The cortisol awakening response (CAR): Facts and future directions

Autoradiographic localization of opiate receptors in rat brain. I. Spinal cord and lower medulla.

Opiate receptor binding in primate spinal cord: distribution and changes after dorsal root section.

Cellular signaling and factors involved in Müller cell gliosis: neuroprotective and detrimental effects.

A nuclear framework structure termed the nuclear matrix has been isolated and characterized. This matrix forms the major residual structure of isolated nuclei and consists largely of protein with smaller amounts of RNA, DNA, carbohydrate, and phospholipid. The nuclear matrix can be further resolved by combined treatment with DNase and RNase. The remaining nuclear protein structure, after extraction of 90 percent of the nuclear protein, 99.9 percent of the DNA, and 98 percent of the RNA and phospholipid, is termed the nuclear protein matrix. Electron microscopy of this final nuclear protein matrix reveals an interior framework structure composed of residual nucleolar structures associated with a granular and fibrous internal matrix structure. The internal matrix framework is derived from the interchromatinic structures of the nucleus, and is connected to a surrounding residual nuclear envelope layer containing residual nuclear pore complex structures. Sodium dodecyl sulfate-acrylamide gel electrophoresis of the nuclear matrix proteins demonstrates three major polypeptide fractions, P-1, P-2, and P-3, with average molecular weights of approximately 69,000, 66,000 and 62,000, as well as several minor polypeptides which migrate at approximately 50,000 and at higher molecular weights (>100,000). Polypeptides with molecular weights identical to those of P-1, P-2 and P-3 are also components of isolated nuclear envelopes and nucleoli, whereas isolated chromatin contains no detectable matrix polypeptides. This suggests that the major matrix polypeptides are localized in specific structural regions of the nucleus, i.e., nuclear envelope, nucleoli, and interchromatinic structures. The presence of cytochrome oxidase activity in the isolated nuclear matrix indicates that at least some integral proteins of the nuclear membrane are associated with the matrix.

Nuclear matrix: Isolation and characterization of a framework structure from rat liver nuclei

The rat substantia gelatinosa Rolandi (lamina II) was found to contain synaptic glomeruli at the centre of which was a dark terminal (C-terminal) full of round synaptic vesicles. The C-terminal was presynaptic to several dendritic profiles and to terminals containing sparse pleomorphic synaptic vesicles, and was occasionally postsynaptic at symmetrical contacts to other terminals containing numerous pleomorphic vesicles of which about one-third were elongated. Acid phosphatase activity was observed on, and between, the membranes of the synaptic vesicles of the central bouton, as well as in the hyaloplasm of the peripheral elements of the glomeruli. Dorsal root section caused electrondense degeneration of the central boutons. Acid phosphatase activity disappeared from synaptic vesicle membranes in C-boutons, and gradually filled their dense cytoplasmic matrix. The enzyme disappeared completely from the peripheral profiles. The synaptic glomeruli of the rat gelatinosa are thus a synaptic relay station for primary afferents, whose terminals possess an extralysosomal acid phosphatase possibly concerned with the metabolism of a local synaptic transmitter. Enzyme accumulation in degenerating knobs seems to be an autolytic process distinct from the normal function of this acid phosphatase.

The substantia gelatinosa Rolandi of the rat. Fine structure, cytochemistry (acid phosphatase) and changes after dorsal root section.

The adrenal gland plays a pivotal role in the stress response since this response involves the hypothalamic-pituitary-adrenal axis (HPAA) and the sympatho-adrenomedullary system (SAMS) as its two principal components. An important relation between the immune system and the other stress response systems is also centered on the adrenal gland. It is well known that the cortex secretes glucocorticoids while the medulla secretes epinephrine, two of the major effects of the stress response. Some other aspects, however, also deserve special consideration: The paracrine effects of the cortical secretion on the medullary cells through the special irrigation system of the gland and reciprocally the influence of the medulla upon the cortex, either by direct close contact or by local innervation. The influence of vascular events also needs to be considered as well as the existence of some local hormonal axis such as those resulting from the local production of renin or CRH in adrenal cells. Some other cells such as mast cells, macrophages and endothelial cells seem to play a role in the regulation of the adrenal cortex and hence in the tuning of the stress response. Stressors stimulate the release of CRH from the hypothalamic paraventricular nucleus inducing the secretion of ACTH from the pituitary and that of corticosteroids from the adrenal cortex. Through the activation of the sympathetic system the adrenal can be stimulated even before adequate levels of ACTH are reached. In conditions of chronic stress the adrenal cortex undergoes an adaptation that allows the hypersecretion of glucocorticoids to occur even without the increment of ACTH.

M. M. Magalhães

Papers

The substantia gelatinosa Rolandi of the rat. Fine structure, cytochemistry (acid phosphatase) and changes after dorsal root section.

Direct effects of stress on adrenocortical function.

Pulmonary function electronic monitoring devices: a randomized agreement study.

The rabbit retina Müller cell. A fine structural and cytochemical study

Microbodies (Peroxisomes) in rat adrenal cortex