Aluminum Formaldehyde Research Articles

Room-Temperature Luminescence of Formaldehyde-Condensed Amines Adsorbed on Filter Paper

The luminescence of tryptophan, dopamine, and epinephrine adsorbed on filter paper and condensed by the aluminum formaldehyde (ALFA) histoluminescence method is reported. The resultant luminescence is a short-lived phosphorescence or long-lived fluorescence which is partially dependent on the inhibition of oxygen quenching by aluminum. Attempts to condense the amines by the formaldehyde (FA) method were not successful. Filter paper is a surface that can potentially be used for histochemical modeling and the influence of albumin and pH on such models is discussed. The room temperature phosphorescence characteristics of tryptophan, dopamine, epinephrine, tryptamine, and 5-methoxytryptamine are compared with the luminescence of the condensed amines.

Catecholamine innervation of the caudal spinal cord in the rat.

By means of the aluminum-formaldehyde (ALFA) fluorescence technique for monoamine visualization the distribution of catecholamines was studied in the caudal spinal cord, particularly in relation to motoneurons innervating pelvic structures. In the lumbosacral cord all parts of the spinal gray matter were found to contain catecholamines. In the dorsal horn the most intense fluorescence was seen in the superficial layers. The motoneuron neuropil exhibited the most prominent catecholamine-fluorescence of the ventral horn layers. In the sixth lumbar segment, which contains the motor nuclei that innervate the pelvic striated muscles as well as one innervating muscles in the lower limb, a differential distribution of the density of catecholamine fluorescence was presented by the individual nuclei. The catecholamine fibers in the motoneuron neuropil were seen closely surrounding the motoneuron somata, suggesting the existence of axosomatic contacts, and by utilizing the fluorescent retrograde tracer True Blue in combination with the ALFA method tentative axosomatic noradrenergic synapses on identified neurons innervating small striated pelvic muscles could be visualized in the light microscope. In the intermediate gray the intermediolateral nucleus in thoracic and upper lumbar segments was the most heavily innervated area, followed by the medial lumbar sympathetic group, which contains the majority of the sympathetic preganglionic neurons innervating the pelvic organs. The parasympathetic intermediolateral nucleus in the upper sacral segments received a catecholamine innervation of moderate density. The catecholamine innervation pattern is discussed in relation to the patterns of other putative transmitters. The distribution of catecholamine fluorescence in relation to nuclei that control the pelvic organs differs from the arrangement of other transmitters in this region. The complexity of the innervation of the pelvic organs and their related striated muscles is thus further stressed.

Plasticity of catecholaminergic neurons in aged rat brain: Reinnervation and functional recovery after axotomy

Regenerative growth at the lesion site, reinnervation of a target nucleus and functional manifestations of recovery were studied in aged (20 and 30 months old) rats subjected to long-term transection of catecholaminergic (CA) fibers which contact and influence neurons of the supraoptic nucleus (SON). Small bilateral knife cuts were placed stereotaxically just caudal and medial to the SON. CA histofluorescence, induced by formaldehyde-glutaraldehyde (FAGLU) or aluminum-formaldehyde (ALFA) methods, was examined in hypothalamus at 2, 14, 21 and 60 days postsurgically. Water consumption, and urine volume and osmolality, were monitored presurgically, and through survival times. Subtotal CA denervation in the SON, and typical axonal transmitter “pile-up” at the lesion site, were evident two days after surgery. Among these degenerative profiles, which persisted for up to three weeks, fine-sized new fibers were apparent at the lesion, beginning between 2 and 14 days, and persisting throughout the period studied. At 21 days, and progressively thereafter, SON neurons were rimmed with fluorescent varicosites. Water consumption initially was depressed, but returned to presurgical mean levels by nine days. Urine volume returned to normal by 32 days. Urine osmolality showed a recovery by approximately three weeks. These functional parameters rebounded to levels higher than presurgical means among 20 month old, but not 30 month old, rats beyond 6 weeks survival, concurrent with a morphological hyperinnervation. The results reaffirm morphological regeneration, and support reinnervation and functional recovery, which extend considerably into the aging process.

Recent developments in aldehyde-induced monoamine fluorescence: the aluminum-formaldehyde (ALFA) method applied to immature and adult central nervous tissue.

