Altered pain perception in hypertensive humans

Sensory and pain thresholds to electrical stimulation of tooth pulps were measured in normotensive and essential hypertensive unmedicated human subjects. In both adult and young subjects there was a significant correlation between blood pressure and pain sensitivity: hypertensives had a higher threshold for sensation of pain in the tooth-pulp test than normotensive controls. An interrelationship between blood pressure and pain regulation is suggested.

Immunohistochemical localization of a melanin concentrating hormone-like peptide in the rat brain

Using antisera generated in rabbits against salmon melanin concentrating hormone (MCH) coupled to human thyroglobulin, the distribution of MCH-like immunoreactivity was mapped throughout the rat central nervous system. The distribution of MCH-like immunoreactivity in rat brain is unique and different from the distribution of other neuropeptides. MCH-like immunoreactive perikarya and fibers are predominant in the posterior hypothalamic area, mostly in the medial forebrain bundle-lateral hypothalamic area subzona incerta and the perifornical area. Cell bodies are located mainly in the medial forebrain bundle and in proximity to well defined hypothalamic nuclei. Fibers are seen throughout the rat brain in all neocortical areas, the neostriatum and the amygdala, in the diencephalon in most hypothalamic nuclei, the habenula, the mamillary body and very dense in the medial forebrain bundle and just ventral to the zona incerta ("subzona incerta"). In the mesencephalon there are fibers in the central gray; in the pons-medulla fibers are contained in the dorsal and ventral parabrachial nuclei; in the tegmental area ventral to the fourth ventricle; in the spinal trigeminal area, the substantia gelatinosa and the reticular nuclei. In the spinal cord there are more fibers in the dorsal than in the ventral horn. The posterior pituitary also contained few MCH-like fibers. It is suggested that a peptide similar, but not identical, to salmon MCH is present in the rat central nervous system.

Pain sensitivity and opioid activity in genetically and experimentally hypertensive rats

Pain sensitivity was studied in renal and DOCA-salt hypertensive rats, and in two strains of rats derived from the same parental strain for their sensitivity (H) or immunity (N) to hypertension induced by DOCA-salt treatment. Experimentally hypertensive rats, and H and N rats were less sensitive to painful stimuli than their appropriate controls, as assessed in the hot-plate and paw pinch tests. Naloxone reversed this hypoalgesia in both experimentally and genetically hypertensive rats while it did not affect blood pressure in any rat-type tested. Opioid activity was measured with the radioreceptor assay in several brain regions and pituitary gland of both experimentally and genetically hypertensive rats. Experimentally hypertensive rats had a 45% higher level of opioid activity in the spinal cord compared to control. Rats of the H and N strains both exhibited higher levels of opioid activity in the spinal cord, hypothalamus and pituitary. It is suggested that control systems for blood pressure and pain sensitivity are closely associated in the rat.

Evidence for the existence of atrial natriuretic factor-containing neurons in the rat brain

Immunoreactive atrial natriuretic factor- (ANF-)positive nerve fibers and cell bodies were observed in the preoptic area, hypothalamus, mesencephalon, and pons of rats. In colchicine-treated animals a large number of immunoreactive ANF-positive cell bodies were seen in the organum vasculosum of the lamina terminalis, in several hypothalamic nuclei (e.g. periventricular, arcuate, and ventral premammillary nuclei), and in the dorsolateral tegmental nuclei of the pons. Varicose nerve fibers containing ANF were generally observed in the vicinity of the cells. These findings indicate that a widespread network of ANF-containing neurons is present in the brain.

