Abstract: The invention provides methods of treatment using retro-inverso peptides derived from interleukin-3 (IL-3) having between 12 and about 40 amino acids and including the sequence that is retro-inverso with respect to SEQ ID NO: 1. These peptides of the invention have the same activity as native IL-3 and also have neurotrophic activity. The peptides of the invention are also less susceptible to proteolytic degradation in vivo because of their D-amino acid linkage.

Abstract: The invention provides methods of treatment using retro-inverso peptides derived from leukemia inhibitory factor (LIF) having between 18 and about 40 amino acids and including the sequence that is retro-inverso with respect to SEQ ID NO: 1. The peptides of the invention have the same activity as native LIF and also have neurotrophic activity. The peptides of the invention are also less susceptible to proteolytic degradation in vivo because of their D-amino acid linkage.

Abstract: This invention provides methods of treatment using retro-inverso peptides derived from interleukin-6 (IL-6) having between 15 and about 40 amino acids, and including the sequence that is retro-inverso with respect to SEQ ID NO: 1, i.e. wherein said peptide comprises the sequence D-Glu-D-Ala-D-Met-D-Lys-D-Pro-D-Leu-D-Asn-D-Leu-D-Asn-D-Asn-D-Glu-D-Ala-D-Leu-D-Ala-D-Glu. The peptides of the invention have the same activity as native IL-6 and also have neurotrophic activity. The peptides of the invention are also less susceptible to proteolytic degradation in vivo because of their D-amino acid linkage.

Abstract: A method for stimulating prosaposin receptor activity in a cell by transfecting the cell with a DNA or RNA molecule encoding prosaposin or a prosaposin receptor agonist. The DNA or RNA molecule is administered either in vivo or used to transfect neural cells or neural stem cells ex vivo followed by reintroduction of the cells into an individual.