Complex, multimodal behavioral profile of the Homer1 knockout mouse.

Proteins of the Homer1 immediate early gene family have been associated with synaptogenesis and synaptic plasticity suggesting broad behavioral consequences of loss of function. This study examined the behavior of male Homer1 knockout (KO) mice compared with wild-type (WT) and heterozygous mice using a battery of 10 behavioral tests probing sensory, motor, social, emotional and learning/memory functions. KO mice showed mild somatic growth retardation, poor motor coordination, enhanced sensory reactivity and learning deficits. Heterozygous mice showed increased aggression in social interactions with conspecifics. The distribution of mGluR5 and N-methyl-D-aspartate receptors (NMDA) receptors appeared to be unaltered in the hippocampus (HIP) of Homer1 KO mice. The results indicate an extensive range of disrupted behaviors that should contribute to the understanding of the Homer1 gene in brain development and behavior.

Regulation of emotional response in juvenile monkeys treated with fluoxetine: MAOA interactions.

Juvenile male rhesus macaques received therapeutic doses of fluoxetine daily from one to three years of age and were compared to vehicle-treated controls (N=16/group). Genotyping for monoamine oxidase A (MAOA) polymorphisms was used to form subgroups (N=8) with high and low expression of the gene. Behavioral responses were scored during 30-second exposures to pictures differing in affective content. As expected from its therapeutic effect, fluoxetine decreased the behavioral response to emotionally evocative pictures. A 44% reduction in number of expressive behaviors was seen, but only in subjects with low expression MAOA polymorphisms. In general, this effect occurred for pictures of varying affective content and was not due to altered occurrence of one specific behavior or type of behavior. The drug*genotype interaction was seen after one and two years of treatment and did not reverse one year after discontinuation of dosing. Two potential translational implications are suggested: (1) MAOA genetic polymorphisms may be the source of some of the variability in response to fluoxetine treatment in children; (2) extended fluoxetine treatment during juvenile brain development may result in persistent effects on emotional regulation.

Dopaminergic modulation of aldosterone secretion is independent of alterations in renin secretion.

This study was designed to determine if dopaminergic modulation of aldosterone secretion is mediated through the renin-angiotensin system. In rats, intraarterial administration of metoclopramide (MCP), a dopamine antagonist, resulted in a significant elevation of plasma aldosterone (PA) 5 min after administration and a peak response 10 min after administration. Pretreatment with L-dopa (30 mg/kg) 30 min before administration of MCP suppressed the early PA response to MCP. PRA after MCP showed no change at 5 min but increased significantly at 10 min, with peak responses occurring at 30 min. Preadministration of L-dopa blunted and delayed the PRA response to MCP. Preadministration of the angiotensin-converting enzyme inhibitor, SQ 14,225 (1 mg/kg), did not inhibit the PA response to MCP. Infusion of the angiotensin II antagonist, saralasin (10 micrograms/kg min-1), begun 30 min before MCP, depressed basal levels of PA slightly but did not significantly alter the PA response to MCP. Rats studied 36 h after bilateral nephrectomy displayed intact PA responses to MCP, but there was no PRA response to MCP. The results indicate that dopaminergic modulation of PA secretion occurs independently of alterations in renin secretion.

Desensitization of vascular tissue to parathyroid hormone and parathyroid hormone-related protein.

