Beta-adrenoblockers in the reorganizing of the food center of the hypothalamus under the influence of substance P]

An ability of substance P (15 nmol intracerebroventricularly) to transform functional properties of the hypothalamic feeding center manifested in escape reaction in response to threshold electrical stimulation of this motivation center in rabbits. Beta-adrenergic antagonists inderal and obsidan (0.25, 0.5 mg, respectively) injected intravenously were found to restore feeding elicited by electrostimulation of the hypothalamic feeding center. However, escape reaction, elicited from the feeding center under substance P was found unchanged after intravenous administration of 0.25 mg kalipsol. The data obtained suggested an important role of beta-adrenergic mechanisms in substance P transformation of the functional properties of the hypothalamic feeding centre.     

Substance P in the central mechanisms of the escape reaction

The role of substance P in the central mechanisms of escape reaction elicited by electrical stimulation of the ventromedial hypothalamus was investigated in chronic experiments on rabbits. Intravenous injection of substance P (30 micrograms/kg) led to a short-term (less than 10 min) increase in the threshold of stimulation of the ventromedial hypothalamus and to more stable (up to 1.5 h) disorders of the hippocampal-hypothalamic relations. After substance P injection the inhibitory effects of the dorsal hippocampus but not the facilitating influences of the midbrain reticular formation on excitability of the hypothalamic motivation center were found to be lacking. Disorders of the central mechanisms of escape reaction after substance P injection correlated with new patterns of the main EEG rhythms in different areas of the brain cortex in response to the ascending excitations of the limbic-midbrain structures. Interpreting the mechanisms of substance P involvement in escape reaction the authors point to the ability of the given peptide to interact with different transmitter systems of the brain and opiate receptors and to alter the brain blood circulation.     

Responses of neurons of the frontal area of the cortex of the rabbit to electric stimulation of certain limbic-mesencephalic structures after administration of substance P

In rabbits tested on behavioural reactions by electrical stimulation of certain limbic-midbrain structures, intravenous injection of substance P (30 mcg/kg) led after 10 min of silent period to a decrease of spontaneous neuronal activity in the frontal cortex. Convergence of excitations arising from the lateral hypothalamus, the dorsal hippocampus and the midbrain reticular formation was also found to decrease after the substance P injection. Analysis of neuronal responses allowed to establish that substance P markedly changed the ascending excitations of the lateral hypothalamus and was less effective for the influences from the midbrain reticular formation.     

Effect of ethanol on central mechanisms of alimentary and defensive motivation in the rabbit

A single intravenous administration of ethanol (0.5 g/kg) to rabbits had different effects on the excitability of feeding and defensive motivational centers of the lateral and ventromedial hypothalamus. Ethanol abolished both inhibitory effects of the dorsal hippocampus and facilitatory action of the midbrain reticular formation on alimentary and defensive motivations. It elicited new power distributions of the main rhythms of general electrical cortical activity in the background and under stimulation of limbic-midbrain structures. Analysis of the activity of organello-specific enzymes in limbic-midbrain neurones revealed disturbances of cellular energetic processes caused by ethanol.     

Opposite effects of intraventricular and intracisternal administration of vasopressin on blood pressure in rats

Lysine-8-vasopressin (LVP) was injected into the lateral ventricle (ICV) or into the cisterna magna (c.m.) of ether-anesthetized rats. ICV injection of LVP decreased the blood pressure (BP), whereas c.m. administration increased it. The opposite effects of ICV versus c.m. administration of the peptide might be related to differences in brainstem versus limbic-midbrain structures in the regulation of blood pressure, and suggest that both mechanisms can be influenced by vasopressin.     

