Time course of VMN lesion effects on lordosis and ultrasound production in hamsters

Lesions of the ventromedial hypothalamus (VMN) depress lordosis but increase ultrasonic vocalization in female hamsters. These changes are consistent with the behavioral incompatibility of lordosis and ultrasound production and suggest that the VMN coordinates short-term changes in these behaviors. In keeping with past results, unilateral lesions disrupted lordosis responses to contralateral flank stimulation. The change appeared within 15 min after the lesion and was much more rapid than the corresponding effect in rats. For hamsters, these findings support other evidence suggesting VMN mediation of somatosensory, not just hormonal, influences on lordosis. In a companion study, ultrasound rates became depressed within 15 min of bilateral lesion of the VMN, suggesting a role for the VMN in the short-term control of ultrasound production. Calling at later time intervals was facilitated by the lesions. The direction and time course of the lesion effects on lordosis and ultrasound production suggest that the VMN cannot easily account for the behavioral incompatibility of these 2 responses.     

Differential effects of prefrontal lesions and combined prefrontal and limbic lesions on subsequent learning performance in the cat.

15 cats were given lesions in either the prefrontal cortex alone (n?=?7) or in the prefrontal cortex, anterior thalamus, mamillary bodies, and subiculum (n?=?8) before being tested in the acquisition of visual-reversal, delayed-alternation, and 2-way active-avoidance tasks. Lesioned Ss were compared to 6 unoperated and 4 sham-operated controls. As an extension of E. Irle and H. J. Markowitsch's (see record 1984-19842-001) study, in which triple limbic lesions failed to impair learning behavior of cats, the present study examined the effects of a lesion in the 4th brain structure (in addition to the original triple lesions). Results indicate that, compared with controls, Ss with prefrontal lesions were impaired in the acquisition of the avoidance task. In contrast, Ss with combined lesions were unimpaired in the acquisition of the visual-reversal task, facilitated in the acquisition of the avoidance task, but impaired in the acquisition of the delayed-alternation task. The superior performance Ss with combined lesions is interpreted as due to a lesion-induced functional shift acting on intact brain structures which, prior to massive limbic lesions, remained inhibited. (56 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of beta-endorphin and Met- and Leu-enkephalin on steroid hormone-induced lordosis in ovariectomized female rats

The effect of intrathirdventricular (I.T.V.) injections of beta-endorphin, anti-beta-endorphin antiserum, Met-enkephalin, Leu-enkephalin, and naloxone on the initial activation and final development of steroid hormone-mediated induction of female sexual receptivity was studied in ovariectomized female rats. The lordosis response to male mounts in ovariectomized rats after subcutaneous (S.C.) estradiol benzoate (EB) and progesterone (Prog) priming was facilitated by beta-endorphin, and Met-enkephalin (10 microg x 5 microl(-1)), but inhibited by Leu-enkephalin, when the peptides were injected into the third ventricle at the time of S.C. EB priming. A lower dose Met-enkephalin had no effects. Lordosis behavior in steroid hormone-primed rats was significantly facilitated when I.T.V. injections of Met-enkephalin were given 1 h prior to behavioral testing (47 h after EB priming). At 1 h prior to behavioral testing (47 h after EB priming), I.T.V. injection of beta-endorphin significantly inhibited lordosis behavior, especially at the higher dose of beta-endorphin (10 microg x 5 microl(-1)). Under those conditions, Leu-enkephalin had no effect. Lordosis behavior of ovariectomized female rats receiving S.C. steroid hormones and I.T.V. injection of anti-beta-endorphin antiserum was significantly inhibited when anti-beta-endorphin antiserum was injected at the time of EB priming. However, lordosis was significantly facilitated when anti-beta-endorphin antiserum was injected 1 h prior to the behavior testing (47 h after EB priming). In contrast, I.T.V. injection of the opioid antagonist naloxone given either at the time of EB priming or 1 h prior to behavioral testing (47 h after EB priming) decreased lordosis behavior. The present results suggest that 1) beta-endorphin, Met-enkephalin, and Leu-enkephalin have differential effects in the control of lordosis behavior; 2) the opioidergic systems may modulate initial-stage and final-stage estrogen-induced lordosis behavior; and 3) the opioidergic systems could be divided into the endorphinergic modulation-type and enkephalinergic modulation-type, based on their effects on lordosis behavior.     