Distribution of atrial natriuretic factor-like immunoreactive neurons in the rat brain

Using antisera generated in rabbits against rat atriopeptin III [alpha-rANP(5-28)] and human alpha-atrial natriuretic polypeptide we mapped the distribution of atrial natriuretic factor-like immunoreactivity throughout the rat central nervous system. Cell bodies were observed in the telencephalon (nucleus interstitialis striae terminalis and between the amygdala centralis and medialis), throughout the diencephalon in all nuclei of the "anteroventral third ventricle", the base of the hypothalamus, the subzona incerta area, the medial forebrain bundle and the medial habenula, in the mesencephalon (mamillary body, substantia nigra lateralis, dorsal and ventral parabrachial nuclei) and very sparse in the medulla oblongata along the fourth ventricle towards the vestibular nuclei, the nucleus tractus solitarii and nervi trigemini. Fibers were present wherever cell bodies were located. The highest relative densities were observed in the anteroventral third ventricle area and the medial habenula. Sparse fibers were also seen in the spinal cord (dorsal and ventral horn and around the central canal) and in the posterior pituitary. The predominance of the atrial natriuretic factor-like perikarya and fibers in the anteroventral third ventricle area suggests an involvement of this peptide in central blood pressure control.

A dynorphinergic pathway of Leu-enkephalin production in rat substantia nigra

The amino acid sequence of the opioid peptide Leu-enkephalin is found within several larger peptides, which are generated from the precursors proenkephalin and prodynorphin. Proenkephalin contains four copies of the sequence of Met-enkephalin, a single copy of the sequence of Leu-enkephalin and one copy each of two extended Met-enkephalin sequences. Proenkephalin contains three peptides--alpha-neo-endorphin, dynorphin A and dynorphin B--the N-terminal sequences of which are identical to that of Leu-enkephalin. There is good evidence that the large amounts of Leu-enkephalin found in the adrenal medulla are generated from the precursor proenkephalin, but as yet prodynorphin has not been shown to be processed to yield Leu-enkephalin. We show here that the relatively high levels of Leu-enkephalin found in the rat substantia nigra are supplied by striatonigral axons and generated from the precursor prodynorphin.

Distribution of immunoreactive atrial natriuretic peptides in the central nervous system of the rat

The distribution of immunoreactive (ir) atrial natriuretic peptides (ANPs) in 47 microdissected brain and spinal cord regions of the rat was determined by radioimmunoassay. The highest concentrations of ir-ANPs exist in the paraventricular nucleus and median preoptic nucleus (580.9 and 558.0 fmol/mg protein, respectively). High concentrations of ir-ANP (greater than 300 fmol/mg protein) are present in the interpeduncular nucleus, preoptic and hypothalamic periventricular nuclei, median eminence and organum vasculosum of the lamina terminalis. Moderate concentrations of ir-ANPs (between 100 and 300 fmol/mg protein) are found in 16 brain regions such as the bed nucleus of the stria terminalis, nucleus of the diagonal band, most of the hypothalamic nuclei, central gray, locus coeruleus and parabrachial nuclei. Low levels of ir-ANPs (less than 100 fmol/mg protein) exist in 22 brain regions including cortical areas, amygdala, caudate nucleus, nucleus accumbens, hippocampus, supraoptic nucleus, subfornical organ, medial mammillary nucleus, substantia nigra, dorsal raphe nucleus, cerebellum, nucleus of the solitary tract and others. Cervical spinal cord and neurointermediate lobe of pituitary gland contain low levels of ir-ANPs.

Circulating atrial natriuretic peptides in conscious rats: regulation of release by multiple factors

Cardiocytes in the atria contain a prohormone that gives rise to atrial natriuretic peptides (ANP's), which have intrinsic hemodynamic regulatory activity. The distribution of ANP's in the brain suggests the involvement of these peptides in central cardiovascular regulation. In conscious rats with chronic indwelling catheters, volume loading with isotonic saline or glucose increased the amount of circulating immunoreactive ANP's by a factor of 4 to 5, as determined by radioimmunoassay. Hyperosmotic challenge with a hypertonic NaCl solution or anesthesia with halothane caused similar increases in plasma ANP's. Results obtained with the denervated-heart preparation indicate that neuronal influences are important in the release of ANP's induced by volume loading. As judged from reversed-phase high-performance liquid chromatography of extracted plasma and radioimmunoassay of collected fractions, the circulating physiologically important ANP's in the conscious rodent appear to be alpha-rANP(5-28) (atriopeptin III) and either alpha-rANP(3-28) [ANF(8-33)] or alpha-rANP(1-28) (ANF).

