Behavioral Effects of Gut Hormones in Neonatal Rats: I. Somatostatin Administration During the First Postnatal Week

Abstract

This exploratory study attempted to uncover behavioral and physical outcomes of changes in the peripheral SMS system in the first postnatal week. On postnatal days 1–7, Sprague-Dawley rat pups received daily s.c. injections of Somatostatin (SMS; 8 or 40 μg/kg), saline, or CPP-1 (8 or 40 μg/kg), a putative SMS receptor antagonist. Physical growth and neurobehavioral development of the pups, assessed on days 3, 6, 9 and 12, were not affected, in 3 separate replications (n = 11/treatment/ replication). In contrast, neonatal CPP-1 (40 μg/kg) reduced separation distress on day 14, as measured by ultrasonic vocalization and activity. In addition, neonatal SMS (40 μg/kg) tended to impair learning on a milk-rewarded Y-maze on days 15–16. These findings support further examination of the potential role of SMS in behavioral development.

Key Words:

• Somatostatin
• gut-hormones
• neonatal rats
• neurobehavioral development
• learning
• ultrasonic vocalization