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The effects of electrical stimulation of the satiety and feeding centers (SC, FC) on gastric, cecal and rectal motility were studied in rats anesthetized with urethane. Each center produced excitatory, inhibitory and biphasic responses in these organs. Cecal and rectal responses to stimulation of SC or FC were usually the opposite of the gastric response; for example, the gastric response was excitatory, whereas cecal and rectal responses were inhibitory. Gastric and cecal excitatory responses were abolished by vagotomy and the rectal response by severance of parasympathetic branches of the pudendal plexus (PSB). Gastric and ceca inhibitory responses were fairly depressed by vagotomy and abolished by successive splanchnicotomy, while the rectal inhibitory response was abolished by severance of inferior mesenteric nerves (IMN) and PSB. It was concluded that the satiety and feeding centers modulate not only gastric motility but also cecal and rectal motility, and that the excitatory response is conveyed through vagus nerves to the stomach and cecum and through PSB to the rectum. The inhibitory response is mediated mainly through vagus nerves, partially through splanchnic nerves to the stomach and cecum, and through IMN and PSB to the rectum. The characteristics of efferent terminal neurons eliciting excitatory and inhibitory responses were studied pharmacologically.

Neurons of cerebellar nuclei in the rat brain had a marked surface coat which was stained with cationic iron colloid or aldehyde fuchsin. Neurons with a similar surface coat were also noted in the retrosplenial cortex. The surface coat was stained doubly with cationic iron colloid and aldehyde fuchsin. Digestion with hyaluronidase eliminated the stainability of the surface coat to both agents. Combined digestion with chondroitinase ABC, heparitinase and keratanase eliminated the cationic iron colloid staining but did not interfere with the aldehyde fuchsin staining. Electron microscopy of ultrathin sections revealed that the iron particles were deposited in the perineuronal tissue spaces. These findings indicate that the surface coat consists of sulfated proteoglycans which occupy, as the extracellular matrix, the perineuronal tissue spaces. Many neurons in the retrosplenial cortex were labeled with lectin Vicia villosa agglutinin. Double staining revealed that these lectin-labeled neurons are usually reactive to cationic iron colloid. Few neurons in the cerebellar nuclei were labeled with lectin V. villosa agglutinin.

Many neurons in the adult rat cingulate cortex possess perineuronal sulfated proteoglycans detectable with cationic iron colloid and aldehyde fuchsin, or cell surface glycoproteins reactive to lectin Vicia villosa or soybean agglutinin. The perineuronal sulfated proteoglycans develop three to four weeks after birth. The cell surface glycoproteins develop at earlier stage or two to three weeks after birth. Dark or active neurons begin to appear three to four weeks after birth. These findings indicate that the brain matures after birth or during weaning period.

The use of ligand-binding methods to study neurotransmitter-receptor sites has made its impact on almost all aspects of biological pursuits including research on aging and neurodegenerative diseases. In the past, most of the research in biochemical gerontology has largely centered around changes in various neurotransmitters and enzymatic activities. The molecular basis of aging and neurodegeneration at the level of neurotransmitter-receptor interactions has been highly appreciated in the last two decades as a result of receptor binding studies. It is now possible to obtain information about the regional distribution of neurotransmitter receptors in the brain, the pharmacological and biochemical characteristics of these sites, and the functional interrelationships between different neuronal systems in normal and pathological conditions. The passage of time after maturity is accompanied by measurable physiologic decline in virtually all systems. It is the aim of this work to discuss the practical aspects of neurotransmitter and/or drug (ligand)-receptor binding studies, highlighting some examples of their applications to geriatric neuropharmacology research, with special consideration to learning impairment and memory loss in normal and in pathological aging processes.

We studied the brains of two cases of amyotrophic lateral sclerosis with dementia. Bunina bodies were found in the motor neurons of cranial nerve nuclei (trigeminal, facial and hypoglossal nerves) as well as in the spinal motoneurons. They appeared mostly in the cytoplasm and occasionally in the neuronal processes. However, the present electron microscopic study disclosed clearly that Bunina bodies were present not only in the cell body but also in the dendrites. No Bunina bodies were observed in the axons. It is inferred that the Bunina bodies were degenerative products formed as a result of a protein metabolism disorder.

