Effect of Lithium on Concentrations of Glutamate and GABA Levels in Amygdala and Hypothalamus of Rat

LITHIUM salts have been used to treat manic-depressive psychosis^1,2 and reduce aggressive behaviour in animals^3–5. The hypothalamus and limbic structures, known to be involved in emotional behaviour, responded to lithium with specific changes in electrolyte distribution⁶ and EEG pattern⁷, respectively. “Attack” and “flight” behaviour associated with hypothalamic sites was evoked by glutamate and blocked by γ-aminobutyric acid (GABA)⁸. We have, therefore, studied the effects of lithium treatment, acute and prolonged, on the glutamate and GABA levels in the amygdala and hypothalamus of the rat.     

The response of riparian vegetation to flood‐maintained habitat heterogeneity†

Abstract Riparian environments are subject to the scouring and depositional effects of floods. Riparian vegetation and substrates are scoured during high flows, while litter and sediment is deposited downstream. In the Prosser and Little Swanport River catchments in south‐east Tasmania, vascular plant species were surveyed in large riparian relevés. Within these relevés, 1 × 1 m subplots were placed in both flood‐scoured and depositional environments. Species composition was compared between these three datasets, to investigate the importance of floods in determining species richness and species composition of riparian vegetation. Species richness and diversity were highest in areas experiencing flood scour. Herbs appear particularly reliant on the creation of gaps for colonization, and some major riparian shrub species may also require disturbance to maintain their abundance. The depositional environment tended to favour shrubs and graminoids. Given that differences in species composition are related to flood‐induced features of the riparian environment, the regulation of these rivers might reduce the diversity of the riparian vegetation downstream of dams.     

Unlocking the Past: Celebrating Historical Archaeology in North America

Unlocking the Past: Celebrating Historical Archaeology in North America. Lu Ann De Cunzo and John H. JamesonJr., eds. Gainesville: University Press of Florida, 2005. 255 pp.     

Can Black‐and‐White Ruffed Lemurs (Varecia variegata) Solve Object Permanence Tasks?

We examined object permanence in black‐and‐white‐ruffed lemurs (Varecia variegata) at Zoo Atlanta. A series of visible and invisible displacement tasks with suitable controls were presented to five adult subjects. Subjects performed significantly above chance on all regular tasks, except for the double invisible displacements. Subjects failed visible and invisible controls. Failure on the control trials did not appear to be because subjects used the “last box touched” strategy (subjects did not choose the last box touched significantly more than expected by chance). However, a substantial percentage of choices was made to the last box touched by the experimenter. There was no significant difference between this percentage, and the percentage of choices made to the baited box (on both visible and invisible controls), which indicates that subjects were drawn to both boxes which the experimenter visited/touched, and thus failed the controls. Based on the results from the present study, we believe that there is no evidence that black‐and‐white ruffed lemurs understand visible and invisible tasks in the traditional object permanence battery. Am. J. Primatol. 75:376‐386, 2013. © 2013 Wiley Periodicals, Inc.     

The Prothoracicotropes: Source of the Prothoracicotropic Hormone

SYNOPSIS. An in vitro assay for the insect prothoracicolropichormone (PTTH) has been developed which measures the rate ofecdysone synthesized by Manduca sexta prothoracic glands (PG)stimulated in vitro by PTTH. This assay has been used to quantifyPTTH in single neurosecretory cells (NSC) resulting in the identificationof one NSC in each hemisphere of the brain as the prothoracicotrope,source of PTTH. The axonal and dendritic distribution of theprothoracicotrope has been determined by cobalt filling withsilver intensification. From a comparison of the titers of PTTHin brains, corpora cardiaca and corpora allata during larval-pupaldevelopment, the corpus allatum has been identifiedas the neurohemalorgan for PTTH. Electron microscopic analyses suggest that theacellular sheath surrounding the corpus allatum contains theaxon terminals of the prothoracicotropes. There is at least one form of PTTH, {small tilde}22,000 molwt (big PTTH), and possibly a smaller form of about 7,000 molwt (small PTTH). Bioassay and PTTH hemolymph titer data duringthe head critical period (HCP) for larval-larval developmentreveal that big PTTH is released as a single peak lasting {smalltilde}6 hr. By contrast, during the first HCP of the last larvalinstar PTTH is released over a period of {small tilde}18 hrin three bursts, but its molecular weight has not been establishedwith certainty. The kinetics of PG activation by these two formssuggest that big PTTH may function to activate the PG dramaticallyand thereby elicit molting, while small PTTH may activate thePG minimally at the time of cellular reprogramming.