Hypothalamic accessory nuclei and their relation to the angiotensinergic and vasopressinergic systems.

The existence and colocalization of angiotensin II- and vasopressin-like immunoreactivity in individual magnocellular cell groups of the hypothalamus has been demonstrated by using immunocytochemical methods. These neurosecretory magnocellular groups consist of the paraventricular nucleus and the supraoptic nucleus, as well as different accessory cell groups. The fibers from the neurons of the accessory nuclei project directly to adjacent blood vessels and do not comigrate with the hypothalamo-neurohypophysial fiber pathway. On the basis of these findings it can be concluded that in the hypothalamus two different angiotensinergic and vasopressinergic neurosecretory systems exist: (1) an intrinsic hypothalamic and (2) a hypothalamo-neurohypophysial system. The distribution of the accessory cell groups in the hypothalamus is shown in a 3D reconstruction which includes the connection of these magnocellular nuclei with the vascular system in this area.

Vasopressinergic neurons and the associated blood vessels in the rat anterior hypothalamus: an immunohistochemical study.

The paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamic neurosecretory system have been extensively investigated by many workers. The functional aspects of vasopressin secretion (elaborated by the PVN and SON neurons) in relation to the vasculature of the anterior hypothalamus are also well documented. However, the available data concerning vasopressin (VP) functions are largely based on physiological studies. Corroborative morphological correlation with regard to this has received little attention. The present report elucidates the intricate anatomical relationships between the VP-neurons and the adjoining capillaries in the rat anterior hypothalamus. A peroxidase-antiperoxidase (PAP) immunocytochemical study, using a commercial VP antibody, was carried out for this purpose. The observations are interpreted from a functional standpoint. VP-immunostained elements, i.e. the somata and the processes (mainly dendrites), were localized (i) close to the wall, (ii) on the endothelium, and (iii) occasionally, in the lumen of the hypothalamic capillaries. The findings provide immunocytochemical evidence that the vasopressinergic elements are in direct relationship with the hypothalamic vasculature. This raises some interesting possibilities for the former to be involved in: (i) affecting the permeability of the blood-brain barrier for transport of various nutrient substances (important in aging and Alzheimer's disease), (ii) inducing an alteration in the water permeability of the brain vessels on which depends the precise adjustment of brain water content and of brain volume (fundamental to normal functioning of the brain), and (iii) serving as osmoreceptors of the blood flowing through the capillaries and thus providing a feedback mechanism for VP modulation.

[Blood flow and pO2 in the posterior hypothalamus of cats during paradoxical sleep]. / Krovotok i pO2 v zadnem gipotalamuse koshek vo vremia paradoksal'nogo sna.

In chronic experiments on cats it has been found by recording of the brain local blood flow (BLBF) and of oxygen tension (pO2) in the posterior and anterior hypothalamus, that at sleep phases alternation, the changes of these parameters are differently directed: during the paradoxical sleep the level of BLBF and pO2 oscillations frequency increased in the posterior hypothalamus and decreased in the anterior one. During slow-wave sleep opposite relations were observed. Opposite directions of changes of BLBF level and pO2 oscillations frequency in one and the same phase of sleep show that they are of local origin and must be determined by functional-metabolic shifts. In particular, the increase of BLBF level and frequency of pO2 oscillations must reflect a rise of posterior hypothalamus functional-metabolic activity during paradoxical sleep.

[Microsurgical anatomy of extraorganic arteries of the hypothalamo-hypophyseal complex and the rational technic of its removal for transplantation]. / Mikrokhirurgicheskaia anatomiia ékstraorgannykh arterii gipotalamo-gipofizarnogo kompleksa i ratsional'naia tekhnika ego zabora dlia peresadki.

The authors ascertained the existence of numerous anastomoses between the right and left hypophyseal arteries on the level of both the interlobar sulcus and the base of the hypophyseal funnel in the form of an inferior and superior hypophyseal anastomotic rings, as well as a system of arterial connections between the anterosuperior and anteroinferior subgroups of the hypothalamic arteries located in front of and lateral to the chiasma as prechiasmal networks. This creates anatomo-physiological preconditions for adequate circulation in the hypothalamo-hypophyseal graft after its transplantation and inclusion in the blood flow of the internal carotid artery or one of its terminal branches. Bearing in mind the close connection of the hypophyseal and hypothalamic arteries with the cavernous sinuses, chiasma, and components of the sella turcica, the hypothalamo-hypophyseal graft must be removed in a complex with these structures.

[Dynamics of local blood flow in different areas of the hypothalamus during the sleep-wakefulness cycle]. / Dinamika mestnogo krovotoka v razlichnykh oblastiakh gipotalamusa v tsikle bodrstvovanie--son.

In cats with implanted electrodes, the local blood flow (LCBF) was studied in different hypothalamic areas using the electrochemically generated hydrogen. During paradoxical sleep (PS), the level of LCBF increases in the posterior hypothalamus, while decreasing in the anterior hypothalamus and preoptic area. In slow wave sleep (SWS), however, the level of LCBF increases in the anterior hypothalamus and preoptic area, while decreasing in the posterior hypothalamus. These shifts of LCBF during PS are supposed to reflect an enhancement of the posterior hypothalamus functional activity. During SWS the functional activity must be enhanced in the anterior hypothalamus and preoptic area, while being suppressed in the posterior hypothalamus.

