Lasuna

The LC also receives been questions regarding their efficacy (45) lasuna 60 caps generic. Interestingly buy generic lasuna 60caps line, CRF input from limbic brain regions purchase lasuna 60caps with visa, including the central there is a relatively dense network of substance P immunore- nucleus of the amygdala, as well as the bed nucleus of the active fibers in the human LC and surrounding regions (50). These Many of these fibers may originate from the nucleus of limbic CRF neurons project to the peri-cerulea area, and the solitary tract (50,100,145). In addition, there is a high in particular to the rostrolateral peri-LC. CRF terminals density of binding of radiolabeled substance P to neuroki- form direct contacts with noradrenergic dendrites (176). Substance P potently stimu- CRF, injected intracerebroventrically or directly into the lates the firing of LC neurons (62). There is considerable LC, activates LC neurons and enhances release of NE in evidence that substance P plays a role in the central response projection areas (163). Internal and external stressors are to stress (13,65). Interestingly, substance P antagonists (in known to activate the LC via CRF, including colonic disten- particular, selective neurokinin-1 receptor antagonists), sion, hypotensive challenge, and foot shock. The ability of when administered intracerebroventricularly, attenuate re- these stressors to activate the LC is blocked by CRF antago- straint stress-induced biochemical indices of LC activation nists (32,85,104,174). Repeated administration of rats with antidepressant CRF projections to the LC are thought to coordinate cogni- drugs (perhaps not all types) down-regulates substance P in tive and autonomic responses to internal physiologic chal- several brain regions (27,158). Interestingly, administration of a CRF antagonist respectively (12,155). Substance P-containing serotonergic blocks stress-induced increases in LC tyrosine hydroxylase neurons are not randomly located within the raphe nuclei, (104), an effect shared by antidepressant drugs (105). CRF terminals in raphe nuclei originate from local dorsal raphe nuclei also receive innervation from substance and distant cell bodies (148,151). The effects of CRF on P-containing neurons with cell bodies occurring outside the raphe firing are complex (77). At low doses, CRF produces region of the raphe (92). There is a high density of substance primarily inhibitory effects on raphe discharge. In contrast, P receptors in the region of the dorsal raphe nuclei (91). Likewise, the Substance P appears to activate raphe neurons and microin- 1058 Neuropsychopharmacology: The Fifth Generation of Progress jection of substance P into the dorsal raphe increases hippo- is low in patients with major depression (133–135). Finally, GABA agonists appear to in DA neurons of the human and rat midbrain (188); sub- have some antidepressant activity in humans (135). Infusion of a substance P receptor ago- from the nucleus prepositus, stimulation of which inhibits nist into the VTA stimulates locomotor activity and the firing of LC neurons (44). There are apparently no increases DA turnover in the nucleus accumbens (149), GABA cell bodies intrinsic to the LC, but glutamic acid indicating an excitatory action of substance P on DA neuro- decarboxylase immunoreactive nerve terminals are present, transmission. GABA inhibits the firing of LC neurons primarily by activation of GABAA receptors (123), and these receptors Glutamate have been autoradiographically identified in the LC (29, NMDA receptor antagonists have antidepressant actions in 126). The dorsal raphe nuclei receive GABAergic innerva- animal models of depression (129) and demonstrated anti- tion from local interneurons and from multiple distant depressant effects in humans (20). High levels of serum sources (54,184) and dorsal raphe neurons express GABAA glutamate levels in