PubMed Health⌕ Search

Biomedical subjects

R B Mailman

Publications and source records attributed to R B Mailman.

At least 19 recordsLinked to original sources
PubMed1992

Dihydrexidine, a novel full efficacy D1 dopamine receptor agonist.

The present work provides a detailed pharmacological characterization of dihydrexidine (DHX) (trans-10,11-dihydroxy- 5,6,6a,7,8,12b-hexahydrobenzo[a]phenanthridine), the first high-potency, full efficacy, bioavailable D1 dopamine receptor agonist. DHX represents a new conformationally rigid structural class of dopamine receptor ligands. It competes stereoselectively and potently for D1 binding sites in rat striatal membranes labeled with [3H]SCH23390 with an IC50 of about 10 nM compared to about 30 nM for the prototypical D1 agonist SKF38393. Like other dopamine agonists, DHX has a shallow competition curve (nH = ca. 0.7) that can be fitted by a two-site model consisting of high-affinity (63%; KD = 3 nM) and low-affinity (37%; KD = 75 nM) sites. DHX was screened for activity against 40 other binding sites, and was inactive (IC50 greater than 10 microM) against all except D2 dopamine receptors (IC50 = 130 nM) and alpha 2 adrenoreceptors (IC50 = ca. 230 nM). Functionally, DHX is a full efficacy dopamine D1 agonist. In homogenates of rat striatum, DHX or dopamine doubles the rate of cyclic AMP synthesis, whereas SKF38393 only causes a maximal increase of about 50%. These effects of DHX are blocked by the selective D1 antagonist SCH23390, but are not affected by D2, 5-hydroxytryptamine2, muscarinic, or alpha or beta adrenergic antagonists. Because DHX is known to cause D2-like behavioral effects at high doses, the nature of its D2 activity was characterized using prolactin release as an end-point. DHX and the prototypical D2 agonist quinpirole both caused a significant inhibition of the prolactin release induced by 5-hydroxytryptophan. These effects of DHX are not due to "indirect" alterations at the presynaptic terminal, because DHX is essentially inactive at inhibiting the dopamine uptake system, and does not cause the release of dopamine. These data demonstrate the utility of DHX for probing the biochemistry and function of D1 dopamine receptors.

Adenylyl Cyclases↗
PubMed1991

Dopamine receptor 'supersensitivity' occurring without receptor up-regulation.

Unilateral 6-hydroxydopamine (6-OHDA)-induced lesions of the substantia nigra have been widely used to study various aspects of dopamine neurobiology, and to screen for antiparkinsonian drugs. This study examined the role of receptor alterations in the pharmacological supersensitivity seen in response to lesioning of central dopamine pathways in rats by intracisternal (IC) administration of 6-OHDA (200 micrograms), as well as by bilateral (BIL) or unilateral (UNI) infusion of 6-OHDA into the substantia nigra (8 micrograms/side). Both IC and BIL lesions resulted in permanent decreases in dopamine concentration in the striatum, the major terminal projection from the substantia nigra. When challenged with apomorphine (0.3 mg/kg), IC-lesioned rats exhibited bursts of rapid locomotion interspersed by rearing, whereas BIL-lesioned rats displayed intense grooming or gnawing and nose poking of the cage floor; these behaviors were not seen in respective sham (i.e. vehicle)-lesioned rats injected with apomorphine. Scatchard analysis of saturation isotherms of both D1 [( 3H]SCH23390 binding sites) and D2 [( 3H]spiperone binding sites) dopamine receptors in the striatum revealed no difference in either the maximum number of binding sites (Bmax), or the dissociation constant (Kd) of either receptor type when BIL and IC lesioned rats were compared to appropriate controls. Conversely, the UNI lesioned rats had, under identical conditions of analysis, the expected increase in the density of D2 receptors on the lesioned side. There was no change in dopamine-sensitive adenylate cyclase activity in the striata of supersensitive IC-lesioned rats, but there was a shift to the left in the dose-response curve in striata from rats bilaterally-lesioned in the substantia nigra, similar to what occurs in UNI lesioned rats. Together, these data clearly demonstrate that although increases in receptor density and changes in cAMP systems are seen in the UNI model, neither mechanism is a requirement for functional supersensitivity in response to 6-OHDA lesions. These data suggest that other cellular events (e.g. alterations in receptor interactions) may play a role in the response to insult, and raise questions about the utility of the unilateral model as a screen for antiparkinsonian drugs.