Substance P and the ethanol-evoked changes in the independent motivated behavioral reactions of rabbits

Ethanol (0.5 g/kg) administered intravenously led to alterations in central mechanisms of feeding and escape, elicited by threshold electrical stimulation either of lateral or of ventromedial hypothalamic centers of the rabbit. Subsequent intravenous injection of substance P (30 mcg/kg) restored the excitability of the ventromedial hypothalamus and facilitatory effects on this motivational center of the midbrain reticular formation. The restoration of both inhibitory influences of the dorsal hippocampus and facilitatory ones of the midbrain reticular formation on the excitability of the lateral hypothalamus was also observed after SP administration. Data obtained suggest that oligopeptides could be used to increase the tolerance to ethanol or to cure the negative acute effects of alcohol in motivated behaviours.     

Substance P in the central mechanism of the rabbit feeding response evoked by stimulation of the lateral hypothalamus

The effects of substance P on the central mechanisms of food motivation elicited by electrical stimulation of the lateral hypothalamus were studied in chronic experiments on rabbits. Intravenous injection of substance P (30 micrograms/kg) brought about a dramatic reduction in the excitability of the "food center" in the hypothalamus, which returned to normal 45-60 minutes after injection. Higher concentrations of substance P provoked food behavior inversion up to the replacement of food motivation by avoidance behavior. Intravenous injections of substance P disturbed the relationships between the hippocamp, midbrain reticular formation and hypothalamus seen in health. This manifested in complete cessation of the inhibitory effects of the dorsal hippocamp and facilitating influences of the midbrain reticular formation on the excitability of the hypothalamic "food center". It is assumed that disorders of the central mechanisms of food motivation may arise from the effects produced by substance P directly on the central nervous system or on the brain via changes in the hormonal balance and responses of the autonomous nervous system.     

Orexins (hypocretins): novel hypothalamic peptides with divergent functions.

The hypothalamus is the most important region in the control of food intake and body weight. The ventromedial "satiety center" and lateral hypothalamic "feeding center" have been implicated in the regulation of feeding and energy homeostasis by various studies of brain lesions. The discovery of orexin peptides, whose neurons are localized in the lateral hypothalamus and adjacent areas, has given us new insight into the regulation of feeding. Dense fiber projections are found throughout the brain, especially in the raphe nucleus, locus coeruleus, paraventricular thalamic nucleus, arcuate nucleus, and central gray. Orexins mainly stimulate food intake, but by the virtue of wide immunoreactive projections throughout the brain and spinal cord, orexins interact with various neuronal pathways to potentiate divergent functions. In this review, we summarize recent progress in the physiological, neuroanatomical, and molecular studies of the novel neuropeptide orexins (hypocretins).     

A symmetrical approach to the analysis of cardiocyte electrical and contractile activity]

Based on the systemic symmetrical approach, experimentally determined parameters of action potential and contractile response of frog myocardial strip were analyzed prior to and after the administration of several physiologically active drugs (caffeine, neoepinephrine, nembutal, ouabain) into the perfusate. It was shown that the satisfactory functional state of preparation was characterized by an interrelation between parameters in the form of a harmonic proportion with relatively constant coefficient. When the functional state of subject is affected by a physiologically active substance, the interrelation between the parameters is considerably changed. Based on the analysis of the data of literature, it was found that the interrelation between temporary parameters of action potential in various structures from human heart has the form of a harmonic proportion with a constant coefficient close to the invariant of "Gold Wurf" proportion. The similarity is underlined of principles of cardiac function temporary arrangement at levels of cell, organ and organism.     

Effect of substance P on the 5,7-dihydroxytryptamine induced alteration of the postnatal development of central serotonin neurons

Systemic treatment with the serotonin neurotoxin 5,7-dihydroxytryptamine [5,7-HT]in the neonatal stage leads to a permanent alteration of the postnatal development of the serotonin neurons in rat brain with denervation of distant nerve terminal projections and hyperinnervation in regions close to the serotonin perikarya. Intracisternal administration of substance P was found to counteract both the denervation and the hyperinnervation, as evaluated by measuring endogenous serotonin levels and [3H]-serotonin uptake in vitro. Furthermore, substance P was found to potentiate the reduction of serotonin induced by tryptophan hydroxylase inhibition with alpha-propyldopacetamide, indicating that substance P can produce an increase in serotonin utilization and turnover. The results suggest that substance P has a degeneration preventing and/or regrowth stimulatory effect on damaged serotonin neurons during ontogeny.     

