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At least 883 records · Page 49Linked to original sources
PubMed1984

Effect of chronic administration of delta 9-tetrahydrocannabinol on the endogenous opioid peptide and catecholamine levels in the diencephalon and plasma of the rat.

The effect of chronic administration of delta 9-tetrahydrocannabinol (delta 9-THC) on the endogenous opiate and catecholamine levels was investigated. Intact male rats were injected daily either with vehicle (50 microliters oil) or delta 9-THC in oil (3 mg delta 9-THC/kg body wt). The treatments were administered subcutaneously over a period of 25 days. All animals were decapitated after the last injection and trunk plasma was assayed for prolactin, beta-endorphin-like immunoreactivity (beta-end LI), norepinephrine (NE), epinephrine (E), dihydroxyphenyl acetic acid (DOPAC) and dopamine (DA). The preoptic area (POA) and medial basal hypothalamus were assayed for methionine enkephalin, beta-endorphin and catecholamines. Chronic delta 9-THC treatment resulted in an increase in POA and MBH methioine-enkephalin and beta-end LI as well as an increase in plasma beta-end LI. The POA, MBH and plasma NE and E levels were lower in these animals when compared with the controls. In the MBH, however, the delta 9-THC treated rats contained higher DA and DOPAC levels when compared with the controls. These results support our view that chronic delta 9-THC administration alters the activities of the endogenous opiate system as well as the catecholaminergic system and consequently impairs the endocrine functions.

Animals↗
PubMed1980

The morphology of the diencephalon in the Prosimii. II. The Lemuroidea and Lorisoidea. Part I. Thalamus and metathalamus.

This study (Part I) covers the comparative structure of the thalamus and metathalamus in the prosimian superfamilies, Lorisoidea and Lemuroidea. Several lemuroid specimens, namely Lemus, Cheirogaleus, Microcebus, Avahi and Daubentonia, and lorisoid specimens such as Galago, Perodicticus and Loris have been used in this extensive study. The anterior nuclear group does not show much difference among these species, although attention is focussed on the differentiation of the principal anterior nucleus into anteromedial and anteroventral parts; the latter increases in structural complexity. The anterodorsal nucleus has regressed into a small, flattened cap-line structure covering the dorsal surface of the anteroventral nucleus. The midline thalamic nuclei are more or less the same throughout the entire prosimian primate scale, though the gradual fusion of the nucleus rhomboidalis with the nucleus centralis medialis is observed from Microcebus to Daubentonia. The medial thalamic nuclear region is dominated by the nucleus mediodorsalis which is clearly differentiated into dorsomedial magnocellular and ventrolateral parvocellular protions. A third division consisting of rather large, darkly staining cells have been observed in the caudal region of the nucleus mediodorsalis. The nuclei centrum medianum and parafascicularis are both large in size, but is not completely demarcated from each other. The dorsolateral thalamic nuclei--the nuclei laterales dorsalis, intermedius and posterior, are well developed, but cannot be distinguished from one another. The pulvinar shows a remarkable phylogenetic development; it does not only enlarge, but is differentiated into several distinct parts. The ventrolateral thalamic nuclear group is comparably larger in structural size than the dorsolateral thalamic nuclei. The nuclei ventrales anterior and lateralis are not clearly demarcated from each other, but on both cyto- and myelo-architectonic grounds, are separate entities. The nucleus ventralis posterior is differentiated into lateral, medial and inferior parts. The posterior thalamic nuclei show the beginnings of regression. The nucleus pretectalis remains comparatively large in size and divided into medial and lateral parts. The nucleus posterior thalamicus is either absent or involuted into other nuclei. The nucleus limitans makes its first appearance in the Prosimii. The lateral geniculate body is very variable in size in all respects among the prosimian species, that is, in the dorsoventral shift along the lateral surface of the thalamus, the cellular differentiation of the lateral geniculate nucleus into 5 or 6 layers, the topographical position of the pregeniculate nucleus and the degree of inversion. The medial geniculate body is shown to be clearly subdivided on cyto-architectonic grounds into dorsomedial and ventrolateral parts; a magnocellular protion can be seen on the dorsal region of this nucleus, and appears to be closely related to the nucleus suprageniculatus.

Animals↗
PubMed1976

[Quantitative growth analysis of limbic nuclei areas fresh volume in diencephalon and mesencephalon of an albino mouse ontogenic series. II. Corpus mammillare].

The fresh volumes of the Nucl. medialis and of the Nucl. lateralis corporis mammillaris of 52 white mice aged between 17 and 60 days of ontogenesis have been determined. The fresh volume of the left Nucl. lateralis is significantly larger than that of the right side. The data of the Nucl. laterales have been fitted by a 3parametric logistic function. The data of the Nucl. medialis have been fitted by a sum of logistic functions. This sum has an increasing and a decreasing component and it shows a maximum of the sum of both components near 32 days of ontogenesis. The degree of maturity and the growth-rate of maturity have been discussed. Both nuclei belong to the group of brain regions in white mice with an early development. The growth of different brain regions is asynchronous. There is a need for further quantitative analyses.

Age Factors↗
PubMed1976

[Effect of transection of the forebrain, diencephalon and midbrain on respiration in cats].

In vagotomized cats, after removal of the brain portion 5 mm rostral to the visual nerves crossing, the eupnoea type of respiration was preserved. Transection in the area of the visual nerves crossing was followed by a stable acceleration of respiration. Starting from the level of the posterior border of the visual nerves crossing and more caudal, successive transections of the brain entailed sharp decrease in the breathing rate, increase of the respiratory volume, and complicated changes of the lungs ventilation.

Animals↗
PubMed1976

[Quantitative growth analysis of limbic nuclei areas fresh volume in diencephalon and mesencephalon of an albino mouse ontogenic series. III. Nucleus interpe-uncularis].