Corticotropin releasing factor-like immunoreactivity in sensory ganglia and capsaicin sensitive neurons of the rat central nervous system: colocalization with other neuropeptides

Immunohistochemistry and radioimmunoassay (RIA) revealed that corticotropin releasing factor (CRF)-like immunoreactivity was found to be colocalized with substance P (SP)-, somatostatin (SST)- and leu-enkephalin (LENK)-like immunoreactivity in the dorsal root- and trigeminal ganglia, the dorsal horn of the spinal cord (laminae I and II), the substantia gelatinosa, and at the lateral border of the spinal nucleus and in the tractus spinalis of the trigeminal nerve. These peptides were also located in fast blue labeled cells of the trigeminal ganglion following injection of the dye into the spinal trigeminal area. This indicates that there are possible sensory projections of these peptides into the spinal trigeminal area. Capsaicin treatment of neonatal rats resulted in a marked decrease in the density of CRF-, SP-, VIP- and CCK-containing neurons in the above mentioned hindbrain areas, whereas SST- and LENK-immunoreactivity were not changed. RIA revealed that, compared to controls, CRF, SP and VIP concentrations in these areas were decreased in rats pretreated with capsaicin, while SST levels were increased; CCK and LENK levels were unchanged. It is concluded that the primary afferent neurons of the nucleus and tractus spinalis of the trigeminal nerve are richly endowed with a number of peptides some of which are sensitive to capsaicin action. The close anatomical proximity of these peptide containing neurons suggests the possibility of a coexistance of one or more of these substances.

The relationship between cardiovascular and pain regulatory systems

An increasing amount of anatomical, physiological, and pharmacological evidence suggest that pain inhibitory circuitry is linked with cardiovascular regulatory systems in man and laboratory animals. Induction of hypertension in rats by different methods (mineralocorticoid treatment, stenosis of renal artery, or social deprivation) is associated with reduced responsiveness to noxious thermal stimuli (hot-plate) or to noxious mechanical stimuli (paw pressure). Genetically hypertension-prone rats derived from the SABRA strain and spontaneously hypertensive rats derived from Wistar/Kyoto strain also display a similar hypoalgesia. Acute increases in blood pressure are associated with reduced sensitivity to painful stimuli. Additionally, the interaction between blood pressure and pain perception has also been supported by the demonstration that various experimental interventions that diminish the magnitude of hypertension also attenuate the hypoalgesia. Recent clinical findings are also in agreement with the laboratory animal findings since sensory and pain thresholds have been shown to be significantly higher in unmedicated essential hypertensive subjects compared to normotensive controls. Thus, the human data corroborate animal data and suggest that a relation between blood pressure and pain sensitivity is likely to be a general phenomenon. It is unlikely that damage to peripheral pain fibers caused by a change in blood pressure contributes to the observed hypoalgesia. Naloxone, which has no effect on blood pressure, returns the pain sensitivity to normal levels. Behavioral tests (open field and motor activity cage) of normotensive and of renal and genetically (SBH and SHR) hypertensive rats exclude the possibility of a general motor deficit in hypertensive rats. Endogenous opioid peptides in central and peripheral nervous systems as well as in endocrine organs are implicated, although non-opioid mechanisms are also evident. Activation of baroreceptor afferents by acute or chronic increases in arterial or venous blood pressure may play an important role in the somatosensory responses associated with the increase in blood pressure. Coordinated cardiovascular-pain regulatory responses may be part of an adaptive mechanism that helps the body to face stressful events.

