Dopamine receptor agonistic activities of R- and S-enantiomers of 4-hydroxy-2-di-n-propylaminoindan in cat hearts

In-vitro and in-vivo studies were used to evaluate the presynaptic dopamine receptor stimulating activities of R- and S-enantiomers of 4-hydroxy-2-di-n-propylaminoindan in cat hearts. Bioassay results show that the R-enantiomer is 100 times more potent than the S-enantiomer in both in-vitro and in-vivo preparations.

Quantitation of alpha 1-adrenergic receptors in porcine uterine and mesenteric arteries

The activation of vascular alpha-adrenergic receptors may be involved in the control of uterine blood flow. A radioligand binding assay with the use of the alpha 1-adrenergic antagonist 3H-WB-4101 was established to characterize the alpha-adrenergic receptors in uterine and mesenteric arterial membranes obtained from nonpregnant pigs. Specific binding of 3H-WB-4101 was rapid, saturable, and exhibited the alpha-adrenergic agonist potency order of (-)-epinephrine inhibition constant [Ki] = 0.6 mumol/L greater than (-)-norepinephrine (Ki = 1.5 mumol/L) much greater than (-)-isoproterenol (Ki = 120 mumol/L). The alpha-adrenergic antagonist phentolamine (Ki = 6.0 nmol/L) was 200 times more potent than the beta-adrenergic antagonist (+/-)-propranolol (Ki = 1,200 nmol/L); the alpha 1-selective antagonist prazosin (Ki = 1.2 nmol/L) was 130 times more potent than the alpha 2-selective antagonist yohimbine (Ki = 160 nmol/L). Scatchard analysis, as well as iterative curve-fitting analysis, demonstrated that 3H-WB-4101 binding by arterial membranes was to a single class of binding sites. Uterine arteries exhibited greater maximal binding capacity (BMax) than that of mesenteric arteries (47.5 +/- 3.2 versus 30.9 +/- 3.6 fmol per milligram of protein, p less than 0.01), but the uterine artery dissociation constant (Kd) was higher, thus indicating a lower affinity, when compared with mesenteric artery (0.43 +/- 0.04 versus 0.33 +/- 0.04 nmol/L, p less than 0.05).

Interaction of ovarian steroids and periarterial alpha 1-adrenergic receptors in altering uterine blood flow during the estrous cycle of gilts

In vivo exposure to progesterone increases while estrogen decreases in vitro contractility of uterine arteries to nerve stimulation. In addition, uterine blood flow is highly correlated with the estrogen: progesterone ratio in systemic blood throughout the porcine estrous cycle (approximately 21 days). This study was conducted to compare the function of uterine periarterial sympathetic nerves of eight pigs during the follicular phase, the period of highest uterine blood flow and estrogen: progesterone ratio (days 19 to 21), with eight animals during the luteal phase, the period of lowest uterine blood flow and estrogen: progesterone ratio (day 13). The first day of behavioral estrus was designated as day 0. Uterine arteries from each pig were evaluated for (1) in vitro contractility to nerve stimulation, (2) alpha 1-adrenergic receptor binding with use of the specific ligand 3H-WB-4101, and (3) concentrations of norepinephrine with use of a radioenzymatic assay. Uterine arterial contractility to nerve stimulation was greater (p less than 0.01) for pigs in the luteal phase than for those in the follicular phase (216 +/- 36 versus 56 +/- 26 mm Hg). Furthermore, uterine arteries from luteal phase pigs had greater (p less than 0.05) alpha 1-receptor binding (47 +/- 6 versus 35 +/- 5 fmol/mg of protein) than those from follicular phase pigs. Uterine arterial concentrations of norepinephrine were similar for follicular phase and luteal phase pigs. These results suggest that ovarian steroids alter the function of uterine periarterial sympathetic nerves through changes in alpha 1-adrenergic receptor numbers, which may contribute to the marked changes in uterine blood flow observed during the porcine estrous cycle.

Influence of carbon and nitrogen sources on arginine biosynthesis in Mycobacterium smegmatis ATCC 14468

Arginine biosynthesis and its regulation by the presence of different carbon and nitrogen sources in the growth medium of Mycobacterium smegmatis was studied. Replacement of glycerol by glucose and fructose increased the activities of acetylglutamate kinase, acetylornithinase and ornithine transcarbamylase and the enzyme activities of the arginine biosynthetic pathway. The presence of succinate, fumarate, pyruvate or acetate in the growth medium (replacement for citrate) also increased these enzyme activities. However, when glutamate or glutamine was used as nitrogen source in place of asparagine, the enzyme activities decreased. The presence of ornithine or arginine in the growth medium repressed these enzyme activities, though the degree of repression was slight. The phenomenon of repression by arginine and ornithine was confirmed by dialysis experiments. Arginine inhibited the ornithine transcarbamylase activity from cells grown with asparagine as nitrogen source, but activated it when the cells were grown with arginine. Thus, in addition to the weak transcriptional control of arginine biosynthetic enzymes, feedback regulation of ornithine transcarbamylase by arginine also regulated arginine biosynthesis in M. smegmatis grown with asparagine as nitrogen source.