Adenylyl Cyclases↗
PubMed1991

Guanine nucleotide binding proteins and the regulation of cyclic AMP synthesis in NS20Y neuroblastoma cells: role of D1 dopamine and muscarinic receptors.

D1 dopamine receptors on NS20Y neuroblastoma cells stimulate adenylate cyclase activity, whereas muscarinic receptors on the same cells negatively regulate adenylate cyclase. To determine the mechanisms which underlie these processes, cyclic AMP accumulation was measured in intact cells following either cholera or pertussis toxin treatment. Pretreatment with pertussis toxin (100 ng/ml), which ribosylated greater than 95% of inhibitory quinine nucleotide binding protein (Gi), caused the complete loss of muscarinic induced inhibition. Conversely, pertussis toxin did not affect the ability of dihydrexidine (1 microM, a full efficacy D1 agonist), PGE1 (100 nM), or forskolin (1 microM, a direct activator) to stimulate cAMP accumulation. Both the dihydrexidine-induced stimulation and the carbachol-induced inhibition of cyclic AMP accumulation were unaffected by either removal of extracellular calcium, or increased intracellular calcium caused by the addition of the calcium ionophore A23187. Cholera toxin dose- and time-dependently induced large accumulations of cAMP. At low cholera toxin concentrations, the effects of dihydrexidine (300 nM) were additive with those of cholera toxin. At cholera toxin concentrations greater than 100 ng/ml, dihydrexidine became ineffective in stimulating further cAMP synthesis. Conversely, forskolin (1 microM) still caused marked increases in cAMP accumulation after all cholera toxin treatments. Dihydrexidine-stimulated cAMP accumulation was additive with forskolin-stimulated cAMP accumulation at low forskolin concentrations (10 nM-3 microM), but synergistic at high concentrations (3-100 microM). Additionally, forskolin was much more potent after cholera toxin treatment, suggesting that an activated stimulatory guanine nucleotide binding protein (Gs) may be required for full activation of adenylate cyclase by forskolin in this cell type.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylate Cyclase Toxin↗
PubMed1991

Synthesis and in vitro evaluation of 2,3-dimethoxy-5-(fluoroalkyl)-substituted benzamides: high-affinity ligands for CNS dopamine D2 receptors.

A number of 2,3-dimethoxy-5-(fluoroalkyl)-N-[(1-ethyl-2- pyrrolidinyl)methyl]benzamides (with or without a 6-hydroxy group) were synthesized and evaluated as dopamine D2 receptor ligands. The parent acids were synthesized via the Claisen rearrangement of the appropriate O-allyl ethers, which were derived from o-vanillic acid or 2,3-dimethoxysalicylic acid. A decrease in reactivity was found to be characteristic of pentasubstituted benzoates, and difficulties were encountered with the introduction of fluorine onto the ethyl side chains. The (fluoroethyl)- and (fluoropropyl)salicylamides were 5 times more potent than the corresponding benzamides in inhibiting [3H]spiperone binding to the D2 receptor. These (fluoroalkyl)salicylamides are of potential value for in vivo positron emission tomography (PET) studies upon the basis of their relatively selective, high potency binding affinity for the D2 receptor.

Animals↗
PubMed1991

Neurochemical and immunocytochemical studies of catecholamine system in the brindled mouse.

The distribution of immunoreactive catecholamine neurons and fibers was investigated in brindled mottled mouse, a murine model of Kinky hair syndrome (KHS), using antisera against tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH). In all mice, including normal littermate controls, a transient increase of TH-immunoreactive neurons (TH-IN) was observed in the cerebral cortex during the second postnatal week. The numbers of TH-IN were more pronounced in hemizygous brindled males (MObr/y). In addition, TH-IN appeared and rapidly increased in number in the striatum of MObr/y after postnatal day 11 (P11). Striatal TH-IN were rarely detected in controls. After cupric chloride (CuCl2) treatment, TH-IN in the striatum of some of the MObr/y mice became less conspicuous. In the substantia nigra and ventral tegmental area where TH-IN are normally present, no differences either in the immunostaining of TH-IN or the pattern of TH immunoreactive fibers were detected between MObr/y and controls. In MObr/y, a superficial plexus of DBH immunoreactive fibers was more pronounced than in controls but there were no DBH immunoreactive neurons in the cerebral cortex or striatum in any of the mice examined. Neurochemical analysis revealed a marked decrease in norepinephrine levels and increase of serotonin and its metabolites in the brain in MObr/y. Together, these data suggest that the unusual expression of TH-IN in MObr/y represents perturbations of normal development of catecholamine neurons in this copper deficient mutant mouse.