Distribution of immunoreactive dynorphin in the central nervous system of the rat

A widespread distribution of immunoreactive dynorphin (ir-Dyn) in rat brain and spinal cord was demonstrated by means of a highly specific radioimmunoassay. The highest concentrations of ir-Dyn (greater than 399 pg/mg protein) were found in hypothalamic nuclei, i.e. the premamillary, anterior hypothalamic and dorsomedial nuclei and median eminence. Relatively high concentrations of ir-Dyn (between 320 and 399 pg/mg protein) were found in other hypothalamic nuclei such as the medial and lateral preoptic, perifornical, suprachiasmatic, ventromedial nuclei and in the medulla oblongata in the area postrema and in the nucleus of the solitary tract (commissural part). Moderate levels of ir-Dyn (between 140 and 320 pg/mg protein) were found in most diencephalic areas other than the hypothalamic nuclei and further nuclei in the medulla oblongata, in the mesencephalon, pons and spinal cord. Low to moderate levels of ir-Dyn were found in the telencephalon, with lowest levels (less than 140 pg/mg protein) found in the cerebral cortex, olfactory bulb, dorsal septal nucleus, medial amygdaloid nucleus, caudate-putamen, superior collicle, cerebellum and certain areas of the reticular formation.

Environmentally-induced modification of the benzodiazepine/GABA receptor coupled chloride ionophore

The benzodiazepine/GABA receptor coupled chloride ionophore was examined in brain membranes of rats maintained in either a conventional animal facility or a "protected" (low-stress) environment. Following a 10 min ambient temperature swim, animals maintained in both environments had qualitatively similar increases in the number (Bmax) of [35S]t-butylbicyclophosphorothionate (TBPS) binding sites, the apparent affinity of this radioligand, and the efficacy and potency of Cl- to enhance [3H]flunitrazepam binding. Nonetheless, the Bmax of [35S]TBPS and efficacy of Cl- to enhance [3H]flunitrazepam binding were significantly lower in animals housed in the protected environment compared to those maintained in a conventional facility both before and after swim stress. Furthermore, in rats housed in a protected environment, sequential removal of animals from a common cage (cohort removal), produced a very rapid increase (less than or equal to 15 s) in Cl(-)-enhanced [3H]flunitrazepam binding in cortical and hippocampal but not cerebellar membranes. Cohort removal also produced a sequential increase in the number of [35S]TBPS binding sites and apparent affinity of this radioligand in cerebral cortical membranes. The effects of cohort removal were not observed in animals subjected to ambient temperature swim or if animals were removed from different cages. Changes in the benzodiazepine/GABA receptor coupled chloride ionophore produced by cohort removal from a common cage preceded any statistically significant changes in circulating levels of alpha-MSH, beta-endorphin, ACTH or corticosterone. These findings suggest that the benzodiazepine/GABA receptor chloride ionophore complex (supramolecular complex) is under both tonic and acute regulation by the environment, and may subserve a physiologically relevant function in the response to stressful or anxiety producing stimuli.

Melanin-concentrating hormone: unique peptide neuronal system in the rat brain and pituitary gland

A unique neuronal system was detected in the rat central nervous system by immunohistochemistry and radioimmunoassay with antibodies to salmon melanin-concentrating hormone (MCH). MCH-like immunoreactive (MCH-LI) cell bodies were confined to the hypothalamus. MCH-LI fibers were found throughout the brain but were most prevalent in hypothalamus, mesencephalon, and pons-medulla regions. High concentrations of MCH-LI were measured in the hypothalamic medial forebrain bundle (MFB), posterior hypothalamic nucleus, and nucleus of the diagonal band. Reversed-phase high-performance liquid chromatography of MFB extracts from rat brain indicate that MCH-like peptide from the rat has a different retention time than that of the salmon MCH. An osmotic stimulus (2% NaCl as drinking water for 120 hr) caused a marked increase in MCH-LI concentrations in the lateral hypothalamus and neurointermediate lobe. The present studies establish the presence of MCH-like peptide in the rat brain. The MCH-LI neuronal system is well situated to coordinate complex functions such as regulation of water intake.