Genetic and environmental influences on developing autonomic control of heart rate

Individual differences in cardiovascular regulation result from a dynamic interaction between genetically programmed developmental processes and extrinsic (environmental) conditions. The alterations in autonomic functioning previously identified among pups of the spontaneously hypertensive rat (SHR) strain suggest a genetic influence on autonomic development. In the present studies, an early stimulation procedure previously shown to reduce the behavioral and endocrine responsiveness of rodents in adulthood was demonstrated to alter both neural control of heart rate and regional brain catecholamine levels during the preweaning period. Pups from litters of SHR and Wistar-Kyoto (WKY) rats were handled daily during the first postnatal week. Selective pharmacological blockade with atenolol and atropine methylnitrate was used to identify autonomic controls of heart rate at 16 and 28 days of age. Combined blockade was used to estimate intrinsic heart rate. In both SHR and WKY, early handling was associated with elevated basal heart rate, elevated intrinsic heart rate, and decreased sympathetic tone. Parasympathetic influence on heart rate was elevated by early handling in WKY and decreased by handling in SHR. In addition, an increase in dorsal cortical norepinephrine concentration was produced by early handling in both strains. These data suggest that early environmental conditions can interact with the genetic predisposition for elevated blood pressure and may play a potentially important role in organizing the neural controls of cardiovascular regulation.

Interaction of dihydroxy-2-aminotetralin derivatives at sites labelled with [3H]clonidine, [3H]prazosin and [3H]spiperone in rat brain membranes

The interactions of 5,6- and 6,7-dihydroxy derivatives of 2-aminotetralin with [3H]clonidine and [3H]prazosin as well as with [3H]spiperone binding sites in rat cerebral cortex membrane preparations were investigated. The hydroxy derivatives of 2-aminotetralin tested showed significant interaction with [3H]clonidine as well as with [3H]peiperone binding sites while for [3H]prazosin binding site these agents appeared virtually inactive. For interaction with [3H]clonidine binding site 6,7-dihyroxy substitutions impart greater potency that 5,6-dihydroxy substitutions and N-alkyl substitutions either make no differece or reduce the affinity of these compounds. N-alkyl substitutions, however, markedly enhance the affinity of 5,6-dihydroxy derivatives for interaction with [3H]spiperone binding site. The results suggest that some hydroxy derivatives of aminotetralin have significant interaction with both central alpha 2-adrenoceptor and D2-dopamine receptor systems.

Conformationally restricted congeners of dopamine derived from octahydrobenzo[g]quinoline and octahydrobenzo[f]quinoline

Series of N-alkylated derivatives of trans-octahydrobenzo[g]quinoline and of cis- and trans-octahydrobenzo[f]quinoline were prepared for pharmacological testing as congeners of 2-amino-5,7-dihydroxytetralin, which elicits dopaminergic effects in a variety of assays. Trans-fused compounds bearing N-ethyl or N-n-propyl displayed high potency/activity in inhibition of effect of stimulation of the cat cardioaccelerator nerve. Certain N-alkyl homologues in the octahydrobenzo[f]quinoline series showed high potency in binding studies in rat caudate homogenate.

Evidence that central dopamine receptors modulate sympathetic neuronal activity to the adrenal medulla to alter glucoregulatory mechanisms

Previous reports suggest that analogs of dopamine (DA) can produce hyperglycemia in rats by interacting with DA receptors. Experiments reported here indicate the site of action and describe the metabolic sequalae associated with the hyperglycemic effect of apomorphine (APO), produced in conscious unrestrained rats. Apomorphine was more potent when administered by intracerebroventricular (i.c.v.) injection than when given subcutaneously (s.c.). Very small doses of the DA receptor antagonist pimozide, given intraventricularly, blocked the hyperglycemic effect of apomorphine administered subcutaneously. Sectioning of the spinal cord at thoracic vertebra T1-2 or sectioning the greater splanchnic nerve blocked apomorphine-induced hyperglycemia; whereas section of the superior colliculus or section at T5-6 had no effect. A dose of apomorphine or epinephrine (EPI) producing a similar degree of hyperglycemia elevated the concentration of EPI in serum to a similar degree, and the increase in EPI in serum preceded the increase in glucose in serum. Fasting animals for 2 or 18 hr had no significant effect on EPI- or apomorphine-induced hyperglycemia despite a reduction (91-93%) of the glycogen content of liver and skeletal muscle during the 18 hr fast. 5-Methoxyindole-2-carboxylic acid (MICA), an inhibitor of gluconeogenesis, blocked EPI- and apomorphine-induced hyperglycemia in rats fasted for 18 hr. However, 5-methoxyindole-2-carboxylic acid was ineffective in blocking hyperglycemia in animals fasted for 2 hr. Changes in insulin or glucagon in serum alone cannot account for the hyperglycemic action of apomorphine. These data demonstrate that apomorphine interacts with central DA receptors located in the hindbrain to activate sympathetic neuronal activity to the adrenal gland which subsequently releases epinephrine to alter homeostasis of glucose. Epinephrine may then, depending on the nutritional status, facilitate glycogenolytic or gluconeogenic processes to produce hyperglycemia.

