Åke Seiger

Early prenatal ontogeny of central monoamine neurons in the rat: Fluorescence histochemical observations

SummaryThe early ontogeny of the monoamine neuron systems in the rat brain has been analysed using Falck-Hillarp fluorescence histochemistry. Serial sagittal sections of embryos with a crown rump length between 7 and 13 mm, approximately corresponding to gestational days 12 to 15 were obtained from mothers treated with a monoamine oxidase inhibitor given in order to increase the monoamine levels of the embryos. 5-hydroxytryptamine (5-HT)-neurons made their first appearance in the 8 mm embryo, dopamine (DA)-neurons in the 9 mm embryo, and noradrenaline (NA)-neurons in the 11 mm embryo. Small, rounded, weakly fluorescent cell bodies forming sparse aggregations appeared first. Fluorescent processes of two types soon appeared. Short processes from the cell bodies were running perpendicular to the long axis of the brain stem within the cell groups, while long slender axon bundles could be traced ascending through the met- and mesencephalon and into the prosencephalon as well as descending in the myelencephalon andspinal cord. In the 12 mm embryo the primordial DA cell formation of the substantia nigra with its striatal projections, the 5-HT neuron formations of the caudal mesencephalon, met- and myelencephalon as well as the NA neurons of the met- and myelencephalon are relatively well developed.It is concluded that the monoamine-neurons develop mechanisms for synthesis and storage of amines at a very early stage during ontogeny, thus recapitulating the phylogeny of these old systems. Likewise, monoamine oxidase is present early. The presence of neurotransmitters specifying the different developing neurons long before development of their nerve terminal areas and therefore before the establishment of normal synaptic function may indicate a role of these substances during ontogeny other than transmission of nerve impulses.

In vitro expansion of a multipotent population of human neural progenitor cells.

The isolation and expansion of human neural progenitor cells have important potential clinical applications, because these cells may be used as graft material in cell therapies to regenerate tissue and/or function in patients with central nervous system (CNS) disorders. This paper describes a continuously dividing multipotent population of progenitor cells in the human embryonic forebrain that can be propagated in vitro. These cells can be maintained and expanded using a serum-free defined medium containing basic fibroblast growth factor (bFGF), leukemia inhibitory factor (LIF), and epidermal growth factor (EGF). Using these three factors, the cell cultures expand and remain multipotent for at least 1 year in vitro. This period of expansion results in a 10(7)-fold increase of this heterogeneous population of cells. Upon differentiation, they form neurons, astrocytes, and oligodendrocytes, the three main phenotypes in the CNS. Moreover, GABA-immunoreactive and tyrosine hydroxylase-immunoreactive neurons can be identified. These results demonstrate the feasibility of long-term in vitro expansion of human neural progenitor cells. The advantages of such a population of neural precursors for allogeneic transplantation include the ability to provide an expandable, well-characterized, defined cell source which can form specific neuronal or glial subtypes.

Intracerebroventricular Infusion of Nerve Growth Factor in Three Patients with Alzheimer’s Disease

Nerve growth factor (NGF) is important for the survival and maintenance of central cholinergic neurons, a signalling system impaired in Alzheimer’s disease. We have treated 3 patients with Alzheimer’s disease with a total of 6.6 mg NGF administered continuously into the lateral cerebral ventricle for 3 months in the first 2 patients and a total of 0.55 mg for 3 shorter periods in the third patient. The patients were extensively evaluated with clinical, neuropsychological, neurophysiological and neuroradiological techniques. Three months after the NGF treatment ended, a significant increase in nicotine binding was found in several brain areas in the first 2 patients and in the hippocampus in the third patient as studied by positron emission tomography. A clear cognitive amelioration could not be demonstrated, although a few neuropsychology tests showed slight improvements. The amount of slow-wave cortical activity as studied by electroencephalography was reduced in the first 2 patients. Two negative side effects occurred with NGF treatment: first, a dull, constant back pain was observed in all 3 patients, which in 1 patient was aggravated by axial loading resulting in sharp, shooting pain of short duration. When stopping the NGF infusion, the pain disappeared within a couple of days. Reducing the dose of NGF lessened the pain. Secondly, a marked weight reduction during the infusion with a clear weight gain after ending the infusion was seen in the first 2 patients. We conclude from this limited trial that, while long-term intracerebroventricular NGF administration may cause certain potentially beneficial effects, the intraventricular route of administration is also associated with negative side effects that appear to outweigh the positive effects of the present protocol. Alternative routes of administration, and/or lower doses of NGF, perhaps combined with low doses of other neurotrophic factors, may shift this balance in favor of positive effects.