Although PTH and PTH-related protein (PTHrP) are vasodilators, prolonged exposure to elevated levels of PTH is often associated with hypertension. We investigated the effects of prolonged incubation with PTH or PTHrP on arterial segments and cultured vascular smooth muscle cells (VSMC). PTH or PTHrP transiently relaxed precontracted arterial segments within 10 min. Additional PTH or PTHrP added after 40-min exposure to these peptides had little effect on vascular tone, whereas forskolin, isoproterenol, isobutylmethyl-xanthine, or acetylcholine were still potent. In fura 2-loaded VSMC, 5-min incubation with PTH or PTHrP attenuated angiotensin II (Ang II)-induced calcium mobilization, an effect that was reduced by preincubation of VSMC with PTH for 1.5 h. Similarly, 1.5-h preincubation with PTH or PTHrP decreased the cAMP response to these peptides but not to forskolin or NaF. Ang II potentiated the cAMP response to PTH and PTHrP but was also subject to desensitization. Nle8, 18Tyr34 bovine PTH(3-34) amide did not desensitize vascular tissue to PTH or PTHrP. Our results suggest that homologous desensitization to PTH or PTHrP in vascular tissue requires receptor stimulation, occurs proximal to G stimulatory protein, and impairs attenuation of calcium mobilization by PTH or PTHrP. This may be a mechanism by which vasodilator effects of these peptides are decreased with prolonged elevation of PTH levels.

Direct augmentation by cyclosporin A of the vascular contractile response to nerve stimulation.

Cyclosporin A administration is associated with an increased incidence of hypertension. To evaluate the direct effects of the drug on the contractile responses of vascular tissue to adrenergic stimuli, rat caudal artery ring segments were studied before and after the addition of cyclosporin A or its ethanol vehicle in vitro. In a dose-related manner, cyclosporin A augmented the contractile response to transmural nerve stimulation, with a highly significant (p less than 0.001 relative to that produced by the vehicle) lowering of the stimulation rate, a 50% of maximum contractile response (ED50) that elicited. The difference between pretreatment and treatment maximal responses to transmural nerve stimulation was also significantly greater (p less than 0.01) in the cyclosporin A-treated preparations than in those receiving the vehicle. In similar experiments, the responses to exogenous norepinephrine were not significantly affected. The effect of cyclosporin A on transmural nerve stimulation was demonstrated at several extracellular calcium concentrations. The results suggest that cyclosporin A enhances nerve stimulation responses by a presynaptic mechanism.

Dopaminergic control of plasma catecholamine and aldosterone responses to acute stimuli in normal man.

This study examines the influence of dopamine on catecholamine and aldosterone secretion in normotensive individuals. The responses of plasma aldosterone (PA), norepinephrine (NE), and PRA to upright posture and isometric handgrip were studied in five normal males on a constant 50-meq Na intake before and after 4 days of administration of the dopamine agonist, bromergocriptine (BEC; 2.5 mg three times a day). In addition, the PA responses to graded angiotensin II and ACTH infusions were examined before and during BEC. Supine PA and PRA were not altered by BEC, but basal NE was reduced significantly (P < 0.01) from 204 +/- 29 to 98 +/- 12 pg/ml after BEC. There was an accompanying significant reduction in upright mean arterial pressure during BEC administration. The PA and NE during upright posture and isometric handgrip were significantly suppressed by BEC, but PRA responses were unaltered. BEC produced a significiant (P < 0.025) suppression of the PA response to graded angiotensin II infusions but did not alter the PA response to graded ACTH. Our findings indicate that in normal man there is a pronounced inhibitory effect of dopaminergic pathways on catecholamine scretion and regulation of upright mean arterial pressure. Results of the posture study would suggest that dopamine-mediated PA alterations occur independently of changes in the levels of PRA. The finding that BEC suppressed PA responses to angiotensin II and posture but not to ACTH would imply that dopamine selectively exerts its effect or adrenal angiotensin II-mediated aldosterone secretion.

Dopaminergic modulation of pressor and hormonal responses in essential hypertension.

