Nest Making and Oxytocin Comparably Promote Wound Healing in Isolation Reared Rats

Abstract

BackgroundEnvironmental enrichment (EE) fosters attachment behavior through its effect on brain oxytocin levels in the hippocampus and other brain regions, which in turn modulate the hypothalamic-pituitary axis (HPA). Social isolation and other stressors negatively impact physical healing through their effect on the HPA. Therefore, we reasoned that: 1) provision of a rat EE (nest building with Nestlets®) would improve wound healing in rats undergoing stress due to isolation rearing and 2) that oxytocin would have a similar beneficial effect on wound healing.Methodology/Principal FindingsIn the first two experiments, we provided isolation reared rats with either EE or oxytocin and compared their wound healing to group reared rats and isolation reared rats that did not receive Nestlets or oxytocin. In the third experiment, we examined the effect of Nestlets on open field locomotion and immediate early gene (IEG) expression. We found that isolation reared rats treated with Nestlets a) healed significantly better than without Nestlets, 2) healed at a similar rate to rats treated with oxytocin, 3) had decreased hyperactivity in the open field test, and 4) had normalized IEG expression in brain hippocampus.Conclusions/SignificanceThis study shows that when an EE strategy or oxytocin is given to isolation reared rats, the peripheral stress response, as measured by burn injury healing, is decreased. The findings indicate an association between the effect of nest making on wound healing and administration of the pro-bonding hormone oxytocin. Further elucidation of this animal model should lead to improved understanding of how EE strategies can ameliorate poor wound healing and other symptoms that result from isolation stress.

Oxytocin effects on experimental skin wound healing

“…Herein, it could be demonstrated that OXY is able to ameliorate skin regeneration as given by a fast epithelial recovery with mostly intact dermal structures [13,51]. One major reason for these findings might also be the fact of better social interactions, as group housed rats as well as rats that have been given environmental enrichment presented with overall better healing performances most likely associated with increased OXY and decreased cortisol levels [12,13,51]. On the contrary, it could further be demonstrated that the application of OXY resulted in less remote-to-injury organ damage [51][52][53].…”

“…Male homozygous SKH-1-h hairless mice (12)(13)(14)(15)(16) weeks old) with a body weight (bw) of 30-40 g were used in the study. The animals were housed in standard laboratories with a 12 h light-dark cycle and had free ad libitum access to standard laboratory food and water.…”

“…Additionally, different animal models proved that OXY supported better social interactions (i.e. less stress), which were associated with overall better healing performances [12,13]. If applied repetitively, the effects on other transmitter systems could demonstrate long-lasting effects that show interaction in both growth and healing actions [7,[12][13][14].…”

“…less stress), which were associated with overall better healing performances [12,13]. If applied repetitively, the effects on other transmitter systems could demonstrate long-lasting effects that show interaction in both growth and healing actions [7,[12][13][14]. Herein, it could be demonstrated that OXY application in rats leads to an acute antiinflammatory response [15].…”

Environmental enrichment for laboratory animals in practice

“…Πρόσφατη μελέτη των Vitalo et al (2009) απέδειξε την άμεση θετική επίδρα ση που έχει η προσθήκη υλικού για την κατασκευή φω λιάς στο χρόνο επούλωσης των τραυμάτων σε επίμυες.…”