Substance P and hydra: an immunohistochemical and physiological study

1. The distribution of substance P-like immunoreactivity was studied in Hydra attenuata using the peroxidase-antiperoxidase technique. 2. Positive immunoreactivity was observed in ectodermal nerve cells and fibers as well as in nematoblasts at various stages of differentiation. 3. Administration of synthetic substance P to regenerating hydra did not affect regeneration rates. Exogenous substance P administration stimulated tentacle contraction and nematocyst displacement within battery cells. 4. It is suggested that substance P acts on the contractile apparatus of Hydra tissues.     

The Delta-Sleep Inducing Peptide in Cerebral Mechanisms of Emotional Stress

The problem of the anti-stressor effect of the delta-sleep inducing peptide (DSIP) and of its neurophysiological mechanisms of action is considered. Physiological data are exposed that indicate an intraventricular administration of DSIP in rats to results in an increase of resistance to emotional stress, according to behavioral and autonomous reactions, and in a decrease of excitability of the brain structures responsible for protective reaction. Radioimmunological evidence is presented for the resistance of animals to emotional stress to depend on the content in hypothalamus of certain oligopeptides, such as -endorphin, DSIP, and the substance P. It was shown that animals resistant to emotional stress had a higher content of these oligopeptides in hypothalamus than those predisposed to stress. The issue is discussed that the prolonged anti-stressor effects after the DSIP administration are determined by considerable changes of the content of other polypeptides and hormones in hypothalamus and blood, which are involved in the reaction under the effect of DSIP.     

Enhancement of the resistance of the escape reaction to ethanol after substance P]

An ability of substance P (30 micrograms/kg intravenously) to prevent deleterious effects of ethanol (E) (0.5 g/kg intravenously) on central mechanisms of escape reaction elicited by threshold electrical stimulation of the ventromedial hypothalamus was investigated in chronic experiments upon rabbits. Substance P was found to prevent E effects on excitability of the ventromedial hypothalamus (VMH) and on facilitatory influences of the midbrain reticular formation on this emotional centre which were observed in intact animals. Inhibitory effects of the dorsal hippocampus on the VMH could not be evaluated due to its alterations in response to previous substance P administration. The authors suggest that substance P can be considered to be a possible endogenous factor to increase a tolerance of emotional behavioural reactions of an organism to alcohol.     

Substance P in the suprachiasmatic nucleus of the rat: an immunohistochemical and in situ hybridization study

Using a biotin-streptavidin-horseradish peroxidase (HRP) immunohistochemical technique the distribution of substance P-immunoreactive neuronal elements was investigated in the rat suprachiasmatic nucleus (SCN). Substance P-immunoreactive nerve fibres and varicosities were distributed throughout the suprachiasmatic nucleus, with the largest accumulation in its ventral part. Because this location overlaps with the innervation of retinal afferents, the distribution and density of substance P-immunoreactive fibres in bilaterally enucleated rats were compared to normal rats. The density of substance P-immunoreactive fibres and nerve terminals in the ventral part of the suprachiasmatic nuclei was reduced in the rats with bilateral destruction of the optic nerves, whereas the density of fibres and nerve terminals in the dorsal part as well as other retinal target areas in the thalamus and mesencephalon was unaffected. In rats pretreated with an intraventricular injection of colchicine several substance P-immunoreactive perikarya were identified in the suprachiasmatic nucleus. The immunoreactive neurons, measuring 9.7 m±1.1 m in diameter, were frequently observed in the central core of the nucleus and to a lesser extent in the dorsomedial and ventrolateral subparts. Using in situ hybridization histochemistry pre-protachykinin-A mRNA was found in the same part of the SCN indicating that synthesis of substance P takes place in SCN neurons. Using a double immunohistochemical approach applying diaminobenzidine and benzidinedihydrochloride as chromagens substance P-, vasoactive intestinal peptide (VIP)-, and vasopressin/neurophysin-immunoreactivities were identified in the same brain section. The substance P-immunoreactive perikarya constituted a separate population of SCN neurons, which were not vasopressin-, neurophysin- or VIP-immunoreactive. Taken together, these observations show that substance P is contained in the retinohypothalamic pathway and within a group of SCN cell bodies, indiating that substance P may play a role in the generation and entrainment of circadian rhythmicity.     

