Sex-specific effects of met-enkephalin treatment on vasopressin immunoreactivity in the rat supraoptic nucleus.
The supraoptic nucleus of male and female rats treated with met-enkephalin or naloxone and met-enkephalin was examined with light microscopical immunocytochemistry for Arginine-vasopressin. Both genders exhibited the same distribution of immunostained magnocellular neurons. Met-enkephalin treatment caused an increase in number of immunostained vasopressin neurons. This effect was more pronounced in females than in males. Naloxone treatment diminished immunoreactive cytoplasmic vasopressin in males more effectively than in females. In enkephalin-treated animals numerous vasopressin immunoreactive varicosities appeared within the supraoptic nucleus, but were mostly absent in naloxone-treated animals and in controls. Our results indicate that met-enkephalin treatment either stimulates vasopressin synthesis or inhibits secretion. It is likely that steroid hormones mediate the action of enkephalin on vasopressin secretion in a specific manner.
Blanco
E
E
Departmento de Ciencias Morfològicas, Biologìa Celular y Anatomìa Patològica (Anatomìa Humana). Facultad de Medicina, Universidad de Salamanca, Spain.
Carretero
J
J
Sànchez
F
F
Riesco
J M
JM
Vàzquez
R
R
D000818:Animals; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D005260:Female; D007124:Immunoenzyme Techniques; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013194:Staining and Labeling; D013495:Supraoptic Nucleus / Q000166:cytology / Q000187:drug effects*; D014667:Vasopressins / Q000032:analysis* / Q000276:immunology
D014667:Vasopressins; D009270:Naloxone; D004744:Enkephalin, Methionine