Resorcinol congeners of dopamine derived from benzocycloheptene and indan

Series of N-alkylated derivatives of 2-amino-4,6-dihydroxyindan 3 and 6-amino-1,3-dihydroxybenzocycloheptene 2 were prepared for pharmacological testing as congeners of 2-amino-5,7-dihydroxytetralin, which elicits dopaminergic effects in a variety of assays. All of the subject compounds demonstrated a lower order of dopamine-like activity than the tetralin derivatives. Some of the subject compounds showed weak interactions with alpha 1- and beta 1-adrenoceptors, but the major determinant of activity seemed to be the nature of the N-alkyl substituent rather than ring size.

Chronic naltrexone increases opiate binding in brain and produces supersensitivity to morphine in the locus coeruleus of the rat

Rats were implanted subcutaneously for 2-4 weeks with slow-release pellets of naltrexone (10 mg) or placebo and then the pellets were removed. One day after removal of the pellet, animals were either (1) sacrificed and various CNS regions examined for specific binding of [3H]naloxone, [3H]etorphine or [3H]rauwolscine or (2) they were anesthetized and prepared acutely for assessing morphine-induced changes in the spontaneous activity of neurons in the locus coeruleus (LC). Naltrexone treatment significantly increased the number of specific binding sites for opiates, but not for alpha 2-adrenergic antagonists, in spinal cord, hypothalamus, striatum and cortex. Specific binding of [3H]naloxone was also increased in the LC. The spontaneous activity of neurons in the LC was reduced by the chronic naltrexone treatment, suggesting that these neurons became supersensitive to the tonic inhibitory effect of endogenous opioid peptides. Moreover, neurons in the LC of chronic naltrexone-treated rats exhibited an enhanced response to the inhibitory effects of morphine administered systemically. These results demonstrate that chronic opiate receptor blockade increases the number of receptor sites for morphine and that this increase in receptors is accompanied by a neuronal supersensitivity in the LC to morphine which can be assessed electrophysiologically.

Secondary cerebral amebiasis

Four cases of E. histolytica infection of the brain among 80 cases of hepatic amebiasis collected over a period of 18 years are reported. The patients were males aged 2, 30, 40 and 50 years. Three cases presented with chest and neurological manifestations. Intestinal and hepatic lesions were present in all and lung lesions in three cases. The cases with neurological manifestations showed extensive, almost confluent lesions in the brain. It is proposed that the condition should be called "Secondary cerebral amebiasis".

Norepinephrine depletion in the spinal cord gray matter of rats with experimental allergic encephalomyelitis

Norepinephrine and dopamine concentrations were determined by radioenzymatic assay in discrete gray matter regions of the spinal cords of rats with experimental allergic encephalomyelitis (EAE). Norepinephrine was depleted in most spinal cord regions of EAE rats compared with controls, whereas dopamine depletion in EAE rats was restricted to the cervical dorsal horn. There was a rostrocaudal gradient of norepinephrine reduction in the spinal cords of the EAE rats with most severe depletion in the lumbar region. The results of this experiment confirmed recent anatomical observations that suggested that catecholamine-fluorescent axons and terminals were damaged in spinal cords of rats with EAE.

Age-related differences in the effect of chronic administration of naloxone on opiate binding in rat brain

Infant and adult rats were injected chronically with either naloxone or saline for 21 consecutive days. At various intervals after cessation of the pretreatment with naloxone, animals were sacrificed and assessed for specific binding of [3H]naloxone in different regions of the CNS. Infants displayed an increase in opiate binding in the spinal cord, hypothalamus, striatum and cortex one day after cessation of the pretreatment with naloxone, but the increase in opiate binding was dissipated within one week after cessation of the pretreatment. The increase in opiate binding in infants was accompanied by an increase in the antinociceptive efficacy of morphine. In contrast to infants, adults failed to display any alteration in opiate binding following the chronic pretreatment with naloxone. Infants may be especially susceptible to naloxone-induced receptor supersensitivity because infants excrete naloxone more slowly than adults, and thus their opiate receptors may be blocked for a longer duration following an injection of naloxone.

Is domperidone a selective peripheral dopamine-receptor antagonist in vivo?

The ability of domperidone (DOM) to antagonize dopamine (DA) receptor agonist-induced hypothermia or hyperactivity was investigated in rats. Apomorphine (APO) or RDS-127 (2-di-n-propylamino-4,7-dimethoxyindane), two DA receptor agonists, produced dose-dependent hypothermia following subcutaneous (s.c.) administration. Also, RDS-127 produced hypothermia following lateral ventricular (i.c.v.) administration. The hypothermia produced by apomorphine or RDS-127 (given s.c. or i.c.v.) was antagonized by pretreatment with pimozide (0.25 mg/kg, i.p.) or domperidone (0.2, 1.0 and 5.0 mg/kg, i.p.). The hyperactivity produced by apomorphine was unaffected by pretreatment with domperidone. These data suggested that central DA receptors mediating temperature regulation, but not those mediating locomotor activity are accessible to peripherally administered domperidone. Therefore, domperidone may not be useful to differentiate hypothalamic (central) vs peripheral sites of action for DA receptor agonists in the rat.