Animals↗
PubMed1991

D1 dopamine receptors of NS20Y neuroblastoma cells are functionally similar to rat striatal D1 receptors.

Dopamine or agonists with D1 receptor potency stimulated cyclic AMP (cAMP) accumulation in whole cell preparations of NS20Y neuroblastoma cells. The accumulation of cAMP after D1 stimulation was rapid and linear for 3 min. Both dopamine and the novel D1 receptor agonist dihydrexidine stimulated cAMP accumulation two- to three-fold over baseline. The pseudo-Km for dopamine was approximately 2 microM, whereas for dihydrexidine it was approximately 30 nM. The effects of both drugs were blocked by either the D1-selective antagonist SCH23390 (Ki, 0.3 nM) or the nonselective antagonist (+)-butaclamol (Ki, 5 nM). Both (-)-butaclamol and the D2-selective antagonist (-)-sulpiride were ineffective (Ki greater than 3 microM). Forskolin (10 microM), prostaglandin E1 (1 microM), and adenosine (10 microM) also stimulated cAMP accumulation, but none were antagonized by SCH23390 (1 microM). Finally, muscarinic receptor stimulation (100 microM carbachol) inhibited both D1- and forskolin-stimulated increases in cAMP accumulation by 80%. The present results indicate that NS20Y neuroblastoma cells have D1 receptors that are coupled to adenylate cyclase, and that these receptors have a pharmacological profile similar to that of the D1 receptor(s) found in rat striatum.

Benzazepines↗
PubMed1991

The female brindled mouse as a model of Menkes' disease: the relationship of fur pattern to behavioral and neurochemical abnormalities.

The brindled mottled mutant mouse, a model of Menkes' disease, has alterations in copper homeostasis which cause, among other sequelae, neuronal degeneration in selected areas of brain. This work examined the neurochemical changes at postnatal days (PND) 15, 30 and 60 in females heterozygous for the sex-linked brindled mutation. These data were compared to behavioral alterations and to fur coat color at these same time points. The brindled heterozygotic females had lower concentrations of norepinephrine (NE) in the cingulate cortex, and higher levels of dopamine or dopamine metabolites in the cingulate cortex, thalamus and hypothalamus across all ages, although the difference was greatest at PND 15. The brindled females were much less active than their normal littermates at PND 15, but the differences were no longer evident at PND 30 and 60. Mottling of the fur is believed to result from low tyrosinase activity caused by abnormalities in copper metabolism. The fur pattern and behavior of the brindled mice were highly correlated with NE levels in the cingulate cortex and thalamus. These data show that female brindled mice have neurochemical abnormalities similar to (if less severe than) the male hemizygotes, that these abnormalities are regionally specific, are most apparent prior to 30 days of age, and are linked to behavioral deficits. These data also show that the extent of such deficits can be predicted by a quantitative analysis of the fur pattern of these females.

Age Factors↗
PubMed1991

D1 and D2 dopamine receptors independently regulate spontaneous blink rate in the vervet monkey.