Hormonal and mean arterial pressure (MAP) responses to posture, isometric handgrip, angiotensin II (AII), adrenocorticotrophic hormone (ACTH), and metoclopramide (MCP), a dopamine (DA) antagonist, were examined in nine men with essential hypertension and nine age- and weight-matched normotensive men on a constant 100 mEq sodium and 80 mEq potassium intake before and after 4 days of administration of the DA agonist, bromocriptine (BEC; 2.5 mg three times a day). BEC depressed supine basal MAP in the hypertensives, and decreased MAP response to posture and isometric exercise in both groups. Hypertensives displayed greater (p less than 0.01) NE responses to posture and exercise than the normotensives. BEC decreased the NE response to 10 minutes of upright posture and exercise more in hypertensives (p less than 0.01) than in normotensives, but following BEC, the responses were similar. BEC did not affect basal PRA or PRA responses to posture and exercise in the two groups. PA responses to ACTH and MCP were similar in both groups, but the hypertensives displayed greater (p less than 0.01) PA responses to AII. BEC suppressed PA responses to AII (p less than 0.01) and to high dose ACTH (p less than 0.05) to a similar extent in both groups. The prolactin as well as the PA response to DA antagonism with MCP was similar in the two groups. These results suggest that dopaminergic control of NE secretion may be altered in essential hypertension. Blood pressure lowering effects of BEC in patients with essential hypertension may be related, in part, to depression of sympathetic nervous system activity.

Behavioral and hematologic consequences of marginal iron-zinc nutrition in adolescent monkeys and the effect of a powdered beef supplement.

BACKGROUND: The adolescent growth spurt and menarche increase iron and zinc needs and could precipitate functional deficiencies if dietary sources are inadequate. OBJECTIVE: The effects of mild, combined zinc and iron deprivation during the growth spurt and the ability of meat as a common dietary source of zinc and iron to reverse these effects was studied. DESIGN: Pubertal female rhesus monkeys were fed control diets (n = 8) or diets marginally deficient in zinc (2 microg/g diet; n = 8) and iron (10 microg/g diet; n = 8) for 3 mo. A powdered beef supplement (104 microg Zn/g and 43 microg Fe/g, 11 +/- 2 g/d) was then fed daily to half of the deprived group for 3 additional months. RESULTS: Growth and hematology were not affected significantly by iron-zinc deprivation, but plasma zinc and iron were somewhat lower in the deprived group than in the control group after 3 mo. The deprived monkeys reduced their participation in behavioral testing, responded more slowly and less frequently to test stimuli, and were less active. The beef supplement increased participation in testing and stabilized activity levels, but response times remained depressed. Plasma ferritin was lower in the nonsupplemented deprived monkeys than in the controls by the end of the experiment. Four of 8 of the deprived monkeys had iron deficiency anemia compared with none of the controls and 1 of 8 who received the beef supplement. CONCLUSIONS: Marginal zinc and iron deprivation in early adolescence can lead to behavioral and hematologic dysfunction in nonhuman primates and dietary beef supplements can prevent and reverse some of these effects.

Studies of marginal zinc deprivation in rhesus monkeys. III. Use of liver biopsy in the assessment of zinc status.

Studies of marginal zinc deficiency in rhesus monkeys have demonstrated that plasma Zn levels are often a poor indication of Zn status. To better assess the Zn status of these animals, we examined their liver concentration of Zn as well as of other minerals, metallothionein (MT), and superoxide dismutase (SOD). Liver-wedge biopsies were obtained from adult rhesus monkeys fed for 15 mo, either a control (100 micrograms Zn/g) or a marginally Zn deficient diet (4 micrograms/g; ZD). Liver Zn and MT concentrations were lower in ZD monkeys than in controls whereas iron concentration was higher in ZD monkeys than in controls. Liver copper, manganese, and magnesium concentrations and activities of CuZnSOD and MnSOD were similar in the two groups. Data from the groups were pooled for regression analysis. Measurement of liver Zn and MT concentrations are useful in the assessment of the effects of long-term Zn deprivation in primates.

Studies of marginal zinc deprivation in rhesus monkeys. VIII. Effects in early adolescence.

Arrested adolescent growth and sexual maturation are striking symptoms of severe dietary zinc deprivation. More general implications of mild or marginal Zn deficiency during adolescence are not known. Five marginally Zn-deprived (ZD) male monkeys (4 mg Zn/kg diet) were compared with five controls pair fed a diet containing 100 mg Zn/kg during early adolescence. Mean plasma Zn levels were 38% lower in ZD group than in controls when evaluations began. During rapid growth plasma Zn decreased in controls but not ZD animals. ZD animals had delayed onset of accelerated weight gain and linear growth; loss of subcutaneous fat typical of early adolescence did not occur. ZD monkeys required two to three times more trials for both learning and reversal a visual discrimination task. Immune function was depressed 20-30% as reflected in early reduced proliferative response of peripheral lymphocytes and later lower immunoglobulin levels. Marginal dietary Zn deprivation affects growth and function in adolescence without producing frank developmental retardation.