Differential effects of double and triple lesions of the cat's limbic system on subsequent learning behavior.

Investigated the effects of multiple lesions of the chain-linked subicular cortex, mamillary bodies, and anterior thalamus on the acquisition of a visual reversal and an active 2-way avoidance task by 45 cats. Compared with controls, Ss with lesions of the anterior thalamus and the mamillary bodies (Group AT/MM), of the anterior thalamus and the subiculum (Group AT/SUB), or of the mamillary bodies and the subiculum (Group MM/SUB) were strongly impaired in acquiring the reversal task; Ss with lesions of all 3 structures (Group AT/MM/SUB) were unimpaired. Similarly, in the active avoidance task, 2 of the 3 groups with double lesions (MM/SUB and AT/SUB) were impaired, but Groups AT/MM and AT/MM/SUB were not, compared with the control group. It is suggested that lesion-induced shifts possibly act on intact cortical and/or thalamic structures that, prior to massive limbic lesion, remained inhibited or otherwise suppressed. It is assumed that the influence of 1 of the 3 core regions of the modified Papez-circuit is sufficient for inhibiting the action of such structures, which, following a complete lesion of the system, may control essential parts of the behaviors tested. (60 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decisional analysis of the effects of limbic lesions on learning in monkeys.

Examined the hypothesis that behavior during discrimination learning and reversal is under control of 2 competing variables: the patterned cues to be discriminated and the noncontingent schedule of reinforcement. An experiment was conducted with 8 adolescent rhesus monkeys using a modified decision theoretic procedure. Results show that the 2 variables were operative and that noncontingent reinforcement produced a strong position bias against discriminating. This bias was quantitatively more easily overcome by normal Ss than by Ss with hippocampal-amygdala lesions though the strategy and tactics used were the same for both groups. It is concluded that the hippocampus and amygdala influence attention through mechanisms that regulate motivational bias. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential influence of stereoisomers of estradiol on sexual behavior of female hamsters.

Morphological and behavioral responses to estradiol-17β (E?-17β) and estradiol-17α (E?-17α) were examined in a series of 3 experiments with golden hamsters. The E?-17β augmented uterine growth to a greater extent than E?-17α. Lordosis in ovariectomized adults was elicited by treatment with E?-17β but not with E?-17α (each tested in combination with progesterone). When administered neonatally, only E?-17β disrupted estrous cyclicity in the intact female and induced the ability to mount in ovariectomized, androgen-treated adults. Results suggest the existence of a stereospecific response to estrogenic stimulation in neural tissue comparable with that occurring in the uterus. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Separation of septal influences on lordosis, ultrasound production, and body weight

It is well known that macromolecules like albumin are markedly restricted in their passage across the glomerular capillary wall. However, the relative importance of solute size, charge and shape is currently debated since much of the previous work is based on dextran in neutral or charge-modified forms. These polymers have certain drawbacks that make them less suitable for analysis of capillary permeability and the notion of a glomerular charge barrier has therefore been questioned. Moreover, macromolecules larger than albumin (mol. wt. 69,000) have been suggested to pass through nonselective 'shunt' pathways. In order to study glomerular permeability, isolated rat kidneys were perfused with albumin solutions containing trace amounts of two differently radiolabelled isoenzymes of lactate dehydrogenase (LDH) at low temperature to inhibit tubular function. The isoenzymes have similar size (mol. wt. 140,000) and shape but differ in charge, one carrying a negative net surface charge (LDH1, -19) and the other being slightly cationic (LDH5, +2). The urine and perfusate samples were subjected to high pressure liquid chromatography (HPLC) gel-filtration to allow for measurements of intact LDH. The fractional clearance was 0.11% +/- 0.04% for the anionic LDH1 and 0.56% +/- 0.07% for LDH5, whereas that for albumin was 0.21% +/- 0.03% at a glomerular filtration rate of 0.11 +/- 0.01 mL min-1 g-1 kidney wet weight. The results were analysed using a homogenously charged membrane model and are compatible with a charge density of 35 mEq L-1, with 95% confidence interval of 26-41 mEq L-1. These findings suggest a significant glomerular charge selectivity for proteins substantially larger than albumin. The charge density is, however, far less than estimated from dextran studies.     