Distribution of immunoreactive Met-enkephalin-Arg6-Gly7-Leu8 and Leu-enkephalin in discrete regions of the rat brain

The distribution of immunoreactive (ir) leucine-enkephalin (LE) and ir-methionine-enkephalin-Arg-Gly-Leu (ME-RGL) in 101 microdissected rat brain and spinal cord regions was determined using specific and sensitive radioimmunoassays. The highest concentrations of LE and ME-RGL were measured in globus pallidus (5190 and 4378.8 fmol/mg protein, respectively). Very high concentrations of LE and ME-RGL (greater than 750 fmol/mg protein) were found in the central amygdaloid nucleus, anterior hypothalamic nucleus, lateral preoptic area, nucleus of the solitary tract (medial and commissural parts), bed nucleus of stria terminalis, dorsomedial nucleus, parabrachial nuclei, periaqueductal gray and motor hypoglossal nucleus. Very high concentrations of ME-RGL were found in 14 additional brain regions including medial preoptic area, area postrema, nucleus ambiguus, periventricular nucleus, ventromedial nucleus, interpeduncular nucleus, paraventricular, arcuate and others. High concentrations of LE (between 500 and 750 fmol/mg protein) were found in 15 brain areas, among them the periventricular nucleus, medial preoptic area, suprachiasmatic nucleus, dorsal premamillary nucleus, ventromedial nucleus, arcuate nucleus, nucleus ambiguus, locus coeruleus, substantia nigra. High concentrations of ME-RGL were measured in 13 brain areas including the suprachiasmatic nucleus, lateral septal nucleus, raphe magnus, motor facial nucleus, lateral amygdaloid nucleus, sensory trigeminal nucleus, nucleus accumbens, caudate-putamen. Moderate concentrations of LE (between 250 and 500 fmol/mg) were found in 46 brain areas such as the lateral septal nucleus, nucleus accumbens, caudate-putamen, several amygdaloid nuclei, supraoptic nucleus, the perifornical nucleus, posterior hypothalamic nucleus, red nucleus. Moderate concentrations of ME-RGL were detected in 27 areas such as the median eminence, nuclei of the reticular formation, supraoptic nucleus, red nucleus and others.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of immunoreactive melanin-concentrating hormone in the central nervous system of the rat

The distribution of melanin-concentrating hormone-like immunoreactivity (MCH-LI) in 41 microdissected brain and spinal cord regions was determined using radioimmunoassay with antibodies to salmon MCH. The highest concentration of MCH-LI was detected just ventral to the zona incerta (subzona incerta) (2923.2 fmol/mg protein). Very high concentrations of MCH-LI (greater than 1000 fmol/mg protein) were detected also in the nucleus of the diagonal band, medial forebrain bundle, posterior hypothalamic nucleus and medial mammillary nucleus. High concentrations of the peptide (between 500-1000 fmol/mg protein) were measured in 11 brain regions, including bed nucleus of stria terminalis, paraventricular nucleus, anterior hypothalamic nucleus, median eminence, parabrachial nucleus. Moderate concentrations of MCH-LI (between 250-500 fmol/mg protein) were measured in 16 brain regions, such as frontal cortex, central amygdaloid nucleus, medial septum, periventricular nucleus (preoptic) and nucleus of the solitary tract. Low concentrations of MCH-LI (less than 250 fmol/mg protein) were measured in 9 brain regions such as cortical areas, hippocampus, caudate nucleus and substantia nigra. Cervical spinal cord and neurointermediate lobe of the pituitary gland contain low concentrations of the peptide.

The localization and characterization of substance P and substance K in striatonigral neurons

Specific substance P and substance K radioimmunoassays coupled to high-performance liquid chromatography were used to characterize striatal and nigral tachykinin immunoreactivity. Using these assays, authentic substance P and substance K accounted for nearly all substance P and substance K immunoreactivity, respectively. A series of coronal knife cuts of the striatum caused parallel depletions in nigral substance P and substance K, consistent with the possible colocalization of these tachykinins in striatonigral neurons.

Possible interactions between dynorphin and dopaminergic systems in rat basal ganglia and substantia nigra

Chronic haloperidol treatment markedly increases dynorphin-related peptide contents in caudate-putamen, globus pallidus and substantia nigra. Leu-enkephalin levels follow dynorphin-related peptide concentrations in these areas while Met-enkephalin-related peptide contents are unchanged in the substantia nigra following a similar treatment. An acute haloperidol injection had no effect on any opioid peptide levels in the basal ganglia. This suggests that Leu-enkephalin is likely to be derived from prodynorphin in the rat striatonigral pathway. Moreover, the Leu-enkephalin/dynorphin projection appears to be under striatal dopaminergic control.