Mapping of tachykinins in the cat spinal cord

Using an indirect immunoperoxidase technique, the location of cell bodies and fibers containing substance P, neurokinin A and neurokinin B was studied in the cat spinal cord. The former two neuropeptides showed a widespread distribution throughout the whole spinal cord, whereas the distribution of neurokinin B was more restricted. Neurokinin A-immunoreactive structures showed a more widespread distribution and a higher density than the immunoreactive structures observed to contain substance P. In the cat spinal cord, we observed cell bodies containing neurokinin A, but no cell bodies containing neurokinin B or substance P were found. These cell bodies were located in laminae V (sacral 1 and 2 levels), VI (sacral 1 and 3), VII (lumbar 7, sacral 1 and 3, caudal 1) and X (sacral 1). Laminae I and II showed the highest density of immunoreactive fibers for each of the three tachykinins studied, being in general lamina IV who showed the lowest number of immunoreactive fibers containing substance P, neurokinin A or B. The anatomical distribution of the three tachykinins studied in the cat spinal cord indicates that the neuropeptides could be involved in the neurotransmission and/or in the neuromodulation of nociceptive information, as well as in autonomic and affective responses to pain. Moreover, the involvement of substance P, neurokinin A or B in other functions unrelated to the transmission of pain is also possible (autonomic and motor functions). The distribution of the neuropeptides studied in the cat is compared with the location of the same neuropeptides in the spinal cord of other species. The possible origin of the tachykinergic fibers in the cat spinal cord is also discussed.     

Cell to cell relationships in the seminiferous epithelium in the mouse embryo

Summary Germ cells and Sertoli cells in embryonic mouse testes (day 14 to 20 of gestation) were examined by sectioning and freeze-fracture. Intercellular cytoplasmic bridges between the germ cells are observed in day 14 and older embryos. Membrane specializations with dense fuzzy material similar to the socalled desmosome-like structures are found between Sertoli cells and germ cells. A cell contact area with dense opposed membranes is also found between adjacent germ cells. Asymmetrical dense fuzzy lining of both Sertoli and germ cell membranes is noted. Pinocytotic pits or caveolae are frequently found in the Sertoli cell membrane. Between adjacent Sertoli cells, gap junctions of various sizes and focal meshworks of the occluding junctions are found. Most of the occluding junctional particles are located in the center of the grooves in the E face, and are similar to those in postnatal and adult Sertoli cell junctions. In addition, on both fractured faces there are ridges and grooves devoid of particles which are continuous with occluding junctions with particles, suggesting an initial stage in the formation of occluding junctions of the Sertoli cells. Particles gathered at the site of desmosome-like structures are present on the P face of the Sertoli cell.This work is supported by the Japanese Ministry of Education     

Neuronal location of the bombesin-like immunoreactivity in the central nervous system of the rat

The immunohistochemical distribution of bombesin-like immunoreactivity in the central nervous system of the rat was revealed using a rabbit antibody against [Glu⁷]bombesin(6–14). In radioimmunoassay, the antibody had minimal cross reactivity with substance P thereby enhancing the significance of histochemical controls proving that the immunoreactivity detected was related to bombesin but not to substance P. Bombesin-immunoreactive neurons were detected in several brain structures including the hypothalamus, interpeduncular nucleus, central grey, dorsolateral tegmental nucleus, dorsal parabrachial nucleus, nucleus of the solitary tract and trigeminal complex. In the spinal cord, intense immunoreactivity was found in the superficial layers of the posterior horn. Since in this area the reaction diminished after rhizotomy the location of the peptide in afferent neurons was considered. In the anterior horn the bombesin-like immunoreactivity located in nerve terminal-like structures was unchanged after rhizotomy suggesting that the cell bodies were located in CNS.     

