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192-IgG-Saporin is an anti-neuronal immunotoxin that combines the 192 monoclonal antibody to the p75 neurotrophin receptor found on terminals and cell bodies of neurons in the cholinergic basal forebrain with the ribosome-inactivating protein saporin. Bilateral intraventricular injection of the 192-saporin produced a variety of dose-related behavioral, neurochemical, and histological alterations in adult male rats. While both the 2 micrograms and 4 micrograms dose produced comparable cholinergic hypofunction only the high dose produced behavioral changes. Behavioral deficits induced by the 4 micrograms dose of 192-saporin induced alterations in rotorod performance and reactivity on the hot-plate which recovered over 8 weeks. In addition, the 4 micrograms dose produced a persistent impairment in the acquisition and performance of standard Morris water maze task as well as a cued version of the task. The neurobiological alterations induced by 192-saporin involved both cholinergic and non-cholinergic systems. Both doses of 192-saporin produced a 60-80% decrease in high affinity choline transport in the hippocampus and cortex without altering this parameter in the striatum. In addition, there was a significant dose-related decrease of norepinephrine in the hippocampus in the high dose group. 192-saporin did not alter the content of dopamine, serotonin, or their metabolites in any region examined. 192-saporin also produced a loss of Purkinje cells in the cerebellum. This cell type also expresses the p75 receptor and appears to be a target for intraventricular 192-saporin. This complex interplay of factors makes the i.c.v. model of 192-saporin very problematic for studying the functional properties of the cholinergic basal forebrain. However, recent data suggest that injection of 192-saporin directly into components of the cholinergic basal forebrain can be used to further elaborate the function of this brain system and to model disorders of cholinergic hypofunction such as Alzheimer's disease.

Rats were given a single gavage of trimethyltin chloride (TMT) providing a dose of 0, 4.3, or 6.7 mg/kg of alkyltin. Gross changes in brain structures were quantified and analyzed statistically. Behavioral and functional measures were taken to verify efficacy of TMT dose. The high dose produced transient weight loss and seizures. In the fourth week after gavage, the high dose produced hyperactivity in the residential maze and activity wheel. High and low TMT doses decreased auditory startle responsiveness. Estrus cycle was normal in all groups. Brains were sectioned and stained with the Timm stain which delimited subregions of hippocampus and connected structures and also revealed mossy fibers. Linear and areal measures were made at three positions along the septotemporal axis of Ammon's horn. The low dose produced reductions in size in a few isolated subareas of the brain. The high dose produced, at the three planes studied, extensive (15-40%) loss of tissue in Ammon's horn and structures to which Ammon's horn is interconnected--subiculum, entorhinal cortex, dentate gyrus, hilus, CA3, and CA1 region. Neocortex and caudate-putamen were unaffected. These findings suggest that a single TMT gavage may disrupt brain structures important to linking neocortex with subcortex via structures in the hippocampal region.

The development of the acetylcholinesterase (AChE) texture of the cortex of the rat brain was studied during the first three weeks of life. The Tago technique enables visualization of both AChE+ cells and fibers with both shown in exquisite detail making quantification possible. At each age--0 (birth), 7, 14, 21 and 60 days (adult)--four brain areas were studied (cingulate, dorsal neocortex, lateral neocortex and olfactory) at each of three coronal planes in the brain (anterior, intermediate, posterior). Fiber density reached adult levels by Day 21 in cingulate cortex in intermediate and posterior planes. In other areas fiber density reached adult levels by Day 14 indicating a high rate of fiber growth during the first two weeks of life since at birth rat cortex is innervated only by a sparse AChE+ fiber invasion into neocortex in the anterior plane. Fiber density did not regress after adult levels were reached, however, cell staining showed a different pattern. At birth many lightly stained cells were seen in the olfactory cortex in all three planes, but other areas were devoid of cells. In all areas there was a peak at Day 7 in number of cells stained and in intensity of cells staining with a gradual decline in cell staining until by Day 21 very few stained cells were seen in the cortex (typical adult pattern).

Rats 24-hr water deprived were injected IP with a fixed amount (10 ml/kg) of solution of various concentrations of LiCl and NaCl in dosage ranges which in previous experiments either increased or had no effect on water intake. Intake of 0.01% QHCl decreased with increasing concentrations of both NaCl and LiCl. On a molar basis, LiCl was more effeictive. LiCl also produced an aversion to a palatable solution, 0.1% sodium saccharin; however, NaCl produced no aversion over the dosage range which can be tolerated by the animals.

Phenylethylamine (PEA) has the same structure as amphetamine (AMP) except that PEA lacks a methyl group at the alpha carbon. Although these analogues produce many similar neurobehavioral actions, a previous study found that PEA did not support formation of conditioned taste aversion (CTA). Using somewhat different procedures, in the present study a transient taste aversion was seen in rats. Use of noradrenergic blocking agents to attempt to pharmacologically tailor PEA action to make it more like that of AMP did not improve efficacy to form CTA. A robust PEA-induced CTA was seen in mice even when PEA produced multiple seizures.