Nerve growth factor affects11C-nicotine binding, blood flow, EEG, and verbal episodic memory in an Alzheimer patient (Case Report)

SummaryBased on animal research suggesting that nerve growth factor (NGF) can stimulate central cholinergic neurons, the known losses of cholinergic innervation of the cortices in Alzheimers disease (AD), and our experience of infusing NGF to support adrenal grafts in parkinsonian patients, we have initiated clinical trials of NGF infusions into the brain of patients with AD. Here we report a follow-up of our first case, a 69-year-old woman, with symptoms of dementia since 8 years. Intraventricular infusion of 6.6 mg NGF during three months resulted in a marked transient increase in uptake and binding of11C-nicotine in frontal and temporal cortex and a persistent increase in cortical blood flow as measured by PET as well as progressive decreases of slow wave EEG activity. After one month of NGF, tests of verbal episodic memory were improved whereas other cognitive tests were not. No adverse effects could be ascribed to the NGF infusion. Taken together, the results of this case study indicate that NGF may counteract cholinergic deficits in AD, and suggest that further clinical trials of NGF infusion in AD are warranted.

Histochemical demonstration and mapping of 5-hydroxytryptamine- and catecholamine-containing neuron systems in the human fetal brain.

SummaryThe distribution of monoamine neurons in the human fetal brain was studied by Falck-Hillarp fluorescence histochemistry. Catecholamine (CA)- and 5-hydroxytryptamine (5-HT)-neuron systems were found in the smallest brain studied, obtained from an embryo having a total length of 2.1 cm and a gestational age of 7 weeks. A marked proliferation and differentiation of the monoamine neuron systems took place between the 7th and 23rd week of gestation (the range covered in the present investigation) permitting a mapping of major cell groups, as well as several axon pathways and terminal innervation patterns.The basic cytoarchitectonic features of the central monoamine neurons in human fetuses were strikingly similar to those of the fetal rat. Thus, a large complex of cell bodies was found in the developing substantia nigra area, in all probability the CA neurons of the nigro-striatal dopamine system. Axons projected towards the corpus striatum. Here, the putamen and, somewhat later, the caudate nucleus became richly innervated by CA nerve terminals. Small clusters of CA nerve cells were found in the hypothalamus, e. g. in the ventral periventricular area.5-hydroxytryptamine nerve cell bodies were distributed throughout the raphe areas from the medulla oblongata to the mesencephalon forming several well delineated groups, e.g. a large group in the area of nuc. raphe dorsalis. 5-HT axons projected caudally in the ventral parts of the medulla oblongata and into the spinal cord and rostrally through the mesencephalon and into the forebrain.CA cell bodies were also found in several large complexes of the medulla oblongata and pons, where such cell bodies are of the noradrenaline type in animals. The principal locus coeruleus consisted of densely packed fluorescent cells and several loosely packed groups extended laterally, medially, dorsally and rostrally from this area. Several axon bundles ascended dorsally from this complex. Ventrally and dorsally located CA cell groups were found in the medulla oblongata, and green fluorescent axons descended into the spinal cord.Varicose nerve terminals of the CA type were found, e.g. in the spinal cord, around the third ventricle and, using brain smears, also in the developing cerebral and cerebellar cortices.There seemed to be an outflow of CA axons in ventral nerve roots of cranial and spinal nerves. The developing pineal gland showed scattered 5-HT-containing parenchymal cells. Area postrema contained a number of strongly fluorescent CA cells and some weaker fluorescent 5-HT cells.

