Postnatally induced differences in adult pain sensitivity depend on genetics, gender and specific experiences: reversal of maternal deprivation effects by additional postnatal tactile stimulation or chronic imipramine treatment.
Postnatal endotoxin exposure, handling or maternal deprivation produce long-lasting individual differences in various neuroendocrine and behavioural responses. However, the impact of postnatal experiences on adult pain sensitivity and its reversibility by postnatal additional tactile stimulation or antidepressants in adulthood is not well understood. Therefore, postnatal endotoxin application as a model for infection, maternal deprivation as a model for depression, and postnatal handling as a model for stimulation were compared with respect to the effects on pain sensitivity in adult Fischer 344 (F344) and Lewis (LEW) rats. Handling increased hot plate latencies in adult F344 and LEW rats, while maternal deprivation shortened hot plate latencies only in LEW rats. Prophylactic treatment strategies, such as tactile stimulation of the dorsal neck region of pups directly after maternal deprivation, or chronic treatment of adult maternally deprived rats using imipramine, successfully provide protection against the maternal deprivation-induced shortening of hot plate latencies. Thus, there is considerable specificity of certain postnatal experiences in modulating adult pain sensitivity and the maternal deprivation-induced hyperalgesia is reversible by different interventional regimes. These findings may explain some of the individual differences in pain sensitivity of humans and the differential efficacy of antidepressants in pain syndromes.
Stephan
Michael
M
Department of Functional and Applied Anatomy, Medical School of Hannover, OE4120, Carl-Neuberg-Str. 1, Germany.
Helfritz
Fabian
F
Pabst
Reinhard
R
von Hörsten
Stephan
S
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology*; D004731:Endotoxins / Q000494:pharmacology; D005260:Female; D006234:Handling, Psychological; D007099:Imipramine / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008426:Maternal Deprivation; D010146:Pain / Q000235:genetics* / Q000503:physiopathology* / Q000523:psychology; D010147:Pain Measurement; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D011930:Reaction Time / Q000502:physiology; D012727:Sex Characteristics
D000929:Antidepressive Agents, Tricyclic; D004731:Endotoxins; D008070:Lipopolysaccharides; D007099:Imipramine