An improved filtration procedure for measuring opiate receptors in small regions of rat brain

A modified filtration method for in vitro receptor binding was used to determine specific binding of [3H]naloxone to small regions of adult rat brain. Reliable determinations of ligand binding were quantified with about 50 micrograms of protein per assay tube. Large differences in [3H]naloxone binding were obtained between various brain nuclei, and these differences were consistent with prior determinations of opiate receptor densities in various rat brain nuclei using autoradiographic techniques.

Conformationally restricted congeners of dopamine derived from 2-aminoindan

Two series of N-substituted 2-aminoindan systems have been prepared: 4,5-dihydroxy-2-aminoindan (1) has a hydroxylation pattern analogous to the alpha conformer of dopamine, and 5,6-dihydroxy-2-aminoindan (2) has a hydroxylation pattern of the beta conformer of dopamine. All members of both series demonstrated only extremely weak binding to calf caudate homogenate. Certain N-alkylated 4,5-dihydroxyindans were violent emetics in the dog and were potent in blockade of the effect of stimulation of the cardioaccelerator nerve of the cat. In contrast, the 5,6-dihydroxy series displayed low or no activity/potency in these assays. Conformational analysis of the 2-aminoindan system is described and discussed.

Role of blastospores in protecting Aspergillus parasiticus NRRL 3240 from high levels of aflatoxins

The role of blastospores in the protection of Aspergillus parasiticus from high levels of aflatoxins was studied. The strain protects itself from aflatoxicity by forming thick-walled blastospores. The formation of blastospores was not observed under conditions of reduced aflatoxin formation, e.g., under zinc and asparagine deficiencies. The germination of blastospores coincided with an increase in the specific activity of glutamate dehydrogenase (NADP) and a simultaneous decrease in the specific aflatoxin production.

Selective sympathetic neural changes in hypertrophied right ventricle

Selective pressure overload of the right ventricle in guinea pigs resulted in early and sustained reductions in tyrosine hydroxylase and dopamine-beta-hydroxylase activities in the right ventricle. No changes in tyrosine hydroxylase activity were detected in stellate ganglia sinoatrial (SA) nodal region, atrioventricular (AV) nodal region, or left ventricle. Reductions in tyrosine hydroxylase activity in stressed right ventricle were similar regardless of duration of pulmonary artery constriction, extent of hypertrophy, presence or absence of hepatic congestion, and preservation or depletion of catecholamines. The changes may represent localized loss of sympathetic nerve fibers; factors involved directly in the process of pressure-overload-induced hypertrophy may be responsible. However, sympathetic nerves remaining in hypertrophied ventricle respond normally to cold-induced sympathetic activation. The reduction in tyrosine hydroxylase activity and the maintenance of norepinephrine turnover in residual innervation to hypertrophied right ventricle support the concept that sympathetic neural regulation of hypertrophied cardiac tissue is altered but not lost.

2-Amino-4,7-dimethoxyindan derivatives: synthesis and assessment of dopaminergic and cardiovascular actions

N-Alkylated derivatives of 2-amino-4,7-dimethoxyindan were prepared for evaluation of central and peripheral dopaminergic activity using biochemical and behavioral tests in the rat and cardiovascular responses in the cat. 2-(Di-n-propylamino)-4,7-dimethoxyindan (4e) demonstrated equal activity with apomorphine to activate peripheral presynaptic dopamine receptors. Central pre- and postsynaptic dopamine receptors were also activated with 4e. In contrast to the intense long-acting sympathomimetic actions previously reported for the 2-amino-5,8-dimethoxytetralins, these compounds produced weak, transient effects in heart rate and blood pressure. The majority of 2-amino-4,7-dimethoxyindan derivatives tested are weak or inactive pre- and postsynaptic dopamine receptor agonists.

Normal exercise capacity in patients with severe left ventricular dysfunction: compensatory mechanisms

About one-third of patients who have severe left ventricular dysfunction can achieve normal levels of exercise. To elucidate the mechanisms that permit this to occur, we studied six patients with severe left ventricular dysfunction (average left ventricular ejection fraction 17 +/- 2.5% [mean +/- SEM]) who achieved nearly normal levels of exercise tolerance (greater than 11 minutes of treadmill exercise, Sheffield protocol). All patients had normal pulmonary function at rest and during exercise. Hemodynamics were measured at rest and during supine and upright exercise. The major mechanisms of the preserved exercise capacity in these patients were chronotropic competence, ability to tolerate elevated wedge pressures (33 +/- 3 mm Hg) without dyspnea, ventricular dilation, and increased levels of plasma norepinephrine at rest and during exercise. Also, whereas peripheral vascular resistance was unchanged during supine exercise, it decreased by 50% during similar levels of upright exercise. As a consequence, increases in cardiac output from rest to exercise were greater during upright than supine exercise (100% vs 50%, respectively) (p less than 0.05), and pulmonary wedge pressures were lower during upright than supine exercise (21 +/- 5 mm Hg vs 33 +/- 3 mm Hg). Thus, multiple mechanisms permit some patients with severe left ventricular dysfunction to achieve normal levels of exercise. These studies emphasize that left ventricular function must be assessed by direct means rather than inferring function of the left ventricle from the results of an exercise tolerance test.