In the extrinsically denervated smooth muscle esophagus of the hen anesthetized with urethane (1 g/kg, i. m.), it was studied whether peptidergic neurons in the intramural plexus are involved in the intrinsic reflex. Ascending and descending contractions, and descending relaxation were induced by electrical stimulation of a narrow segment of the esophagus. Naloxone (1 microM), desensitization to substance P (0.3 microM) and spantide (20 microM) inhibited the ascending and descending contractions, respectively. The degree of the inhibition of the contractile response by a combination of naloxone and substance P was nearly the same as that by a single administration of naloxone or substance P. The ascending and descending contractions were reduced to one-third of the control by hexamethonium (100 microM) and abolished by atropine (10 microM). The descending relaxation was abolished after desensitization to vasoactive intestinal peptide (0.3 microM). Taken together the results suggest that in the hen's esophagus, opioid- and substance P-containing neurons in the intramural plexus may act as preganglionic neurons of cholinergic motor neurons in the ascending and descending excitatory pathways and that vasoactive intestinal peptide-containing neurons are involved in the descending inhibitory pathway.

The effects of salt loading and adrenalectomy on arginine vasopressin (AVP) mRNA levels in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) of the hypothalamus were studied by semiquantitative in situ hybridization histochemistry, using a synthetic oligonucleotide probe and a computer-assisted image analysis system. Salt loading (2% NaCl) for 7 days produced marked increases in AVP mRNA levels in the magnocellular neurons of the PVN, SON, and accessory nuclei. Adrenalectomy caused an increase in AVP mRNA expression in the magnocellular part of the PVN and the expansion of hybridization signals into its medial parvocellular region, where the cell bodies of corticotropin-releasing hormone (CRH) neurons are located. No apparent alteration of AVP mRNA levels was observed in the SON following adrenalectomy. These results indicate that hyperosmotic stimulation and the loss of circulating glucocorticoids had differential effects on AVP gene expression in the PVN and SON, and that the magnocellular PVN and SON neurons responded in different manners to the loss of feedback signals.

Effects of mesenteric nerve (MN) stimulation on the electrophysiological behavior of myenteric neurons in the guinea pig ileum were investigated with intracellular recording techniques in the myenteric flaps innervated with mesenteric nerves. MN stimulation at 0.11-6 Hz evoked fast excitatory postsynaptic potentials (EPSPs) in 6 myenteric neurons (2 Type 2/AH, 3 NS and 1 Type 1/S cells) and rarely evoked antidromic soma spike potentials in 3 myenteric neurons. Fast EPSPs were abolished by hexamethonium. Slow EPSPs evoked by MN stimulation (Takaki and Nakayama (1988) Brain Res., 442, 351-353) were also obtained in 5 Type 2/AH neurons and were irreversibly abolished by superfusion with capsaicin 10 microM. It is, therefore, likely that fast EPSPs mediated by nicotinic cholinergic receptors are due to stimulation of the vagus nerve and slow EPSPs are mediated by a release of substance P at axosomatic synapses due to antidromic activation of the capsaicin-sensitive sensory nerves.

In the present study, tryptamine produced a slow hyperpolarization in a few neurons other than a slow depolarization in myenteric neurons of the isolated guinea-pig ileum. Neither the adrenergic neuron blocker, guanethidine nor the 5-hydroxytryptamine uptake inhibitor, zimelidine, which can inhibit the release of 5-hydroxytryptamine from enteric neurites induced by tryptamine (M. Takaki et al. (1985) Neuroscience 16, 223-240), affected this slow hyperpolarization. Therefore, it was concluded that the slow hyperpolarization induced by tryptamine in myenteric neurons was not mediated via the release of 5-hydroxytryptamine or noradrenaline. It might be possible that the hyperpolarization was induced by a direct action of tryptamine on myenteric neurons per se.

The participation of the parasympathetic and sympathetic nerves in the canine gallbladder motility was examined. Efferent stimulation of the parasympathetic (vagus) and sympathetic (celiac) nerves caused contraction or inhibition of the neck, body and fundus of the gallbladder. The contractile response induced by vagus nerve stimulation was reduced by subthreshold efferent stimulation of the celiac nerve, while the inhibitory response was neither reduced nor enhanced by subthreshold efferent stimulation of the celiac nerve. The contractile and inhibitory response induced by celiac nerve stimulation was not reduced in the neck, body and fundus by subthreshold efferent stimulation of the vagus nerve. The contractile response to vagus nerve stimulation was reversed to a relaxant response by atropine administration, which was reduced or abolished by hexamethonium. It is suggested that the vagus nerve-induced contractile response in the canine gallbladder is modulated by sympathetic nerves presynaptically at the vagus nerve endings in the enteric ganglion, but the vagus nerve-induced relaxant response, which probably was induced by non-adrenergic non-cholinergic inhibitory neurons, is not modulated by the sympathetic nerves.