depressed subject have been reported receptors (53). Iontophoretic application of GABA strongly (2,76) with exception (1). In addition, alterations in the inhibits the firing of dorsal raphe nuclei neurons (52). DA allosterism of NMDA receptor binding in the frontal cortex neurons in the VTA are innervated by GABAergic afferents of suicide victims (115), and elevated levels of CSF gluta- projecting mainly from the forebrain. GABA terminals also mine (glutamate metabolite/precursor) in depressed patients synapse on GABA interneurons that themselves synapse have been reported (88). Such findings have led to specula- onto DA neurons (73). GABA inhibits the activity of DA tion that there may be excessive glutamate neurotransmis- neurons by acting through GABA receptors (GABAB)on sion in depressive disorders. Glu- tamatergic innervation of the LC derives largely from the nucleus paragigantocellularis (9). Glutamate activates the INTEGRATION OF MONOAMINE AND LC through activation of both NDMA and non-NMDA OTHER NEUROTRANSMITTER THEORIES (aspartate) receptors (117). Handling and immobilization stress increases glutamate measured in the rat LC by micro- Investigations of the neurochemical pathology of depressive dialysis (161,170). Interestingly, noise stress-induced en- disorders reveal abnormalities in monoamine systems as well hancement of glutamate release in the LC is abolished by as other neurotransmitter systems. Nevertheless, it is con- superfusion of the LC with a CRF antagonist (160), demon- ceivable that a root cause of depression is a failure or deficit strating an important interaction between CRF and gluta- in a single neurotransmitter system. Because of the intercon- mate systems at the level of the LC (88). It is tempting to nectivity of the monoamine systems, it is likely that failure speculate that a deficit in noradrenergic transmission in in one system to adequately respond to demand would major depression is secondary to a chronic elevation in glu- quickly lead to compensations, or possibly failure, of the tamatergic input into the LC and a resulting depletion of other monoamine systems, as well as changes and/or bio- central NE. At rectly regulated by the pathogenic neurotransmitter system. As is the case for the monoaminergic, as well as nonmonoaminergic, neurotrans- LC, glutamate is excitatory in the raphe nuclei. The activity mitter systems in depression compels us to integrate neuro- of DA neurons in the mesolimbic and mesocortical circuitry transmitter interactions into theoretical models of the neu- can also be modulated by excitatory amino acids (73). This is a difficult neurons in the VTA receive direct glutamatergic innervation undertaking and requires translation and integration of clin- from the prefrontal cortex (73). Glutamate excites DA cell ical, preclinical, and basic research findings. The postulate activity via inotropic and metabotropic receptors (167). That is, depression is associated with reduced GABA function. Petty elevated tyrosine hydroxylase in the LC, as observed in has reviewed this topic (135). To summarize, plasma GABA major depressive suicide victims, can be experimentally pro- Chapter 73: Neurocircuitry of Mood Disorders 1059 duced by pharmacologically depleting NE or chronically in major depression. Plasma and platelet sine hydroxylase in the LC, as can chronic administration excitatory amino acids in psychiatric disorders. Interestingly, CRF is reported to be elevated in 1993;150:1731–1733. Together, these data suggest that elevated CRF in demonstration of increased serotonin 5-HT2 and -adrenergic depression increases demand for NE, probably leading to receptor binding sites in the brain of suicide victims. Quantitative autoradi- also contribute to reduce serotonergic transmission in ography of 1 and 2 adrenergic receptors in the cerebral cortex depression, given the CRF can inhibit dorsal raphe neurons.