The Stockholm spinal cord injury study: 1. Medical problems in a regional SCI population

Out of a regional traumatic spinal cord injury population consisting of 379 individuals, 353 (93.1%) participated in the present study. Subjects were individually interviewed using semi-structured protocols. In addition, previous medical records were available for over 96% of subjects, and were used in all these cases to minimise recall bias. Cause of injury, prevalence of present medical symptoms and occurrence of medical complications in the post-acute, post-discharge phase were recorded. Neurological classification was verified by physical examination according to ASIA/IMSOP standards. Many subjects had experienced complications since discharge from initial hospitalisation, especially urinary tract infections, decubitus ulcers, urolithiasis, and neurological deterioration. Prevalence of medical symptoms was also high. More than 41% of subjects with spastic paralysis reported excessive spasticity to be associated with additional functional impairment and/or pain. Almost two-thirds of subjects reported significant pain, with a predominance of neurogenic-type pain. Bladder and bowel dysfunction were each rated by nearly 41% of subjects as a moderate to severe life problem. As expected, sexual dysfunction was also commonly reported. Prevalence of reported symptoms by general systems review was high, particularly fatigue, constipation, ankle oedema, joint and muscle problems, and disturbed sleep. However, lack of adequate normative data precludes comparison with the general population. The frequent occurrence of reported medical problems and complications support advocacy of comprehensive, life-long care for SCI patients. The commonly reported problems of neurogenic pain and neurological deterioration, in particular, require more attention, as these symptoms are not seldom ominous, either by virtue of their impact on quality of life, or because of underlying pathology.

Chronic pain-related syndrome in rats after ischemic spinal cord lesion: a possible animal model for pain in patients with spinal cord injury

&NA; We examined a pain‐related syndrome, which includes mechanical allodynia and autotomy, in rats after ischemic spinal cord injury photochemically induced by laser irradiation for 5–20 min. This procedure results in an acute allodynia‐like phenomenon which lasts for several days and is possibly related to dysfunction of the GABAB system in the spinal cord. In some animals this is followed by a chronic allodynia‐like symptom with an onset varying between 1 week and 1.5 months after injury, expressed as a clearly painful reaction to light pressure applied to a skin area at or near the dermatome of the injured spinal segments. In the majority of rats the allodynia persists over several months, in some cases accompanied by autotomy of the hind paws. Pharmacological studies indicated that the allodynia in the majority of rats could be relieved by systemic tocainide (75 mg/kg). Morphine was only effective at a sedative dose (5 mg/kg). The allodynia was not relieved by baclofen, muscimol, clonidine or carbamazepine. Low‐dose systemic pentobarbital (5 mg/kg) had a slight beneficial effect. Guanethidine (20 mg/kg s.c.) did not abolish the allodynia in most of the rats. Histological examination revealed massive damage in the spinal cord. The dorsal roots of the irradiated segments were also injured. No morphological abnormalities were seen in the dorsal root ganglia. The mechanism that may account for this chronic pain‐related syndrome in spinally injured rats probably involves abnormalities in the central nervous system. The allodynia seen in chronic spinally injured rats was similar to some painful symptoms in patients after spinal cord injury or stroke. It is suggested that the chronic allodynia‐like phenomenon may represent an animal model for studying the mechanisms of chronic central pain.

Spasticity after traumatic spinal cord injury: Nature, severity, and location

OBJECTIVE To assess spasticity in a prevalence population of persons with traumatic spinal cord injury (SCI), and determine the degree of correspondence between self-reported spasticity and investigator-elicited spasticity using the modified Ashworth scale. DESIGN Survey of a near total (88%) prevalence population. SETTING Outpatient clinic of a university hospital. PATIENTS A total of 354 individuals with SCI. MAIN OUTCOME MEASURES The survey includes self-reported symptoms, neurologic examination (American Spinal Injury Association [ASIA] classification), physical therapy examination, range of motion (ROM), and complications. RESULTS Presence of problematic spasticity was significantly correlated with cervical incomplete (ASIA B-D) injury. Reports of beneficial effects of spasticity were significantly less common in women. Self-reported problematic spasticity was significantly correlated with extensor spasticity. Spasticity was elicitable by movement provocation in 60% of the patients reporting spasticity. Significant correlations were found between elicitable spasticity and limited ROM. CONCLUSION Flexion, extension, and abduction movements performed with the patient placed in a standardized supine test position are suitable both for test of ROM and degree of spasticity. Spasticity was not elicitable by movement provocation on physical examination in 40% of the patients who reported spasticity, thus indicating that the patients self-report is an important complement to the clinical assessment. A significant association between spasticity and contractures (reduced ROM) was seen.

