Sublethal lead affects pituitary function of rainbow trout during exogenous vitellogenesis

Area of Science:

• Environmental Toxicology
• Fish Reproduction
• Endocrinology

Background:

• Vitellogenesis is crucial for oocyte development in female fish.
• Lead exposure can disrupt endocrine functions and reproductive health in aquatic organisms.
• Understanding lead's impact on fish reproduction is vital for environmental risk assessment.

Purpose of the Study:

• To investigate the effects of waterborne lead on vitellogenesis in female rainbow trout (Oncorhynchus mykiss).
• To determine if lead exposure during different stages of vitellogenesis impacts gonadosomatic indices (GSI) and oocyte growth.
• To correlate lead-induced reproductive changes with pituitary basophil activity.

Main Methods:

• Female rainbow trout were exposed to 10 microg/L lead nitrate during endogenous and exogenous vitellogenesis.
• Gonadosomatic indices and oocyte diameters were measured.
• Lead levels in liver, ovaries, and blood were analyzed using atomic absorption spectroscopy.
• Pituitary basophils were analyzed and compared with reproductive parameters.

Main Results:

• Lead exposure during exogenous vitellogenesis significantly reduced GSI and oocyte growth.
• Lead accumulated in blood but not in liver or ovaries.
• Pituitary basophil populations increased in control fish during exogenous vitellogenesis but not in lead-exposed fish.
• No significant effects were observed during endogenous vitellogenesis.

Conclusions:

• Lead exposure during exogenous vitellogenesis impairs reproductive parameters in rainbow trout.
• The disruption is associated with altered pituitary basophil function, affecting gonadotropin (GtH) production.
• Lead's impact on fish reproduction is stage-dependent, with exogenous vitellogenesis being more sensitive.