PubMed Health⌕ Search

Biomedical subjects

G E Bestetti

Publications and source records attributed to G E Bestetti.

40 records · Page 3Linked to original sources
PubMed1986

Varied effects of experimental diabetes on the autonomic nervous system of the rat.

Disorders of the autonomic nervous system are a frequent late complication of human diabetes. They have been extensively studied clinically, yet their pathologic aspects are still poorly understood. Also, reports on the autonomic nervous system in animal models for diabetes are scanty. Therefore we have investigated sympathetic preganglionic and postganglionic nerve fibers, vagal fibers, as well as sympathetic and enteric neurons of male Wistar rats 1 year after streptozotocin or vehicle injection. By light and electron microscopic morphology we observed: various degenerative changes in sympathetic neurons and in Schwann cells of the sympathetic fibers; intraaxonal glycogen deposits in all fiber types; and a large amount of lipoid material in intraganglionic and endoneural mesenchymal cells. By morphometry, the cytoplasmic area and perimeter as well as the cytoplasmic to nuclear ratio were significantly reduced in the sympathetic neurons of diabetic rats. Further we found axonal dwindling, enlarged myelin-axons space and an increased number of Schwann cell pi-granules in the sympathetic preganglionic fibers of diabetic animals. Axonal glycogenosomes were absent in the vagus of control and were present in that of diabetic rats. By stereology, the mitochondria and smooth endoplasmic reticulum were reduced in the sympathetic neurons of diabetic rats, whereas in the same animals the volume density of the Golgi complex was increased in the sympathetic neurons and decreased in the enteric neurons. In conclusion, relevant changes occur in the sympathetic preganglionic nerve fibers which suggest a causal relationship between fiber and neuronal lesions. Further, the stereologic findings imply decreased cellular activity and imbalance between cellular synthesis and secretion in the sympathetic neurons.

Animals↗
PubMedDate not supplied

Tuberoinfundibular dopaminergic neurons and lactotropes in young and old female rats.

Aging in female rats is accompanied by several endocrine dysfunctions, such as reproductive decline associated with characteristic hyperprolactinemia, lactotrope hyperplasia, and functional impairment of hypothalamic tuberoinfundibular dopaminergic (TIDA) neurons. The aim of this morphometrical, immunocytochemical, and densitometrical study was to gain a better anatomical knowledge of TIDA neurons and axons as well as of lactotropes in old female rats with (A) or without (NA) pituitary adenomas, compared with young animals. At the hypothalamic level, we found that tyrosine hydroxylase (TH)-labeled neurons in the arcuate nucleus were comparable in young and old NA yet their size and TH-content were increased in A animals. Also the TH-labeled median eminence axons did not differ significantly between young and old NA but were more numerous in the old A rats. Independently from adenomas, both number of prolactin (PRL)-labeled structures and content of immunoreactive PRL were increased in pituitaries of old rats, the plasma PRL levels, however, were high only in A. Our findings support the documented lactotrope hypertrophy and hyperplasia in old female rats and suggest that TIDA-neuron changes only occur in hyperprolactinemic animals carrier of adenomas.

Adenoma↗
PubMedDate not supplied

The changes in the hypothalamo-pituitary-gonadal axis of streptozotocin-treated male rats depend from age at diabetes onset.

The influence of age at diabetes onset and of capillary microangiopathy on the severity and evolution of hypothalamo-pituitary-gonadal changes was studied morphologically and morphometrically in male rats 4 and 8 months after streptozotocin injection. At each time period we studied 2 groups of rats, one made diabetic before (age 1 month), the other after puberty (age 3 months), and compared them with corresponding controls. The size of hypothalamic axons, numerical density and size of pituitary gonadotrophs, size of testicular tubules, and basement membrane thickness of retinal capillaries were measured. Major differences were found at 8 months. Changes of pituitary glands (i.e. small and numerous gonadotrophs) and testes (i.e. small tubular size) were more important in pre- than in postpubertal diabetic rats. This was a consequence of the aggravating prepubertal diabetes between 4 and 8 months. On the contrary, these changes partially regressed in postpubertal diabetic animals. Pituitary and testicular changes were correlated. Other lesions, such as swollen axonal processes in the hypothalamus, increased thickness of seminiferous epithelium and of capillary basement membranes, though very evident in diabetics, were independent from age at induction. Neither microangiopathy nor glycemia were correlated with any other change which confirmed their secondary role in diabetic neuroendocrine disorders. Thus, two types of diabetic disorders of the hypothalamo-pituitary-gonadal axis could be distinguished: 1) those with irreversible effects on immature yet partially reversible effects on mature structures; and 2) those independent from age at induction.

Animals↗