Previous studies have revealed the involvement of a dopaminergic link in the regulation of spontaneous eye blink rate in primates. Based on the effect of dopamine D2 receptor-selective drugs and the anecdotal failure of the partial D1 agonist, SKF 38393, to alter blink rate in monkeys, it was assumed that D1 dopamine receptors did not control blink rate. The recent availability of dihydrexidine, a full D1 agonist, prompted us to reevaluate the role of D1 and D2 receptors in the regulation of blink rate. African green monkeys (n = 5) were used in all studies. Dihydrexidine produced a rapid and dose-dependent (up to 1 mg/kg, i.m.) increase in blink rate. The elevation in blink rate elicited by 0.3 mg/kg dihydrexidine was completely reversed by prior administration of a specific D1 antagonist, SCH 23390 (0.01 mg/kg, i.m.), but was unaffected by prior administration of a specific D2 antagonist, remoxipride (1 mg/kg, i.m.). Treatment with the specific D2 agonist, (+)-4-propyl-9-hydroxynaphthoxazine, led to a rapid and dose-dependent (up to 0.01 mg/kg, i.m.) increase in blink rate. The raised blink rate produced by (+)-4-propyl-9-hydroxynaphthoxazine (0.001 mg/kg) was abolished by pretreatment with remoxipride, but was not influenced by pretreatment with SCH 23390. These data indicate that spontaneous blink rate in the primate can be regulated by both D1 and D2 dopamine receptors. Furthermore, the receptor subtypes appear to affect blink rate in the same direction, yet function independently. Measurement of blink rate may provide a noninvasive method to assess the potency and selectivity of dopamine agonists and antagonists in primates.

Animals↗
PubMed1991

Behavioral effects in the rat of dihydrexidine, a high-potency, full-efficacy D1 dopamine receptor agonist.

Dihydrexidine (trans-10,11-dihydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a]phena nthridine) was reported recently to be the first full efficacy, potent D1 receptor agonist, but one also having some potency for D2 receptors. This study reports the effects of dihydrexidine on behavior of the rat. In study 1, the dose-response relationships of dihydrexidine (0.3 to 30 mg/kg) to various behaviors were assessed using direct observations. The frequency of three behaviors (grooming, sniffing, and locomotion) was significantly increased by this drug. The dose-response curve for drug-induced grooming approximated an inverted U shape. Dihydrexidine increased locomotion at two of the higher doses (3 and 30 mg/kg), and increased sniffing at doses greater than or equal to 1.0 mg/kg. Other behavioral topographies, such as licking, gnawing, and rearing, were not systematically affected by drug administration. Also, there was no indication of convulsion in any dihydrexidine-treated rat. In study 2, rats were pretreated with either the selective D1 antagonist SCH23390 or the selective D2 antagonist remoxipride prior to receiving dihydrexidine. SCH23390 antagonized the effects of dihydrexidine on grooming, locomotion, and sniffing. Conversely, remoxipride blocked dihydrexidine-induced locomotion, but had no effect on dihydrexidine-induced grooming or sniffing. Numerous behaviors are believed to be mediated by the interactions of D1 and D2 receptors. These data indicate that dihydrexidine can be an important tool for characterizing both the behavioral actions of D1 receptors, and the nature of D1/D2 interactions in mammalian brain. In addition, its high potency and full efficacy at D1 receptors, coupled with its significant D2 properties, may provide specific utility in certain clinical situations.

Animals↗
PubMed1990

Long-term effects of early social isolation in Macaca mulatta: changes in dopamine receptor function following apomorphine challenge.

The hypothesis that early social isolation results in long-term alterations in dopamine receptor sensitivity was tested using older adult rhesus monkeys. Isolated and control monkeys were challenged with apomorphine (0.1 and 0.3 mg/kg), and the drug effects on spontaneous blink rate, stereotyped behavior, and self-injurious behavior were quantified using observational measures. Monoamine metabolites were quantified from cisternal CSF by HPLC-EC, prior to pharmacological challenge. Isolated and control monkeys did not differ in CSF concentrations of HVA, 5-HIAA, or MHPG. At the higher dose, apomorphine significantly increased the rate of blinking, the occurrence of whole-body stereotypies, and the intensity of stereotyped behavior (as measured by observer ratings) in isolated monkeys. The frequency of occurrence of self-injurious behavior was too low to allow for meaningful comparisons. These significant differences in response to apomorphine challenge support the hypothesis that long-term or permanent alterations in dopamine receptor sensitivity, as assessed by drug challenge, are a consequence of early social deprivation.

Animals↗
PubMed1990

Triadimefon, a triazole fungicide, induces stereotyped behavior and alters monoamine metabolism in rats.