Intraocular Transplantation in Rodents: A Detailed Account of the Procedure and Examples of its Use in Neurobiology with Special Reference to Brain Tissue Grafting

Publisher Summary This chapter focuses on an in oculo technique with emphasis on technical details and step-by-step procedures and presents an analysis of various types of grafts. The two most obvious advantages of the in oculo approach are that it provides a chamber in which grafts can exist without being squeezed by or exerting pressure on host tissues and the transparency of the cornea through which grafts can be noninvasively observed. The grafted tissue that acts as a receptor of nerves from the host iris may itself be nervous tissue. The chapter presents a demonstration of partial phenotypic transformation of adult chromaffin cells to neuron-like cells as fiber outgrowth from chromaffin cells grafted to sympathetically denervated irises. Intraocular grafting, when properly performed, is probably among the least harmful types of experimental surgery that can be performed on a rat.

Allodynia-like effects in rat after ischaemic spinal cord injury photochemically induced by laser irradiation

&NA; We report behaviours suggesting the presence of allodynia elicited by non‐noxious brushing and mechanical pressure following photochemically induced ischaemic spinal cord injury in the rat. Female rats were intravenously injected with Erythrosin B and the T10 vertebra was irradiated with a laser beam for 1, 5 or 10 min. These procedures initiated an intravascular photochemical reaction, resulting in ischaemic spinal cord injury. After irradiation a clear allodynia was observed in most rats, The animals vocalized intensely to light touch during gentle handling and were clearly agitated to light brushing of the flanks. The vocalization threshold in response to the mechanical pressure measured with von Frey hairs was markedly decreased during this period. In some animals the existence of spontaneous pain was suggested by spontaneous vocalization. The duration of the allodynia varied among animals from several hours to several days. The severity and duration of allodynia seemed not to be related to the duration of irradiation. In sham‐operated rats a slight, transient allodynia was also noted around the wound within a few hours after surgery, which was effectively relieved by systemic morphine (2 mg/kg, i.p.). Morphine (2 mg/kg, i.p.) also partially relieved the allodynia in spinally injured rats 4 h after irradiation. However, morphine, even at a higher dose (5 mg/kg, i.p.), failed to alleviate the allodynia in spinally injured rats 24–48 h after the injury. Systemic injection of the GABAB agonist baclofen (0.01‐0.1 mg/kg, i.p.), but not the GABAA agonist muscimol (1 mg/kg, i.p.), effectively relieved allodynia during this period. Pretreatment with guanethidine 24 h and just prior to the irradiation (20 mg/kg, s.c.) did not prevent the occurrence of allodynia in spinal cord injured rats, The present observation is the first to show that ischaemic spinal cord injury could result in cutaneous mechanical allodynia. This phenomenon is resistant to morphine and may not involve the sympathetic system. Histological examination of allodynic animals 3 days after spinal cord injury revealed considerable morphological damage in the dorsal spinal cord of a rat irradiated for 5 min. The related dorsal roots were also slightly affected in this animal, while the dorsal root ganglia were normal. However, in rats irradiated for 1 min, despite the existence of strong allodynia, no damage could be found at this time in the spinal cord, dorsal roots or dorsal root ganglia. It is suggested that functional deficits in the GABAB system in the spinal cord may be related to this allodynia‐like phenomenon. Allodynia following laser‐induced spinal cord injury may be a useful pain model for testing the efficacy of analgesic drugs against central pain of ischaemic origin.