Effects of assisted feeding on Wobbler mouse motoneuron disease and on serotonergic and peptidergic sprouting in the cervical spinal ventral horn

The Wobbler mouse is used as a model of human motoneuron disease (MND). Dur ing the disease progress, the significant loss of motoneurons in cervical s pinal cord and cranial motor nuclei leads to the progressive loss of motor function in the forelimb, head, and neck regions. The loss of cutting and c hewing ability that results in the inability to feed properly might lead to a lower mean body weight (b. wt.) that is generally one-half that of the n ormal phenotype littermate controls. Nutritional deficit might also influen ce neuronal processes sprouting in the cervical spinal ventral horn. To det ermine whether nutritional deficits contribute to the wt. loss, and influen ce the progress of MND as well as its sprouting phenomenon, Wobbler and nor mal phenotype control littermates were dropper-fed three times daily on a r egular laboratory diet of Rat Chow. Weight measurements and behavioral test s were taken to monitor the disease. Immunocytochemisty of serotonin, subst ance P, and leucine enkephalin were conducted in the cervical spinal cord t o investigate if any alteration occurred on the previously reported values in ad lib-fed animals. Organ wts. were measured to determine where nutritio nal benefit was incurred. Although mean wt. loss in Wobblers was reduced, w t. differed significantly from the control values after dropper feeding. Ho wever, the progress of the disease or alteration of neurotransmitters conta ining neuronal processes were not affected by nutritional factors. Therefor e, nutritional intake affects wt, gain, but is not a primary consideration in the progress of MND, Behavioral deficits and neurotransmitter alteration s are probably directly caused by motoneuron losses. (C) 1999 Elsevier Scie nce Inc.