Nature 366, 742 - 745 (30 December 1993); doi:10.1038/366742a0

A role for Fyn tyrosine kinase in the suckling behaviour of neonatal mice

Takeshi Yagi^*†, Shinichi Aizawa^*, Tomoyuki Tokunaga^*, Yasuyo Shigetani^*, Naoki Takeda^* & Yoji Ikawa^*‡§

^*Laboratory of Molecular Oncology, Tsukuba Life Science Center, Institute of Physical and Chemical Research (RIKEN),Ibaraki 305, Japan
^‡Department of Biochemistry, Tokyo Medical and Dental University School of Medicine, Tokyo 113, Japan
^† Present address: Department of Neurobiology and Behavioral Genetics, National Institute for Physiological Sciences, Myodaiji, Okazaki 444, Japan.
^§To whom correspondence should be addressed

NON-RECEPTOR-TYPE tyrosine kinases of the Src family, such as Src, Yes and Fyn, are strongly expressed in the brain and have been suggested to have an important function in the central nervous system^1–5. We generated Fyn-deficient mice by inserting the -galactosidase gene (lacZ) into the fyn gene. The homozygous Fyn-mutant neonates from homozygous Fyn-deficient parents died because of a suckling problem. Neonates were, however, able to suckle milk normally when the homozygous mother's mammary glands had been activated by suckling of a heterozygous or wild-type pup. In these homozygous pups, the modified glomerular complex of the olfactory bulb, which had been suggested to play a role in perceiving pheromones, was abnormal in shape and reduced in size, and the hippocampal cell-layer was undulated. These results suggest that Fyn may be involved in the initial step of instinctive suckling behaviour in neonates.

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