Differential effects of chronic morphine and naloxone on opiate receptors, monoamines, and morphine-induced behaviors in preweanling rats

Rats were administered either chronic morphine, naloxone or saline from 1 to 21 days of age. At 22 days of age, animals were sacrificed and various CNS areas were assayed for specific binding of [3H]naloxone and steady-state levels of norepinephrine, dopamine and serotonin, as well as turnover of norepinephrine and dopamine. In addition, some animals at 22 days of age were assessed for morphine-induced changes in activity, hot-plate paw-lick latency, and rectal body temperature. Chronic naloxone treatment produced an increase in the number of ligand binding sites in hypothalamus, striatum and cortex, but did not alter monoamine systems or the efficacy of morphine. In contrast, chronic morphine treatment produced tolerance to the hypoactive and antinociceptive effects of morphine, but did not alter ligand binding or monoamine systems. These results demonstrate that developing opiate receptor systems in brain are more responsive to chronic receptor blockade than to chronic receptor activation and that an alteration in the development of opiate receptor systems does not necessarily produce a concomitant alteration in either monoamine systems or the behavioral efficacy of morphine.

Opiate receptor development in midbrain and forebrain of posthatch chicks

Specific binding [3H]naloxone to midbrain and forebrain was examined from chicks which were either 1, 7, 14, 21 or 28 posthatch days of age. While there was a significant age-related increase in the total number of [3H]naloxone binding sites in both brain regions, the increase was greater in magnitude in forebrain than in midbrain. In both brain regions, there was a concomitant age-related decrease in the density of receptor sites without any alteration in receptor affinity for naloxone. The decrease in receptor density was more rapid in onset and was greater in magnitude in midbrain than in forebrain.

Changes in parasympathetic and sympathetic neurochemical indices in hearts of myopathic hamsters

Sympathetic neurochemical indices in heart are increased in Syrian golden hamsters with skeletal and cardiac myopathy. The possibility that parasympathetic neurochemical indices might be altered was investigated in myopathic and normal hearts by measuring activity of choline acetyltransferase involved in acetylcholine synthesis. Confirming a previous report, tyrosine hydroxylase activity increased in failing myopathic hearts and norepinephrine concentration decreased. Extending previous work, tyrosine hydroxylase and dopamine-beta-hydroxylase activities in myopathic hearts demonstrated progressive, age-related increases. These changes were associated with reduced choline acetyltransferase activity in hearts of older myopathic hamsters (180 to 300-plus days). Decreases tended to be more pronounced in hamsters with cardiac hypertrophy and fluid retention (290-360 days old). Neurochemical evidence of increased sympathetic indices (dopamine-beta-hydroxylase activity) was detected at 30 days of age. Evidence of decreased parasympathetic indices (choline acetyltransferase activity) was detected at 180 days of age and persisted through terminal phases of heart failure. This study demonstrated that there are abnormalities in cardiac parasympathetic as well as cardiac sympathetic indices in myopathic hamsters.

Structure activity relationships of presynaptic dopamine receptor agonists

Structure activity relationship (SAR) studies have identified many structural entities that interact with dopamine receptors. The aminotetralin structure may be regarded as an active moiety of apomorphine. An unanswered question concerns the SAR of the 4,7-dimethoxy indane derivatives. These agents do not appear to match well with models of dopamine receptors. At least there can be little doubt that SAR research has been a powerful stimulus during the past decade for understanding the function, distribution, and spatial aspects of dopamine receptors.

Opiate receptor ontogeny and morphine-induced effects: influence of chronic footshock stress in preweanling rats

The ontogeny of opiate receptors was examined in various CNS regions of preweanling rats which received either daily inescapable footshock stress, exposure to a footshock apparatus without shock, or no handling from birth to 21 days of age. At 21 days of age, each of these treatment groups was also assessed for morphine-induced changes in activity, hot-plate paw-lick latency, and core body temperature. Marked regional differences in [3H]naloxone binding capacity were observed from 7 to 21 days of age in spinal cord, medulla-pons, midbrain, hypothalamus, striatum, and cortex. Caudal regions approached adult-like [3H]naloxone binding before rostral regions. The normal ontogeny of opiate receptors was not significantly influenced by the chronic footshock treatment. However, footshock treatment significantly reduced the efficacy of morphine (2 mg/kg) in producing hypoactive and antinociceptive effects, but not in producing a hyperthermic effect. These results demonstrate that stress-related changes in the behavioral efficacy of morphine do not necessarily depend upon changes in those opiate receptor populations that bind naloxone.

Dopamine receptor stimulating activity of 5-hydroxy-6-methyl-2-aminotetralin derivatives

The effects of 5-hydroxy-6-methyl-2-aminotetralins were evaluated for central and presynaptic peripheral dopaminergic activity. Di-ethyl (DK-121) and di-propyl (DK-118) derivatives inhibited the tachycardia produced by postganglionic cardioaccelerator nerve stimulation in the cat. This effect was blocked by haloperidol (100 micrograms/kg). DK-118 inhibited stimulation-induced contraction of the cat nictitating membrane. The pressor response produced by lumbar sympathetic chain stimulation in the isolated hindlimb of the cat was inhibited by DK-118 following intravenous administration. Reflex sympathetic activation produced by 30 sec bilateral carotid occlusion was also inhibited by DK-118 in the dog. Centrally, DK-118 caused contralateral circling behavior in rats who had unilateral lesions of the caudate nucleus. DK-118 did not effect DOPA levels in either the caudate nucleus or olfactory tubercle. In contrast, DK-121 decreased DOPA levels in the caudate nucleus but did not produce circling behavior in rats. Both compounds have weak emetic activity in dogs. These results suggest that DK-121 and DK-118 possess stimulant properties on dopaminergic receptors in the central and peripheral nervous system. However, DK-121 does not appear to stimulate postsynaptic dopamine receptors in the central nervous system.