Long-term marginal zinc deprivation in rhesus monkeys. II. Effects on maternal health and fetal growth at midgestation.

Adult nonpregnant female rhesus monkeys fed purified diets containing 100 or 4 ppm zinc for 1 yr were mated then studied through midgestation. At mating, zinc-deprived (ZD) monkeys showed maternal lymphocyte response to mitogens concanavalin A (Con A) and phytohemagglutinin (PHA), serum uric acid and carbon dioxide, and WBC lower than in control (C) monkeys. There was a significant positive association between plasma zinc and PHA response. At midgestation, discriminant analysis revealed that maternal lymphocyte response to Con A, fetal abdominal circumference (by ultrasound), plasma fibrinogen, serum IgM, and amniotic fluid iron level were discriminators for diet group, all lower in ZD than in C monkeys. Maternal plasma and RBC zinc at midgestation were positively associated with fetal growth and plasma uric acid. These observations suggest that immune function (ie, mitogen response and serum immunoglobulin level) is a strong discriminator of dietary zinc deprivation in rhesus monkeys, both before and during pregnancy.

Activity and attention in zinc-deprived adolescent monkeys.

Lethargy is characteristic of malnourished populations, but little is known about the biologic mechanism or consequences for cognitive performance. In the current experiment, 24-h activity patterns and performance of an attention task were studied in adolescent female monkeys (18-33 mo of age, n = 10/group) under conditions of moderate dietary zinc deprivation (2 micrograms Zn/g diet) and adequate dietary zinc (50 micrograms Zn/g). There were progressive decreases in daytime activity levels in the zinc-deprived group followed by slowing of growth around the time of the growth spurt. Attention performance was also impaired before the onset of growth retardation. Zinc-deprived monkeys failed to show the shift to later initiation of the rest phase of the diurnal cycle seen in controls in late adolescence. These data support previous findings that activity and attention can be affected during early stages of zinc deprivation before the onset of growth retardation.

Studies of marginal zinc deprivation in rhesus monkeys. I. Influence on pregnant dams.

Rhesus monkeys were fed a diet marginally deficient in zinc (4 ppm zinc) throughout pregnancy and were monitored for changes in hematological, biochemical, and immunological parameters. This dietary zinc level was chosen because it did not produce an overt deficiency syndrome when fed for 10 wk to nonpregnant monkeys. Deprived animals were compared to control groups fed a zinc replete (100 ppm) diet ad libitum or on a food restricted (pair fed) basis. Beginning in the 3rd trimester zinc-deprived monkeys exhibited characteristic signs of deficiency including dermatitis, anorexia, and low levels of plasma zinc (less than 65 micrograms/100 ml) and of serum alkaline phosphatase activity. The extent of plasma zinc depression in deficient monkeys was dependent on total food intake; severely anorexic monkeys lost weight but maintained normal plasma zinc levels; monkeys that gained 20 to 30% of their body weight during pregnancy had severely depressed plasma zinc. Plasma vitamin A was reduced in the deprived group while copper, magnesium, and folate levels remained similar to controls. Hematological changes indicative of iron deficiency anemia (reduced packed cell volume, mean corpuscular volume, and Hb) were also seen in severely deficient monkeys. In addition, the peripheral lymphocyte mitogen response was reduced in deficient dams. We conclude that marginal deficiency of dietary zinc can produce significant abnormalities of nutritional status and has the potential for producing serious immunohematological dysfunction during pregnancy.

Studies of marginal zinc deprivation in rhesus monkeys. III. Effects on vitamin A metabolism.