The fresh volume of the Nucl. interpeduncularis of 52 white mice aged between 17 and 60 days of ontogenesis has been determined. The data have been fitted by the logistic function and the ideal volume (0.32 mm3) the half value time (21.6 days of ontogenesis) and the factor of enlargement (2.65) have been derived. The Nucl. interpeduncularis is one of the early and fast growing brain regions. The growth parameters of this nucleus have been discussed and have been compared with the parameters of other cortical and subcortical limbic brain regions.

Age Factors↗
PubMed1982

Brain extracellular fluid pH and blood flow during isocapnic and hypocapnic hypoxia.

Cerebrovascular responses to 30 min of isocapnic hypoxia [arterial O2 partial pressure (PaO2) = 33 +/- 1 Torr; means +/- SE] were examined in eight chloralose-urethan-anesthetized, paralyzed, and artificially ventilated New Zealand White rabbits. Cerebral blood flow (Q) was measured using the radioactive microsphere technique. Vascular resistance (R) was calculated from arterial pressure and Q. Brain extracellular fluid (ECF) pH was measured continuously in the same animals using pH microelectrodes (1- to 2-micrometers tip diameter) placed stereotaxically in the diencephalon. Diencephalon Q increased from 40 +/- 2 to 69 +/- 4 ml . 100 g-1 . min-1 (P less than 0.05) as R decreased (P less than 0.05) after 4-6 min of isocapnic hypoxia. Total brain Q and R changes resembled those of the diencephalon. The ECF pH of the diencephalon increased by 0.016 +/- 0.006 (P less than 0.05) after 1 min of isocapnic hypoxia and remained significantly elevated through the first 20 min of hypoxia. Ten minutes after the return of normoxia Q and R were at control levels, whereas diencephalon ECF pH was 0.043 +/- 0.006 below control (P less than 0.05). Five additional rabbits were prepared as described above then made hypocapnic [arterial CO2 partial pressure (PaCO2) = 21 +/- 0.3 Torr] for 18 min. Diencephalon and total brain Q and R remained at control levels through 12-14 min of hyperventilation, whereas diencephalon ECF pH was elevated by 0.03 +/- 0.006 (P less than 0.05). Hyperventilation was then continued with hypoxic gas to lower PaO2 to 35 +/- 4 Torr for 30 min. Both diencephalon and total brain R decreased (P less than 0.05), with no change in Q after 4-6 min of hypocapnic hypoxia. Diencephalon ECF pH was not significantly different from control throughout the hypocapnic-hypoxic period. We conclude that the early cerebral vasodilation during hypoxia is not mediated by increased brain ECF acidity.

Animals↗
PubMed1988

The development and morphogenesis of the human pituitary gland.

In order to clarify the environmental factors which are involved in the development of the primordium of the pituitary gland such as cell-cell interactions, a three-dimensional reconstruction of this organ and its surrounding tissues was carried out. Pituitary material was obtained from human fetuses mainly during the period of organogenesis. Rathke's diverticulum was found to stretch rostrally from the stomodeal epithelium to the middle of the mesoderm, and already by the 5th week of fetal growth, it was clearly seen to be involved with the diencephalon. The area of contact between Rathke's pouch and the diencephalon gradually moved from the rostral to caudal regions and, after 13 weeks of development, had a position similar to that found in the newborn infant. Among the cells forming Rathke's pouch, it was found that the closer their relationship was to the diencephalon, the greater were their epithelial characteristics. When the relationship of such cells to the diencephalon was weaker, their differentiation to endocrine cells occurred earlier. Immunohistochemically, that portion of the pituitary primordium which has a close relationship with the diencephalon, later to become the pars intermedia, showed an adrenocorticotropic hormone (ACTH) immunoreactivity later than that of the pars anterior. On the other hand, in the 21st fetal week, nearly all of the cells of the pars intermedia were found to be ACTH-positive. This finding is thought to indicate a close connection between the physical contact between the brain (diencephalon) and the pituitary primordium and the development of the pars intermedia; the differentiation of ACTH cells. The surface of the epithelium of Rathke's cavity continues to increase at least until the 21st fetal week, so the growth of the epithelium of Rathke's pouch is thought to be heavily involved in the growth of the primordium of the pituitary gland in the early stages of development.

Cell Communication↗
PubMed1999

Roles of Pax-2 in initiation of the chick tectal development.

Transplantation experiments have shown that the mes-metencephalic boundary (isthmus) acts as an organizer for the development of the optic tectum. We have cloned Pax-2 which is expressed in the isthmus. Previously it was shown that Pax-5, a member of the same Pax subfamily as Pax-2, transformed the diencephalon into a tectum-like structure and induced isthmus- and tectum-related genes both in the mesencephalon and in the diencephalon. In order to define the distinct roles between Pax-2 and Pax-5 in development of the tectum, we expressed Pax-2 ectopically in the mesencephalon and the diencephalon of E2 chick embryos by in ovo electroporation. Histological observation demonstrated that Pax-2 transformed the diencephalon into a tectum-like structure. In Pax-2, transfected embryos the expression of isthmus- and tectum-related genes such as Fgf8 and En-2 was induced in the diencephalon. However, neither Fgf8 nor En-2 expression was induced in the mesencephalon, making a striking contrast with the result of Pax-5 misexpression. In E2 chick embryos, the mesencephalon is committed of its fate to differentiate into the tectum, but the diencephalon has plasticity on its fate. Moreover, Pax-2 expression in the isthmus precedes Pax-5 expression. Taking these results into consideration, it is suggested that Pax-2 plays a crucial role in initiation of the tectal development, and that Pax-5 functions to maintain the state of tectal differentiation.

Amino Acid Sequence↗