Neural regulation of the motility between the haustra and taenia coli was studied in the isolated rabbit proximal colon. Four types of haustral and taenial preparations were used: the haustral strip without the taenia coli (type 1), the haustral strip including the taenia coli (type 2), the L-shaped (taenia-haustra) preparations for recording the haustral (circular) response to taenial stimulation (type 3) and the L-shaped (haustra-taenia) preparation for recording the taenial (longitudinal) response to haustral stimulation (type 4). Field electrical stimulation induced a contractile response in the haustra and taenia coli. Hexamethonium reduced the contraction in type 2, 3 and 4 preparations. The desensitization to serotonin reduced the response in type 2 and 3 preparations. After atropinization, the response in types 1 and 4 was reversed to relaxation, and the response in types 2 and 3 was reversed to relaxation followed by contraction which was reduced or abolished by indomethacin. The responses remaining after atropinization in all types of preparations were not affected by other blocking agents tested or desensitization to neuropeptides. Tetrodotoxin abolished all relaxation and contractile responses in all types of preparations. These results suggest that the indirect contractile response to field stimulation is induced mainly via cholinergic and serotonergic neurons, and that the relaxation is mainly mediated by nonadrenergic noncholinergic neurons. The late haustral contractions after atropine may be caused by endogenous prostaglandin.

Neuroprotective therapy for Parkinson's disease (PD) is a treatment intended to prevent or reduce neuronal degeneration. Since clinical studies to evaluate such an effect would be prolonged, the choice of agents for use as possible neuroprotective therapy is based on the results of in vitro and animal experiments. Free radicals are currently regarded as the most important factor in the progression of PD. One current possible neuroprotective therapy is reduction of levodopa dose, since levodopa is a source of free radical formation. Dopamine (DA) metabolism inhibition, and administration of the DA agonist bromocriptine that eliminates hydroxyl free radicals have neuroprotective effects experimentally. The other candidates for neuroprotective agents are still under development. However, those whose clinical use is permitted should be considered for use, since patients with long-standing PD cannot wait until the neuroprotective efficacy of these agents is confirmed by clinical study.

In guinea pigs whose pelvic nerves were bilaterally sectioned, afferent stimulation of rectoanal branches of the pelvic nerve (PAS) could produce an intense contraction in the rectum similar to propulsive contractions elicited during defecation. The mechanism of this reflex was analyzed. Rectal contraction by PAS was abolished after transecting the spinal cord at T13 or sectioning the lumbar splanchnic nerves (LSN) or lumbar colonic nerves (LCN), but was unaffected by severing the intermesenteric and hypogastric nerves. Rectal contraction induced by PAS was abolished peripherally by atropine, guanethidine or yohimbine, while propranolol had no affect. Yohimbine antagonized the inhibitory effect of LSN or LCN stimulation on atropine-sensitive rectal contractions. It may, therefore, be concluded that PAS blocks the inhibition, by LCN efferents acting through alpha-adrenoreceptors, of cholinergic neurons in the myenteric plexus, thus facilitating recto-rectal propulsive contractions initiated by the defecation reflex.

The present study investigated the brain catecholamine metabolism of rats with liver injury induced either by malnutrition or with CCl4. In the malnutrition group, the plasma tyrosine concentration was low, while it showed a tendency to be high in the cerebral cortex. Dopamine concentrations were low in both the cerebral cortex and diencephalon. Norepinephrine concentrations were low in the cerebral cortex, striatum and diencephalon. Tyrosine hydroxylase activity was elevated while monoamine oxidase activity was decreased in the striatum. In the CCl4 group, tyrosine concentrations in the plasma and cerebral cortex did not change. The dopamine concentration in the cerebral cortex increased five days after, and the norepinephrine concentration in the diencephalon increased 24 h after the last administration of CCl4. These data suggest that catecholaminergic neurons in the brain may be substantially affected by liver injury. It may be considered that malnutrition disturbs brain development, particularly in young rats.