The relationship between dietary zinc, vitamin A, and retinol-binding protein (RBP) was studied in pregnant rhesus monkeys. Beginning on day 0 of gestation, monkeys were divided into three groups; 1) eight ad libitum-fed controls (AL) fed a diet containing 100 micrograms/g zinc, 2) 15 zinc-deprived (ZD) fed a diet containing 4 micrograms/g zinc, 3) 11 pair-fed controls (PF) fed the 100 micrograms/g control diet in amounts equal to those consumed by ZD animals. ZD monkeys had lower plasma zinc levels than did the AL and PF groups at day 135 of gestation, and at 1 and 3 months gestation. A positive correlation between plasma vitamin A and plasma zinc was observed (r = 0.5150, p less than 0.05) and between RBP and zinc (r = 0.883, p less than 0.001) in the ZD group at day 135 of pregnancy. By 3 months postpartum, plasma zinc levels increased in all groups; a positive correlation between zinc and vitamin A was observed in the ZD group (r = 0.5162, p less than 0.05) and in the PF group (r = 0.6353, p less than 0.05); however, no correlation between zinc and RBP was observed. In ZD monkeys, the ratio of RBP to vitamin A was higher (p less than 0.05) than in controls at day 135 of pregnancy. Polynomial regression of the interaction between plasma vitamin A and zinc, and the RBP/vitamin A and zinc, indicated a curvilinear relationship between plasma zinc and these two parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of marginal zinc deprivation in rhesus monkeys. IV. Growth of infants in the first year.

Growth was evaluated in rhesus monkey infants that were the offspring of females given a marginally zinc-deficient diet (4 micrograms/g zinc) from the beginning of pregnancy and through 12 months of postnatal life. These zinc-deficient (ZD) infants were compared to controls whose mothers were fed a complete diet, either ad libitum or pair-fed to zinc-deficient dams, throughout gestation and lactation. Male ZD infants had evidence of growth retardation at birth. In contrast, growth retardation in female ZD infants was not observed until 1 month of age. From 3 to 9 months of age (late lactation and subsequent to weaning) ZD infants attained weights similar to those of the control group. However, analysis of crown-rump and femur length indicated that ZD infants' growth was less than optimal throughout the entire 1st yr of observation. In addition, skinfold thickness was markedly higher in ZD than in control infants in the postweaning period. In the juvenile period (9-12 months of age) both male and female ZD animals fell behind controls in body weight. ZD juveniles were also hypogeusic, as determined by a quinine acceptance test. Low weight ZD infants had reduced somatic growth as reflected in sitting height, long bone growth, head circumference, and limb circumference. Regression analysis indicated that impaired growth rates from 9 to 12 months were associated with both lower food intake and reduced food use efficiency. Plasma zinc concentration was, in general, inversely related to weight gain in both groups during the 1st yr.

Studies of marginal zinc deprivation in rhesus monkeys: infant behavior.

Rhesus monkey infants were marginally deprived of zinc (4 ppm diet) from conception and were compared to controls (100 ppm diet) during the first year of life in development of reflexes and motor patterns, mother-infant interaction, delayed response performance, discrimination learning and reversal, and open field behavior. Deficits in amount and variety of behavior were recorded in deprived infants; spontaneous locomotor activity was 50% below control levels in males at 1 mo of age; spontaneous activity was 7-10% lower in both males and females at 3 mo of age; response latencies were 50% lower than controls at 7-9 mo; failure to reach discrimination reversal criterion was seen in 71% of deprived infants as compared to 10% of controls at 10 mo of age; and abnormally low levels of climbing and exploration were seen in two of six deprived infants at 12 mo of age. No abnormalities in the rate of behavioral development or in emotional adaptability were observed. These and other results suggest that syndromes of lethargy, apathy, and hypoactivity are characteristic of behavioral effects of marginal zinc deprivation in primates.

Studies of marginal zinc deprivation in rhesus monkeys: II. Pregnancy outcome.