Pregnant rats were injected with 0, 6 or 10 mg/kg of methylmercuric chloride on Days 6-9 of gestation. Dams given the 10 mg/kg dose failed to deliver young or produced stillborn. External morphology was normal for rats given either the 0 or 6 mg/kg dose. Whole brains were examined from male and female rats, 21 or 90 days old. External brain dimensions were measured with calipers. Brains were sectioned at three criterion locations. A microprojector was used to project brain sections in order to measure intrastructural distances. Sections were examined with a light microscope to look for abnormalities. Various expected age-related changes were noted showing the sensitivity of the anatomical methods. Methylmercury produced hydrocephalus, decreased thickness of cerebral cortex in the parietal section and increased thickness of hippocampus in the occipital section. With these exceptions, the brains of mercury-treated rats showed normal development.

Water-deprived mice were injected with various concentrations of LiCl or NaCl 15 min before they were allowed to drink either water or 0.1% saccharin. The NaCl injections produced a dose-dependent increase in intake of both fluids: however, the higher dosages of LiCl produced a selective depression of fluid intakes. Saccharin intakes were depressed for less than one hr but water intakes were not affected. LiCl injections also depressed general activity and produced an apparent shift of water from blood into cells. The LiCl-induced depression of saccharin was not significantly influenced by extensive previous experience with the drinking fluid.

Rats homozygous for the mutant gene for diabetes insipidus (Brattleboro strain) are stunted in growth compared to rats heterozygous for the mutant gene and normal rats without the mutant gene. The hypothesis was tested that normal growth depends upon the presence of vasopressin. It was expected that replacement therapy of vasopressin rats homozygous for diabetes insipidus would make possible a normal growth rate similar to that of rats heterozygous for diabetes insipidus. Rats heterozygous and homozygous for diabetes insipidus were treated with 0.25 U (Days 0-9) and 0.5 U (Days 10-29) of vasopressin during the first month of life. During the treatment period, vasopressin significantly increased the urine osmolatities of the homozygous rats demonstrating the renal effectiveness of the vasopressin. The results showed that remedial vasopressin administration could not produce normal growth rates in homozygous rats and may be detrimental. Six weeks following vasopressin treatment, homozygous, diabetes insipidus rats which had received vasopressin had increased 24 hr water intakes and decreased urine osmolalities compared to control, homozygous rats, Heterozygous rats also had decreased urine osmolalities resulting from vasopressin six weeks after the cessation of vasopressin treatment.

A procedure is described for treating the skull with an acidulated fluoride solution at the time of intracranial implantation of cannulas or electrodes. Fluoride has a stabilizing effect on the hydroxyapatite of bones and teeth. In our experience, fluoride treatment has reduced the incidence of dislodgment of intracranially implanted appliances.

The action of the delipidization step and the type of differentiation fluid was assessed for two stains, Harris' hematoxylin and thionin, in frozen sections of rat brains. For thionin, all procedural variations used produced a blue or purple cell staining. Myelin stained red when sections were delipidized and differentiated in acetic acid, acid-formalin, or acid-alcohol. Myelin remained white when the delipidization step was omitted or when differentiation was performed in alcohol. Myelin staining was achieved with Harris' hematoxylin when sections were delipidized and were differentiated in either acid-formalin or borax-ferricyanide. The former produced red fibers against a red-purple or light purple cell background with some cell staining. The latter produced purple fibers contrasting sharply with a buff background and minimal cell staining. Cells were further accentuated in the hematoxylin techniques by a thionin counterstain.

Procedural variables are crucial in using taste aversion as a measure of lead toxicity. Rats were given saccharin and water to drink while ingesting a diet containing lead acetate (PbAc). Rats showed high preference for saccharin (over water) before lead was introduced. Saccharian preference fell during PbAc ingestion and rose when PbAc was removed from the diet suggesting that saccharin preference may correlate with the physiologic action of the toxicant. When saccharin was introduced simultaneously with PbAc aversion was almost total, but recovered with continuous PbAc exposure. When saccharin was introduced after the start of PbAc exposure saccharin aversion diminished with the duration of presaccharin PbAc exposure.

Experiments were conducted to investigate the feasibility of using the pattern of saccharin and water drinking to detect acute and chronic administration of drugs and toxicants. Procedural variables were found to be crucial. When rats were naive for the saccharin drinking fluid, a single injection of LiCl or 2-deoxyglucose produced persistant saccharin aversion. Hypertonic saline produced only a transient saccharin aversion. If rats were pre-exposed to saccharin, the 2-deoxyglucose injection and hypertonic NaCl produced an increase in saccharin drinking but LiCl was without effect. Several types of chronic treatment were given to saccharin-experienced rats. Chronic 2-deoxyglucose, LiCl, and Pb administration produced gradually developing saccharin aversion and qualitatively different patterns of saccharin and water drinking. Chronic administration of hypertonic NaCl or insulin or chronic food deprivation had no impact on saccharin preference. It was concluded that patterns of saccharin and water drinking can be used to detect the administration of a drug or toxicant and perhaps even the time course of action, but may not detect a substance given previous to saccharin, perhaps because the animal cannot associate these now familiar perturbations with the novel saccharin solution. This means that existing toxic states may not be detected by using saccharin preference as a probe.

