The effects of structure-conformation modifications of melanotropin analogs on learning and memory: D-amino acid substituted linear and cyclic analogs
Autor: | Fahad Al-Obeidi, Tomi K. Sawyer, Bill E. Beckwith, Timothy P. Tinius, J.A. Affholter, Victor J. Hruby |
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Rok vydání: | 1989 |
Předmět: |
Male
medicine.medical_specialty Protein Conformation Physiology Amnesia Peptide Peptide hormone Biochemistry Structure-Activity Relationship Cellular and Molecular Neuroscience Endocrinology Isomerism Memory Reference Values Internal medicine medicine Animals Learning D-amino acid Amino Acid Sequence Receptor chemistry.chemical_classification Electroshock Memoria Rats chemistry alpha-MSH Pituitary hormones Biophysics Passive avoidance medicine.symptom |
Zdroj: | Peptides. 10:361-368 |
ISSN: | 0196-9781 |
Popis: | Alpha-MSH has a wide variety of putative biological activities in addition to its classical melanocyte dispersing activity. Since each of these activities appears to be mediated by a discrete receptor, this peptide is an excellent candidate for exploring conformational restrictions which determine the chemical-physical basis for hormone action on specific activities. Experiments One and Two evaluated several cyclic and linear analogs of alpha-MSH on retrieval of memory during the reactivation of memory for a passive avoidance response following hypothermia-induced amnesia. Three of the cyclic analogs appear to have enhanced the peptide's ability to serve as a reactivation agent. One of the linear Nle4,D-Phe7 analogs antagonized whereas three others enhanced reactivation. The D-Phe7 substitution in cyclic analogs did not affect reactivation. Another group of animals were trained on a step-through passive avoidance task and tested 25 days later. The cyclic analog enhanced memory whereas the D-Phe7 analog and alpha-MSH had no effect. Finally, two analogs were tested on a black-white discrimination. Although the cyclic analog had no effect on either acquisition or reversal of this learning, the Nle4,D-Phe7 analog significantly impaired reversal learning. The results from these preliminary studies suggest that structural modifications of alpha-MSH do alter its potency and pattern of actions in learning and memory situations. |
Databáze: | OpenAIRE |
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