Regenerative critical periods for locus coeruleus in postnatal rat pups following intracisternal 6-hydroxydopamine: a model of noradrenergic development

Rat pups were injected intracisternally with 20, 40 or 80 microgram of 6-hydroxydopamine (6-OHDA) at various ages over the first 12 postnatal days in order to determine the critical period of the noradrenergic regenerative-sprouting response in the cerebellum. Twenty-four hours after the treatment NE fibers in the cerebellum had become extensively degenerated. NE levels were reduced by greater than 90-95% and histofluorescence microscopy revealed an absence of innervation except for lesioned axon stumps in the basal white matter and peduncles. The 80 microgram dose produced considerable cellular degeneration in the locus coeruleus and no regenerative growth was seen to follow this treatment. Following the two lower doses, however, regenerative growth did occur. This was maximal in those rats treated closest to birth and declined progressively to become insignificant in rats which were treated on postnatal days 5-12, depending upon the cerebellar subregion. This decline in regenerative potential paralleled the time course for development of NE levels in control cerebella. For this reason the mechanism(s) controlling noradrenergic developmental and regenerative growth in the cerebellum appear to be similar. Such regenerative growth may thus be a useful model for the study of developmental growth of locus coeruleus axons. Contrary to the cerebellar projection, regenerative growth of the forebrain noradrenergic projection was not detected until the rats were between 7 and 12 days old at the time of treatment. This regeneration in the cerebral cortex was preceded by incomplete initial destruction of NE fibers there, in apparent similarity to regenerative growth described to occur in the adult rat forebrain.

Uterine catecholamines and prostaglandins during the estrous cycle of the rat

The uterine contents of norepinephrine, epinephrine, dopamine, and prostaglandins F and E were determined on each day of the rat estrous cycle. Catecholamines were determined by high performance liquid chromatography with electrochemical detection (HPLC-EC) as well as by a radioenzymatic technique; prostaglandins were quantitated by RIA. The norepinephrine and dopamine values obtained by the radioenzymatic assay were approximately 1.5 times as high as the values obtained by HPLC-EC (norepinephrine, 285 vs. 188 ng/g; dopamine, 11.0 vs. 7.5 ng/g). Despite this difference in levels, both analytic techniques showed a decline in uterine norepinephrine from diestrus to estrus, followed by a significant (P less than 0.01) increase in norepinephrine on the day of metestrus. A cyclic pattern was also revealed for uterine dopamine concentration. There was a decline in dopamine concentration from diestrus to proestrus (radioenzymatic, P less than 0.01), followed by a return to high levels at metestrus (HPLC-EC). Epinephrine levels were low (undetectable by radioenzymatic assay; 24 ng/g by HPLC-EC) and showed no variation during the estrous cycle. Prostaglandin F was uniformly higher than prostaglandin E (10 vs. 2.5 ng/uterus). Significant increases in the uterine contents of both prostaglandins were shown on the day of proestrus.

Intracisternal dose-response analysis of 6-hydroxydopamine-induced noradrenergic sprouting in the neonatal rat cerebellum

The dose-response relationship between neonatal 6-hydroxydopamine and noradrenergic regenerative sprouting in the cerebellum was characterized by using intracisternal doses of 10 to 80 micrograms of the drug. Noradrenergic regeneration was assessed in seven subregions of the cerebellum by measurement of norepinephrine (NE) levels once the rats were one-month-old. Regenerative sprouting occurred to a significant extent at drug doses between 10 to 40 micrograms, with peak NE elevations occurring after a 20-microgram dose. Recovery of NE was not uniform throughout the cerebellum but was maximal in the anterior vermis and minimal in the posterior vermis. An 80-microgram dose produced near total loss of cerebellar NE. This is contrasted to the cerebral cortical noradrenergic innervation which responded with significant long-term degeneration to a dose as low as 10 micrograms. In both areas, the initial effect of the drug treatment was to reduce NE levels by 95% or more. A couple of conclusions can be made. The magnitude of the difference between the cerebellar and cerebral cortical dose-response relationships is consistent with a regenerative mechanism subserving the recovery of NE in the cerebellum. Secondly, the increase of NE in the cerebellum is reciprocally related to destruction of the forebrain noradrenergic projection.

