Isolation alters striatal met-enkephalin immunoreactivity in rat pups

被引:8
作者
Carden, SE
Tempel, A
Hernandez, N
Hofer, MA
机构
[1] COLUMBIA UNIV COLL PHYS & SURG,NEW YORK STATE PSYCHIAT INST,DEPT DEV PSYCHOBIOL,NEW YORK,NY 10032
[2] LONG ISL JEWISH MED CTR,DEPT ANESTHESIOL,NEW HYDE PK,NY 11042
[3] ALBERT EINSTEIN COLL MED,NEW HYDE PK,NY 11042
关键词
isolation distress; ultrasonic vocalization; maternal separation; endogenous opioids; met-enkephalin; attachment;
D O I
10.1016/0031-9384(95)02243-0
中图分类号
B84 [心理学];
学科分类号
04 ; 0402 ;
摘要
Isolated preweanling rats emit ultrasonic vocalizations. Mu- and delta-opioid agonists quiet isolated pups; naltrexone, an opioid receptor blocker, prevents this quieting. A littermate companion is as effective as morphine in quieting vocalizations, and naltrexone also blocks companion quieting. We have now quantified methionine enkephalin (Met-ENK) immunoreactivity in the brains of 10-day-old Wistar rat pups taken directly from the home cage or kept either alone or with a companion for a brief or prolonged period. Met-ENK is an endogenous ligand that binds to the mu- and delta-opioid receptors. Striatal peptide levels were higher when pups were with a companion than when they were kept alone; the peptide level of pups in the home cage did not differ from either. Comparisons of pups in the brief (5 min) and prolonged (60 min) separation conditions showed significantly higher peptide levels following a brief period out of the nest than at the end of an hour. In hypothalamus, hippocampus, and frontal cortex neither social condition nor duration of separation significantly altered peptide quantity. Larger amounts of Met-ENK in pups provided with a companion could reflect an increase in posttranslational cleavage of the precursor molecule leading to stimulation of receptors that act to diminish USV. Reduced levels following 60 min out of the home cage might reflect depletion of the peptide following an initial release during the period when the pup's vocal response is most vociferous.
引用
收藏
页码:51 / 53
页数:3
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