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Published on: December 4, 2013
Neonatal isolation alters LTP in freely moving juvenile rats: sex differences
J D Bronzino1, P Kehoe, R J Austin-LaFrance
1Trinity College, Neuroscience Program, Hartford, CT 06106, USA. joseph.bronzino@trincoll.edu
Insights
Neonatal isolation enhances hippocampal long-term potentiation (LTP) in juvenile rats. This effect differs between males and females, impacting LTP magnitude and duration differently.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Developmental Neuroscience
Background:
- Neonatal isolation is known to enhance hippocampal long-term potentiation (LTP) in adult male rats.
- Previous research has focused primarily on male subjects, leaving sex-specific effects under-explored.
Purpose of the Study:
- To investigate the impact of neonatal isolation on hippocampal LTP in both male and female juvenile rats.
- To determine if sex differences exist in the effects of neonatal isolation on LTP magnitude and duration.
Main Methods:
- Assessed dentate granule cell population measures (EPSP slope, population spike amplitude) following medial perforant pathway tetanization.
- Compared LTP establishment and maintenance over 96 hours in neonatally isolated and control male and female rats.
Main Results:
- Males exhibited higher baseline EPSP slope and population spike amplitude than females.
- Neonatally isolated males showed significantly greater LTP enhancement than all other groups at 1 hour post-tetanization.
- At 96 hours, both isolated males and females displayed enhanced LTP compared to controls, indicating sex-specific alterations in LTP maintenance.
Conclusions:
- Males and females demonstrate distinct LTP enhancement profiles regarding magnitude and duration.
- Neonatal isolation modifies these sex-specific LTP profiles in a manner dependent on sex.
Abstract:
We have previously reported that neonatal isolation significantly enhanced the magnitude of hippocampal long-term potentiation (LTP) recorded from freely moving male rats tested at 30 days of age. The present study extends this work to examine the effects of neonatal isolation on hippocampal LTP in male and female juvenile rats. Changes in dentate granule cell population measures, i.e., EPSP slope and population spike amplitude (PSA), evoked by tetanization of the medial perforant pathway were used to assess the effects of neonatal isolation on LTP over a period of 96 hrs. Prior to tetanization, significant sex differences were obtained for input/output (I/O) response measures of EPSP slope and PSA, with males showing consistently higher values than females. No significant effect of treatment was obtained within either sex for baseline measures. Following tetanization significant sex differences were also obtained for both measures, with males showing significantly greater enhancement than females. Comparisons made at 1 hr post-tetanization (establishment of LTP) indicated that isolated males showed significantly greater enhancement than any other group. On the other hand, treatment differences were not obtained from females. At 96 hrs (maintenance of LTP), however, both neonatally isolated males and females showed significantly greater enhancement than either non-isolated siblings or unhandled controls. These results indicate that males and females exhibit different enhancement profiles with respect to both the magnitude and duration of LTP, and that neonatal isolation alters these profiles in a sex-specific manner.
