Metabolic and endocrine aspects of the ventromedial hypothalamic syndrome in the rat.

Subjected 8 male Long-Evans hooded rats to parasagittal knife cuts that separated the medial from the lateral hypothalamic areas; following surgery, some Ss were given free access to food while others were restricted to normal quantities. Compared with 6 sham-operated controls, the restricted-food Ss exhibited hyperinsulinemia as early as 36 hr after surgery without any change in plasma glucose levels. The blood samples of free-food Ss which had become obese, showed hyperinsulinemia, mild hyperglycemia, and elevated levels of free fatty acids. These results suggest that the interruption of mediolateral hypothalamic connections produces hyperinsulinemia directly, and that further increases in insulin, glucose, and free fatty acid levels are caused by overeating. The surgical cuts produced an increase in aggressive behavior but no change in the circulating levels of testosterone. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypothalamic and midbrain neural pathways involved in eating, drinking, irritability, aggression, and copulation in rats.

Investigated in 3 experiments with male hooded rats (N = 61) the effects of parasagittal cuts placed at 3 anterior-posterior positions. Cuts that separated portions of the medial from the lateral hypothalamus produced severe hyposexuality if they lay lateral to the medial preoptic-anterior hypothalamic continuum. Hyperphagia, irritability, and modest sexual impairment were produced if the cuts lay lateral to the anterior tips of the ventromedial hypothalamic nuclei and slightly invaded the anterior hypothalamus. Posterior, but not anterior, medial-forebrain-bundle (MFB) cuts disrupted copulation. Central gray cuts resulted in slight hyperphagia, and reticular formation cuts resulted in hyposexuality. It is concluded that the medial hypothalamic nuclei exert their effects on eating, irritability, and copulation through their lateral connections with the lateral hypothalamus and those components of the MFB that descend on (or ascend from) the lower brainstem. (40 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypothalamic knife cuts: Effects on eating, drinking, irritability, aggression, and copulation in the male rat.

Describes 2 experiments with a total of 43 male hooded rats. In Exp. I, Ss with parasagittal knife cuts that separated the medial from the lateral hypothalamic areas (a) became hyperphagic, hyperdipsic, obese, and irritable; (b) did not change their level of aggressive responses against mice; and (c) copulated at an impaired rate or not at all. In Exp. II, 2 groups of Ss were subjected to coronal cuts restricted between the fornices at levels either anterior or posterior to the ventromedial hypothalamic nuclei. Most of the anterior-cut Ss increased their food and water intake, and some became irritable. Of the posterior-cut Ss, none increased and 1/2 decreased their food intake, some became hyperdipsic, and 1 became irritable. Neither of the coronal-cut groups changed levels of aggressive or sexual responses. It is concluded that the mediolateral hypothalamic connections are important for eating, irritability, and copulation. (42 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The hypothalamus: Neural systems involved in feeding, irritability, aggression, and copulation in male rats.

In 3 experiments with a total of 58 male hooded rats, cuts of the ventral amygdalofugal pathway resulted in slight aphagia, and cuts anterior to the medial preoptic area resulted in transient hyposexuality. A unilateral posterior medial forebrain bundle (MFB) cut combined with a contralateral parasagittal cut resulted in severe hyposexuality if the parasagittal cut lay lateral to the anterior hypothalamic nucleus, and in irritability if the parasagittal cut lay lateral to the ventromedial hypothalamic nucleus. It is concluded that (a) the medial hypothalamic nuclei exert their effects on irritability and copulation through their lateral connections with those components of the MFB that descend on, or ascend from, the lower brain stem; and (b) the neural pathways mediating the consummatory aspects of feeding, irritability, aggression, and copulation are distinct. (58 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The septum: Neural systems involved in eating, drinking, irritability, muricide, copulation, and activity in rats.