In this review, the new aluminum-formaldehyde (ALFA) histofluorescence method for the highly sensitive visualization of monoamine-containing neurones in adult and immature central nervous tissue is summarized. Animals are first perfused with a buffer containing high concentrations of aluminum ions and the brains are then freeze-dried, reacted with formaldehyde vapour and further processed according to the Falck-Hillarp fluorescence method. The ALFA technique applied to adult brains visualizes all known catecholamine neurone systems with a sensitivity comparable to, and for certain noradrenergic systems higher than, that of the previously published glyoxylic acid-Vibratome method. The catecholamine systems in immature brains are demonstrated with a sensitivity clearly superior to that of any other available method. If the ALFA method is combined with systemic injections of alpha-methylnoradrenaline into young animals (less than one week old), there is a dramatic increase in the intensity and number of catecholaminergic fibres. Many catecholaminergic systems which have too low concentrations of transmitter to be visualized in the untreated animal even with the ALFA method, can be demonstrated after administration of alpha-methylnoradrenaline. The use of freeze-dried, paraffin-embedded tissue in the ALFA method makes possible convenient storage and parallel processing of many specimens. This mode of processing also allows en bloc reaction, which is the only way by which consistent and reproducible fluorescence yields can be obtained throughout large series of sections and parallel-processed specimens. In animals pretreated with L-tryptophan and monoamine oxidase-inhibitor, the technique is also useful for studies on central indolamine-containing systems.

A modified aluminum-formaldehyde (ALFA) histofluorescence method for enhanced visualization of central techolamine.

We designed a modification of the aluminum-formaldehyde (ALFA) histofluorescence method based on preperfusion with buffer containing formaldehyde (FA). This modified ALFA technique enables visualization of all catecholamine (CA) neuron systems with a sensitivity comparable to that of the previously published glyoxlic acid (GA)-Vibratome method, providing better reproducibility and facility of the procedure than the ALFA method.

The aluminum-formaldehyde (ALFA) histofluorescence method for improved visualization of catecholamines and indoleamines. 1. A detailed account of methodology for central nervous tissue using paraffin, cryostat or vibratome sections

This present paper presents a new aluminum-formaldehyde (ALFA) histofluorescence method for highly sensitive visualization of central monoamine-containing neurons, based on perfusion with or immersion in buffers containing high concentrations of aluminum ions. Our previous studies have shown that perfusion or immersion of tissues with solutions containing high concentrations of magnesium results in an improvement in the visualization of intraneuronal catecholamines in the reaction with formaldehyde and glyoxylic acid. This study demonstrates that aluminum is considerably more efficient as a fluorescence-promoting agent, thus causing a further increase in the sensitivity of the formaldehyde method. Detailed protocols are given for the ALFA-method applied to paraffin sections of freeze-dried tissue, and to cryostat and Vibratome sections. The present ALFA technique applied to paraffin sections of freeze-dried tissue visualizes all known catecholamine neuron systems with a sensitivity comparable to, and for certain noradrenergic systems higher than, that of the previously published glyoxylic acid-Vibratome method. Furthermore, the use of freeze-dried, paraffin embedded tissue makes possible convenient storage and parallel processing of many specimens. This mode of processing also allows en bloc reaction, which is the only way by which consistent and reproducible fluorescence yields can be obtained throughout large series of sections and parallelly processed specimens. In animals pretreated with l-tryptophanand MAO-inhibitor the technique is also useful for studies on central indoleamine-containing systems in freeze-dried tissue. The ALFA procedure applied to cryostat and Vibratome sections gives a more sensitive and reproducible visualization of central catecholamine neurons than previous methods.

Application of the aluminum-formaldehyde (ALFA) histofluorescence method for demonstration of peripheral stores of catecholamines and indolamines in freeze-dried paraffin-embedded tissue, cryostat sections and whole-mounts.

This paper describes new procedures for highly sensitive visualization of monoamine stores in peripheral tissues, taking advantage of the recently introduced aluminum-catalysed formaldehyde (ALFA) reaction. The tissues are exposed to an aluminum sulphate solution (with or without formaldehyde fixation) in a perfusion and/or immersion step, followed by formaldehyde vapour treatment. Procedures are described for freeze-dried, paraffin embedded tissue, cryostat sections and whole mount preparations. For all these tissue preparations the ALFA method gives a highly sensitive and precise demonstration of catecholamine-containing neurons and 5-HT-containing cells in a variety of peripheral tissues. For freeze-dried tissue and cryostat sections the ALFA method represents an improvement in comparison with other available methods. This is particularly noticeable for the very delicate adrenergic nerves in such organs as the thyroid, ovary, pancreas and the gastrointestinal tract.