Distribution of hypertrophied locus coeruleus projection to adult cerebellum after neonatal 6-hydroxydopamine

Following treatment as neonates with a high subcutaneous dose of 6-hydroxydopamine (6-OHDA), the projections of the locus coeruleus were mapped in the brains of adult rats. This was done using the technique of unilateral lesions in the nucleus followed by simultaneous determinations of norepinephrine (NE) levels, dopamine-beta-hydroxylase (DBH) activity and synaptosomal [3H]NE uptake in various terminal areas. In particular the cerebellum was subdivided into 3 areas in order to assess any changes from normal in the distribution of the hypertrophied noradrenergic projections here. In vehicle-control rats the lesions resulted in an 80--85% loss of NE in the parietal cortex ipsilateral to the lesion and a 15--20% loss contralaterally. In the control cerebellum the locus coeruleus projection, based upon changes in all 3 markers, is distributed 2/3 ipsilaterally and 1/3 contralaterally with the same pattern present in all 3 subregions. The neonatal 6-OHDA treatment resulted in virtually complete loss of noradrenergic terminals in the cerebral cortex. Following neonatal 6-OHDA treatment cerebellar levels of NE, DBH and [3H]NE uptake increased by between 20--60%, with the smallest increases occurring in [3H]NE uptake. In these rats the locus coeruleus accounted for at least 75--80% of the cerebellar noradrenergic parameters. Unlike control rats however, the lesions in these rats produced only ipsilateral decreases in NE and DBH. On the other hand changes in [3H]NE uptake indicated a normal 2/3 ipsilateral, 1/3 contralateral pattern. It is suggested that two separable events occur in the noradrenergic projection to the cerebellum. The first is the regeneration of an increased number of nerve terminals, or sprouting, and the second is a build-up of synaptic vesicles, or collateral accumulation. The sprouting, judging from the [3H]NE uptake data, occurs with apparently normal distribution, but the accumulation of NE and DBH is confined predominantly to the ipsilaterally projecting axon terminals. This may be the consequence of collateral accumulation resulting from the degeneration of the largely ipsilateral coeruleocortical projection.

Humoral regulation of vascular resistance after 30 days of pulmonary artery constriction

In an earlier study of guinea pigs with constriction of the pulmonary artery (PA) for 30 days, hindquarters' vascular resistance was maintained primarily by humoral mechanisms. In the present study, we investigated the contribution of circulating catecholamines, angiotensin II, and other constrictor stimuli to hindquarters' vascular resistance by observing vasodilator responses to specific competitive antagonists. Pressure-flow curves indicated vascular resistances in isolated, perfused, sympathectomized hindquarters of anesthetized guinea pigs. Phentolamine produced significantly greater (P less than 0.05) vasodilatation in animals with constriction of pulmonary artery than in sham animals [Sar1-Ala8]angiotensin II produced no vasodilation in either group. After alpha-adrenergic blockade, papaverine produced similar vasodilatation and similar final perfusion pressures in both groups. It appears that circulating catecholamines and augmented vasoconstrictor responsiveness to norepinephrine are totally responsible for the increased humoral regulation of vascular resistance in this experimental model of right ventricular hypertrophy.

Regional development of norepinephrine, dopamine-beta-hydroxylase and tyrosine hydroxylase in the rat brain subsequent to neonatal treatment with subcutaneous 6-hydroxydopamine

Neonatal rats were injected subcutaneously with 100 mg/kg 6-hydroxydopamine (6-OHDA), or vehicle, on postnatal days 1, 2 and 3. At several times thereafter, determinations of tyrosine hydroxylase (TOH) and dopamine-beta-hydroxylase (DBH) activities, and norepinephrine (NE) concentration were made in the parietal cortex, cerebellum and pons-medulla in order to assess the extent of initial noradrenergic degeneration induced, and the rate of any ensuing regeneration. By the day following completion of the treatment (postnatal day 4), degeneration of noradrenergic terminals in the parietal cortex and cerebellum was very extensive, with NE levels and DBH activities reduced by more than 80%, and TOH activities reduced by 50%. In the parietal cortex noradrenergic degeneration remained virtually complete; and 9 and 70 days postnatal NE concentration and DBH and TOH activities were all decreased by more than 90--95%. In the cerebellum a progressive regeneration and apparent sprouting of NE fibers was observed. By postnatal day 9, NE, DBH and TOH in this tissue had all recovered to near control levels, and by day 70 these measures exceeded control levels by 95%, 115% and 50% respectively. In the pons-medulla, the initial effect of 6-OHDA on any of the measured parameters was negligible. By postnatal day 9 an increase in NE concentration was apparent, which increased further by day 70 to surpass the control level by 70%. At this same time DBH activity was increased by only 15% and TOH activity was unchanged. Separate analysis of the rostral half of the pons, which contains the locus coeruleus, revealed that on day 70 NE and DBH levels were increased much more substantially than in the whole pons-medulla, and TOH activity was also significantly elevated. This data indicates that the initial amount of degeneration induced by the 6-OHDA treatment is similar in both the parietal cortex and cerebellum, but regeneration proceeds only in the cerebellum. This suggests that noradrenergic fiber growth and regeneration in each target tissue is under independent regulation, possibly by the individual target neurons themselves.