Triadimefon, a triazole fungicide, has been observed to increase locomotion and induce stereotyped behavior in rodents. The present experiments designed to characterize the stereotyped behavior induced by triadimefon used a computer-supported observational method, and tested the hypothesis that these observed effects involved central dopaminergic systems. Adult male and female Sprague-Dawley rats were injected with triadimefon (0, 50, 100, and 200 mg/kg) in corn oil (2 ml/kg ip) 4 hr prior to behavioral assessment. The two lowest doses of triadimefon increased the frequency of locomotion and rearing, while the highest dose induced highly stereotyped behaviors, including backward locomotion, circling, and head weaving. Immediately after behavioral testing, the rats were sacrificed, and the striata and olfactory tubercles, terminal fields of the nigrostriatal and mesolimbic dopamine systems, respectively, were removed. Steady-state concentrations of the monoamines dopamine and serotonin and their metabolites were determined by HPLC-EC. In independent experiments, the direct effects of triadimefon on dopamine (D1 and D2) receptor binding and dopamine-sensitive adenylate cyclase activity were assessed in vitro using rat striata. Dopamine concentrations were increased in olfactory tubercles, but decreased in striatum. Concentrations of 5-hydroxyindoleacetic acid (the major metabolite of serotonin) were increased only in striatum, and only in animals treated with 200 mg/kg triadimefon. In vitro, triadimefon neither competed with D1 or D2 dopaminergic radioligands nor affected dopamine-stimulated adenylate cyclase activity. Together these behavioral and biochemical data lend support to the hypothesis that triadimefon may have actions similar to those produced by indirect-acting dopamine agonists.

Adenylyl Cyclases↗
PubMed1990

trans-10,11-dihydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a]phenanthridine: a highly potent selective dopamine D1 full agonist.

trans-10,11-Dihydroxy-5,6,6a,7,8,12b-hexahydrobenzo[a]phenan thridine (4a, dihydrexidine) has been found to be a highly potent and selective agonist of the dopamine D1 receptor in rat brain. Dihydrexidine had an EC50 of approximately 70 nM in activating dopamine-sensitive rat striatal adenylate cyclase and a maximal stimulation equal to or slightly greater than that produced by dopamine. Dihydrexidine had an IC50 of 12 nM in competing for [3H]SCH23390 (1a) binding sites in rat striatal homogenate, and of 120 nM versus [3H]spiperone. These data demonstrate that dihydroxidine has about ten-fold selectivity for D1/D2 receptors. More importantly, however, is the fact that dihydrexidine is a full agonist. Previously available agents, such as SKF38393 (1b), while being somewhat more selective for the D1 receptor, are only partial agonists. The isomeric cis-dihydroxybenzo[a]-phenanthridine neither stimulated cAMP synthesis nor inhibited the cAMP synthesis induced by dopamine. The cis isomer also lacked appreciable affinity for [3H]-1a binding sites. N-Methylation of the title compound decreased affinity for D1 sites about 7-8-fold and markedly decreased ability to stimulate adenylate cyclase. Addition of an N-n-propyl group reduced affinity for D1 sites by about 50-fold and essentially abolished the ability to stimulate adenylate cyclase. However, this latter derivative had twice the affinity of the D2-selective agonist quinpirole for the D2 receptor. The results are discussed in the context of a conceptual model for the agonist state of the D1 receptor.

Adenylyl Cyclases↗
PubMed1989

Blockade of only spinal alpha 1 adrenoceptors is insufficient to attenuate DDT-induced alterations in motor function.