The effects of limbic lesions on locomotion and stereotypy elicited by dopamine agonists in the rat

The purpose of this experiment was to investigate the functional contributions of various limbic structures to locomotion and stereotypy induced by dopaminergic drugs. Female rats were randomly assigned to one of 5 groups (n = 10-14 rats/group) that received either a lesion of the hippocampus (colchicine + kainic acid), basolateral amygdala (quinolinic acid), frontal cortex (aspiration), nucleus accumbens (ibotenic acid), or served as unoperated controls. Beginning at least 2 weeks following surgery locomotion (measured as photocell beam breaks) elicited by D-amphetamine (0.0, 0.32, 1.0 and 3.2 mg/kg), SKF 82958 (0.0, 0.04, 0.08 and 0.16 mg/kg) or quinpirole (0.0, 0.25, 0.1 and 0.5 mg/kg) was determined. In agreement with previous results rats with hippocampal lesions were hyperactive in response to amphetamine. In comparison to these changes in drug-induced locomotion, lesions of the basolateral amygdala, and frontal cortex had only minor effects on drug-induced locomotion. Lesions of the nucleus accumbens produced consistent hyperactivity that was suppressed by doses of amphetamine or quinpirole that elicited behavioral stereotypy. These results provide evidence suggesting that, in comparison to other limbic structures that have substantial inputs to the nucleus accumbens, the hippocampus play a relatively prominent role in the modulation of drug-induced locomotion.     

X-ray cinematographic analysis of lordosis in female rats.

X-ray movies were used to analyze skeletal movements of 10 hormone-primed female Sprague-Dawley rats during the onset of lordosis. The pattern of movements of the vertebral column and rear legs during lordosis indicates that this behavior is caused mainly by muscles acting to dorsiflex the vertebral column. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of behavioral deficits caused by lesions in septal and ventromedial hypothalamic areas of female rats.

41 female Holtzman rats with lesions in ventromedial hypothalamic (VMH) area and 37 Ss with lesions in septal area were compared with 30 normal Ss for passive-avoidance performance (Exp I), reversal learning (Exp II), and spontaneous alternation (Exp III). Lesions in both septal and VMH areas produced a deficit in passive-avoidance performance, a greater number of errors in reversal learning, and reduced spontaneous alternation in a -maze. The qualitatively similar behavioral deficits produced by septal and VMH lesions suggests that at least part of the functions of both of these areas may overlap in a single system. An attempt was made to identify such a functional system, and an explanation for the behavioral deficits produced by VMH damage was offered. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of three vocational counseling treatments.

Compared 3 treatments which included 2 self-administering counseling modes, Holland's Self-Directed Search (SDS), a modification of the SDS entitled Individual Vocational Planning (IVP), and traditional vocational counseling. 113 undergraduates seeking counseling at a college counseling center were randomly assigned to 1 of the 3 treatment or control groups. Pre- and posttest scores were obtained on frequency and variety of vocational information seeking, satisfaction with treatment, and other measures. In addition, differential costs of providing the treatments were examined. Results indicate that all treatments were about equally effective as measured and the college users appeared equally satisfied with them. Cost analysis indicated that the traditional counseling treatment cost 6 times more per S than SDS and 4 times more than the IVP. Low delivery cost and comparable effectiveness provide evidence for the self-administrable treatment modes as additional alternatives to traditional methods. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of posterior septal lesions on dispositional and representational memory.