Assessment of the effects of neonatal subcutaneous 6-hydroxydopamine on noradrenergic and dopaminergic innervation of the cerebral cortex

Female rats, treated at birth with 6-hydroxydopamine (3 x 100 mg/kg s.c. at 24 h intervals) or vehicle, were subjected at 112 days of age to unilateral electrolytic lesions of the locus coeruleus. Two weeks later regions of the telencephalon, both ipsi- and contralateral to the lesion, were simultaneously assayed for norepinephrine (NE) and dopamine (DA) content, and for tyrosine hydroxylase (TOH) and dopamine-beta-hydroxylase (DBH) activities. In the vehicle-treated rats the lesion resulted in at least an 80% reduction of NE and DBH on the ipsilateral side, relative to the contralateral side. TOH was reduced to a similar extent only in the parietal cortex and hippocampus. In the prefrontal cortex and cingulate gyrus TOH was decreased by only 31% and 64% respectively; the remainder was interpreted to be associated with projections of the mesocortical dopamine system. From this data it was possible to calculate that the ratio of TOH to DA in dopaminergic terminals is about 10-fold greater than the ratio of TOH to NE in noradrenergic terminals. Neonatal 6-hydroxydopamine treatment resulted in practically total elimination of noradrenergic terminals throughout the telencephalon, and the locus coeruleus lesion had no additional effect. The drug treatment produced no significant change in DA content or in the TOH to DA ratio in the prefrontal cortex and cingulate gyrus, indicating complete sparing of the mesocortical DA projections.

The effects of subhypnotic doses of ethanol on regional catecholamine turnover

A 2 g/kg dose of ethanol given intraperitoneally to rats significantly reduced the turnover of dopamine in the substantia nigra and caudate nucleus, increased dopamine turnover in the olfactory tubercle and had no effect on dopamine turnover in the nucleus accumbens, amygdala and hypothalamus. The same dose of ethanol decreased the probenecid-induced homovanillic acid accumulation in the caudate nucleus. The turnover of norepinephrine was also decreased in hypothalamus and increased in the pons medulla region. No change in norepinephrine turnover was observed in frontal cortex, parietal cortex, cerebellum, amygdala, hippocampus and locus ceruleus region. The distribution of ethanol was similar in cortex, caudate nucleus, hypothalamus and pons-medulla. Catecholamine turnover in different brain regions seems to be differentially sensitive to the effects of ethanol, with most regions being unaffected by ethanol.

Histochemical and biochemical characterization of the rat paracervical ganglion

The nature and identity of the catecholamines in the paracervical ganglion and superior cervical ganglion small, intensely fluorescent (SIF) cells were investigated using fluorescence histochemical and immunohistochemical techniques. The paracervical ganglion SIF cells were found to contain norepinephrine and the superior cervical ganglion SIF cells, dopamine. The norepinephrine content of the paracervical ganglion SIF cells averaged about 72 ng/ganglion and did not change during the rat estrus cycle. The activity of the enzyme tyrosine hydroxylase in the PCG was very low (about 0.48 nmoles DOPA formed/h/mg protein) and was about 1/50th of the activity of the enzyme in the SCG, where it averaged about 23.90 nmoles DOPA formed/h/mg protein. These experiments suggested that the paracervical ganglion has large numbers of norepinephrine containing SIF cells with a relatively slow turnover of their catecholamine content.

Differentiation between stains of human blood and blood of monkey

The precipitin tube test fails to differentiate between blood stains of closely related animals such as man and monkey because of the close similarity between antigenic determinants of serum proteins of such closely related species. The quantitative precipitin technique cannot be applied to forensic work. This paper cites a case where definite opinion on the species of origin of some blood stains suspected to have come from a monkey was possible. In the method used, extracts of the questioned stain were tested with similar extracts of known human and known monkey blood stains against human globulin antiserum, by comparative double diffusion method in agar gel on microslides.

Dopaminergic nature of amphetamine-induced pecking in pigeons

d-Amphetamine was found to induce a pecking response in pigeons. The pecking response induced by d-amphetamine was antagonized by chlorpromazine, haloperidol or bulbocapnine indicating that this pecking response was caused by dopaminergic receptor stimulation. Pretreatment of pigeons with alpha-methyltyrosine (alpha-MT) reduced d-amphetamine-induced pecking, while the combined treatment of pigeons with alpha-MT and L-dihydroxyphenylalanine (L-DOPA, 100 mg/kg) partially restored the pecking response. d-Amphetamine-induced pecking was not reduced by a dopamine-beta-hydroxylase inhibitor, 1-phenyl-3-(2-thiazolyl)-2-thiourea (U-14,624). Alpha-MT reduced brain dopamine but not norepinephrine level, whereas U-14,624 decreased brain norepinephrine but not dopamine. Thus there is a correlation between brain dopamine level and d-amphetamine-induced pecking response. It is concluded that d-amphetamine-induced pecking is mediated indirectly by the release of dopamine.

In vitro synthesis of noradrenaline in ganglia and salivary glands after in vivo preganglionic stimulation

The extent of synthesis of [14C]noradrenaline from [14C]tyrosine and from [14C]dopamine was assessed in slices of superior cervical ganglia, representing cell bodies, and in submaxillary salivary glands, representing terminals of noradrenergic neurons of the cat. Immediately and 6 h after preganglionic stimulation for 3 h the rate of synthesis of noradrenaline from tyrosine and dopamine was not altered in ganglia. In salivary glands, however, synthesis of noradrenaline from both tyrosine and dopamine was increased at both times. These results suggest that acute periods of increased neural activity results in the acceleration of noradrenaline synthesis in the terminals but not in the cell bodies of noradrenergic neurons.