Enzymatic and Radioimmunoassay Procedures Combined with Electrophoresis and HPLC for the Recovery and Characterization of Substance P in Human Brain

Immunoreactive substance P was recovered from human brain (hypothalamus and substantia nigra) by acetic acid extraction, ion exchange chromatography (SP-Sephadex), molecular sieving (Sephadex C-50) and column electrophoresis in agarose suspension. The chemical nature of the active material was further studied with various biochemical techniques including agarose suspension electrophoresis, HPLC and different kinds of enzyme radioimmunoassays. By combining these techniques it was possible to confirm structure identity between the recovered active component and substance P previously isolated from bovine brain. Thus, the major activity reacting with the substance P antibodies was indistinguishable from the synthetic bovine analogue in all chromatographic systems including analytical electrophoresis at different pH:s and HPLC. Furthermore, digestion of the active material with post-proline cleaving enzyme and trypsin yielded fragments identical with those expected from the bovine peptide as confirmed by specific radioimmunoassays in conjuction with electrophoresis or HPLC. The result also indicates the usefulness of the present procedures for identifying peptides structures available only in minute amounts.     

Enzymatic and radioimmunoassay procedures combined with electrophoresis and HPLC for the recovery and characterization of substance P in human brain.

Immunoreactive substance P was recovered from human brain (hypothalamus and substantia nigra) by acetic acid extraction, ion exchange chromatography (SP-Sephadex), molecular sieving (Sephadex G-50) and column electrophoresis in agarose suspension. The chemical nature of the active material was further studied with various biochemical techniques including agarose suspension electrophoresis, HPLC and different kinds of enzyme radioimmunoassays. By combining these techniques it was possible to confirm structure identity between the recovered active component and substance P previously isolated from bovine brain. Thus, the major activity reacting with the substance P antibodies was indistinguishable from the synthetic bovine analogue in all chromatographic systems including analytical electrophoresis at different pH:s and HPLC. Furthermore, digestion of the active material with post-proline cleaving enzyme and trypsin yielded fragments identical with those expected from the bovine peptide as confirmed by specific radioimmunoassays in conjunction with electrophoresis or HPLC. The result also indicates the usefulness of the present procedures for identifying peptides structures available only in minute amounts.     

Administration of the anabolic androgenic steroid nandrolone decanoate affects substance P endopeptidase-like activity in the rat brain

The effect of the anabolic androgenic steroid, nandrolone decanoate, on substance P endopeptidase-like activity was examined in adult male Sprague-Dawley rats. Nandrolone decanoate (15 mg/kg day) or oil vehicle (sterile arachidis oleum) were administered by intramuscular injections during 14 days. Substance P endopeptidase, a predominantly cytosolic enzyme, generates the bioactive N-terminal fragment substance P(1-7) from the enzyme substrate substance P. Nandrolone decanoate significantly reduced the substance P endopeptidase-like activity compared to control animals in hypothalamus (43% reduction), caudate putamen (44%), substantia nigra (32%) and the ventral tegmental area (27%). It was previously reported that both hypothalamus and caudate putamen contained significantly higher levels of substance P after nandrolone administration. The higher concentration of substance P in these regions could to an extent be attributed to the reduction in substance P endopeptidase-like activity. This result elucidates the important role of peptidase activity in the regulation of the substance P transmitter system. The present study provides additional support for the hypothesis that alterations in the substance P system in certain brain areas may contribute to some of the personality changes reported in connection with AAS abuse.