The angiotensin II pressor system of the rat forebrain.

An anterior hypothalamic knife cut that leaves intact two central sites of action of angiotension II produces the same deficits in the pressor responses to angiotensin II that have been attributed to destruction of two circumventricular organs (the subfornical organ and the organum vasculosum of the lamina terminalis). The central pressor actions of angiotensin II are necessary for the full expression of renin-dependent renal hypertension. The anterior hypothalamic knife cut attenuates renin-dependent aortic ligation hypertension. It has been shown that electrolytic destruction more anterior to this knife cut, in the anteroventral 3rd ventricle region, also attenuates two forms of renin-dependent hypertension, aortic ligation hypertension and two-kidney Goldblatt hypertension in the rat. Electrolytic lesions in the subfornical organ also reduce renin-dependent, two-kidney Goldblatt hypertension. These data are consistent with the hypothesis that a common efferent system from the organum vasculosum of the lamina terminalis and subfornical organ mediates the central pressor response to angiotensin II and is involved in the development of renin-dependent hypertension. A model is proposed for the circuitry in the rat forebrain that is involved in the pressor response to angiotensin II.

Systemic and regional hemodynamic changes associated with anterior hypothalamic lesions in conscious rats.

Systemic and regional hemodynamics were determined with the radioactive microsphere technique either in conscious "sham-lesioned" Wistar rats or after bilateral electrolytic lesions of the nuclei of the anterior hypothalamus. Both mean arterial pressure (111 +/- 4 vs 152 +/- 3 mm Hg) and heart rate (376 +/- 15 vs 504 +/- 12 beats/min) were significantly increased 2 hours after lesioning (p less than 0.001). Although cardiac output tended to increase, it did not attain statistical significance; therefore this form of neurogenic hypertension is characterized by increased total peripheral resistance. Regional hemodynamics were measured 2 hours after placement of the lesions: skeletal muscle flow increased, renal cutaneous and splanchnic flows decreased, and brain and myocardial flows were preserved. These hemodynamic alterations were associated with significant elevations in plasma norepinephrine and epinephrine levels, and behavioral changes characterized by hypermotility, aggressitivity, and irritability, which resembled those seen during fighting and exercise.

Selective traumatic infarction of the human anterior hypothalamus. Clinical anatomical correlation.

A case of assult with bilateral manual avulsion of the eyes was followed by highly selective infarction of the anterior hypothalamus. The hypothalamic infarction occurred as a result of avulsion of part of the optic chiasm together with the anterior perforating arteries passing through it; Following this assault, symptoms of hypothalamic dysfunction included altered thermoregulation, alternating diabetes insipidus, and inappropriate antidiuretic hormone (ADH) secretion, altered patterns of sleep and arousal, and changing cardiac arrhythmias. The case casts light upon the vascular supply of the human hypothalamus and on the degree of localization existing for various hypothalamic functions.

[Development of neuron-capillary interrelationships in the nuclei of the anterior portion of the human hypothalamus during ontogenesis]. / Osobennosti razvitiia neiron-kapilliarnykh vzaimootnoshenii v iadrakh perednego otdela gipotalamusa cheloveka v ontogeneze.

Three periods in the formation of the spatial arrangement of the neuronal nuclei have been stated: 1) from the prenatal period, infancy including--pronounced decrease in the density of the neuronal cells arrangement; 2) from the childhood up to adolescence--relative stabilization in the hypothalamic cellular composition; 3) mature and old age--secondary decrease in the dencity of the neuronal cells arrangement. Certain peculiarities in the nuclear capillary composition and in their neuronal-capillary relationships have been revealed: during the prenatal ontogenesis, the dencity of the neuronal cells arrangement decreases and their size increases that is followed by decrease in their capillary loops. In postnatal ontogenesis no proportional relationship between the dencity of neuronal cells arrangement and that of capillary network in the nuclei of the anterior hypothalamus was noted.

Capillary innervation in the mammalian central nervous system: an electron microscopic demonstration.

Capillaries in the cat hypothalamus receive axon terminals which are comparable to neurovascular junctions in cerebral and systemic arteries and arterioles. The innervation of capillaries in the central nervous system may be derived from central neurons, in contrast to cerebral arterial vessels, which are supplied by the peripheral autonomic nervous system.

Blood supply of the rat hypothalamus. III. Anterior region of the hypothalamus (nucleus suprachiasmatis, nucleus hypothalamicus anterior, nucleus periventricularis).

The arterial and venous blood supply of the anterior hypothalamus was studied by means of double perfusion technique. The angiotopography and cytoarchitecture of the hypothalamus were compared on serial sections by accounting for the three-dimensional coordinates. A detailed description is given of the arteries and veins contributing to the blood supply of the suprachiasmatic, the anterior hypothalamic and the periventricular nuclei. The topography of the arterial and venous trunk on the base surface of the rat diencephalon is described, as well as that of the larger branches which enter from below and pass through the anterior hypothalamus.