Anatomical localization of immunoreactive oxytocin and beta-endorphin in the bovine neurointermediate lobe

BACKGROUND

Beta-endorphin and oxytocin immunocytochemical localization were examined in the neurointermediate lobe (lobus nervosus and pars intermedia) of the bovine hypophysis in order to describe the anatomical distribution of these two neurointermediate lobe hormones.

METHODS

Twenty-seven bovine hypophyses were collected from slaughterhouse animals (seven mature lactating cows, eleven mature nonlactating cows, three nulliparous heifers, and six steers). Hypophyses were immunostained for oxytocin-containing fibers and beta-endorphin-secreting cells by using the avidin biotin-immunoperoxidase method. The distributions of beta-endorphin-positive cells and oxytocin-positive nerve fibers were plotted on projected outlines of the hypophyses. Immunoreactive staining intensity was graded numerically as weak, moderate, or heavy by three individuals who had no knowledge of the animals' physiological status.

RESULTS

Oxytocin immunoreactivity was confined to the lobus nervosus while beta-endorphin staining was confined to the pars intermedia and the pars distalis. However, oxytocin immunopositive neurosecretory terminals were distributed more heavily in that part of the lobus nervosus bordering the pars intermedia than in the center of the lobe.

CONCLUSIONS

These results were similar to those previously reported for the rat (Swaab et al., 1975; J. Neural Transm., 36:195-215; Deftos and Catherwood, 1980; Life Sci., 27:223-228).

Interaction of dimethylsulfoxide and arachidonic acid with the teratogenic effects of caffeine in mice

Dose-response of the teratogenic effect of caffeine (CA) and the potential role of facial hematomas in the pathogenesis of caffeine-induced cleft palate were investigated using CD1 mice treated with 150, 200, or 250 mg CA/kg i.p. on gestational day (GD) 12. Dimethylsulfoxide (DMSO; 20%) and arachidonic acid (AA, 200 mg/kg) were administered along with CA (200 mg/kg) to study their interaction with CA-induced teratogenesis and elevation in maternal glucocorticoids (MGC, measured by RIA) on GD 13 and 14. Dose-dependent increase in the incidence of cleft palate (CP) was noted in CA-exposed mice. High maternal deaths, an increased number of resorptions, gross facial hematomas (GFH), and club foot (CF) were produced only by the highest (250 mg/kg) dose of CA. Palates from all offspring with GFH were clefted at this dose level. None of the control or CA-treated nonclefted offspring had GFH or microscopic hematomas (MH). At 200 mg/kg of CA, DMSO in combination with CA actually increased CA-induced CP from 30% to 100% and also produced 100% GFH as compared to 0% by CA alone at this dose. Greater than 50% of clefted offspring without GFH, given either dose (200 or 250 mg/kg) of CA, had MH. Very high levels of MGC were present in CA-treated mice on GD 13 and 14. Although simultaneous administration of DMSO reduced the magnitude of CA-induced MGC elevations on GD 14, the MGC levels remained high for greater than 24 hours following CA exposure. Increase in maternal mortality and fetal resorptions, a decrease in the number of live pups and their body weights, and no change in the incidence of CP were seen when CA-treated mice were simultaneously exposed to AA. These results suggest a correlation between caffeine-induced FH and CP; a role for increased hematomagenic effects of DMSO in its potentiation of the cleft-palatogenic effect of caffeine; and absence of a role for AA-mediated effects of MGC in the causation of CA-induced CP and other malformations.