Prostaglandin E2 AN P— atrial natrivretic peptide; ET-1— endothelin-1; CGRP— calcitonin gene related Encephalins TNF peptide; RAAS— renin/angiotensin/aldosterone system ; TN F— tum or necrosis factor; Andrenomedullin VIP— vasoactive intestinal peptide buy cheap lasuna 60caps online. Com pared with control subjects (A) cheap lasuna 60caps overnight delivery, patients with cirrhosis (B) have decreased central and increased non- 1 purchase cheapest lasuna. The higher cardiac output (CO ) results from peripheral vasodila- 1. Perfusion of the kidney is reduced significantly in patients with cirrhosis. Com pared with control rats, rats having cir- Cirrhosis & L-name rhosis induced by carbon tetrachloride and phenobarbital exhibited increased plasm a renin activity (PRA) and plasm a arginine vaso- 10 10 pressin (AVP) concentrations. At steady state, the urinary N a excre- tion (UN aV) was sim ilar in both groups. After treatm ent with L- N AM E for 7 days, plasm a renin activity decreased to norm al lev- els, AVP concentrations decreased toward norm al levels, and urinary N a excretion increased by threefold. These changes were 5 5 associated with a norm alization of m ean arterial pressure and car- diac output. A prim ary decrease in system ic + 20 Fluid intake 20 vascular resistance (indicated by dark blue Net volume arrow), induced by m ediators shown in intake 10 10 Figure 2-31, leads to a decrease in arterial Nonrenal fluid loss – pressure. The reduction in system ic vascular + 0 0 resistance, however, is not uniform and 0 10 20 30 favors m ovem ent of blood from the central ECF volume, L (“effective”) circulation into the peripheral + – Rate of change + circulation, as shown in Figure 2-32. Arterial Kidney volume Extracellular of extracellular H ypoalbum inem ia shifts the interstitial to pressure output fluid volume fluid volume blood volum e ratio upward (com pare the + interstitial volum e with norm al [dashed Total peripheral line], and low [solid line], protein levels in Central Peripheral + resistance blood volume blood volume the inset graph). Because cardiac output increases and venous return m ust equal car- + + diac output, dram atic expansion of the + M ean circulatory extracellular fluid (ECF) volum e occurs. Cardiac output Venous return filling pressure M echanisms of Extracellular Fluid Volume Expansion in Nephrotic Syndrome FIGURE 2-35 14 Changes in plasm a protein concentration affect the net oncotic pressure difference across 12 capillaries ( c - i) in hum ans. N ote that m oderate reductions in plasm a protein concen- tration have little effect on differences in transcapillary oncotic pressure. O nly when plas- 10 m a protein concentration decreases below 5 g/dL do changes becom e significant. N ote that urinary N a excretion (squares) increases Plasm a renin activity (PRA) and atrial natriuretic peptide (AN P) before serum album in concentration increases. The data suggest concentration in the nephrotic syndrom e. Shown are PRA and that the natriuresis reflects a change in intrinsic renal N a retention. AN P concentration ( standard error) in norm al persons ingesting The data also em phasize that factors other than hypoalbum inem ia diets high (300 m Eq/d) and low (20 m Eq/d) in sodium (N a) and in m ust contribute to the N a retention that occurs in nephrosis. PRA suppression suggests that prim ary renal N aCl retention plays an im portant role in the pathogenesis of volum e expansion in AGN. Although plasm a renin activity in patients with nephrotic syndrom e is not suppressed to the sam e degree, the absence of PRA elevation in these patients suggests that prim ary renal N a retention plays a significant role in the pathogen- esis of N a retention in N S as well. The glom erular filtration rates (GFR) in norm al and nephrotic rats are shown by the hatched bars. N ote the m odest reduction in GFR in the nephrotic group, a finding that is com m on 60 60 in hum an nephrosis. Fractional reabsorption rates along the proxi- m al tubule, the loop of H enle, and the superficial distal tubule are indicated. The fractional reabsorption along the collecting duct 40 40 (CD) is estim ated from the difference between the end distal and urine deliveries. The data suggest that the predom inant site of 20 20 increased reabsorption is the collecting duct. Because superficial and deep nephrons m ay differ in reabsorptive rates, these data would also be consistent with enhanced reabsorption by deep 0 0 nephrons. Asterisk— data inferred from the difference between dis- GFR Proximal Loop Distal CD (*) tal and urine sam ples. As + 0 0 discussed in Figure 2-35, these effects of 0 10 20 30 hypoalbuminemia are evident when serum ECF volume, L albumin concentrations decrease by more + – Rate of change + than half. In addition, however, hypoalbu- Arterial Kidney volume Extracellular of extracellular minemia may induce vasodilation and arteri- pressure output fluid volume fluid volume al hypotension that lead to sodium (Na) + retention, independent of transudation of Total peripheral fluid into the interstitium [73,74]. Unlike + resistance Blood volume other states of hypoproteinemia and vasodi- + lation, however, nephrotic syndrome usually + is associated with normotension or hyperten- + M ean circulatory sion. Coupled with the observation made in Cardiac output Venous return filling pressure Figure 2-36 that natriuresis may take place before increases in serum albumin concentra- tion in patients with nephrotic syndrome, these data implicate an important role for primary renal Na retention in this disorder (dark blue arrow). As suggested by Figure 2- 37, the decrease in urinary Na excretion may play a larger role in patients with acute glomerulonephritis than in patients with minimal change nephropathy. Extracellular Fluid Volume Homeostasis in Chronic Renal Failure FIGURE 2-40 35 Relation between glom erular filtration rate (GFR) and fractional sodium (N a) excretion 30 (FEN a). Adaptations in chronic renal failure m aintain 25 urinary N a excretion equal to dietary intake until end-stage renal disease is reached. To achieve this, the FEN a m ust increase as the GFR decreases. Com pared with norm al M ild CRF 17 13 persons, patients with CRF have expanded ECF volum e at norm al Severe CRF 12 N a intake. Furtherm ore, the tim e necessary to return to neutral 16 balance on shifting from one to another level of N a intake is 11 increased. Thus, whereas urinary N a excretion equals dietary 10 intake of N a within 3 to 5 days in norm al persons, this process 15 9 m ay take up to 2 weeks in patients with CRF. This tim e delay 8 m eans that not only are these patients susceptible to volum e over- 14 load, but also to volum e depletion. This phenom enon can be m od- 7 eled sim ply by reducing the tim e constant (k) given in the equation 13 6 in Figure 2-2, and leaving the set point (A0) unchanged. W alser M : Phenom enological analysis of renal regulation of sodium 12. Briggs JP: W hys and the wherefores of juxtaglom erular apparatus and potassium balance. Sim pson FO : Sodium intake, body sodium , and sodium excretion. Barajas L: Architecture of the juxtaglom erular apparatus. H ypertension: Pathophysiology, D iagnosis and Treatm ent. Luft FC, W einberger M H , Grim CE: Sodium sensitivity and resistance Laragh JH , Brenner BM. Skott O , Briggs JP: Direct dem onstration of m acula densa m ediated 4. Guyton AC: Blood pressure control: special role of the kidneys and renin secretion. H all JE, Guyton AC: Changes in renal hem odynam ics and renin 5.

Biochem J 1998;335: turnover in the human gastric cell line HGT1 buy lasuna 60caps fast delivery. Stable expression in chinese hamster ovary cells high-voltage–activated calcium channels in neurons dissociated 1 reveals the interaction with three major signal transduction from the rat tuberomammillary nucleus cheap 60caps lasuna fast delivery. Cloning and func- activity of the histamine H receptor reveals inverse agonism of tional expression of the human histamine H3 receptor purchase discount lasuna line. Eur J Pharmacol 2000;387: Pharmacol 1999;55:1101–1107. In: cerebral expression of the guinea pig histamine H3 receptor: Schwartz JC, Haas HL, eds. Subclassification of hista- Wiley Liss, 1992:161–177. The histamine mode in cat and guinea pig LGNd by histamine: possible cellular H3 receptor: a target for new drugs. Amsterdam: Elsevier, 1998: mechanisms of histaminergic control of arousal. Mechanisms of antihistamine-induced 3 and primate [ H]N -methylhistamine binding differ from that sedation in the human brain: H1 receptor activation reduces a of rodents. Three histamine amino acids in the third transmembrane domain. Br J Pharmacol receptors (H1,H2 and H3) visualized in the brain of human 2000;131 :1247–1250. Mapping of hista- ity of native H receptors regulates histamine neurons in brain. Cholinergic nucleus basalis graphic localization in rat brain. Distribution of hista- cortical activation and wakefulness in the cat. J Neurosci 1996; mine H3-receptor binding in the normal human basal ganglia: 16:1523–1527. Molecular cloning of a Eur J Neurosci 1999;11:449–456. Subunit-specific potentiation of recombinant N- USA 1991;88:429–433. Naunyn Schmiedebergs Arch Pharmacol 1991;343: H1 receptor–mediated facilitation of NMDA responses. Histamine phase shifts turnover via muscarinic and nicotinic receptors in the brain. J the hamster circadian pacemaker via an NMDA dependent Neurochem 1990;55:1899–1904. Naunyn Schmiedebergs Arch