A marginal state of zinc deficiency was induced in the pregnant nonhuman primate, Macaca mulatta, by feeding a diet containing 4 ppm zinc beginning at conception. Pregnancy outcome of marginally zinc-deficient monkeys (ZD) was compared to both pair-fed (PF) and ad libitum fed (AL) control animals (100 ppm zinc). Stillbirths, abortions, and delivery complications were more frequent in both ZD and PF dams than in AL controls; no malformations were detected (maternal plasma zinc was normal during organogenesis). Male ZD neonates weighed significantly less than same sex controls; also, in relation to colony norms, 7/8 ZD males, 2/8 ZD females, and 1/10 PF controls were of low birth weight. Further, plasma zinc and iron levels were lower in ZD neonates than in AL and PF controls. ZD neonates also had reduced muscle tonus. Birth weight and maternal plasma zinc concentration were negatively correlated in ZD group but positively correlated in AL and PF groups. Indeed, maternal plasma zinc concentration alone did not identify a state of zinc deficiency which impaired fetal growth in monkeys.

Extracellular superoxide dismutase activity is affected by dietary zinc intake in nonhuman primate and rodent models.

Assessment of zinc nutriture is often compromised by the lack of reliable biomarkers. In the present study the effect of dietary zinc deprivation on plasma extracellular superoxide dismutase (EC SOD) activity was investigated in rat and rhesus macaque models. This enzyme, which contains both zinc and copper, is distinct from cytosolic copper-zinc SOD. Young, growing rats fed zinc-deficient diets (1.5 nmol Zn/g diet) were characterized by low plasma zinc concentrations and plasma EC SOD activities (16% and 56% of controls, respectively). Adolescent rhesus macaques fed diets that contained a marginal amount of zinc (30.6nmol Zn/g diet) also had low plasma zinc concentrations and low EC SOD activities compared with controls fed diets containing 765 nmol Zn/g diet (75% and 40%, respectively). Enzyme activity was not affected after in vitro addition of zinc to plasma samples from control, restrict-fed, and zinc-deficient rats. Taken together, these data support the concept that plasma EC SOD activity can be a biomarker for zinc status.

Modulation of behavioral performance of prepubertal monkeys by moderate dietary zinc deprivation.

Young rhesus monkeys (Macaca mulatta, n = 14) 25-30 mo of age were fed a zinc-deficient (ZD) diet (2 micrograms Zn/g diet) (moderate zinc deprivation) over 15 week. The ZD diet period was compared with a zinc-adequate (ZA) diet period (50 micrograms Zn/g diet) of the same duration, which either preceded or followed it (crossover design). Plasma zinc was lower at the end of the ZD than after the ZA period. There were no overt signs of zinc deficiency or effects on growth rate. Spontaneous motor activity was lower and performance of a visual-attention task and short-term-memory task were poorer during the ZD period than during the ZA period. Behavioral effects were detected as changes from individual baseline values, and often represented a failure to improve. The results suggests that dietary zinc deprivation can modulate behavior in prepubertal monkeys without affecting growth.

Long-term marginal zinc deprivation in rhesus monkeys. I. Effects on adult female breeders before conception.

To assess long-term effects of marginal zinc deprivation on pregnancy, adult non-pregnant female rhesus monkeys were fed diets containing 100 or 4 ppm zinc for 1 yr. then mated; effects on pregnancy and its outcome are under study. During this year, food intake was not depressed in zinc-deprived (ZD) monkeys, and there were relatively few effects on biochemical or hematological indices. By the end of the year, plasma zinc concentration was somewhat lower in ZD monkeys than in controls. Several immune variables, including serum IgM and IgG levels and polymorphonuclear leukocyte (PMN) function, were depressed in the ZD group, changes closely reflecting circannual fluctuations in plasma zinc levels in both diet groups. Endotoxin-activated plasma from ZD monkeys had less potential to promote chemotaxis than that from control monkeys, suggesting that defective PMN function may relate to a plasma effect. Marginal zinc deprivation may thus influence immune function before other variables are affected.