens

Studies have been made of the effect of stimulation of the anterior and posterior hypothalamus on the electrical activity of the hemispheres, arterial blood pressure, heart and respiration rates. Mainly desynchronizing mechanisms were revealed in the ascending influences from both the anterior and posterior hypothalamus. Concerning the descending influences, it was found that stimulation of the anterior hypothalamus evokes depressor reactions, whereas stimulation of the posterior hypothalamus results in pressor reactions. Peculiarities of evolutionary development of the ascending and descending mechanisms of the posterior and anterior hypothalamus are discussed.     

Corticotropin-releasing factor release from in vitro superfused and incubated rat hypothalamus. Effect of potassium, norepinephrine, and dopamine

We have compared the release of CRF induced by potassium depolarization, noradrenaline or dopamine as monitored either during superfusion of mediobasal hypothalamus or during incubation of whole hypothalamus. The superfusion device was improved in order to prevent gas leakage and to keep constant pO2 and pCO2 in the superfusion chamber. Basal CRF secretion as well as KCl- and norepinephrine-induced CRF release were comparable in superfusion and incubation experiments. Pharmacological investigations suggest that the stimulatory effect of norepinephrine on CRF release is mediated mainly through alpha 1 and alpha 2 adrenergic receptors, and partially through beta receptors.