Measured eating, drinking, irritability, muricide, and copulation in 45 male albino Wistar rats before and after 1 of 3 coronal knife cuts in the septal region or a control operation. Activity was also measured postoperatively in the 3 experiments. Cuts posteroventral to the septum resulted in slight hypophagia, marked hyperdipsia, irritability, asexuality, and decrease in activity. Cuts of the fornix resulted only in slight decrease in activity. Cuts through the anterior septum resulted in irritability, slight hyposexuality, and slight decrease in activity. No significant correlations between the various behavioral effects were found. It is suggested that the neural pathways mediating eating, drinking, irritability, muricide, copulation, and activity are relatively distinct and that neural activity in the septal region probably does not influence behavior in any unitary fashion. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Midbrain and motivated behavior.

Obtained measures of eating, drinking, irritability, aggression, and copulation in 57 hooded male rats before and after they were subjected to midbrain knife cuts or control operations. Slight hypophagia resulted from cuts through the supramammillary and ventral tegmental decussations. Severe-to-moderate hyposexuality resulted from cuts involving either the medial lemniscus and zona incerta or the ventral reticular formation. Cuts through the central gray or dorsal reticular formation produced no significant behavioral effects. It is suggested that the medial lemniscus and the ventral reticular formation convey an ascending sensory-arousal influence that facilitates copulation. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the distribution of cholecystokinin B receptors in monkey brain

In view of recent evidence for a role for the B subtype of cholecystokinin (CCKB) receptor in panic and anxiety, the distribution of CCKB receptors in the forebrain of a Rhesus macaca monkey was examined by receptor autoradiography employing [125I]D-Tyr25(Nleu28,31)-CCK25-33S. CCKB receptors were widely and topographically distributed in cortex. Other structures with notable labelling included the basal ganglia, presubiculum, amygdala, mamillary bodies, cerebellar cortex and pineal gland. The distribution of CCKB receptors further supports roles for this peptide in behavioural processes.     

Corrosion protection of secondary lithium electrodes in organic electrolytes

Hydrocarbons show considerable surface activity in organic electrolytes; they, at least partially, displace the polar organic solvent molecules from any solid/electrolyte interface. Saturated hydrocarbons are chemically stable even versus lithium or lithium-rich alloys, and thus they are able to delay the irreversible reduction of organic electrolytes by these highly active negatives, i.e., they delay corrosion and surface filming of the negatives.

As surface filming of lithium strongly controls the growth of lithium dendrites during electroplating, a delay in the filming process significantly decreases dendrite growth. Prevention of dendrite growth, however, requires speedy protection of freshly created “dynamic’ surfaces and, hence, a high concentration (and solubility) of the hydrocarbon surfactant. On the other hand, for the protection of “static‘ electrodes under open cell conditions, even relatively insoluble surfactants may suffice.     

EphA4 (Sek1) receptor tyrosine kinase is required for the development of the corticospinal tract

Members of the Eph family of tyrosine kinase receptors have been implicated in the regulation of developmental processes and, in particular, axon guidance in the developing nervous system. The function of the EphA4 (Sek1) receptor was explored through creation of a null mutant mouse. Mice with a null mutation in the EphA4 gene are viable and fertile but have a gross motor dysfunction, which is evidenced by a loss of coordination of limb movement and a resultant hopping, kangaroo-like gait. Consistent with the observed phenotype, anatomical studies and anterograde tracing experiments reveal major disruptions of the corticospinal tract within the medulla and spinal cord in the null mutant animals. These results demonstrate a critical role for EphA4 in establishing the corticospinal projection.     

Olfactory bulbectomy and mucosal damage: Effects on copulation, irritability, and interspecific aggression in male rats.

Assigned 77 male hooded rats to groups receiving bilateral olfactory bulb ablations or nasal mucosal damage with zinc sulphate and to control groups. Bilateral olfactory bulbectomy resulted in markedly impaired copulation, irritability, and an increase in the number of Ss which would kill mice. Damage to the nasal mucosa did not change copulatory effectiveness or mouse killing, and resulted in transient mild irritability. Change in irritability was significantly correlated with mouse killing in both groups. It is concluded that the effects of bulbectomy are not due to an olfactory deficit, but rather to the olfactory deficit combined with the central nervous ablation, and that the bulbectomy-induced mouse killing and irritability may be the result of altering a common motivational mechanism. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)