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Biomedical subjects

F F Marciano

Publications and source records attributed to F F Marciano.

24 records · Page 2Linked to original sources
PubMed1989

Fetal hypothalamic transplants promote survival and functional regeneration of axotomized adult supraoptic magnocellular neurons.

This study investigated the mechanisms by which fetal hypothalamic transplants promote functional recovery in neurohypophysectomized rats. Seven days after neurohypophysectomy (resulting in urine osmolalities of about 800 mOsm), young adult male Long-Evans rats received either fetal hypothalamic grafts (n = 10) or sham transplants (n = 7). Recovery from the lesioned-induced diabetes insipidus was monitored for 6 months and then the transplant sites were evaluated by immunocytochemistry. Surviving host supraoptic magnocellular neurons and neurophysin-positive grafted neurons were counted and their formation of neurohemal contacts evaluated by retrograde transport of systemically injected horseradish peroxidase (HRP). There were significantly more surviving supraoptic magnocellular neurons in neurohypophysectomized animals with median eminence-placed grafts (2236 +/- 261 neurons/animal) than in animals with ectopic tissue grafts (895 +/- 142 neurons/animal) or sham implants (1052 +/- 92 neurons/animal). Almost all surviving host magnocellular neurons were labeled with retrogradely transported HRP while virtually none of the grafted neurophysin positive cells showed evidence of HRP uptake. The degree of functional recovery was directly correlated with the increased survival of host neurons. By 8 weeks post-transplantation, animals with median eminence-placed grafts had recovered from their diabetes insipidus and could concentrate their urine to within normal limits (2,120 +/- 110 mOsm). This recovery was stable for the remainder of the 6 month test period. In contrast, animals with ectopic grafts and sham transplants had permanent deficits in fluid regulation. Our results provide evidence for the long-term capacity of fetal neural tissue implants to rescue host neurons from the cell death that typically occurs in the mature central nervous system after axotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Telencephalic cholinergic system of the New World monkey (Cebus apella): morphological and cytoarchitectonic assessment and analysis of the projection to the amygdala.

While the cholinergic projection from the nucleus basalis to the cortical mantle has received considerable attention, a similar projection to the magnocellular basal nucleus of the amygdala has not been studied in such detail. The present study analyzed the cholinergic basal forebrain projection to the amygdala in the Cebus apella monkey by using combined tract-tracing and immunocytochemical techniques. As a foundation for this assessment, the morphological and cytoarchitectonic organization of the cholinergic telencephalic system of the New World C. apella monkey was examined by using choline acetyltransferase (ChAT) immunocytochemistry. Although there were minor differences, the telencephalic cholinergic system of Cebus monkeys is similar to that seen in Old World nonhuman primates. ChAT-immunoreactive neurons were observed throughout the Ch1-4 regions of the basal forebrain, with subdivisions of the Ch4 region similar to those previously described (Mesulam et al., '83a). Most cholinergic neurons were hyperchromic and magnocellular; however, some neurons were parvicellular. Like most species, cholinergic neurons were also observed throughout the striatum. However, unlike in rodents, cholinergic perikarya were not observed within the cortex or hippocampus. To analyze the cholinergic fiber projections from the basal forebrain to the amygdala, monkeys received an intraamygdaloid injection of the retrograde tracer horseradish peroxidase conjugated to wheat germ agglutinin. Retrogradely labeled neurons that colocalized ChAT or acetylcholinesterase (AChE) were found predominantly in the anterolateral portion of the CH4 region. Fewer double-labeled neurons were found in the anteromedial and intermediate portion of CH4 and in the CH3 region. Neurons that exhibited retrograde labeling were only occasionally discerned in the posterior portions of the CH4 region, in the medullary laminae of the globus pallidus, or lodged within the internal capsule. These data are discussed in terms of the putative role this cholinergic input might play in cognitive processing in primates.

Acetylcholinesterase↗
PubMed1987

Selective cell death of magnocellular vasopressin neurons in neurohypophysectomized rats following chronic administration of vasopressin.

Regeneration and functional recovery of the hypothalamoneurohypophysial system (HNS) in neurohypophysectomized rats treated with either saline or vasopressin (VP) were analyzed utilizing specific immunohistochemical and physiological measures. Neural lobe ablation combined with VP administration precipitated a profound diabetes insipidus (following cessation of VP delivery) that persisted for the duration of the experiment. Diabetes insipidus was correlated with a drastic reduction in the number of VP-positive neurons in magnocellular hypothalamic nuclei. In contrast, large numbers of oxytocin (OT)-positive neurons survived neurohypophysectomy in VP-treated neurohypophysectomized rats; OT neurons accounted for the vast majority of magnocellular profiles observed in Nissl-counterstained sections. VP-immunoreactive fibers could be observed in limited quantities in the external lamina of the median eminence of VP-treated neurohypophysectomized rats, with little staining evident in the internal lamina. Saline-treated neurohypophysectomized rats exhibited the recovery of antidiuretic function characteristically seen following this lesion, with evidence of survival of considerable numbers of VP and OT neurons and median eminence hypertrophy. Both the internal and external laminae of the median eminence were densely innervated by large-caliber VP and OT fibers. Sham-operated animals receiving VP treatment did not show any long-term deficit in water metabolism, changes in the complement of VP or OT perikarya in hypothalamus, or changes in the innervation of the median eminence. Results indicate that VP treatment following neurohypophysectomy results in extensive retrograde degeneration of magnocellular VP neurons without affecting the survival of OT cells.

Animals↗
PubMed1986

Vasopressin administration prevents functional recovery of the vasopressinergic neurosecretory system following neurohypophysectomy.

The rodent hypothalamic neurosecretory system normally exhibits remarkable functional and structural plasticity following injury. However, the present study describes a newly observed phenomenon in which neurohypophysectomized animals receiving chronically administered exogenous vasopressin during the post-lesion period (a treatment which insures maximal renal antidiuresis over this time frame) lose all capacity for recovery of antidiuretic function. Functional deficits are accompanied by a severe reduction in the number of neurons exhibiting immunohistochemical staining for arginine vasopressin. These data indicate that the presence of neurological stimulation signaling vasopressin release may play an important role in promoting neural regeneration of the vasopressinergic component of the neurosecretory system.

Animals↗
PubMed1986

Structural and functional relationships of grafted vasopressin neurons.

Fetal vasopressin neurons were grafted into adult Long-Evans rats with vasopressin deficiencies created by neural lobe ablation one week prior to implantation. Control animals and recipients with ectopic grafts still possessed significant deficits in fluid regulation 6 weeks following implantation. However, recipients with grafts fused to the host median eminence and containing magnocellular vasopressin neurons juxtaposed to the host portal vasculature showed restored peripheral vasopressin activity as measured by normal urine volumes and osmolalities. These findings suggest that structural integration of grafted neuroendocrine tissue with the appropriate target in the host brain is a necessary prerequisite for physiological activity.

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