A time-sampling frequency analysis was made of criterion behaviors following injection of 2.5--10 mg/kg dosages of p-chloroamphetamine (PCA). Stereotypic behaviors (forepaw treading, circling, head weaving and inching) increased with increasing dosages and normal behaviors (grooming, rearing, and instances of inactivity) decreased. Composite scores of stereotypic behavior were a positive, linear function of PCA dosage. Composite scores of normal behavior showed near maximal inhibition at 5 mg/kg. Splayed hindlimbs is a reliable and sensitive indicator of PCA action, but vocalization, tremors, diarrhea and autonomic signs are not. Preinjection of PCA strongly attenuated the PCA-induec syndrome, as expected, since the preinjection should deplete brain serotonin and reduce the amount released by the second PCA injection.

In Experiment 1, rats were given a 1% lead acetate diet from Day 100 of life to the termination of the experiment. After 82 days of lead feeding behavioral tests were started. Lead exposure increased wheel-turning hyperactivity produced by food deprivation and phenylethylamine injection. Lead produced no activity change in the unchallenged condition. In the open field, lead-exposure rats were less responsive to the stimulating action of PEA and amphetamine and to the sedating action of pentobarbital. In Experiment 2, the interaction of lead with food deprivation of PEA on wheel-turning was replicated in naive animals given only a 32-day exposure. Chemical analysis was made of tissues. Ingested lead entered the brain. Regional steady-state levels of brain norepinephrine, dopamine and serotonin were not altered by lead treatment when measured following four days of starvation at a time when lead-induced behavioral change was distinct. It was concluded that pharmacological challenges on activity may be sensitive indicators of lead exposure, but the type of activity measure is critical.

Gonadectomies were performed at 25 days of life in SWR/J mice, a strain known to develop age-dependent nephrogenic diabetes insipidus with females drinking far more than males. Effect of gonadectomy was different for each of the 3 nonreproductive behaviors studied. (1) Ovariectomy reduced the age-dependent polydipsia seen in females, but castration was without effect in males. (2) Castration of males resulted in a lower intake of an isotonic NaCl solution, making the castrated males similar to the sham-operated and ovariectomized females which did not differ. (3) For the short-term activity measurement sham-operated males did not differ from sham-operated females and castrated males did not differ from ovariectomized females. In each sex, gonadectomy reduced activity.

The age-dependent polydipsia and polyuria observed in SWR/J mice was found to be caused by relative inability of the kidneys to respond to antidiuretic hormone (ADH), resulting in a concentrating defect, which persisted even following Pitressin injection or water deprivation. Posterior pituitaries contained large amounts of ADH, which was also found in the urine and increased in output following water deprivation, indicating normal, or above normal synthesis and release of ADH. Kidneys of polydipsic SWR/J mice weighed more than those of normal strains and sometimes contained a lesion in the medullary area. No clear relationship was found between the size of the lesion and water intake.

Gerbils which become polydipsic when food-deprived, were refed with mixtures of Laboratory Chow and a non-nutritive material (Sterolit) after 2 days of food deprivation. Suppression of polydipsia was not related to bulk of material ingested. Instead, when the intake of Chow in the mixture reached 6 g, suppression appeared precipitously suggesting the existence of a threshold for suppression. It was concluded that nutritional, rather than stomach fill, factors were primary in suppressing polydipsia on the refeeding day.

Four commonly used anorectics which are amphetamine analogues were tested for their action on responsiveness in an acoustic startle test when rats were given daily IP injections adequate to produce a change in body weight. Drugs were given for 22 days. None of these drugs increased startle responsiveness as does the amphetamine parent compound. Instead, fenfluramine and phenylpropanolamine decreased startle responsiveness and phentermine and diethylpropion produced no change. There was no relationship between drug action and body weight. Partial tolerance was found for the fenfluramine action on startle and complete tolerance was found for its action on body weight gain. The fenfluramine action is compatible with the extensive literature on humans and animals indicating sedative properties.

SWR/J female mice, 8 hr water deprived, were injected intraperitoneally with 0, 10, 50, 200, and 800 mU of aqueous pitressin, 5 min prior to presentation of water. Drinking measurements made at 5, 15, 25, and 35 min of the drinking period revealed a significant transient inhibition of drinking for the three highest dosages. Injections had no measureable effect on blood pressure. Only the highest dosage had an effect on gross motor activity, a significant decline.

Blood pressure of adult male SWR/J mice is approximately 20 mm Hg higher than that of females. Castrating males at weaning eliminated this sex difference. Testosterone restored blood pressure of castrated mice to the level of the intact males within 10 days indicating a pressor effect of testosterone. Ovariectomy had no effect on blood pressure.