[Correction Notice: An erratum for this article was reported in Vol 101(1) of Behavioral Neuroscience (see record 2008-10683-001). A phrase was erroneously deleted from the text. In the seventh paragraph on p. 713, the second sentence should read as follows: Early in training individual differences were great, but by the end of adaptation training, individual differences were quite small and all rats responded at close to asymptotic speeds.] A distinction between 2 classes of memory has been made in terms of the sensory availability of cues at the time of making discriminations that are influenced by past experience. Three tasks objectively defining this distinction were learned in a T-maze by 36 male Long-Evans rats in 3 groups: (a) a delayed non-matching-to-sample (DNMTS) that depended on representational memory; (b) a simple sensory discrimination (SD) that depended on dispositional memory; and (c) a more difficult discrimination that also depended on dispositional memory, called the simultaneous conditional discrimination (SCD). The DNMTS and SD tasks were acquired quickly; the SCD task took many more trials. Posterior septal lesions impaired DNMTS performance but had no effect on retention of tasks that depended on dispositional memory. Results indicate that dispositional and representational memory systems have at least partially distinct anatomical substrates in the brain and that it is the representational and not the conditional aspects of the DNMTS task that are impaired by the septal lesions. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Runway alternation and discrimination of mice with limbic lesions.

Trained 7 normal male HS mice (Norm), and 18 mice with septal (Sept) and cingulate-anterior limbic cortex lesions (Cing) in a straight-alley single-alternation task. Sept Ss performed significantly better than Norms, running faster on reinforced trials and slower on nonreinforced trials. Cing Ss performed as well as Norms. In a 2nd experiment with 64 Ss, Norm and Sept Ss learned a discrimination task using a food pellet or sound of a buzzer as a cue for either reinforced or nonreinforced trials. Sept Ss learned the food-cued task faster than Norms when nonreinforced trials were cued; Norms performed better when reinforced trials were cued with the buzzer. Results suggest that septal lesions enhance the cue value of food, and contradict the hypothesis that the septum is involved in response inhibition. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial amygdaloid lesions and the regulation of sociosexual behavioral patterns across the estrous cycle in female golden hamsters.

Two experiments were conducted to examine the behavioral effects of medial amygdaloid (M) lesions during the estrous cycle in female golden hamsters. In Experiment 1, males were paired with gonadally intact M-lesioned, sham-operated, or ovariectomized M-lesioned females and tested in large enclosures. Medial amygdaloid lesions reduced, significantly, the occurrence of precopulatory biting attack and vaginal scent-marking behavior in females. In contrast, M lesions produced a significant increase in the duration of copulation. Mating behavior was also observed for a brief period of time in 1 M-lesioned female during the diestrus period and in 2 ovariectomized animals. After copulation, M-lesioned females attacked their mating partner less frequently than did sham-lesioned animals, which suggests that M lesions may modulate the reduction of both pre- and postcopulatory aggressive behavior by common processes. The attenuation in aggressive responsiveness was further documented in Experiment 2, which shows that during intrasexual fights, M-lesioned females exhibited significantly fewer offensive agonistic responses than did sham-operated opponents. Collectively, the results demonstrate that M lesions produce significant alterations in both social and sexual response patterns and suggest that M may be a neural component of a forebrain inhibitory system regulating the display of feminine copulatory behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential chemical modification of substrate binding areas in porcine-pancreatic alpha-amylase by three regioisomeric photolabile ligands

Binding studies of metallothionein and rat spermatozoa were performed using 125I-Tyr-metallothionein (125I-MT). Reactions between 125I-MT and spermatozoa indicated that MT bound in two forms, namely, middle affinity (Kd1 = 2 x 10(-9) M) binding and low affinity (Kd2 = 1 x 10(-8) M) binding. Labeled MT binding to spermatozoa was inhibited by adding anti-MT antibody. Total binding reactions of MT were temperature and incubation time dependent. By transmission electron microscopy using a gold conjugate (indirect method), gold particles bound to MT were shown to bind to the cell membrane of the head and the proximal portion of the tail. By optical autoradiography, grains of labeled MT were localized mainly in the head and the proximal portion of the tail. By electron microscopical autoradiography, grains of labeled MT were identified mainly in the cell membrane of the head and tail and partly in the nucleus. These results suggest that MT has both specific and non-specific binding sites on the spermatozoal membrane.     

Differential effects of unilateral and bilateral caudate lesions on side preferences and timing behavior in rats.

