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Query: UNIPROT:Q9UIJ5 (Rec)
 58,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The physiology and behavior of viscacha vary along the year according to the modifications of environmental signals such as the photoperiod length, temperature, rainfall pattern, food composition, and social interactions. The pituitary pars distalis thyrotrophs (TSH cells) of male viscacha were immunohistochemically identified, and the morphometric parameters: percentage of immunopositive area (% IA), cell percentage in pars distalis (% PDC), number of cells per reference area (no. cells/RA), and major cellular and nuclear diameters were analyzed. Three different groups of adult male viscachas were used: (1) captured in their natural habitat during the year, (2) melatonin-administered, and (3) castrated. The thyrotrophs were localized in the ventromedial sector, mainly in the pars distalis cephalic extreme. They were oval or pyramidal in shape, and their immunostaining intensity was heterogeneous. The % IA, % PDC, and no. cells/RA exhibited a significant decrease in June-July (winter, gonadal regression period) in relation to February-March (summer-early autumn, reproductive period), and they were recovered in August-September (later winter-early spring, gonadal recovery period). No morphometric variations of TSH cells were observed in melatonin-treated animals, whereas a decrease of the % IA, % PDC, and no. cells/RA was observed in castrated animals in relation to the intact animals. Our results show TSH cell morphometric variations during the year in agreement with the animal's different physiological conditions during the reproductive cycle, and probably in response to the environmental signals changes. Melatonin does not have a direct effect on the TSH cells. However, castration modifies some thyrotroph morphometric parameters, reinforcing the hypothesis that androgens affect the cells activity.
Anat Rec (Hoboken) 2008 Apr
PMID:Immunohistochemical and morphometric study of pituitary pars distalis thyrotrophs of male viscacha (Lagostomus maximus maximus): seasonal variations and effect of melatonin and castration. 1828 16

Lactotrophs in pituitary pars distalis (PD) of viscacha were studied by immunohistochemistry and morphometric analysis in the following groups: 1) adult males throughout the reproductive cycle (reproductive, gonadal regression, and recovery periods), 2) melatonin-treated adults, 3) castrated adults, 4) prepubertal, 5) non-pregnant females, and 6) pregnant females (early, mid, and late pregnancy). Immunopositive percentage area (%IA), cell percentage in PD (% PDC), number of cells per reference area (no.cell/RA), major cellular and nuclear diameters were analyzed. Lactotrophs were mainly localized in the ventro-medial region and the caudal extreme of PD. In the male viscachas, they were isolated in small and big groups, close to blood vessels and near follicles. These cells were pleomorphic and with a heterogeneous cytoplasmic immunolabeling pattern. In the adult males of the gonadal regression period the morphometric parameters were the lowest. Most parameters of lactotrophs in the prepubertal were significantly lower than in the adult males in the reproductive period. In the melatonin-treated animals and in castrated animals there was a decrease in %IA, %PDC, and no.cell/RA. In the females, the morphometric parameters increased at the end of pregnancy. Non-pregnant females exhibited a higher immunopositive area and number, but a smaller size of cells than males. Our results showed that in the adult male viscacha, lactotrophs vary seasonally, probably due to the photoperiod effect through melatonin. Besides the changes observed after castration, in prepubertal animals, in adults of different sex, and during pregnancy suggest that the gonadal steroid hormones might modify the lactotrophs activity.
Anat Rec (Hoboken) 2010 Jan
PMID:Morphological and morphometric changes of pituitary lactotrophs of viscacha (Lagostomus maximus maximus) in relation to reproductive cycle, age, and sex. 2003 38