Methionine and leucine enkephalin in rat neurohypophysis: different responses to osmotic stimuli and T2 toxin

Specific radioimmunoassays were used to measure the effects of hypertonic saline (salt loading), water deprivation, and trichothecene mycotoxin (T2 toxin) on the content of methionine enkephalin (ME), leucine enkephalin (LE), alpha-neoendorphin, dynorphin A, dynorphin B, vasopressin, and oxytocin in the rat posterior pituitary. Concentrations of vasopressin and oxytocin decreased in response to both osmotic stimuli and treatment with T2 toxin, but the decrease was greater with osmotic stimulations. Similarly, concentrations of LE and dynorphin-related peptides declined after salt loading and water deprivation; LE concentrations also decreased after treatment with T2 toxin. The concentration of ME decreased after water deprivation, did not change after salt loading, and increased after T2 toxin treatment. The differentiating effects of these stimuli on the content of immunoreactive LE and ME are consistent with the hypothesis that LE and ME may be localized in separate populations of nerve endings with different roles in the posterior pituitary.

Distribution of immunoreactive dynorphin B in discrete areas of the rat brain and spinal cord

The distribution of immunoreactive (ir)-dynorphin B in 101 microdissected rat brain and spinal cord regions was determined using a specific radioimmunoassay. The highest concentration of dynorphin B in brain was found in the substantia nigra (1106.2 fmol/mg protein). Very high concentrations of ir-dynorphin B (greater than 400 fmol/mg protein) were also found in the lateral preoptic area, parabrachial nuclei and globus pallidus. Relatively high concentrations of ir-dynorphin B (250-400 fmol/mg protein) were found in 19 nuclei, including the periaqueductal gray matter, anterior hypothalamic nucleus, median eminence, nucleus accumbens and hippocampus. Moderate levels of the peptide (between 100 and 250 fmol/mg protein) were found in 42 brain nuclei such as the perifornical nucleus, nucleus of the diagonal band, medial forebrain bundle, and dorsal premamillary nucleus. Low concentrations of ir-dynorphin B (less than 100 fmol/mg protein) were found in 28 brain areas, e.g. cerebral cortical structures (parietal, cingulate, frontal), claustrum, olfactory bulb, lateral and periventricular thalamic nuclei. The cerebellar cortex has the lowest dynorphin B concentration (53.7 fmol/mg protein). Spinal cord segments exhibit low or moderate (cervical segment) levels of the peptide. The neurointermediate lobe of the pituitary gland is extremely rich in ir-dynorphin B (11,047.1 fmol/mg protein).

Mild footshock stress dissociates substance P from substance K and dynorphin from Met- and Leu-enkephalin

Mild footshock stress selectively activates ventral tegmental area dopamine neurons innervating the prefrontal cortex. The same stressor rapidly dissociates ventral tegmental substance P from its preprotachykinin-derived co-transmitter substance K, and preproenkephalin B-derived dynorphin B from preproenkephalin A-derived Met-enkephalin-Arg-Gly-Leu and Leu-enkephalin. Mild footshock stress may provide a paradigm for studying both peptidergic modulation of brain dopaminergic neurons and the dynamic regulation of tachykinin and opioid peptide transcription, processing and utilization.