The concentrations and alpha-methyl-p-tyrosine (alpha-MPT) induced disappearance of catecholamines, adrenaline, noradrenaline and dopamine, were measured in selected areas of the brainstem and hypothalamus of spontaneously hypertensive rats (SHR) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. The catecholamine levels were measured by a sensitive radioenzymatic assay method combined with microdissection of the rat brain. The adrenaline concentration was higher in the area A1 of young SHR, but not in adult SHR, than in age-matched control rats. Noradrenaline concentrations and the alpha-MPT induced noradrenaline disappearance were less in the rostral part of the nucleus tractus solitarii (NTS) and the nucleus hypothalamic anterior of young SHR, and in the rostral part of the NTS of adult SHR. On the other hand in DOCA-salt hypertensive rats, the concentrations of adrenaline and noradrenaline were the same as in control rats in the examined areas. The alpha-MPT induced noradrenaline disappearance was less in the rostral part of the NTS of DOCA-salt hypertensive rats. Dopamine concentrations and the alpha-MPT induced dopamine disappearance were the same in the examined areas of SHR and DOCA-salt hypertensive rats. The results suggest that SHR have a change in adrenergic neural activity in the brainstem and a decrease in noradrenergic neural activity in the brainstem and hypothalamus while DOCA-salt hypertensive rats have a decrease in noradrenergic neural activity in the brainstem. Such changes in brain catecholaminergic neurons may have played an important role in the development of hypertension in these rats.

In decerebrated cats the impulse discharges were detected by means of an unipolar microelectrode from a single inspiratory neuron in the respiratory centers, and the change in discharge produced by administration of stimulating, as well as depressant agents, was studied. The results were summarized as follows. 1) Inhalation of the air containing all. excess of carbon dioxide, as well as the air deficient of oxygen and the intravenous administration of a small dose of caffeine, aminocordine and lobeline produced a) a remarkable increase of frequency of impulses in the stage of constant frequency of the volley, b) a rapid increase of frequency of impulses in the stage of crescent frequency of the volley and c) a shortening of the duration of the volleys, as well as of silent periods. 2) In narcosis by a moderate dose of morphine, as well as in the recovery stage from apnea produced by over-ventilation, there were observed the phenomena which were exactly opposite to those described in 1). 3) It was concluded that a most essential sign by which one can discern whether the activity of the respiratory Genters is raised or depressed, is the changes of the frequency of impulses produced from an inspiratory neuron. The expense of this research was defrayed from the grant in aid of the Ministry of Education.

Histopathological investigations were carried out on five fatal cases of a type of polyneuritis of unknown etiology diagnosed as Landry-Guillain-Barre syndrome, which endemically occurred in children in the regions surrounding the Inland Sea of Japan. The most characteristic pathologic feature in the nervous system was pronounced patchy degenerative changes with slight or moderate degree of inflammatory cell response of focal type in the peripheral and cranial nerves, predominantly in the nerve fibers of the spinal and cranial roots. In the spinal cord, medulla, pons, and in some portions of the cerebrum and cerebellum, engorgement of the small blood vessels as well as edema and the less predominant scattered degenerative changes of ganglioncells and nerve fibers with extremely slight degree of glial response and sparse perivascular cell collections were encountered. The cerebrospinal meninges displayed edema and congestion of the pial blood vessels with focal collections of a small number of lymphocytes and/or monocytes. No advanced involvement of the anterior horn of the spinal cord in a strict sense of anterior poliomyelitis was, however, recognized. These changes may lead the histopathologic diagnosis of the present disease to infectious encephalomyelo-polyradiculoneuritis or a type of infectious polyneuritis. The main histopathologic changes in the visceral organs were a moderate degree of engorgement of the small blood vessels, degeneration of parencymatous organs such as the liver and kidney, hyperplasia or follicular atrophy of the lymphatic tissues, interalveolar pneumonia, focal myositis, and slight degree of round cell infiltrations in the interstitial tissues of the other viscera, such as the liver, heart, and gastrointestinal canal. Based upon the observations on the histopathological changes as well as clinical manifestations, discussions were made on the pathogenesis and etiologic factor of the present endemic disease with critique on the literatures.