RADIATION INDUCED "HYPOPHYSECTOMY" AND HYPOTHALAMIC LESIONS IN LACTATING GOATS.

Abstract

AbstractRadiolesions were produced in the pituitary gland and/or median eminence‐pituitary stalk region of seven lactating goats by use of a narrow, collimated beam of 185 MeV protons from a synchrocyclotron. Radiation doses of 25 to 30 krad were restricted to these structures by rotation of the goats' heads around the vertical and horizontal axes of the planned lesion. Ten to 15 days after pituitary irradiation in four goats, milk production declined steeply over a ten‐day period to about 20 per cent pre‐lesion levels. In two of the“hypo‐physectdmized” animals with injury also in the median eminence, diabetes insipidus developed concurrently with the onset of lactation block. Daily replacement with prolactin (luteotrophin), somatotro‐phin, ACTH, triiodothyronine, and insulin had restored milk synthesis to 60 per cent of pre‐radiation levels when destruction of trigeminal nerve trunks by continued lateral spread of radiolesions caused an abrupt decline in the health of the goats.In 3 lactating goats, irradiation of the median eminence/pituitary stalk region was followed after 25 to 30 days by (1) disappearance of the milk ejection reflex, (2) onset of diabetes insipidus characterized by absence of the normal interphase, (3) decline in milk production to 30 to 40 per cent of pre‐lesion levels, and (4) in one of them, marked loss of hair. That median eminence lesions blocked lactation secondary to pituitary insufficiency of ACTH, TSH, and STH, but not of prolactin or of oxytocin was suggested by the ability of varied therapeutic regimens to restore lactation.