Altered sympathetic-salivary gland development: delayed response to postnatal castration

Area of Science:

• Neuroendocrinology
• Developmental Biology
• Biochemistry

Background:

• Tyrosine hydroxylase (T-OH) is key in catecholamine synthesis.
• Choline acetyltransferase (CAT) is involved in neurotransmission.
• Hormonal influences on enzyme development are not fully understood.

Purpose of the Study:

• To investigate the role of testosterone in the development of T-OH and CAT activity in male rat superior cervical ganglion (SCG).
• To examine the impact of postnatal castration and testosterone replacement on these enzymes and salivary gland weight.

Main Methods:

• Measurement of T-OH and CAT activity in the SCG of male rats at various time points post-castration.
• Monitoring of submandibular salivary gland weight.
• Hormonal manipulation through castration and testosterone replacement.

Main Results:

• T-OH activity showed two developmental plateaus, with a significant drop in castrated rats post-puberty.
• CAT activity exhibited a single plateau and was unaffected by castration.
• Castration impaired submandibular gland growth, mirroring the effect on T-OH activity.

Conclusions:

• Testosterone significantly influences the development of T-OH activity in the postpubertal male rat SCG, likely through an indirect mechanism.
• The ontogeny of presynaptic CAT activity appears independent of testosterone levels.
• These findings highlight the differential hormonal regulation of neurotransmitter systems during development.