Dendritic Alterations of Cortical Pyramidal Neurons in Postnatally Lead-Exposed Kittens: A Golgi-Cox Study

Abstract

Cortical pyramidal cell development was studied in postnatally lead-exposed kittens by light microscopic and Golgi staining methods. The most evident finding was an elevation of spine density on the distal apical dendritic branches of lead-treated kittens. Also, the branching pattern of the apical dendrites in lead-treated animals was different from control, but there was no overall change in total branch number of the dendritic arbor. Pyramidal cell height and cortical thickness were unaffected. No evidence of vascular damage or other pathologies were found in hematoxylin and eosin-stained sections. The results are discussed with reference to dendritic spine development and function and to other reports of hyperspiny dendrites. Evidence of hyperspiny dendrites in the present study indicates this represents a useful protocol for investigating dendritic spine development and differentiation.

Dendritic Alterations of Cerebellar Purkinje Neurons in Postnatally Lead-Exposed Kittens

“…As previously reported the blood lead value of these kittens at 1 week was 0.300 Ìg/100 ml and rose to 1.2 Ìg/100 ml at 5 weeks of age, well within the low to moderate range [25]. Direct comparison of lead exposure in 1-day-old animals with 35-day-old animals requires care given the developmental changes taking place.…”

“…In contrast, data on lead-treated kittens in this study show increased dendritic spine density and altered branching patterns in Purkinje cells. Similar increases in spine density and modified dendritic branching patterns have been reported in cerebral cortical pyramidal cells of lead-exposed kittens [25]. Lead thus appears to affect large neurons having spiny branchlets with substantial postnatal growth patterns.…”

“…The afferent input determines the morphology of the spine head [44], stabilizes the spine against elimination [45] and may also prevent spine formation [46]. A detailed discussion of dendritic spine development and related reports of hyperspiny dendritic formation have previously been reviewed [25]. The hyperspiny condition occurs in several neuronal populations following many different protocols [47][48][49][50][51][52][53][54][55].…”

“…Hemoglobin and hematocrit were also measured. The details of the spectroscopic analysis and blood lead values for the above cohort have previously been reported [25].…”

“…Subsequent studies of lead toxicity in rodents have shown decreases in brain and body weight, reduction of cerebral cortical and hippocampal thickness in addition to decreases in dendritic arbors, synaptic profiles and spine density without concomitant hemorrhage development [15][16][17][18][19][20][21][22][23][24]. In contrast, cerebral cortical pyramidal cell dendritic spine density increased in lead-treated kittens and dendritic branching patterns were altered without reduction in total dendritic elaboration [25].…”