Pharma- mouse hippocampus. Carter McRee R, Terry-Ferguson M, Langlais PJ, et al. A persistent sodium current nists on neuronal histamine release in the striatum of rats sub- in acutely isolated histaminergic neurons from rat hypothala- jected to acute and chronic treatments with methamphetamine. Okakura-Mochizuki K, Mochizuki T, Yamamoto Y, et al. En- tribute to spontaneous activity in rat tuberomammillary neu- dogenous GABA modulates histamine release from the anterior rons. Glutamatergic current in histaminergic tuberomammillary neurons of the rat regulation of histamine release from rat hypothalamus. Annu Rev of histamine release in rat hypothalamus and hippocampus by Pharmacol Toxicol 1977;17:325–339. Modulation of hista- is caused by a mutation in the hypocretin (orexin) receptor 2 mine synthesis and release in brain via presynaptic autoreceptors gene. 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Recent progress in the development of molecular genetic tations may resemble features of human neuropsychiatric methods enables the manipulation of genes in intact mam- diseases, providing animal models for studying neural pro- malian organisms. The power of such techniques to eluci- cesses relevant to such disorders. Furthermore, as genes that date complex biological systems was initially recognized and confer susceptibility to human diseases are identified, it will exploited by developmental biologists and immunologists. Finally, genetic models has led to their use in neuropsychopharmacology.

Homologous re- combination results in the incorpora- tion of engineered mutation into en- dogenous gene locus best lasuna 60 caps. Arrows indicate the junction of construct se- quences and native locus buy 60 caps lasuna. This exogenous DNA fragment is flanked by regions ciclovir order generic lasuna canada, will selectively kill cells that have randomly incor- of DNA that are homologous to the native gene. Adjacent porated the construct (negative selection), thereby enriching to one of these homologous regions is a gene encoding thy- for targeted clones. ES cell clones that survive this double midine kinase. Treatment with the drug ganciclovir will kill drug selection are then screened for homologous recombina- cells that express this gene. The homologous The targeting construct is typically introduced into ES recombinant clones, which are heterozygous for the intro- cells by electroporation. In this step, cells are subjected to duced mutation, are then used to generate chimeric mice. Those cells that failed to incorporate the cell clones, these cells are microinjected into the fluid-filled targeting construct are killed by the addition of neomycin blastocoele cavity of 3. The injected embryos are then surgically of the remaining cells have incorporated the entire DNA transferred into the uterus of pseudopregnant females. By contrast, during homolo- are derived partly from the injected ES cells and partly from gous recombination, nonhomologous regions of the con- the host embryo. For example, ES cells derived from a struct that are not flanked by homologous sequences are brown strain of mice are often injected into embryos derived excluded from the integration event. Therefore, homolo- from blackC57BL/6 mice, resulting in chimeras with coats 19: Gene Targeting and Transgenic Technologies 245 Uses of Gene Targeted Mice Studies of null mutant mice provide novel insights into the functional roles of neural genes and, in some cases, animal models relevant to human neuropsychiatric disorders. An illustrative example is a recent study of mice lacking the hypothalamic neuropeptide orexin (14). Observations of homozygous mutant mice revealed an unanticipated pheno- typic abnormality. The mutants displayed frequent episodes of inactivity characterized by the sudden collapse of the head and buckling of the extremities. Subsequent electroencepha- logram (EEG) analysis revealed these episodes to be similar to narcoleptic attacks observed in humans and in a strain of narcoleptic dogs. Moreover, a mutation of an orexin re- ceptor gene was found to underlie the canine syndrome (15). Thus, the null mutant phenotype revealed a novel role for orexin in sleep regulation. In addition, this line of mice A represents an important animal model for examining the pathophysiology and treatment of narcolepsy. Another example illustrates the potential utility of null mutant mice to uncover mechanisms underlying the behav- ioral effects of psychoactive drugs. The nonselective seroto- nin (5-hydroxytryptamine, 5-HT) receptor agonist m-chlo- rophenylpiperazine (mCPP) interacts with several subtypes of 5-HT receptors. Although this compound typically re- duces locomotor activity in rodents, it produced a paradoxi- cal