Male Fischer 344N rats were chronically implanted with an intrathecal cannula and gavaged with p,p'-DDT (1,1,1-trichloro-2,2-bis[p-chlorophenyl]ethane; 30 or 45 mg/kg) or corn oil. Seven hours later, subjects were intrathecally infused with vehicle, 15, 30, 60, or 120 micrograms of prazosin (an alpha 1-adrenergic antagonist). Spectral analysis of bodily movements was performed 7.5, 8, and 10 hr after DDT administration. In control rats, 15 micrograms of prazosin reduced the spectral profiles of spontaneous movements. A 30-micrograms dose produced motor impairments, without significantly changing the spectral profiles. Tremulous movements induced by DDT were unaffected by 15 or 30 micrograms, whereas 60 or 120 micrograms of intrathecal prazosin significantly reduced the spectral profiles of rats pretreated with 45 mg/kg of DDT. Other subjects were administered vehicle or DDT (45 mg/kg), intrathecally infused with 15 or 60 micrograms of prazosin (7 hr), and sacrificed (7.5 hr). Noncannulated rats were gavaged with 60 mg/kg of DDT, injected subcutaneously (sc) with 0.5 mg/kg of prazosin (5.5 hr), and sacrificed (8 hr). Cortical and spinal tissues were used in ex vivo binding assay utilizing [3H]prazosin. Fifteen or sixty micrograms of intrathecal prazosin occupied similar percentages of spinal [3H]prazosin binding sites, but produced a dose-related increase in cortical prazosin equivalents. Sixty micrograms of intrathecal or 0.5 mg/kg of sc prazosin resulted in similar concentrations of cortical prazosin equivalents. Together, these data indicate that while intrathecal prazosin will attenuate DDT-induced motor dysfunction, this effect requires blockade of alpha 1 adrenoceptors in regions other than solely the spinal cord.

Analysis of Variance↗
PubMed1989

Buffer effects on high affinity [3H]-prazosin binding in brain and spinal cord.

[3H]-Prazosin binding was characterized in cortical and spinal membranes from Fischer 344N and Sprague-Dawley rats. Estimates of Bmax and Kd values were comparable with earlier studies of these regions in the central nervous system (CNS). However, the Kd obtained using Tris buffer system was greater than when HEPES or phosphate buffer was used. These data indicate that high affinity [3H]-prazosin binding in the homogenates of tissue from the CNS is affected critically by buffer selection.

Animals↗
PubMed1989

The effect of 2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide on tissue cholinesterase and carboxylesterase activities of the rat.

The dose-response (0.1 to 1000 mg/kg sc) effects of 2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide (CBDP; a metabolite of the organophosphorus compound tri-o-cresylphosphate) on total cholinesterase (ChE) and carboxylesterase (CaE) activities in tissues from the rat were examined. Doses of CBDP greater than 1.0 mg/kg inhibited CaE activity maximally (greater than 99%) in plasma and lung, two important sites for detoxification of organophosphorus toxicants. A biphasic dose-dependent inhibition of ChE activity was seen in all tissues; the ED50 values showed a difference of two orders of magnitude between the first and the second phases of the dose-response curves. CBDP inhibited the blood esterases in the order plasma CaE much greater than plasma ChE much greater than red blood cell (RBC) ChE. The biphasic dose-response curve and preferential inhibition of the blood esterases may reflect the inhibition of butyrylcholinesterase in preference to acetylcholinesterase in these tissues. At doses of CBDP below 1.0 mg/kg, plasma, RBC, and brain regional ChE activities were inhibited by less than 10%, whereas at doses above 2.0 mg/kg, ChE activities were inhibited substantially (up to 80% in plasma, up to 60% in RBC, and greater than 90% in brain regions). On the basis of these results, a dose of CBDP between 1.0 and 2.0 mg/kg should prove useful as a pretreatment for studies of OP toxicity in the rat.

Animals↗
PubMed1989

Variability in soman toxicity in the rat: correlation with biochemical and behavioral measures.

The inhibition of cholinesterase (ChE) activity in the central nervous system of the rat by the potent organophosphorus compound soman was examined. At soman doses greater than 55 micrograms/kg s.c. (0.5 LD50), there were: (1) dose-related inhibition of ChE activity in brain regions; (2) variability in the degree of ChE inhibition at each soman dose in each brain region; and (3) variability in the severity of signs of intoxication at each dose. These data suggest that measurements of ChE should be made directly or predicted individually in each animal for which the effects of soman are assessed. At the estimated ED50 soman dose for signs of intoxication (66 micrograms/kg s.c.), the remaining ChE activity in brain correlated poorly with ChE activity in plasma and red blood cells (R = 0.14-0.20), moderately with behavioral scores based on overt signs of intoxication (R = 0.63-0.94), and well with spinal cord ChE activity (R = 0.93-0.98). Finally, ChE activity in the thoracic and lumbosacral regions of spinal cord were not affected by headfocused microwave inactivation of brain enzymes, demonstrating that ChE activity in these regions of the cord can be used to predict the level of ChE inhibition in brain when direct measurement in brain is unfeasible.

Animals↗