Target-derived macromolecules in the peripheral nervous system apparently play an important part in the regulation of neuronal survival and maturation during critical stages of development. Similar trophic factors could also be required in the central nervous system (CNS) for the maintenance of intracerebral connections, and neuronal cell death may result from a decrease or failure of a target-derived trophic support. Recent experiments have demonstrated the presence of factors in brain extracts or astrocytic glial cells which can support the survival of embryonic sympathetic, parasympathetic or sensory ganglionic neurones in vitro. The importance of these putative factors for neuronal survival in vivo has, however, so far not been demonstrated. In the study reported here we have used the intracerebral grafting technique to monitor the availability of survival factors in an adult CNS target area and show here that neonatal rat superior cervical cells, which have an absolute requirement for such factors for their survival, will survive in the hippocampal formation of adult rats only in the presence of a denervating lesion.

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PubMedDate not supplied

Subarachnoid haemorrhage in the rat: effect on the development of cerebral vasospasm of lesions in the central serotoninergic and dopaminergic systems.

In the rat an intracisternal injection of blood induces an angiographically demonstrable biphasic cerebral arterial vasospasm. Chemical destruction of the central serotoninergic and dopaminergic pathways prior to the cisternal blood injection does not affect the spasm pattern after the subarachnoid haemorrhage. It is suggested that neither system plays a role in the development of spasm.

5,7-Dihydroxytryptamine↗

PubMedDate not supplied

Corticosteroid suppression of trauma-induced hyaluronan in rabbit cornea and aqueous.

BACKGROUND: Corneal and aqueous hyaluronan have recently been shown to react in response to several different types of trauma, including cataract surgery. In order to find ways to influence the reaction, we have evaluated the effect of topical dexamethasone (Isopto-Maxidex, Alcon Universal Ltd, Fort Worth, Tex) or indomethacin (Confortid, Dumex Ltd, Copenhagen, Denmark) on the postoperative hyaluronan concentration in rabbit cornea and aqueous after extracapsular lens extraction. METHODS: The drugs were administered as topical eye drops three times daily. The hyaluronan concentration in rabbit cornea and aqueous after extracapsular lens extraction was measured with a radioligand assay. RESULTS: Dexamethasone treatment (1 mg/mL) significantly suppressed the increase in corneal hyaluronan seen after extracapsular lens extraction, 2 (p < or = 0.0022) and 3 weeks (p < or = 0.0002) after surgery, while indomethacin did not induce any significant difference at 2 weeks. When the dexamethasone concentration was lowered to 0.1 and 0.2 mg/mL, there was still a significant decrease (p < or = 0.009) in hyaluronan concentration, but at lower concentrations of dexamethasone (0.01 and 0.02 mg/mL), no significant decrease was seen. The increase in aqueous hyaluronan concentration seen 2 days after surgery in untreated eyes was significantly lowered by both dexamethasone (p < or = 0.0076) and indomethacin (p < 0.036). CONCLUSIONS: Dexamethasone lowers reactive corneal and aqueous hyaluronan concentration in vivo after extracapsular lens extraction.

Administration, Topical↗

PubMedDate not supplied

Regenerative sprouting of central monoamine neurons.

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Animals↗

PubMedDate not supplied

Influence of radial keratotomy on endogenous hyaluronan in cornea and aqueous humour.

BACKGROUND: Hyaluronan is known to appear in corneal wound tissue and is probably involved in the healing process. We measured the changes of endogenous hyaluronan in rabbit cornea and aqueous after radial keratotomy. METHODS: Corneal and aqueous hyaluronan concentrations were measured at different time intervals after radial keratotomies. Hyaluronan was extracted from corneal tissue with two methods employing either pronase or NaCl and measured with a radioimmunoassay. Histochemical staining for hyaluronan was done on the operated eyes. RESULTS: Changes in corneal hyaluronan showed a similar time course with either extraction method. Maximal concentration was reached after 7 to 14 days with a return to normal values in 60 days. Aqueous hyaluronan and proteins were not significantly altered after surgery. Histochemical staining of the corneas demonstrated hyaluronan around the incisions along their entire extent. Blood vessels were absent in the wounds. An increase in elongated fibroblast-like cells was seen in the wound area. CONCLUSIONS: Both quantitatively and histochemically, there is a pronounced increase of corneal hyaluronan in avascular, radial keratomy wounds in the rabbit. The findings suggest a role of hyaluronan in corneal wound healing.

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