Total recovery of response to novelty after ectopic pituitary isografts in Snell Dwarf mice (dw/dw)

The effects of ectopic pituitary isografts on response to novelty were studied in adult Snell Dwarf mice. Because of anterohypophyseal deficiency, these animals exhibit dwarfism, sterility and marked neurochemical and behavioural deficits. When given the opportunity to move around freely in simultaneously presented novel and familiar environments, grafted dwarf (GRAFT Dw) and sham-grafted control (SHAM C) mice showed a significant novelty preference while sham-grafted dwarf (SHAM Dw) mice exhibited no preference. Both SHAM C and GRAFT Dw mice frequently reared and covered the familiar compartment more quickly than the novel compartment, while SHAM Dw mice reared infrequently and covered the two compartments at equal speed. These data reveal in the mutant a total indifference toward its environment and show a total recovery of neotic behaviour after grafting. The literature is very vague concerning the hormonal changes induced after ectopic pituitary grafting but subsequent specific hormonal treatments and biochemical manipulations would facilitate identification of the hypophyseal hormones and/or the growth factors involved in the behavioural changes.