γ-Aminobutyric acid type A receptors modulate cAMP-mediated long-term potentiation and long-term depression at monosynaptic CA3–CA1 synapses

cAMP induces a protein-synthesis-dependent late phase of long-term potentiation (LTP) at CA3–CA1 synapses in acute hippocampal slices. Herein we report cAMP-mediated LTP and long-term depression (LTD) at monosynaptic CA3–CA1 cell pairs in organotypic hippocampal slice cultures. After bath application of the membrane-permeable cAMP analog adenosine 3′,5′-cyclic monophosphorothioate, Sp isomer (Sp-cAMPS), synaptic transmission was enhanced for at least 2 h. Consistent with previous findings, the late phase of LTP requires activation of cAMP-dependent protein kinase A and protein synthesis. There is also an early phase of LTP induced by cAMP; the early phase depends on protein kinase A but, in contrast to the later phase, does not require protein synthesis. In addition, the cAMP-induced LTP is associated with a reduction of paired-pulse facilitation, suggesting that presynaptic modification may be involved. Furthermore, we found that Sp-cAMPS induced LTD in slices pretreated with picrotoxin, a γ-aminobutyric acid type A (GABAA) receptor antagonist. This form of LTD depends on protein synthesis and protein phosphatase(s) and is accompanied by an increased ratio of failed synaptic transmission. These results suggest that GABAA receptors can modulate the effect of cAMP on synaptic transmission and thus determine the direction of synaptic plasticity.

Letter from Artemas Ward to Benjamin Stone, 1787 July 18

Artemas Ward wrote this letter to Benjamin Stone on July 18, 1787, expressing his concern about the expense of his son, Henry Dana Ward's, imminent studies at Harvard. Ward complains to Stone about his own debts and the failure of the government to honor their financial obligations to him, and he also expresses hope that the President of Harvard will allow his son to spend part of his time "keeping a school" during his freshman and sophomore years, thus earning an income sufficient to pay for his studies. Ward also suggests that it might be preferable that his son board with a respectable family, rather than live at the College.

Henry S. Frieze

Professor of Latin and acting president of the University of Michigan. On verso: North & Oswald Photographers. Toledo, Ohio. Established 1864. Take the Passenger Elevator at St. Clair Street Entrance, and Visit our New Studios, 45 Hall Block. Largest and finest in the West. All negatives preserved and Registered. Duplicates of this picture may be had at any time.

Camp, court and siege; a narrative of personal adventure and observation during two wars: 1861-1865; 1870-1871.

The writer served successively on the staffs of Generals T. Williams, T.W. Sherman, and W.B. Franklin, 1862-1864 and E.R.S. Canby, 1865 in Louisiana and the lower Mississippi Valley; and was assistant secretary and secretary of the U.S. legation at Paris, 1866-1871.

Watch and ward.

Mode of access: Internet.

Ward family; descendants of William Ward, who settled in Sudbury, Mass., in 1639.

Mode of access: Internet.

Facts and fancies about our "Son of the woods", Henry Clarence Kendall and his poetry : descriptive of the sights and sounds of Australia's mountains, shores and woodlands, a home of many dreams, Henry C. Kendall as Australia's patriot bard" a singer of the dawn.

Mode of access: Internet.

Shakespeare's King Henry V.

Mode of access: Internet.