Trained 24 female Sprague-Dawley rats to barpress on a DRL-16 sec schedule for water reinforcement. Ss were allowed to barpress on either of 2 levers (left and right). All Ss showed consistent side preferences. For the nonsignaled condition, normal rates were related to the strength of side preferences; lower rates and better timing performance were significantly correlated with greater preferences. Unilateral lesions in the caudate nucleus ipsilateral to side preferences facilitated performance during nonsignaled test sessions and increased side preferences during both. Unilateral lesions contralateral to side preferences impaired performance during nonsignaled test sessions and decreased side preferences during all sessions. Bilateral lesions transiently depressed response rates without significantly affecting timing performance or side preferences. It is suggested that side preferences are intimately involved in the control of behavior by internal stimuli and that an inherent asymmetry in nigrostriatal function underlies side preferences; the effect of a unilateral striatal lesion will depend on whether the lesion is placed in the more or less active striatum. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of neuropeptides on cytokine production by mouse helper T cell subsets

DNA damage caused by tamoxifen and its derivatives was examined by estimating the conversion of supercoiled pUC18 plasmid DNA to linear form by means of agarose gel electrophoresis. N-Desmethyltamoxifen induced DNA cleavage and its effect was enhanced by the addition of reducing agents such as dithiothreitol, NADPH and 2-mercaptoethanol. 4-Hydroxytamoxifen itself had little effect, but the cleavage was slightly enhanced by the addition of reducing agents. DNA damage was higher with alpha-hydroxytoremifene than with alpha-hydroxytamoxifen, which had a prominent effect only at high concentration. The cleavage by alpha-hydroxy derivatives were not enhanced by reducing agents. No damage was induced by tamoxifen, toremifene, 3-hydroxytamoxifen or N-desmethyltoremifene. The DNA cleavage by N-desmethyltamoxifen was inhibited by the addition of EDTA, mannitol, sodium azide, methionine, catalase and superoxide dismutase. The formation of 8-hydroxy-2'-deoxyguanosine was also examined with calf thymus DNA in vitro. A slight increase of its level was found with 4-hydroxytamoxifen in the presence of dithiothreitol and also with N-desmethyltamoxifen in the presence of NADPH, but alpha-hydroxytoremifene and alpha-hydroxytamoxifen were ineffective. These experimental data suggest that among metabolites of tamoxifen, N-desmethyltamoxifen and probably also 4-hydroxytamoxifen cause oxidative DNA damage in which redox cycling is involved. The DNA damage by alpha-hydroxytoremifene appears to involve a different mechanism from that by N-desmethyltamoxifen. Tamoxifen and toremifene are possibly metabolized to the forms contributing to DNA damage.     

Differential effects of parent and grandparent drug use on behavior problems of male and female children.

Examines relations among grandparent and maternal drug use, mate's drug use, mother's dyadic adjustment, and behavioral/developmental problems in children (64 boys and 75 girls, aged 2–8 yrs). Six factors emerged from a 24-item checklist for mothers: Developmental Problems, Fearfulness, Hyperactivity, Acting-Out Behaviors, Psychosomatic Complaints, and Social Problems. Results indicated that (1) boys were more likely than girls to have developmental and social problems and (2) grandparent and maternal drug use significantly predicted more problems for boys than girls. Grandparent use predicted more Hyperactivity, Acting Out, Psychosomatic Complaints, and Social Problems for boys, and more Acting Out by girls. Maternal drug use predicted more Fearfulness, Hyperactivity, and Social Problems for boys, and no problems for girls. Maternal drug use predicted developmental problems for boys and girls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of testosterone propionate administered neonatally on puberty and bisexual behavior in female hamsters.

Treated female golden hamsters with oil, 3-mg, 30-mg, or 300-mg testosterone propionate (TP) as neonates in Exp I. Neonatal TP treatment delayed the onset of puberty by 4.5 days to an age near that previously reported for the male hamster. In addition, neonatal TP altered genital morphology, induced the capacity for mounting behavior, and at the highest dosage, disrupted the ability to bear and rear young. Vaginal and behavioral estrous cycles, however, were not influenced by neonatal TP. In Exp II 600-mg TP administered neonatally blocked estrous cyclicity but did not eliminate the capacity to display feminine sexual behavior. Results imply that masculinization and defeminization are separate aspects of neurobehavioral sexual differentiation, and that defeminization includes several independent physiological processes. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)