Distribution of immunoreactive dynorphin A1-8 in discrete nuclei of the rat brain: comparison with dynorphin A

The distribution of immunoreactive (ir)-dynorphin A1-8 (Dyn A1-8) in 78 microdissected rat brain areas as well as in the neurointermediate lobe of pituitary gland was determined using a highly specific radioimmunoassay. The highest concentrations of Dyn A1-8 in brain were found in substantia nigra (673.8 fmol/mg protein) and lateral preoptic area (565.1 fmol/mg protein). High concentrations of ir-Dyn A1-8 (greater than 240 fmol/mg protein) were found in 5 nuclei: ventral premamillary nucleus, anterior hypothalamic nucleus, dorsomedial nucleus, arcuate nucleus, and medullary reticular nuclei. Moderate concentrations of the peptide (between 120 and 240 fmol/mg protein) were found in 55 brain nuclei such as septal and amygdaloid nuclei, most diencephalic structures, mesencephalic nuclei, pons and medulla oblongata nuclei and others. Low concentrations of ir-Dyn A1-8 (less than 120 fmol/mg protein) were found in 16 regions, e.g. frontal cortex, hippocampus, caudate-putamen cortical amygdaloid nucleus, several thalamic nuclei, mamillary body superior and inferior colliculi, cerebellar nuclei and others. The posterior thalamic nucleus has the lowest ir-Dyn A1-8 concentration (62.0 fmol/mg protein). The neurointermediate lobe of the pituitary gland is extremely rich in ir-Dyn A1-8 (4063.0 fmol/mg protein).

Primate model of Parkinson's disease: alterations in multiple opioid systems in the basal ganglia

A motor disorder similar to idiopathic Parkinson's Disease develops in rhesus monkeys after several daily repeated doses of N-methyl-4-phenyl, 1,2,3,6-tetrahydropyridine (MPTP). The concentrations of peptides derived from proenkephalin A, proenkephalin B, substance P and somatostatin were measured by specific radioimmunoassays in the basal ganglia of MPTP-treated monkeys. In MPTP-treated monkeys, dynorphin B concentration was reduced in the caudate. In the putamen, the concentrations of peptides derived from both proenkephalin A and proenkephalin B were decreased. In the globus pallidus, the concentrations of all opioid peptides tend to be increased, reaching significance only for alpha-neo-endorphin. In the substantia nigra, only Met-enkephalin concentration was reduced, while other peptides derived from either proenkephalin A or proenkephalin B were not changed. Substance P and somatostatin were not changed in any brain area examined. Some of the symptoms associated with Parkinson's Disease may be related to altered activity of endogenous opiates in basal ganglia.

Differential processing of prodynorphin and proenkephalin in specific regions of the rat brain

Prodynorphin-derived peptides [dynorphin A (Dyn A)-(1-17), Dyn A-(1-8), Dyn B, alpha-neo-endorphin, and beta-neo-endorphin] and proenkephalin-derived peptides [[Leu]enkephalin [( Leu]Enk) and [Met]enkephalin-Arg6-Gly7-Leu8 [( Met]Enk-Arg-Gly-Leu]) in selected brain areas of the rat were measured by specific radioimmunoassays. We report here that different regions of rat brain contain strikingly different proportions of the prodynorphin and proenkephalin-derived peptides. There is a molar excess of alpha-neo-endorphin-derived peptides over Dyn B and Dyn A-derived peptides in many brain areas. [Leu]Enk concentrations exceed those of [Met]Enk-Arg-Gly-Leu in certain brain areas such as the substantia nigra, dentate gyrus, globus pallidus, and median eminence (areas rich in dynorphin-related peptides). These results indicated that (i) there is differential processing of prodynorphin in different brain regions and (ii) [Leu]Enk may be derived from Dyn A or Dyn B (or both). In certain brain regions [Leu]Enk may derive from two separate precursors (prodynorphin and proenkephalin) in two distinct neuronal systems.

Atrial natriuretic peptide attracts human spermatozoa in vitro

Here we report that atrial natriuretic peptide (ANP), a known activator of particulate guanylate cyclase, induces attraction and swimming speed enhancement of human spermatozoa in vitro. Using capillary assays under a variety of experimental conditions (ascending or descending gradients of ANP, or no gradient at all) and microscopic assays in which individual spermatozoa could be followed, we found that spermatozoa followed the gradient of ANP and accumulated in it. Speed enhancement was detected in the presence of ANP without a gradient. These observations suggest either that an ANP-like substance is the physiological attractant for human spermatozoa, or, more likely, that ANP directly affects guanylate cyclase in a manner similar to that caused by the physiological attractant.