Sexual dimorphism of activity-dependent neuroprotective protein in the mouse arcuate nucleus.

Activity-dependent neuroprotective protein (ADNP) is a highly conserved vasoactive intestinal peptide (VIP) responsive gene that is expressed abundantly in the brain and in the body and is essential for brain formation and embryonic development. Since, VIP exhibits sexual dimorphism in the hypothalamus, the potential differential expression of ADNP in male and female mice was investigated. Real-time polymerase chain reaction revealed sexual dimorphism in ADNP mRNA expression as well as fluctuations within the estrus cycle. Immunohistochemistry with an antibody to ADNP showed specific staining in the arcuate nucleus of the hypothalamus. ADNP-like immunoreactivity in the arcuate nucleus also exhibited fluctuations during the estrus cycle. Here, brain sections at proestrus were the most immunoreactive and brain sections at estrus--the least. Furthermore, male arcuate nucleus ADNP-like immunoreactivity was significantly lower than that of the female estrus. Many neuropeptides, neurotransmitters and proteins are localized to the arcuate nucleus where they contribute to the regulation of reproductive cyclicity and energy homeostasis. The results presented here suggest that ADNP has a part in the estrus cycle as an affecter or an effector.

Clinical endocrinology and metabolism. Potential clinical applications of vasoactive intestinal peptide: a selected update.

Neuropeptides are expressed in neurons innervating endocrine cells or in endocrine cells and cancer cells, and are released on site to act as hormones and growth factors. Vasoactive intestinal peptide (VIP) was first discovered in the early 1970s and has since become the area of research for many laboratories. VIP has a neuroendocrine role as it is intimately involved with the synthesis, secretion and action of other neuroendocrine hormones as well as cytokines and chemokines. Major outcomes of VIP downregulation encompass developmental and behavioral dysfunctions, including impaired diurnal rhythms. Overexpression of VIP has been associated with diarrhea and cancer, and overexpression of VIP receptors is associated with cancerous growth. This short review outlines some of the recent progress made in VIP research.

Subcellular localization and secretion of activity-dependent neuroprotective protein in astrocytes.

Activity-dependent neuroprotective protein (ADNP, approximately 123562.8 Da), is synthesized in astrocytes and expression of ADNP mRNA is regulated by the neuroprotective peptide vasoactive intestinal peptide (VIP). The gene that encodes ADNP is conserved in human, rat and mouse, and contains a homeobox domain profile that includes a nuclear-export signal and a nuclear-localization signal. ADNP is essential for embryonic brain development, and NAP, an eight-amino acid peptide that is derived from ADNP, confers potent neuroprotection. Here, we investigate the subcellular localization of ADNP through cell fractionation, gel electrophoresis, immunoblotting and immunocytochemistry using alpha-CNAP, an antibody directed to the neuroprotective NAP fragment that constitutes part of an N-terminal epitope of ADNP. Recombinant ADNP was used as a competitive ligand to measure antibody specificity. ADNP-like immunoreactivity was found in the nuclear cell fraction of astrocytes and in the cytoplasm. In the cytoplasm, ADNP-like immunoreactivity colocalized with tubulin-like immunoreactivity and with microtubular structures, but not with actin microfilaments. Because microtubules are key components of developing neurons and brain, possible interaction between tubulin and ADNP might indicate a functional correlate to the role of ADNP in the brain. In addition, ADNP-like immunoreactivity in the extracellular milieu of astrocytes increased by approximately 1.4 fold after incubation of the astrocytes with VIP. VIP is known to cause astrocytes to secrete neuroprotective/neurotrophic factors, and we suggest that ADNP constitutes part of this VIP-stimulated protective milieu.

VIP and drug design.

The following review outlines the physiological outcome of VIP and VIP gene manipulations. Previously, we reviewed the various VIP receptors associated with biological functions ranging from growth regulation, sexual function, bronchodilation, vasodilation and immune interactions to neurotrophism. VIP-based drug design is discussed below.

NAP accelerates the performance of normal rats in the water maze.

NAP (Asn-Ala-Pro-Val-Ser-Ile-Pro-Gln) has neuroprotective, memory enhancing, and neurotrophic properties. NAP is a short peptide sequence derived from the recently cloned, activity-dependent neuroprotective protein. The current study was designed to evaluate NAP activity in normal middle-aged animals to further assess NAP's breadth of neuroprotection. NAP was administered by inhalation. Results showed that in the paradigm of the Morris water maze, assessing short-term memory, only the NAP-treated middle-aged rats and not placebo-treated rats showed significant improvements by the end of the testing period. These results suggest efficacy for NAP in normal aging that is associated with accumulating environmental and genetic toxic factors.