Despite growing evidence that increased brain-derived neurotrophic factor (BDNF) and hippocampal adult neurogenesis are necessary for the behavioral actions of antidepressants in rodents, the cellular mechanisms involved in these effects are still unknown. Li et al. in this issue of Neuron demonstrate that the presence of TrkB, the high-affinity receptor for BDNF, in hippocampal neural progenit...

Foliations by constant mean curvature hypersurfaces provide a possibility of defining a preferred time coordinate in general relativity. In the following various conjectures are made about the existence of foliations of this kind in spacetimes satisfying the strong energy condition and possessing compact Cauchy hypersurfaces. Recent progress on proving these conjectures under supplementary assu...

Let F be a set system over an underlying finite set X, and let μ be a nonnegative measure over X. I.e., for every S ⊆ X, μ(S) = ∑ x∈S μ(x). A measure μ ∗ on X is called a multiplicative λ-approximation of μ on (F , X) if for every S ∈ F it holds that aμ(S) ≤ μ∗(S) ≤ bμ(S), and b/a = λ ≥ 1. The central question raised and partially answered in the present paper is about the existence of meaningf...

The neuropeptide substance P (SP) modulates bone metabolism. This study examined the temporal appearance of the neuropeptides SP and brain-derived nerve growth factor (BDNF) and their receptors (neurokinin-1 receptor (NK1-R) and Trk B, respectively) in the rat trigeminal ganglion to investigate the role of neuropeptides in healing after tooth extraction. Rats were anesthetized and their upper r...

Nerve growth factor (NGF) functions as a ligand for two receptors, the TrkA tyrosine kinase receptor and the p75 neurotrophin receptor (p75NTR). The Ig-like domains of Trk receptors and the cysteine-rich repeats of p75NTR are involved in binding to the neurotrophins. Recently, a closely related gene to p75NTR called neurotrophin receptor homolog-2 (NRH2) was identified; however, the function of...

Neurotrophins bind to two structurally unrelated receptors, the trk tyrosine kinases and the neurotrophin receptor p75(NTR). Ligand activation of these two types of receptor can lead to opposite actions, in particular the prevention or activation of programmed cell death. Many cells co-express trk receptors and p75(NTR), and we found that p75(NTR) was co-precipitated with trkA, trkB and trkC in...