hyperlocomotor response in a line of 5-HT2C receptor null mutant mice (16). This response to mCPP was blocked by pretreatment with a 5-HT1B receptor antagonist, indi- cating that the absence of 5-HT2C receptors unmasked a hyperlocomotor effect of mCPP on 5-HT1B receptors in B mutant mice. These results provide a model whereby genetic FIGURE 19. A: Homolo- endowment may contribute to the development of a para- gous recombinant ES cells are injected into the blastocoele cavity. When a compound alters the func- B: Injected blastocysts are surgically transferred into the uterus of pseudopregnant female mice for the production of chimeric tion of multiple gene products with opposing influences on mice. C: In this example, chimeric mice are bred with C57BL/6 behavior, then mutations or allelic variation of these genes animals. Heterozygous animals may be bred for the produc- used to generate animals with null mutations, subtle muta- tion of homozygous mutant mice. The benefits of such an approach are highlighted by a mutation of a gene encoding the 1 subunit of the - containing blackand brown patches. The extent to which aminobutyric acid A (GABAA) receptor (17). The mutation the ES cells have colonized the animal may be roughly ap- produced a single amino acid change, rendering the 1 sub- proximated by the extent of the brown contribution to the unit–containing subpopulation of GABAA receptors insen- coat. It is most important that ES cell derivatives colonize sitive to benzodiazepines, without affecting their responsive- the germ cells of the chimera, so that the targeted mutation ness to GABA. The resulting animals exhibited reduced can be propagated to subsequent generations. If chimeras sensitivity to the sedative and amnestic effects of diazepam, are mated with C57BL/6 mice, then the germ line transmis- but no change in sensitivity to the anxiolytic-like effects of sion of ES cell–derived genetic material is indicated by the this drug. These results indicate that benzodiazepine site generation of brown offspring. Half of these brown mice ligands devoid of activity at 1 subunit–containing GABAA will be heterozygous for the targeted mutation. These heter- receptors may act as anxiolytics devoid of some of the side ozygous mice are then bred to produce homozygous mutant effects typically associated with benzodiazepines, a predic- mice that completely lackthe normal gene product. These insights would not have The above considerations also pertain to the analysis of been obtained using a conventional gene targeting ap- transgenic mice carrying constitutive mutations. Thus, if a neural gene of interest is also expressed in peripheral tissues, then the absence of Considerations in the Interpretation of the gene product peripherally could lead to a lethal or altered Targeted Mutant Phenotypes phenotype, independent of its neural role. Moreover, for genes that are widely expressed in the CNS, it may also be In interpreting behavioral phenotypes, attention must be difficult to anatomically localize the brain region(s) that paid to the effects of genetic background. New techniques to over- consequences of many targeted mutations may be influ- come these problems by achieving region-specificity and enced by modifying genes that differ among various inbred inducibility of targeted mutations are under development, strains (19). In some cases, phenotypic abnormalities have and are described in the next section. It may therefore be useful to examine the per- sistence of mutant phenotypes in the context of several PROCEDURES FOR ENGINEERING genetic backgrounds. In one example, three groups indepen- CONDITIONAL MUTATIONS dently generated lines of mice with null mutations of the 5-HT1A receptor subtype (21–23). Interestingly, although New technologies are under development for circumventing each group placed this mutation on a different genetic back- the limitations of standard gene targeting approaches by ground, all observed enhanced anxiogenic-like behaviors in creating mutations that may be induced in adult animals the mutant lines. Thus, particularly strong evidence is pro- and/or restricted to particular brain regions. Although these vided for a contribution of the 5-HT1A receptor to the strategies are not yet in widespread use, it is likely that rapid regulation of anxiety. This potential problem may Cell Type–Specific Mutation Strategies be addressed through breeding programs to place targeted When a null mutation of a gene results in a mutant pheno- mutations on different inbred backgrounds, and by the gen- type, limitations in the interpretation of that phenotype can eration of ES cell lines derived from other inbred strains. It is possible that the absence of a gene inherent limitations.