Abstract
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.
Original language | English (US) |
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Pages (from-to) | 361-368 |
Number of pages | 8 |
Journal | Peptides |
Volume | 10 |
Issue number | 2 |
DOIs | |
State | Published - 1989 |
Keywords
- Behavior
- Learning
- MSH
- Melanotropins
- Memory
- Peptides
ASJC Scopus subject areas
- Biochemistry
- Physiology
- Endocrinology
- Cellular and Molecular Neuroscience